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BACKGROUND: Widespread resistance of insect pests to insecticides and transgenic crops in the field is a significant challenge for sustainable agriculture, and calls for the development of novel alternative strategies to control insect pests. One potential resource for the discovery of novel insecticidal molecules is natural toxins, particularly those derived from the venoms of insect predators. RESULTS: In this study, we identified three insecticidal proteinaceous toxins from the venom glands (VGs) of the predatory stink bug, Arma custos (Hemiptera: Asopinae). Transcriptomic analysis of A. custos VGs revealed 151 potentially secreted VG‐rich venom proteins. Three VG‐rich venom proteins (designated AcVP1 ~ 3) were produced by overexpression in Escherichia coli. Injection of the recombinant proteins into tobacco cutworm (Spodoptera litura) larvae showed that all of the three recombinant proteins caused paralysis, liquefaction and death. Injection of recombinant proteins into rice brown planthopper (Nilaparvata lugens) nymphs showed higher insecticidal activities, among which a trypsin (AcVP2) caused 100% mortality postinjection at 1.27 pmol mg−1 body weight. CONCLUSION: A natural toolkit for the discovery of insecticidal toxins from predatory insects has been revealed by the present study. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Mixed cropping with legumes may mitigate negative impacts of maize, Zea mays L. (Poaceae), production on arthropods by providing additional habitat structures and food resources. Still, knowledge about effects of less common legume partner crops for mixed cropping of maize is scarce. Activity density of epigeic predatory arthropods and proxies for ecosystem functions related to biological pest control were assessed on an experimental field. Plots of mixed cropping of maize and sainfoin, Onobrychis viciifolia Scop. (Fabaceae), and respective single plant species (plot size: 6 × 5 m; n = 48) differed in combination of the seed rate of each partner crop and tillage treatment. Using the "rapid ecosystem function assessment" approach in each plot on three occasions, we tested whether the activity density of generalist arthropod predators and their associated ecosystem functions can be promoted by mixed cropping of maize with sainfoin. Our data show that, compared with tilled maize as a pure culture, mixed cropping can increase activity density of generalist arthropod predators and insect predation potential but effects were limited to strip‐tilled cropping systems and partly depended on sampling date. Thus, from an ecological viewpoint, mixed cropping of sainfoin and maize in strip‐till systems offers the possibility to promote predatory insects and their potential for pest regulation. However, this system is inherently more prone to weed occurrence. Competition effects between cropping partners and weeds may reduce yields and hence lead to trade‐offs between enhancement of arthropods and economic viability. [ABSTRACT FROM AUTHOR]

The use of pathogens and other natural enemies to suppress pest populations is a key component of integrated pest management (IPM) strategies. As biocontrol agents may interact synergistically, additively, or antagonistically, it is crucial to assess their interactions for effective pest management. In this study, we investigated the effect of three entomopathogenic fungus (EPF) species—Beauveria bassiana (Bals.‐Criv.) Vuill. CEP 091, Akanthomyces muscarius (Petch) Spatafora, Kepler & B. Shrestha CEP 182, and Cordyceps fumosorosea (Wize) Kepler, B. Shrestha & Spatafora CEP 315 (all Hypocreales)—on the survival, fecundity, and searching behavior of Orius insidiosus (Say) (Hemiptera: Anthocoridae). All three EPF species were found to be pathogenic to O. insidiosus, resulting in a significant decrease in survival compared with the control group. Fecundity remained unaffected by the fungal treatments. No effect of EPF on searching behavior of the predator was found. In relation to the searching behavior, individuals of 2 days post‐infections remained in the food patch longer than individuals of 7 days post‐infections, regardless of treatment. These findings provide valuable insights into the compatibility of EPF and O. insidiosus as combined biocontrol agents for managing whiteflies, aphids, and thrips. Understanding the interactions between EPF and predatory insects is crucial for developing IPM strategies that maximize pest control efficacy. Further studies should explore the long‐term effects of EPF on O. insidiosus populations and their overall impact on pest management in agricultural systems. [ABSTRACT FROM AUTHOR]

Spatial and temporal distribution of food resources influences predatory insects' foraging and dispersal behavior. Orius insidiosus (Say) (Hemiptera: Anthocoridae) is a good biological control agent of western flower thrips (WFT), Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), in the strawberry crop and consumes two‐spotted spider mite (TSSM), Tetranychus urticae Koch (Acari: Tetranychidae), and pollen as well. Augmentative biological control programs may fail if, following release, predators disperse from the crop. We studied the dispersal of O. insidiosus as a function of pollen availability, density of their main prey WFT, and the presence of the alternative prey TSSM, within and between strawberry plants. We found that O. insidiosus remained on the flowers during the 24 h of the assay. The dispersal of predators to a neighboring flower with thrips was approximately six times greater from a flower without pollen than from a flower with pollen. When TSSM was the only prey available, O. insidiosus colonized the leaves, and its dispersal within the plant was greater. At the plot scale, the predator dispersal from the release plant to other plants also depended on the presence of flowering plants and prey. Our results highlight the importance of flowering plants and pollen availability in enhancing the persistence of O. insidiosus in strawberry plants. Releases of this predator in the strawberry crop should be after the beginning of flowering, even at low WFT densities. [ABSTRACT FROM AUTHOR]

Herbivorous insects generally choose host plants that optimize their growth. However, many specialists choose chemically defended host plants that slow their growth, prioritizing protection from natural enemies.Invasive specialist herbivores may have an added advantage in their non‐native range where they lack co‐evolved specialist natural enemies, in addition to being unpalatable to generalist predators.Here, we explore the diet preferences of the invasive yellowmargined leaf beetle, Microtheca ochroloma and those of native natural enemies. We measured M. ochroloma preferences among six Brassica cultivars varying in glucosinolate concentrations.In both field and laboratory experiments, M. ochroloma preferred the relatively less defended host plants, mizuna and Chinese cabbage. M. ochroloma grew quickest on mizuna.Generalist predators also preferred to eat M. ochroloma larvae that had been fed mizuna in choice trials, yet in the field, predatory insects were least commonly found on mizuna, and most commonly found on plants dominated by native herbivores.M. ochroloma consumes plants that increase their susceptibility to predators, but predation pressure in the field appears to be generally low. Our results suggest that invasive specialist herbivores may prioritize growth over protection against natural enemies.Weak top‐down regulation of specialist herbivore invaders might enable them to exploit less‐defended host plants in their novel range that facilitate faster growth and exacerbate crop damage. Invasive pests may be more effectively managed by leveraging plant preferences in the novel host range in trap crop systems. [ABSTRACT FROM AUTHOR]

Mantodea (praying mantises) is a group of exclusively predatory insects, which, together with nonraptorial blattodeans (cockroaches and termites) and groups exclusively found in the fossil record, form the group Dictyoptera. A central characteristic of Mantodea is the specialization of their first pair of legs as raptorial grasping appendages, but the evolution from walking to raptorial legs is not yet fully understood. Here, we trace the evolution of the raptorial appendages in Dictyoptera through time using a morphometric (morphospaces) approach. We also describe two new mantodean nymphs preserved in amber from the Cretaceous and Eocene, which expand the scarce mantodean fossil record. Blattodean and mantodean appendages appear distinct in morphospace, but several appendages of fossil non‐mantodeans can be considered raptorial, providing a potential transitional link between walking and raptorial morphotypes. Therefore, we discuss potential mantodean affinities for other predatory fossil dictyopterans. We examine changes across extant mantodeans, characterized by a straightening of the tibia especially associated with the rise of the diversification of the Mantidea and discuss whether a thickening of the femur could reflect an early adaptation to cursorial hunting. [ABSTRACT FROM AUTHOR]

Multitrophic interactions are common in nature and play a major role in modulating life‐history traits in predatory insects. The sequestration of chemicals and the transfer of nutrients from one trophic level to a higher trophic level have been reported previously. However, the effect of cannibalism, which is prevalent in the food chain, has not been explored yet. In this study, we hypothesised that the varying nutritional condition of the victim would significantly influence the life‐history traits of adult Menochilus sexmaculatus Fabricius (Coleoptera: Coccinellidae). To test this hypothesis, we provided fourth‐instar individuals with first‐instar victims of varying nutritional quality for cannibalism. To create victims of varying nutritional quality, first‐instar victims were fed on high‐quality aphids [Aphis craccivora Koch (Hemiptera: Aphididae)], low‐quality aphids (Aphis nerii Boyer de Fonscolombe) and conspecific eggs. The cannibalistic groups were tested against the control group, in which the fourth instars were provided with their natural prey, A. craccivora. Our results revealed a significant difference in the consumption of prey by the fourth instars between the diet groups, with the control group consuming the most prey. The developmental duration of fourth instars was not significantly influenced by the victims' diet or the amount of victims cannibalised. Furthermore, neither the victims' diet nor the amount of victims cannibalised affected the mating (time to commence mating and copulation duration) and reproductive parameters (egg viability and fecundity) in M. sexmaculatus. Cannibalism here might have compensated for the low‐quality victims, resulting in insignificant effects on the life‐history traits of M. sexmaculatus. Otherwise, given the short duration of the first instars and their potentially limited ability to sequester significant amounts of plant allelochemicals, it is possible that their diet did not affect the development, mating and reproductive attributes of the cannibals. Thus, the use of higher instars as victims may yield substantially different outcomes. [ABSTRACT FROM AUTHOR]

Insects play a crucial role in all ecosystems, and are increasingly exposed to higher in temperature extremes under climate change, which can have substantial effects on their abundances. However, the effects of temperature on changes in abundances or population fitness are filtered through differential responses of life‐history components, such as survival, reproduction, and development, to their environment. Such differential responses, or trade‐offs, have been widely studied in birds and mammals, but comparative studies on insects are largely lacking, limiting our understanding of key mechanisms that may buffer or exacerbate climate‐change effects across insect species. Here, we performed a systematic literature review of the ecological studies of lacewings (Neuroptera), predatory insects that play a crucial role in ecosystem pest regulation, to investigate the impact of temperature on life cycle dynamics across species. We found quantitative information, linking stage‐specific survival, development, and reproduction to temperature variation, for 62 species from 39 locations. We then performed a metanalysis calculating sensitives to temperature across life‐history processes for all publications. We found that developmental times consistently decreased with temperature for all species. Survival and reproduction however showed a weaker response to temperature, and temperature sensitivities varied substantially among species. After controlling for the effect of temperature on life‐history processes, the latter covaried consistently across two main axes of variation related to instar and pupae development, suggesting the presence of life‐history trade‐offs. Our work provides new information that can help generalize life‐history responses of insects to temperature, which can then expand comparative demographic and climate‐change research. We also discuss important remaining knowledge gaps, such as a better assessment of adult survival and diapause. [ABSTRACT FROM AUTHOR]

Ongoing habitat loss and fragmentation caused by human activities represent one of the greatest causes of biodiversity loss. However, the effects of habitat loss and fragmentation are not felt equally among species. Here, we examined how habitat loss influenced the diversity and abundance of species from different trophic levels, with different traits, by taking advantage of an inadvertent experiment that created habitat islands from a once continuous forest via the creation of the Thousand Island Lake, a large reservoir in China. On 28 of these islands with more than a 9000‐fold difference in their area (0.12–1154 ha), we sampled plants, herbivorous insects, and predatory insects using effort‐controlled sampling and analyses. This allowed us to discern whether any observed differences in species diversity were due to passive sampling alone or to demographic effects that disproportionately influenced some species relative to others. We found that while most metrics of sampling effort‐controlled diversity increased with island area, the strength of the effect was exacerbated for species in higher trophic levels. When we more explicitly examined differences in species composition among islands, we found that the pairwise difference in species composition among islands was dominated by species turnover but that nestedness increased with differences in island area, indicating that some species are more likely to be absent from smaller islands. Furthermore, by examining trends of several dispersal‐related traits of species, we found that species with lower dispersal propensity tended to be those that were lost from smaller islands, which was observed for herbivorous and predatory insects. Our results emphasize the importance of incorporating within‐patch demographic effects, as well as the taxa and traits of species when understanding the influence of habitat loss on biodiversity. [ABSTRACT FROM AUTHOR]

Plant diversity aboveground can exert top‐down pressure on herbivores by attracting predatory insects, while organic soil amendments rich in beneficial microbes can limit herbivores from the bottom‐up by enhancing plant defensive chemistry. Aboveground and belowground forces always operate simultaneously to shape herbivore pressure, but understanding how they interact is a longstanding and persistent challenge.Here, we examine how organic composts mediate the effects of plant diversity across trophic levels, using zucchini plants (Cucurbita pepo) as a study system. Over two field seasons, we manipulated vermicompost treatments in 18 experiments in school gardens that varied in surrounding plant and floral resource diversity and measured responses of insect herbivores and their natural enemies.Vermicompost strengthened a positive relationship between flower richness and foliar‐feeding omnivores, suggesting that robust reservoirs of omnivores at flower‐rich sites mounted stronger responses to compost‐treated host plants.Predators increased with flower richness, but were not affected by vermicompost.Net outcomes of vermicompost and plant diversity were neutral for herbivores.Synthesis and applications. Altogether, our results reveal that bottom‐up factors protecting plants are modified by their environmental context, and may more effectively attract natural enemies in landscapes with diverse floral resources. Therefore, we recommend augmentation of biodiversity aboveground (i.e. floral resources) together with biodiversity belowground (organic soil amendments) to strengthen crop protection. [ABSTRACT FROM AUTHOR]

Mantodea is a predatory insect group, its members occupying a diverse array of widely distributed habitats. Praying mantis species utilize hunting strategies including remarkable mimicry and unique camouflage for hiding from natural enemies while catching their prey. The emergence of a "cyclopean ear" in mantises is thought to be a morphological innovation of the group, and an "arms race" with echolocating bats is one of the hypotheses put forward to account for the emergence of the mantis ear from a coevolutionary perspective. However, this hypothesis has not been rigorously tested because of a lack of robust higher‐level phylogeny and a detailed chronogram of Mantodea. Previous phylogenetic studies found an incongruence between traditional classification and molecular phylogenetics due to the convergent evolution of various ecomorphic strategies of the lineage. Here, we performed a comprehensive phylogenetic analysis of Mantodea based on data from 61 mitogenomes. Our analyses showed that the monophyly of Acanthopidae, Haaniidae, Nanomantidae, Miomantidae and Mantidea was supported. The newly updated Gonypetidae were paraphyletic, whereas Eremiaphilidae, Deroplatyidae and Toxoderidae were polyphyletic. Our molecular dating analyses inferred that Spinomantodea originated at ca. 149 Ma (Late Jurassic), whereas the origin of hearing mantises (Cernomantodea) was inferred as Early Cretaceous (119 Ma, 95% CI: 110–129 Ma). The molecular dating results indicated that the hearing organ in mantises did not arise in response to bat predation. Our study provides a robust framework for further evolutionary comparative studies of mantises. [ABSTRACT FROM AUTHOR]

Abiotic factors strongly influence ecological interactions and the spatial distribution of organisms. Despite the essential role of barometric pressure, its influence on insect behaviour remains poorly understood, particularly in predators. The effect of barometric pressure variation can significantly impact biological control programs involving entomophagous insects, as they must efficiently allocate time and energy to search for prey in challenging environments. We investigated how predatory insects from different taxonomic groups (Coleoptera, Dermaptera and Neuroptera) adapt their foraging behaviour in response to variations in barometric pressure (low, medium and high). We also examined the response of different life stages to changes in pressure regimes during foraging activities. Our results showed that the searching time of Doru luteipes (Dermaptera: Forficulidae) was faster in a favourable high‐pressure regime, whereas Chrysoperla externa (Neuroptera: Chrysopidae) and Eriopis connexa (Coleoptera: Coccinellidae) had similar searching times under varying pressure regimes. Although no differences in prey feeding time were observed among the studied species, the consumption rate was influenced by low barometric pressure leading to a decrease in the number of preyed eggs. Moreover, we provide novel insights into how hemimetabolous (D. luteipes) and holometabolous (E. connexa) species at different life stages respond to barometric pressure. Doru luteipes nymphs and adults had similar consumption rates across all pressure regimes tested, whereas E. connexa larvae consumed fewer eggs under low barometric pressure, but adults were unaffected. This highlights the importance of investigating how abiotic factors affect insects foraging efficiency and predator–prey interactions. Such studies are especially relevant in the current context of climate change, as even subtle changes in abiotic factors can have strong effects on insect behaviour. Barometric pressure is a key meteorological variable that serve as a warning signal for insects to seek shelter and avoid exposure to weather events that could potentially increase their mortality. Understanding the effects of barometric pressure on predatory insects' behaviour can help us develop more effective pest management strategies and promote the resilience of agroecosystems. We provide new insights into the complex relationship between barometric pressure and predator–prey interactions. [ABSTRACT FROM AUTHOR]

Summary: RNA interference (RNAi)‐based technologies are starting to be commercialized as a new approach for agricultural pest control. Horizontally transferred genes (HTGs), which have been transferred into insect genomes from viruses, bacteria, fungi or plants, are attractive targets for RNAi‐mediated pest control. HTGs are often unique to a specific insect family or even genus, making it unlikely that RNAi constructs targeting such genes will have negative effects on ladybugs, lacewings and other beneficial predatory insect species. In this study, we sequenced the genome of a red, tobacco‐adapted isolate of Myzus persicae (green peach aphid) and bioinformatically identified 30 HTGs. We then used plant‐mediated virus‐induced gene silencing (VIGS) to show that several HTGs of bacterial and plant origin are important for aphid growth and/or survival. Silencing the expression of fungal‐origin HTGs did not affect aphid survivorship but decreased aphid reproduction. Importantly, although there was uptake of plant‐expressed RNA by Coccinella septempunctata (seven‐spotted ladybugs) via the aphids that they consumed, we did not observe negative effects on ladybugs from aphid‐targeted VIGS constructs. To demonstrate that this approach is more broadly applicable, we also targeted five Bemisia tabaci (whitefly) HTGs using VIGS and demonstrated that knockdown of some of these genes affected whitefly survival. As functional HTGs have been identified in the genomes of numerous pest species, we propose that these HTGs should be explored further as efficient and safe targets for control of insect pests using plant‐mediated RNA interference. [ABSTRACT FROM AUTHOR]

Praying mantids (class Insecta, order Mantodea) are a group of predatory insects comprising approximately 2500 described species, that occur across all continents except Antarctica, with the greatest species diversity in tropical and subtropical regions. Mantids predominantly prey on other invertebrates but are known to feed on small vertebrates. During April and May 2021, we observed mantid feeding events in Manujan County, Kerman Province in southern Iran. Two distinct feeding events were observed where female European Mantids (Mantis religiosa) preyed on Purple Sunbird (Cinnyris asiaticus) and Crested Lark (Galerida cristata) nestlings. In addition, we collated information from online searches of mantids feeding on nestlings elsewhere in the world, revealing two more observations. In Taiwan, a Giant Asian Mantid (Hierodula patellifera) was recorded preying on a nestling Warbling White‐eye (Zosterops japonicus) and in Brazil, a mantid (Stagmatoptera sp.) was recorded feeding on a nestling White‐throated Seedeater (Sporophila albogularis). To date, the only existing scientific evidence of praying mantids feeding on passerine nestlings was recorded in 1922. We propose two potential explanations for the observed trophic interactions between mantids and passerine nestlings: (1) during egg production female mantids, especially those in poor physical condition, may opportunistically feed on nestlings in order to increase fecundity via nutrient gain and (2) mantids may initially be attracted toward the nest by parasitic or coprophagous insects, as a result of poor nest sanitation, and subsequently prey on nestlings after detecting movements. Our unusual observations represent the first records of praying mantids feeding on nestling passerines in nearly 100 years. [ABSTRACT FROM AUTHOR]

Creeping water bugs (Naucoridae) are predatory aquatic insects widely distributed in the Neotropical region. This study describes the structure of the male reproductive tract in two species, Limnocoris porphyros Nieser & Lopez Ruf, 2001 (Limnocorinae) and Pelocoris subflavus Montandon, 1898 (Naucorinae), under light microscopy. Both in L. porphyros and P. subflavus, the reproductive tract of sexually mature males consists of a pair of testes, efferent ducts, deferent ducts, seminal vesicles, two pairs of accessory glands, and an ejaculatory duct. Each testis has seven follicles. Deferent ducts were long with a dilation forming the seminal vesicle. Post‐vesicular deferent ducts were long, coiled, and contained spermatozoa. Characters derived from anatomy and histology of the male reproductive tract in the two species, expand the knowledge on reproductive biology and provide new data that can enhance behavioural research and contribute to understand the evolutionary history of aquatic Heteroptera. [ABSTRACT FROM AUTHOR]

Quantifying functional responses is a cornerstone in evaluating the predation efficiency of biological control agents such as predatory insects and mites. In this study, we investigate whether the efficiency of Neoseiulus californicus (Acari: Phytoseiidae) in consuming prey is driven by intraspecific interactions. For this purpose, laboratory functional response experiments were conducted using one, two, three or four predators at several initial egg densities of the two‐spotted spider mite, Tetranychus urticae (Acari: Tetranychidae).The data fitted to the predator‐dependent Crowley–Martin model which accounts for intraspecific interactions. The results suggest that at high prey densities, i.e. the densities at which the predator is satiated, intraspecific interactions did not affect the predation potential of N. californicus, as the maximum number of T. urticae eggs that can be attacked by predator individuals did not differ between treatments (i.e., predator densities).However, at low prey densities and the highest predator density (i.e., four individuals), intraspecific interactions were detected, as revealed by the estimated attack rates, i.e. the per capita prey consumption at low prey densities. While mean attack rates did not differ significantly when one, two and three predators were exposed to prey, when predator density increased to four individuals, attack rate was considerable lower compared to the other predator densities.These results indicate that intraspecific interactions are more intense at low prey densities, where the predator is not satiated and therefore digestion breaks do not exist. In contrast, at high prey densities digestion breaks exist, so that may fully accommodate the cost of intraspecific interactions. These results also suggest that predator density should be considered when functional responses are measured. [ABSTRACT FROM AUTHOR]

Lithosiini (Lepidoptera: Erebidae: Arctiinae) is distinctive in having some species that feed on lichens, whereas the majority of moths feed on vascular plants. However, the larval diet of most Lithosiini species is poorly known. This study examines whether Lithosiini species, collected in a tropical rainforest of Borneo (nine species) and a temperate forest of Japan (eight species), feed on lichens as larvae, based on stable isotope analyses. As a result, the δ15N values for eight of nine Lithosiini species collected from Borneo were notably lower than those of nine co‐occurring herbivorous non‐Lithosiini species, and were similar to those of sympatric, lichen‐feeding termites; however, δ13C and δ15N values of one Lithosiini species (Adites sp.) were significantly higher than those of the other moth species and similar to those of humus‐feeding termites and predatory insects occurring at the same site. These results have suggested that the Lithosiini in the Southeast Asian tropical rainforests contain some species that feed on lichens as their larval main diet and at least one species whose larvae feed on humus or animal‐derived materials. In contrast, the δ13C and δ15N values of all examined Lithosiini species (eight species) in the temperate forest have suggested that their larvae fed on plants and not on lichens. Our stable isotope ratio analysis presented quantitative evidence suggesting lichen‐feeding by Lithosiini moths in a tropical rainforest without observation of feeding behavior during the larval stages. [ABSTRACT FROM AUTHOR]

To understand trophic interactions and the precise ecological role of each predatory species, it is important to know which arthropod and plant resources are used by generalist predators in agroecosystems. Molecular approaches, such as the use of high‐throughput sequencing (HTS), play a key role in identifying these resources. This study develops a multiprimer metabarcoding approach for screening the most common trophic interactions of two predatory arthropods with contrasting morphologies, Rhagonycha fulva (Coleoptera: Cantharidae) and Anthocoris nemoralis (Hemiptera: Anthocoridae) collected from a peach crop. To reduce the time and cost of this metabarcoding approach, we first evaluated the effect of using two different predator‐pools of different size (10 and 23 individuals of the same species). We also used our system to analyze the performance of one and two primer pairs in the same library. Our results show that the analysis of 23 individuals together with the use of two primer pairs in the same library optimize the HTS analysis. Using these best‐performing conditions, we then analyzed the entire bodies of field‐collected predators as well as the washing solutions used to clean the insect bodies. We were able to identify both gut content (i.e., diet) and external pollen load (i.e., on the insects' bodies). This study also demonstrates the importance of washing predatory insects' bodies prior to HTS analysis when the target species have a considerable size (>10 mm) and hairy structures. This metabarcoding approach has significant potential for the study of trophic links in agriculture, revealing expected and unexpected trophic relationships. [ABSTRACT FROM AUTHOR]

Stream intermittency is predicted to increase where water withdrawals and climate warming are increasing. In regions coupled with high fish diversity, understanding how intermittency influences fish trophic ecology is critical for informing ecosystem function. This study compared fish diets across seasons in perennial and intermittent streams to estimate the immediate and cumulative effects of stream drying on fish foraging patterns. We used gut content analysis to compare the diets of small‐bodied, secondary consumer fishes, including two minnow and three darter species found in the lower Flint River Basin of southwestern Georgia, during both the summer (before stream dry‐down) and fall (post flow resumption) seasons. Fish communities in perennial streams had greater diet richness compared to fishes in intermittent streams for both seasons. Darter diets were characterised by rheophilic aquatic insects in perennial streams and by benthic crustaceans (copepods, cladocerans and isopods) and predatory aquatic insects in intermittent streams. Minnow diets were typified by freshwater sponges, eggs and organic detritus in intermittent streams and by terrestrial insects and diatoms in perennial streams. Fishes in intermittent streams consumed significantly more benthic crustaceans in the fall (37% increase in proportional volume) compared to preflow cessation conditions in the summer, suggesting these organisms play an important, yet relatively unrecognised role in supporting fish communities in southeastern streams. Our findings enhance our understanding of how stream intermittency influences the trophic dynamics of secondary consumer fishes in an agricultural watershed increasingly affected by water scarcity. [ABSTRACT FROM AUTHOR]

Despite extensive studies on the morphology of holometabolous insects and their larvae, the morphological transformations of internal structures during metamorphosis have been rarely documented. Here, we used micro‐computed tomography to investigate the developmental transformations of thoracic structures in the green lacewing Chrysopa pallens (Rambur, 1838) (Neuroptera: Chrysopidae), with emphasis on the development of the digestive, tracheal, and thoracic skeleto‐muscular system. All the adult organs were modified during the prepupal or early pupal stage. The histolysis and remodeling began with the skeletal elements, followed by changes in the digestive system before it concluded with modifications of the musculature. Similar to the tracheal system's development, the digestive system did not disappear completely throughout metamorphosis but underwent a dramatic morphological change, which included the midgut significantly decreasing in size during the pupal stage. Our results provide important evidence for understanding the evolutionary pattern of developmental transformations in different major lineages of Holometabola. [ABSTRACT FROM AUTHOR]

In the absence of environmental heterogeneity, spatial variation among local communities can be mostly attributed to random dispersal, demographic stochasticity and species interactions causing historical contingency in colonization (e.g. priority effects). The consequences of demographic stochasticity and random dispersal are highly dependent on community size, regional richness and local richness, which, along with historical contingency can be strongly affected by spatial isolation and the presence of predators. Here, we tested whether and how the presence of a generalist predatory fish and spatial isolation can change spatial community variability in artificial ponds by manipulating the presence/absence of fish (redbreast tilapia) at three different distances from a source wetland. We then used null models to compute how much the observed community variability within treatments deviates from the expected from randomly reassembled communities (i.e. beta‐deviation). We found that spatial isolation can have both negative and positive effects on community variability, and their importance may depend on the presence of predatory fish. Negative effects likely occurred because predatory insects cannot always successfully colonize highly isolated ponds, causing the abundance of herbivores and detritivores to increase, consequently increasing community size, which is known to decrease the importance of demographic stochasticity. However, when fish are absent, the more isolated communities exhibit more community variability than is expected from random community assembly. We believe that such an increase in variability is most likely due to an increase in the importance of historical contingency in colonization, generating more distinct communities in isolated ponds. Such effects were absent in the presence of generalist predatory fish, likely because fish prevented any early colonizing taxa from becoming too abundant. Our findings show that the presence of generalist predators can change how community variability responds to spatial isolation. [ABSTRACT FROM AUTHOR]

Surface features of plants can influence the searching efficiency and survival of predatory insects. Surfaces act as barriers preventing attachment of both phytophages and also their insect predators. In this regard, we focused on the oviposition site selection and the attachment ability of all life stages (eggs, larvae, imagines) of two common ladybird species, Propylea quatuordecimpunctata and Harmonia axyridis (Coleoptera: Coccinellidae), on artificial and natural substrates with different surface features and properties (roughness, wettability). Both species preferred a hydrophilic surface as the oviposition site and this can be correlated with the better performance of both larvae and adults on these substrates compared with hydrophobic ones. The egg glue of both ladybird species can wet hydrophobic surfaces such as those of many plant leaves and also with prominent 3D wax coverage. The surface roughness has an important role in the oviposition site selection in P. quatuordecimpunctata, but not in H. axyridis. The oviposition preference for smooth surfaces in P. quatuordecimpunctata could be due to better performance of larvae on smooth substrates compared with rough ones. The egg glue of both species can adapt to artificial and natural surfaces characterized by different asperity sizes faithfully replicating their shape, except for very high asperity sizes or big trichomes. The results of the present research can shed light on the mechanical ecology of the evolutionary successful Coccinellidae and may aid in the development of suitable substrates for coccinellid egg‐laying, in order to improve the mass rearing technique of species used in biological control. [ABSTRACT FROM AUTHOR]

Prey evolve antipredator strategies against multiple enemies in nature. We examined how a prey species adopts different predation avoidance tactics against pursuit or sit‐and‐wait predators. As prey, we used three strains of Tribolium beetles artificially selected for short (short strain) or long (long strain) duration of death feigning, and a stock culture (base population). Death feigning is known to be effective for evading a jumping spider in the case of the long strains, while the present study showed that the long‐strain beetles used freezing against a sit‐and‐wait type predator, Amphibolus venator, in this study. The short‐ strain beetles were more easily oriented toward predators. The time to predation was also shorter in the short strains compared to the long strains. The results showed that, as prey, the short strains displayed the same behavior, escaping, against both types of predators. Traditionally, death feigning has been thought to be the last resort in a series of antipredator avoidance behaviors. However, our results showed that freezing and death feigning were not parts of a series of behaviors, but independent strategies against different predators, at least for long‐strain beetles. We also examined the relationship between a predator's starvation level and its predatory behavior. In addition, the orientation behavior toward and predation rate on the prey were observed to determine how often the predatory insect attacked the beetles. [ABSTRACT FROM AUTHOR]

Current conceptual metacommunity models predict that the consequences of local selective pressures on community structure increase with spatial isolation when species favored by local conditions also have higher dispersal rates. This appears to be the case of freshwater insects in the presence of fish. The introduction of predatory fish can produce trophic cascades in freshwater habitats because fish tend to prey upon intermediate predatory taxa, such as predatory insects, indirectly benefiting herbivores and detritivores. Similarly, spatial isolation can limit dispersal and colonization rates of predatory insects more strongly than of herbivores and detritivores, thus generating similar cascading effects. Here we tested the hypothesis that the effect of introduced predatory fish on insect community structure increases with spatial isolation by conducting a field experiment in artificial ponds that manipulated the presence/absence of fish (the redbreast tilapia) at three different distances from a source wetland. Our results showed that fish have direct negative effects on the abundance of predatory insects but probably have variable net effects on the abundance of herbivores and detritivores because the direct negative effects of predation by fish may offset indirect positive ones. Spatial isolation also resulted in indirect positive effects on the abundance of herbivores and detritivores but this effect was stronger in the absence rather than in the presence of fish so that insect communities diverged more strongly between fish and fishless ponds at higher spatial isolation. We argue that an important additional mechanism, ignored in our initial hypothesis, was that as spatial isolation increases fish predation pressure upon herbivores and detritivores increases due to the relative scarcity of predatory insects, thus dampening the positive effect that spatial isolation confers to lower trophic levels. Our results highlight the importance of considering interspecific variation in dispersal and multiple trophic levels to better understand the processes generating community and metacommunity patterns. [ABSTRACT FROM AUTHOR]

In recent years, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae, Cappaeini) has become an invasive pest in North America and Europe, where it caused extensive damage to agriculture, resulting in great economic losses. Evaluating the potential of native predators in the invaded areas, ants might represent good candidates thanks to their biology, ecology, and behavior. In Italy, H. halys proved to be the top key pest in pear orchards, where the black garden ant, Lasius niger (L.) (Hymenoptera: Formicidae, Lasiini), is the most abundant ant species. The aim of this study was to evaluate the predatory ability of L. niger on the eggs and on all the juvenile instars of H. halys under laboratory conditions. The results indicate that L. niger significantly reduces the survival of the second and third nymphal instars by 56 and 58%, respectively, but it is unable to reduce the egg hatching and the survival of the first, fourth, and fifth instars. Our preliminary results obtained in laboratory conditions suggest a possible role of the ant L. niger in controlling H. halys invasion mainly acting on the smaller and more mobile nymphal stages. The effective role of this species as potential biocontrol agents of H. halys in fruit orchards in association with other ant species as well as with other predatory insects is discussed. [ABSTRACT FROM AUTHOR]

Aim: Arthropods as vertebrate predators is a generally overlooked aspect in ecology due to the cryptic nature of these events, the relatively small size of arthropods and the difficulty in finding published data. This study represents the largest global assessment of arthropods preying on vertebrates to provide a conceptual framework, identify global patterns and provide a searchable database. Location: Global. Time period: Present. Major taxa studied: Arthropods and vertebrates. Methods: A systematic literature review was conducted. Results: Over 1,300 recorded observations were collated from 89 countries. Arthropod predators were from 6 classes and 83 families. Vertebrate prey were from 5 classes and 163 families. Spiders represented over half of all predatory events and were the main predator for all vertebrates except birds, which were mostly preyed upon by praying mantises. Forty percent of all prey were amphibians, specifically frogs. Depredated reptiles were nearly all lizards, half of mammal prey were bats, nearly a third of fish were Cypriniformes and half of bird prey were passerines. Predation by spiders was mainly documented from the U.S., Brazil and Australia, and biased mostly everywhere except the U.S.; insect predatory events were mainly documented from Europe, Australia and the Americas, and biased toward North America; amphibian events were mainly from the Americas and strongly biased everywhere, except for the U.S. and Australia; reptiles events were recorded mostly from the Americas and Australia, and biased towards the U.S. and Australia; predation on birds were mainly from the Americas, Australia and Europe, and biased towards Central America and Europe; and mammal events were mostly reported from North and Central America, Australia, and Asia, and strongly biased everywhere except Brazil. Main conclusions: This study demonstrates that arthropods are underestimated predators of vertebrates. Recognizing and quantifying these predator–prey interactions is vital for identifying patterns and the potential impact of these relationships on shaping vertebrate populations and communities. [ABSTRACT FROM AUTHOR]

The commercial production of Orius spp. (Hemiptera: Anthocoridae), including Orius majusculus (Reuter), relies on the use of eggs of Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) as rearing diet. However, E. kuehniella eggs have become an expensive fodder thus increasing the price of these key biological control agents. The use of artificial diets potentially decreases the production costs. In this regard, establishing a link between dietary composition and fitness could advance the development of an optimum alternative artificial diet for these predatory insects. The aim of the current study was to test the effect of six artificial diets with different macronutrient composition on the development and reproductive fitness of O. majusculus when compared with the effect of E. kuehniella eggs. In general, nymphal survival was not affected by diet, whereas development was slightly delayed on artificial diets. However, female body mass and fecundity were significantly lower on all of the artificial diets compared with the E. kuehniella eggs diet, suggesting that artificial diets were of inferior quality. Within artificial diets, females fed the viable diet with highest content in lipid laid more eggs than those raised on the most protein‐rich diets. We found there was some variation in carcass composition between the O. majusculus fed the various diets, but these variations did not match the differences found in the fitness parameters measured. [ABSTRACT FROM AUTHOR]

Plastic and evolutionary changes in traits related to biotic interactions are crucial for the local persistence of populations under global warming. Yet, how acute and developmental thermal plasticity evolve and shape predation rates has been poorly studied, especially in the context of latitude‐driven thermal evolution. A powerful predictive framework is given by the climatic variability hypothesis (CVH) stating that thermal plasticity and acclimation capacity evolve to be higher in high‐latitude populations because these are exposed to higher thermal seasonal variability. We tested the CVH for predation rates and evaluated if the support for the CVH depended on the type of plasticity and acclimation metric. We examined effects of developmental temperature (20 and 24°C) and acute changes in mean and extreme temperatures (20, 24 and 32°C) on the predation rates of high‐ and low‐latitude populations of a predatory aquatic insect, the damselfly Ischnura elegans. We documented opposing and interactive effects between developmental and acute temperatures, which urges caution when using thermal performance curves to forecast the impact of global warming on biotic interactions. Predation rates were higher in low‐latitude than high‐latitude predators, especially at the warmer developmental and test temperatures, suggesting thermal adaptation to the higher low‐latitude temperatures. The latitudinal patterns in acute and developmental plasticities differed, providing mixed support for the CVH. Moreover, there was no latitudinal pattern in post‐acclimation thermal sensitivity, indicative of perfect thermal compensation in predators from both latitudes. Strikingly, the acclimation capacity leading to perfect thermal compensation was ~6 times higher in high‐latitude than in low‐latitude predators. Our study provides new insights into the climatic variability hypothesis (CVH) by documenting that its support is critically dependent on the type of plasticity and acclimation metric used. [ABSTRACT FROM AUTHOR]

1. While there has been considerable focus on prey occurrence as a factor determining the habitat preference of predators, the roles of other factors related to the habitat are less well characterised. 2. In aphidophagous ladybird beetles (Coleoptera: Coccinellidae), a number of species are more restricted in the habitats in which they live than are their prey. A number of such ladybirds appear to show geographic variation in habitat preference. 3. To better understand these phenomena, this study considered geographic variation in habitat preference in one such species, the 5‐spot ladybird Coccinella quinquepunctata. Because of this ladybird's scarcity, a combination of over 20 years' observations, habitat surveys and online data was used to reach the study's conclusions. 4. The data collected indicate that the ladybird is specialised in pioneer habitats close to water, but broadens its range to non‐riverine pioneer habitats in north‐west continental Europe, where it is likely that a damper (micro)climate allows it to do so. Thus, microclimatic factors appear to be important in determining the habitat of this and probably other predators that are not constrained by prey occurrence. 5. Although threatened by river management elsewhere, in north‐western Europe, this species clearly benefits from human activity, which creates many of the disturbed habitats it colonises there. This finding provides further support for the contention that many ladybirds are net beneficiaries of human influence, although they are often characterised as threatened. [ABSTRACT FROM AUTHOR]

1. Although preference–performance relationships in insects are typically studied in a bi‐trophic context, it is well known that host plants can affect both the preference and performance of natural enemies of herbivorous insects. 2. This study presents evidence from field and laboratory studies that two species of milkweeds, the putatively less defended Asclepias incarnata and the putatively more defended Asclepias syriaca, differentially affect adult oviposition and larval performance in Aphidoletes aphidimyza, an aphid‐feeding predatory midge, independent of aphid density. 3. Host plant species affected predatory fly larvae abundance by a factor of 50 in the field and a factor of 8 in the laboratory. Larval and adult emergence rates in our laboratory studies provided strong evidence for reduced performance on A. syriaca. Oviposition in choice and no‐choice settings provided some evidence for preference for A. incarnata, and a potentially suppressive effect of A. syriaca. 4. The results provide limited support for the hypothesis that natural selection can lead to positive correlations between adult oviposition preferences and larval performance upon various food sources, even when predatory insects oviposit onto host plants of their herbivorous prey. 5. Preference and performance are not perfectly aligned in this system, however, because ovipositing females do not reject A. syriaca entirely. Potential explanations for mismatches between preference and performance in this system include the neural constraints associated with being a generalist, adaptive time‐limited foraging strategies, and unique evolutionary histories of laboratory colonies compared with wild insects. [ABSTRACT FROM AUTHOR]

1. The characterisation of energy flow through communities is a primary goal of ecology. Furthermore, predator–prey interactions can influence both species abundance and community composition. The ant subfamily Ponerinae includes many predatory species that range from generalist insectivores to highly specialised hunters that target a single prey type. Given their high diversity and ubiquity in tropical ecosystems, measuring intra‐ and interspecific variation in their trophic ecology is essential for understanding the role of ants as predators of insect communities. 2. The stable isotopic composition of nitrogen of 22 species from the ant subfamily Ponerinae was measured, relative to plants and other predatory and herbivorous insects at two Atlantic Forest sites in Argentina. The study tested the general assumption that ponerine ants are all predatory, and examined intra‐ and interspecific variation in trophic ecology relative to habitat, body size and cytochrome c oxidase subunit 1 sequences (DNA barcoding). 3. Stable isotope analysis revealed that most ponerines occupy high trophic levels (primary and secondary predators), but some species overlapped with known insect herbivores. Species residing at low trophic levels were primarily arboreal and may rely heavily on nectar or other plant‐based resources in their diet. In addition, larger species tend to occupy lower trophic positions than smaller species. 4. Although some of the species were divided into two or more genetic clusters by DNA barcoding analysis, these clusters did not correspond to intraspecific variation in trophic position; therefore, colony dietary flexibility most probably explains species that inhabit more than one trophic level. [ABSTRACT FROM AUTHOR]

The rove beetle tribe Amblyopinini (Coleoptera: Staphylinidae: Staphylininae) is a recently discovered monophyletic lineage comprising an estimated 1000 or more species of mainly leaf‐ and log litter‐dwelling predatory insects found throughout the southern hemisphere. Of these, a single genus Heterothops Stephens somehow conquered all continents in the northern hemisphere as well. A few lineages of amblyopinines independently evolved into highly derived predators of mammal ectoparasites from free‐living ancestors. In return, they are tolerated in the mammal fur and nests, which is a unique example of cleaning symbiosis between insects and vertebrates. For over a century the great majority of free‐living southern amblyopinines were incorrectly placed in the northern hemisphere‐restricted, and superficially similar, rove beetle genera from the subtribe Quediina. Only their mammal‐associated derived forms were understood as amblyopinines, a nonmonophyletic taxon of volatile status and enigmatic sister‐group relationships of its various members. Here we present the first comprehensive phylogeny of Amblyopinini inferred with Bayesian analysis of a six‐gene molecular dataset (4672 bp) across a broad sample of taxa (90 species). This phylogeny provides a framework for the badly needed taxonomic inventory of this group and, in particular, reveals at least two independent origins of mammal association within the tribe. It frames the upcoming in‐depth interdisciplinary exploration of a variety of phenomena such as evolution of the austral biota in response to continental drift and climate change, biotic exchange between southern and northern continents, origin and evolution of beetle–mammal symbiosis, and pathways and constraints of the evolutionary parallelisms. [ABSTRACT FROM AUTHOR]

BACKGROUND: Green lacewings (Neuroptera: Chrysopidae) are important beneficial insects that can be raised on artificial diets for culturing experimental lines. An encapsulation method for embedding a core material within a sealed shell to prevent evaporation and biological contamination is crucial for providing food to these predatory insects. RESULTS: This study presents a new encapsulation process to mass produce a core–shell microcapsule diet for rearing Mallada basalis (Walker) (Neuroptera: Chrysopidae). This new process provided consistent quality control and effectiveness of the microcapsule diet (742.1 ± 11.3 μm in diameter and 44.2 ± 1.9 μm in shell thickness). Furthermore, significant differences were measured in larval development (24.0 ± 0.3 vs. 20.1 ± 0.6 days) and fecundity (465 ± 65.05 vs. 678 ± 54.91 eggs) on comparing the development of M. basalis larvae fed the old and new diets. Survival rates increased in both single‐ and group‐rearing tests for adults fed the new diet during the larval stages. Neither diet affected predation rates for M. basalis larvae preying on nymphs of Aphis gossypii Glover (Hemiptera: Aphididae) and Bemisia argentifolli Bellows and Perring (Hemiptera: Aleyrodidae). CONCLUSION: Compared with the old process, the new encapsulation process requires reduced effort during preparation, and reduces the weight, cost and space occupied by the equipment. The results of this study suggest that this new spherical microcapsule artificial diet is suitable for group‐rearing of M. basalis and may be appropriate for mass‐rearing of other types of carnivorous insects. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Tenuisvalvae notata preys upon several mealybug species (Hemiptera: Pseudococcidae), a group of worldwide pests including Planococcus citri and Ferrisia dasyrilii. Although the consequences of variation in temperature for the development and reproduction of insects are generally appreciated, the consequences of potential interactions between temperature and prey for predatory insects are not. Thermal requirements and predation rates were determined for T. notata at different constant temperatures with both prey species. T. notata larvae developed to adults in experimental conditions > 18 to <38 °C. The upper thermal limit for egg hatch was 34 °C and for pupation was 33 °C. Adults reared at ≥32 °C did not lay eggs and survived less than 1 week. Prey species did not affect lower temperature thresholds or thermal constants for development from egg to adult. Furthermore, prey did not affect a number of reproductive traits, but the interaction between temperature and prey affected changes in developmental times and oviposition rate with age. Predation rate of T. notata increased as a function of temperature, and T. notata adults generally consumed more nymphs of P. citri than F. dasyrilii. These findings indicate that T. notata is well adapted to the tropical and sub‐tropical temperatures and may prove useful for the biological control of some native and non‐native mealybugs. [ABSTRACT FROM AUTHOR]

Natural enemy conservation is known to be affected by ecological processes that range from local to landscape scales. At the farm scale, there are cropped and noncropped areas that differ in their management and plant diversity; these differences affect the spatiotemporal dynamics of natural enemies.We investigated how different habitat types can affect the conservation and spatial dynamics of predatory and herbivore insects in organic vegetable crops in Brazil. Insects were simultaneously sampled in two cropped (focal and neighbourhood crops) and two noncropped habitats (fallow and native forests) during five consecutive focal crop cycles.We found a higher species richness of predators and herbivores in noncropped habitats. All of the habitats shared species from both functional groups throughout the year, indicating that species could disperse among habitats. Fallow areas can serve as a source and sink for species migrating to/from cropped habitats where predators and herbivores can numerically increase their populations during the crop cycles.The spatiotemporal dynamics of herbivores and predators depend on the management and maintenance of natural, seminatural and cropped habitats within the farm. [ABSTRACT FROM AUTHOR]

Invertebrate assemblages of tropical freshwater rock pools (FRPs) are poorly known compared with temperate regions, where FRPs contain specialized, endemic taxa of high conservation value. Invertebrates were sampled from pristine FRPs in the Morgan River catchment in the Australian wet–dry tropics in the 2015 and 2016 wet seasons. Taxa were classified as either active or passive dispersers and by functional feeding groups. A range of physical variables were examined to identify associations with invertebrate assemblages.Forty‐seven taxa were identified from FRPs; most were actively dispersing predatory insects, primarily Coleoptera and Hemiptera. Five adult insect species were found in most pools; other taxa were rare and scattered across FRPs. Two previously undescribed species of Spinicaudata were collected, but few crustacean taxa were recorded, and passively dispersing taxa were rare. Species accumulation curves indicated that had more pools been sampled, more taxa would have been collected in 2015, but in 2016 most species were collected.There was no pattern in FRP assemblages related to any physical variable, but the assemblages in pools were correlated between sampling times. An opportunistic and mobile assemblage composed mostly of actively dispersing predatory insects may explain the absence of relationships with measured variables. Low hydrological stability in the wet–dry tropics may be associated with low taxon richness.The dominance of actively dispersing insects is in contrast with FRP assemblages in temperate and arid regions. Studies of a wider range of FRPs from tropical regions are required to determine whether the fauna of these Kimberley FRPs are typical, and to fully describe short‐range endemic species across the Kimberley and elsewhere.The FRPs have conservation value as habitat for endemic, specialist rock‐pool taxa, contributing to regional species pools. At present, a lack of knowledge of endemic FRP specialist species in tropical regions, including the Kimberley, impedes our ability to protect and conserve these species from disturbance. [ABSTRACT FROM AUTHOR]

In areas of the Cerrado biome (Brazilian savanna) with well‐defined rainy and dry seasons, changes in climate and landscape affect the abundance and seasonality of insects. Larvae of the antlion Myrmeleon brasiliensis (Návas) (Neuroptera: Myrmeleontidae) are predators that build traps in dry sandy soil to capture prey. Here we determined the effect of rain on trap building by M. brasiliensis larvae in a riparian forest in the Cerrado biome. Differences in population size and developmental stage were found between the rainy and dry seasons. In the laboratory, the effect of rain‐soaked soil on trap building was evaluated. Fewer antlion larvae were found in the rainy season. Moreover, a greater abundance of larvae in the final stage of development (third instar) was found in the dry season, whereas more first instars were found in the rainy season. The latter revealed that wet soil affects the trap building of the larvae, as smaller traps were built in the treatment with soaked soil (simulated rain), whereas the larvae in the control treatment (no rain) continued building traps with no change in size. The findings indicate that seasonality in the Cerrado biome exerts a short‐term influence on M. brasiliensis larvae (larvae build fewer traps) as well as a long‐term influence (association with life cycle). [ABSTRACT FROM AUTHOR]

Multiple mating by females is a common phenomenon in nature. Polyandrous females may benefit from genetically diverse progeny that may survive better in a changing environment. Males in polyandrous systems, however, may not achieve their maximum paternity. Therefore, males are predicted to carry traits that prevent or reduce female polyandry. Praying mantids are predatory insects in which females can mate multiple times, predicting the evolution of male counter‐strategies. However, the rate of polyandry and male strategies against polyandry are rarely studied in these insects. In the current study, we used false garden mantids Pseudomantis albofimbriata to quantify the rate of multiple mating when several males are present within close visual range of an unmated female. We further determined how long mated females stay unattractive after mating. We found that in a scramble scenario, the subsequent males stay with a copulating pair and attempt mating once the first male has completed copulation. These second copulation attempts are often successful. If only one male is attracted as a result of the initial pheromone plume, then polyandry is unlikely because the female will remain chemically unattractive for 8 days on average (thus preventing subsequent male attractions), which is longer than the usual latency to lay the first egg sac. From previous studies, we know that single male attraction is the most common scenario in this system in both natural and semi‐natural contexts. Therefore, polyandry depends on the number of males attracted to the initial pheromone plume of the female and is likely to be a relatively uncommon phenomenon in this system. [ABSTRACT FROM AUTHOR]

The invasive cherry vinegar fly, Drosophila suzukii, has been identified in Europe as a destructive fruit pest since its arrival in 2008. In the present laboratory study, three predatory insects (Orius majusculus, Chrysoperla carnea, and Forficula auricularia) naturally occurring on fruit crops in Europe were investigated for their ability to attack and feed on D. suzukii within and outside fruits. The predators were provided with various D. suzukii life stages (eggs, larvae, pupae or adults) exposed or within infested cherries. The anthocorid bug O. majusculus fed on eggs and larvae, but was not able to attack pupae. Larvae of the lacewing C. carnea preyed upon D. suzukii eggs, larvae and pupae and also captured adult flies. The European earwig F. auricularia was the most voracious predator of these three tested species. Although the earwigs were not able to catch adult flies, they readily preyed upon every other developmental stage. Adult O. majusculus or third instar larvae of C. carnea significantly reduced the offspring of D. suzukii from infested cherries, when these contained the egg stage of the pest. None of the predators were able to attack early larval stages inside the cherries. But pupae that protruded from the fruit epicarp or that had pupated outside the fruit were accessible to lacewing larvae and earwigs and significantly reduced by them. Orius bugs, lacewing larvae and earwigs were able, under laboratory conditions, to capture and prey upon various life stages of the invasive pest, if not completely concealed inside the fruit. Our findings suggest that these generalist predators may have some control capacity on infested fruit in cultivated fruit crops and also in non‐crop habitats. [ABSTRACT FROM AUTHOR]

The sensilla type, number and distribution in male and female adults of Carabus elysii Thomson, 1856 (Coleoptera: Carabidae) were studied using scanning electron microscopy. The results showed that there are seven categories and 12 types of sensilla in C. elysii adults: three types of S.Ch, three types of S.T, two types of S.B and one each of B.B, S.Co, S.Ca and S.Cam. There is no difference between male and female in the types of sensilla. Apart from the significant difference in the number and distribution of S.B.2, S.Co and S.Ca between male dorsal and ventral surfaces, there are no significant differences between male and female antennae. In general, the number of sensilla in females is larger than that in males. The results provide a basic reference for future ultrastructure, electrophysiological, and comparative behavioral studies of Carabus species. [ABSTRACT FROM AUTHOR]

Primary succession on bare ground surrounded by intact ecosystems is, during its first stages, characterized by predator‐dominated arthropod communities. However, little is known on what prey sustains these predators at the start of succession and which factors drive the structure of these food webs. As prey availability can be extremely patchy and episodic in pioneer stages, trophic networks might be highly variable. Moreover, the importance of allochthonous versus autochthonous food sources for these pioneer predators is mostly unknown. To answer these questions, the gut content of 1,832 arthropod predators, including four species of carabid beetles, two lycosid and several linyphiid spider species caught in early and late pioneer stages of three glacier forelands, was screened molecularly to track intraguild and extraguild trophic interactions among all major prey groups occurring in these systems. Two‐thirds of the 2,310 identified food detections were collembolans and intraguild prey, while one‐third were allochthonous flying insects. Predator identity and not successional stage or valley had by far the strongest impact on the trophic interaction patterns. Still, the variability of prey spectra increased significantly from early to late pioneer stage, as did the niche width of the predators. As such the structure of pioneer arthropod food webs in recently deglaciated Alpine habitats seems to be driven foremost by predator identity while site and early successional effects contribute to a lesser extent to food web variability. Our findings also suggest that in these pioneer sites, predatory arthropods depend less on allochthonous aeolian prey but are mainly sustained by prey of local production. [ABSTRACT FROM AUTHOR]

1. Flower‐dwelling predators may interfere in plant–pollinator interactions through changes in pollinator behaviour, leading to a reduction in pollination services. Although the context‐dependency of tri‐trophic interactions is often acknowledged, the relative contribution of predator, pollinator and flower traits in shaping pollinator behaviour has been rarely studied simultaneously. 2. Pollinators' responses to predation risk were evaluated using artificial spiders on Alstroemeria aurea flowers in order to experimentally test whether predator traits (colour and size) and nectar availability affect their behaviour and plant fitness. 3. Regarding the predator's traits, both sizes of artificial spiders used were similarly rejected, but spider colour was detected differently. In particular, red and black artificial spiders were more strongly rejected than the rest. In turn, nectar availability increased the time spent in the inflorescences, yet most pollinators rejected flowers with artificial spiders independently of nectar availability. Furthermore, responses to artificial spider colour and nectar availability varied significantly between dipterans and hymenopterans. Finally, artificial spiders reduced seed set and fruit weight of plants owing to changes in the behaviour of the most efficient pollinators. 4. It was shown that poorly studied predator traits such as colour and size may affect pollinator behaviour in different ways among taxa. In addition, feeding necessity in a rich‐resource environment was a weaker selecting force than predation risk. Hence, it is argued here that trade‐offs between predation and flower reward may arise depending on predator detection, relationship between pollinator and predator size, and resource availability in the ecosystem with consequences for plant fitness. Pollinator responses to predation risk are highly context‐dependent, and they might thus be subjected to traits of all interacting organisms, such as predators, pollinators, and flowers.Anti‐predator behaviour turned out to be pollinator taxa‐dependent, with hymenopterans being the most affected, modified by artificial spider colour but not size, and observed only under high nectar availability scenarios.The presence of artificial spiders, by altering the behaviour of the most effective pollinators, increased fruit abortion and decreased overall seed set and fruit weight of their host plants. [ABSTRACT FROM AUTHOR]

1. Beyond killing, predators have nonlethal effects on their potential prey. Because aphids are highly aggregated, their predators aggregate as well, creating conditions optimal for nonconsumptive effects (NCEs) among competing larvae. Although intraguild predator (IGP) density can alter the balance between conflicting forces, little is known about its effect on competing prey. 2. A partitioned Petri‐dish that permitted the passage of signals was used to examine the NCEs between competing stages of similar‐ or different‐sized, conspecific or heterospecific, individuals, on development, survival and reproduction of competing prey. 3. Coccinella undecimpunctata L. larvae suffered developmental and reproductive costs resulting from the presence of conspecific and heterospecific larvae, but showed no impact on their survival. In contrast, larvae of Chrysoperla carnea Stephens and Hippodamia variegata (Goeze) gained developmental benefits, without reproductive costs. Faster development can be construed as adaptive, as it reduces immature mortality. 4. Interestingly, threat‐sensitive prey responses appear to be species‐specific, regardless of predator density. In a C. carnea larva–H. variegata adult competing system, larvae responded to the threat posed by heterospecific adults, with accelerated development, but suffered reproductive costs. In a C. carnea larva–C. undecimpunctata adult system, no overall development costs in response to heterospecific adults were evident. The only cost was on survival at higher IGP density. Thus, the phenotype induced under H. variegata stress was adaptive for development in aphid colonies, whereas that under C. undecimpunctata stress was not. 5. NCEs are not simple vertical forces affecting prey, but can affect guilds on the same trophic level. Co‐release of more than one species and density of these species may adversely increase the aphid populations. Partitioned Petri‐dishes permitting passage of signals were used to examine nonconsumptive effects between competing stages of similar‐ or different‐sized, conspecifics or heterospecifics, on development, survival and reproduction of competing prey.Coccinella undecimpunctata (ESL) larvae suffered developmental and reproductive costs under the presence of conspecific and heterospecific larvae, but not on their survival. But, Chrysoperla carnea (GL) and Hippodamia variegata (VL) larvae gained only developmental benefits.Threat‐sensitive prey responses appear to be species‐specific. The phenotype of GL larva induced under VL adult stress was adaptive for development in aphid colonies, whereas that by ESL was not. [ABSTRACT FROM AUTHOR]

Abstract: A cost associated with the evolution of antiparasite strategies is the failure to recognize parasitic eggs, leading the host to evict its own eggs. However, there is evidence that birds recognize their own eggs through imprinting. This leads to the question of why birds accept parasitic eggs if such eggs can be identified. Here, we tested whether egg ejection per se can be costly due to increased predation risk to the remaining clutch and whether olfactory or visual cues of egg ejection increase predation. We carried out three field experiments to answer the following questions: (a) Does ejecting an egg increase nest predation risk? (b) Does the presence of olfactory cues, such as the smell of a broken egg, increase nest predation risk? And (c) Does the presence of visual cues, such as an egg shell below the nest, increase nest predation risk? We found evidence that egg ejection increases nest predation and that olfactory cues alone also increase nest predation. The presence of visual cues did not change predation rates. These data indicate that egg ejection is costly for both host and parasitic eggs that may remain in the nest. Our results suggest why host and parasite eggs are commonly found within the same nests, despite the possibility that hosts recognize and could possibly eject the parasite’s egg. [ABSTRACT FROM AUTHOR]

Abstract: Functional response studies are often used to determine the suitability of predators as biocontrol agents. Ladybird beetles (Coleoptera: Coccinellidae) are often used for the control of crop pests such as aphids. However, most functional response studies on coccinellids compare a limited number of species at different life stages, temperatures or sexes. A large‐scale comparison of ladybird beetle functional responses is needed to evaluate the utility of these species as potential biocontrol predators and to understand the traits that influence the interaction strength between ladybird beetles and their prey. We compiled 158 ladybird beetle functional responses from 30 studies and tested for effects of taxa, traits, temperature and arena size on functional response parameters using linear mixed‐effects models. Our results show that functional response parameters (handling time and space clearance rate) are affected by predator stage, predator mass, prey type, temperature and arena size. Although complicated by interaction terms, space clearance rate generally increased with predator size, temperature and predator stage, while handling time decreased with predator size, temperature and predator stage. Coleopteran prey induced the highest handling times. Our results also show that experimental arena size has a large, consistent effect on space clearance rate. Arena size is more important in determining foraging rates at low prey densities than any other factor considered here, including predator mass and temperature. Efforts to use laboratory‐based functional response experiments to evaluate the efficacy of biocontrol predators are therefore confounded by the choice of arena size. Synthesis and applications. In addition to confirming known body mass and temperature effects, our study reveals previously unclear age‐related effects and the importance of prey types, which can be used to optimize biocontrol programmes. The arena size effect is unexpected and problematic because failure to account for arena size precludes accurate comparison of biocontrol predator effectiveness. We suggest managers and biocontrol practitioners re‐evaluate the efficacy of candidate biocontrol predators, perhaps by statistically controlling for arena size to minimize the influence of this widely unconsidered factor on functional response estimates. [ABSTRACT FROM AUTHOR]

Abstract: Biological control is widespread in management of greenhouse sweet pepper crops. Several species of predatory mites, bugs, and parasitoids are used against a wide range of pest species. However, biological control of particular pests like aphids, caterpillars, and the tobacco whitefly, Bemisia tabaci Gennadius, remains problematic. Macrolophus pygmaeus Rambur (Hemiptera: Miridae) is a generalist predatory bug which is used on a large scale in Western European tomato greenhouses. It has already been demonstrated that M. pygmaeus is a valuable biocontrol option in sweet pepper crops, but it has yet to find its way into common practice. Macrolophus pygmaeus should be introduced at the start of the growing season and determining an optimal release strategy is a key step in this process. In tomato crops, M. pygmaeus requires supplemental food releases to reach sufficient population numbers and dispersal levels. In this study, the need for food supplementation in sweet pepper is investigated. Three strategies were tested: (1) no food supplementation, (2) local food supplementation, and (3) full field food supplementation. Both population numbers and dispersal rates of the second generation were higher under the third strategy. Macrolophus pygmaeus oviposits near food sources, therefore dispersal rates are higher when food is more spread out. Pest control was achieved in all treatments, but faster and at lower pest levels under the full field strategy. [ABSTRACT FROM AUTHOR]

Abstract: Body size is a multi‐functional trait related to various fitness components, but the relative importance of different selection pressures is seldom resolved. In Carabus japonicus beetles, of which the larvae exclusively prey on earthworms, adult body size is related to the presence/absence of a larger congener and habitat temperature. In sympatry, C. japonicus consistently exhibits smaller body size which is effective for avoiding interspecific mating, but in allopatry, it shows size variation unrelated to temperature. Here, we show that this predator–size variation is attributed to prey–size variation, associated with high phylogenetic diversity in earthworm communities. In allopatry, the predator size was larger where larger prey occurred. Larger adult size may have been selected because larger females produce larger larvae, which can subdue larger prey. Thus, in the absence of a larger congener, variation in prey body size had a pronounced effect on geographic body size divergence in C. japonicus. [ABSTRACT FROM AUTHOR]

Many plants employ indirect defenses against herbivores; often plants provide a shelter or nutritional resource to predators, increasing predator abundance, and lessening herbivory to the plant. Often, predators on the same plant represent different life stages and different species. In these situations intraguild predation (IGP) may occur and may decrease the efficacy of that defense. Recently, several sticky plants have been found to increase indirect defense by provisioning predatory insects with entrapped insects (hereafter: carrion). We conducted observational studies and feeding trials with herbivores and predators on two sticky, insect‐entrapping asters, Hemizonia congesta and Madia elegans, to construct food webs for these species and determine the prevalence of IGP in these carrion‐provisioning systems. In both systems, intraguild predation was the most common interaction observed. To determine whether IGP was driven by resource abundance, whether it reduced efficacy of this indirect defense and whether stickiness or predator attraction was induced by damage, we performed field manipulations on H. congesta. Carrion supplementation led to an increase in predator abundance and IGP. IGP was asymmetric within the predator guild: assassin bugs and spiders preyed on small stilt bugs but not vice versa. Despite increased IGP, carrion provisions decreased the abundance of the two most common herbivores (a weevil and a mealybug). Overall seed set was driven by plant size, but number of seeds produced per fruit significantly increased with increasing carrion, likely because of the reduction in the density of a seed‐feeding weevil. Observationally and experimentally, we found that carrion‐mediated indirect defense of tarweeds led to much intraguild predation, though predators effectively reduced herbivore abundance despite the increase in IGP. [ABSTRACT FROM AUTHOR]

Predation is thought to play a selective role in the emergence of behavioural traits in prey. Differences in behaviour between prey demographics may, therefore, be driven by predation with select components of the population being less vulnerable to predators. While under controlled conditions prey demography has been shown to have consequences for predation success, investigations linking these implications to natural prey population demographics are scarce. Here we assess predator–prey dynamics between notonectid predators (backswimmers) and Lovenula raynerae (Copepoda), key faunal groups in temperate ephemeral pond ecosystems. Using a combination of field and experimental approaches we test for the development and mechanism of predation‐induced sex‐skewed ratios. A natural population of L. raynerae was tracked over time in relation to their predator (notonectid) and prey (Cladocera) numbers. In the laboratory, L. raynerae sex ratios were also assessed over time but in the absence of predation pressure. Predation success and prey performance experiments evaluating differences between L. raynerae male, female, gravid female and copulating pairs exposed to notonectid predation were then examined. Under natural conditions, a female dominated copepod population developed over time and was correlated to predation pressure, while under predator‐free conditions non sex‐skewed prey population demographics persisted. Predator–prey laboratory trials showed no difference in vulnerability and escape performance for male, female and gravid female copepods, but pairs in copula were significantly more vulnerable to predation. This vulnerability was not shared by both sexes, with only female copepods ultimately escaping from successful predation on a mating pair. These results suggest that contact periods during copula may contribute to the development of sex‐skewed copepod ratios over time in ecosystems dominated by hexapod predators. This is discussed within the context of vertebrate and invertebrate predation and how these dissimilar types of predation are likely to have acted as selective pressures for copepod mating systems. [ABSTRACT FROM AUTHOR]

Abstract: The effects of different concentrations and methods of treatment with Metarhizium robertsii Bisch., Rehner & Humber conidia on the non‐target aquatic dragonfly larvae Lestes sponsa Hansemann, Lestes dryas Kirby and Aeshna affinis Vander Linden and on the target bloodsucking mosquito larvae Aedes (O.) flavescens (Muller) were analysed. We found that dragonflies are significantly less susceptible than mosquitoes to the fungus. Larvae of L. sponsa larvae were more susceptible to wet conidia than dry conidia. However, the mortality of the air‐breathing larvae of A. affinis was significantly higher after treatment with dry conidia relative to aqueous suspension. The results help to minimize the negative effects of entomopathogenic fungi on non‐target predator insects under the control of mosquito larvae. [ABSTRACT FROM AUTHOR]