Search

Dinocampus coccinellae (Hymenoptera: Braconidae) can parasitize over 50 species of ladybeetles (Coleoptera: Coccinellidae), including the invasive Harmonia axyridis. The biological invasion success of H. axyridis has been in part attributed to weak control by natural enemies (Enemy Release Hypothesis). The main aim of this study was to examine (i) the intraspecific variation in field parasitism of D. coccinellae attacking H. axyridis populations in its native (Asia) and invasive ranges (North and South America and Europe), and (ii) the interspecific variation in field parasitism of D. coccinellae attacking the invasive H. axyridis and native hosts in the US (Coleomegilla maculata), Chile (Eriopis chilensis), and Italy (Coccinella septempunctata). We also characterized the genetic differentiation of D. coccinellae populations (from different host species and geographical areas) to infer its putative origin. Parasitism of D. coccinellae on invasive H. axyridis and native hosts were remarkably similar at 4–7%, suggesting a low level of resistance, not supporting the enemy release hypothesis. However, parasitism of H. axyridis was much lower in its native than in the invaded areas studied, indicating that under certain field conditions, it may contribute to the control of invasive populations of H. axyridis. Genetic relationships showed widespread D. coccinellae haplotypes with no host-associated genetic structure, consistent with a generalist parasitoid. Genetic relationships of the haplotypes also suggest a complex introduction scenario, with multiple introductions into America and an inferred European origin for D. coccinellae. [ABSTRACT FROM AUTHOR]

The South American tomato pinworm, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), has invaded most Afro-Eurasian countries and is threatening worldwide tomato production. Various strategies have been developed and implemented to manage this pest. Here, we present a timely review on the up-to-date development and practical implementation of integrated pest management (IPM) programs for tomato crops across different world regions infested by T. absoluta. While insecticide resistance is a growing concern, biological control via releasing or conserving arthropod natural enemies and sex pheromone-based biotechnical control are the most successful management practices. Agronomic control-related research is an emerging area where the soil fertilization and/or irrigation, as well as breeding of resistant cultivars, has the potential to enhance IPM effectiveness. Grower survey responses in the native areas (i.e., South America), early-invaded areas (i.e., first report between 2006 and 2012) and newly invaded areas (i.e., first report after 2012) showed that the control programs evolved along with the areas and time since invasion. Growers in the early-invaded areas shifted more rapidly from chemical control to biological control compared to those from the native area. In all concerned regions, the pest control failure risk following chemical insecticide applications and the high cost associated with either biological or biotechnical control methods have been the greatest concerns for growers. The information gathered from the native and/or early-invaded areas may help achieve a more effective management in newly invaded areas. Lastly, researchers are expected to break the bottlenecks of some key issues that would enable lowering application cost of novel biorational alternative management options. [ABSTRACT FROM AUTHOR]

Spotted wing drosophila (SWD) causes significant economic loss in fruit crops to growers worldwide. There is immediate need for efficacious and selective monitoring tools that can detect infestations early. Previously, volatile organic compounds derived from apple were studied and a quinary chemical component blend (QB) was identified as the key SWD attractant in a blueberry orchard in the United States. This study's aim was to determine whether previously observed QB efficacy, selectivity, and early detection levels could be attained within raspberry and cherry fields in the USA and Europe. Results demonstrated that sticky trap baited QB dispenser provided earlier SWD detection potential than the usually adopted apple cider vinegar (ACV) trap. The number of SWD captured/trap by QB baited trapping systems was significantly lower than that of the ACV trap. However, percent SWD/trap of QB baited traps was same within cherry. Lower non-target capture will save farmer/grower's labor and time allocated to traps installation and drosophila species identification. Within the USA, SWD selectivity of QB baited liquid traps was consistently greater than sticky trap in raspberry field, suggesting that the QB dispenser can be an alternative to the standard ACV lure and that trap design could improve selectivity further. [ABSTRACT FROM AUTHOR]

Harmonia axyridis Pallas (Coleoptera: Coccinellidae) is an invasive generalist predator, which has been used as a biological model to investigate several research questions and is also an effective biocontrol agent against agricultural pests. Its laboratory colonies are often maintained on natural prey that are costly, and thus alternative dietary regimens are required. We studied the influence of four different food regimens on the developmental and reproductive life history traits of H. axyridis, including body size and the population demographic parameters. The tested diet regimes were: Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) eggs, a commercial mix of E. kuehniella and Artemia sp. (Anostraca: Artemiidae) cysts, a liver-based artificial diet, and the natural prey, Aphis gossypii Glover (Hemiptera: Aphididae). The food regimes affected the investigated life parameters of H. axyridis in various ways. Larvae developed successfully and in the shortest time on moth eggs, but for H. axyridis reared on the artificial diet development was not successful. The mixture of moth eggs and brine shrimp cysts supported the rearing of H. axyridis. However our findings suggest its use only when no other suitable feedstuff is available. The life table approach used in this study could improve the standardized comparison among diet regimes, thus optimizing the rearing protocols of the species. [ABSTRACT FROM AUTHOR]

Honeydew is a sugar-rich food source produced by sap-feeding insects, notably by major pests such as aphids and whiteflies. It is an important alternative food source for the adult stage of various key natural enemies (e.g., parasitoids), but it may be used also as food by agricultural pests. Necremnus tutae is an idiobiont parasitoid, and it is the most abundant larval parasitoid associated with the South American tomato pinworm, Tuta absoluta, in recently invaded European areas. The impact of N. tutae on T. absoluta populations was evaluated under greenhouse conditions with and without the presence of a honeydew producer, the aphid Macrosiphum euphorbiae. In addition, laboratory experiments were performed to evaluate the longevity of N. tutae and T. absoluta adults when fed with water, honey or honeydew produced by the aphid. In the greenhouse, N. tutae effectively reduced T. absoluta population by the end of the experiment, and this independently of the presence of the aphid; still the presence of M. euphorbiae led to delayed and reduced T. absoluta population peak when controlled by the parasitoid (there was a fourfold increase in parasitoid density in presence of aphid). The longevity of both N. tutae and T. absoluta females increased in the presence of honeydew (when compared to water only) under laboratory conditions; it hinted that honeydew could be used by an herbivore as T. absoluta. The interactions between the two phytophagous species showed contrasting effects, and this mostly independently of parasitoid presence. Tuta absoluta had no impact on aphid population dynamics. By contrast, the production of T. absoluta larvae was higher in the first part of the experiment as the adults lived longer (feeding on aphid honeydew) and produced more larvae. In the second part of the experiment, there were fewer T. absoluta larvae in the presence of the aphid, likely owing to resource competition and/or negative plant-mediated indirect interactions. We demonstrated that honeydew producers could impact parasitoid-host population dynamics both through direct and indirect interactions and that potential positive effects of a sugar food source toward a pest can be nullified in the long term by other negative effects occurring simultaneously. [ABSTRACT FROM AUTHOR]

The development of new strategies to control pest insects is required, in combination with conventional pesticides or replacing them. Essential oils produced from botanical extracts used in management programs should be effective against pests and selective to natural enemies. Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is one of the most destructive pests of solanaceous crops in the world, and a possible management strategy consists of releases of the predator Nesidiocoris tenuis (Hemiptera: Miridae), along with botanical applications. The objective of this study was to evaluate the effects of Prev-am® oil on T. absoluta offspring, either with or without the predator N. tenuis, as well as the oil's effects on N. tenuis predatory behavior and longevity. The oil's effects were compared with distilled water (control) and a synthetic pesticide (lambda-cyhalothrin). The response of populations to lambda-cyhalothrin was similar to that with Prev-am®, compared to the control, showing that N. tenuis had higher capacity to reduce T. absoluta populations. The survival analysis of predators exposed to Prev-am® indicates that none of the concentrations differed significantly from the control. In addition, the canonical variate analysis indicated significant overall differences in the predator behavior submitted to different treatments, suggesting that synthetic pesticide treatment affected predator behavior when compared to control and Prev-am®. Reduction in predatory voracity of N. tenuis adults exposed to leaves treated with pesticide and biopesticide was significant compared to the control treatment. The results obtained could improve IPM programs against T. absoluta through the Prev-am® applications and N. tenuis releases. [ABSTRACT FROM AUTHOR]

The South American tomato pinworm, Tuta absoluta, is considered worldwide as one of the most important tomato pests. Insecticide resistance reported on the moth and the awareness about the negative impact of agrochemicals on the environment and human health have raised the demand for new control tools. Among these, RNA interference (RNAi) can represent a valid tool to be included into new control strategies against this pest. Here we report the results of trials aimed at evaluating the effects of dsRNAs targeting acetylcholinesterase (AChE), nicotinic acetylcholine alpha 6 (nAChRs), ryanodine (RyRs) receptors by injection and root delivery. In the injection procedure, 2 and 5 µg of dsRNA were able to reduce the gene expression in a range of 62.7–75.4%, inducing a maximum mortality rate of 92.59%. The dsRNAs administered at 5 µg by root absorption revealed the potential of this delivery system to affect the gene expression (47–69% reduction) and the mortality (ranging from 67.1 to 80.5%) of treated specimens. The delivered dsRNAs (both injected and root administered) affected the weight of both T. absoluta pre-pupae and pupae. The selected AChE, nAChRs and RyRs genes can be suitable targets for T. absoluta control by means of in planta delivery dsRNAs. [ABSTRACT FROM AUTHOR]

Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), a pinworm native to South America, has invaded Tunisia, as well as the whole African continent, since 2008 inducing severe crop damages and substantial economic losses in all tomato-producing areas. During the last decade, several research studies and management efforts have been performed in an attempt to find out the most effective and sustainable pest control options against this devastating pest. Herein we explore, comprehensively summarize and discuss the most up-to-date state of scientific knowledge regarding bio-ecological aspects of the pest, its indigenous natural enemies and all categories of management strategies adopted so far against this economic pest in Tunisia. [ABSTRACT FROM AUTHOR]

Nesidiocoris tenuis (Hemiptera: Miridae) is an important biocontrol agent of several key arthropod pests, including the South American tomato pinworm, Tuta absoluta (Lepidoptera: Gelechiidae). However, it can cause economic damage owing to its herbivory. Risk assessment on plant for the predator under different temperature thresholds is necessary for managing its phytophagy in tomato cultivation. We investigated the predator plant damage and its development under the influence of temperature and tomato variety. Ten commercial tomato varieties of different types (round red, small cherry, date baby plum, piccadilly plum and marmande beefsteak) were tested in the laboratory under five constant temperatures (15, 20, 25, 30 and 35 °C). The amount of fourth-instar nymphs moulted into adults and stem necrotic rings induced by the feeding activity was evaluated. The plant damage differed among the varieties and increased significantly across the temperatures up to 30 °C, with a slight decline at 35 °C. Temperature and variety significantly affected the nymphal development with an increasing number of moulted adults at increasing temperature, but with slight differences among tomato varieties. Our findings provide valuable information on the mirid response to the tested abiotic and biotic factors, which can help in the management and exploitation of N. tenuis as a biocontrol agent in tomato crop. [ABSTRACT FROM AUTHOR]

Since its first detection in Tunisia in 2008, the tomato pinworm, Tuta absoluta, has become a serious problem to tomato crops by causing heavy yield losses. The aim of this work was to evaluate the efficacy of some actives ingredients, commonly used by Tunisian farmers, under laboratory and greenhouse conditions in controlling T. absoluta larvae. We also tested the role of mass trapping as control method for T. absoluta while performing two greenhouse trials: one to test the most effective number of pheromone traps to be used and the second evaluating the combination of insecticides and pheromone traps. Our study demonstrated that the product combining abamectin and chlorantraniliprole was the most effective 2 h after the treatment in laboratory trials. Moreover, this study indicated that the dose of two sex pheromone traps/greenhouse was the most effective compared to the other tested dose. Also, mass trapping alone (2 sex pheromone traps/greenhouse) was not effective in reducing larval populations: flubendiamid and cyromazin caused 96 and 77% larval mortality, respectively. [ABSTRACT FROM AUTHOR]

Insect parasitoids are often manipulated to improve biological control programs for various arthropod pests. Volatile compounds can be a relevant cue used by most parasitoid hymenoptera for host or host microhabitat location. Here, we studied olfactory responses of the braconid Asobara japonica Belokobylskij, an Asiatic endoparasitoid of the invasive pest Drosophila suzukii (Matsumura), toward its host and host substrates. Adult A. japonica displayed an innate attraction to undescribed volatile cues from infested host fruits irrespectively of the juvenile rearing experience, i.e. they respond to a novel cue subsequently used for microhabitat selection. These data suggest that A. japonica parasitoids mass-reared on artificial diet and factitious host ( D. melanogaster) can successfully locate their hosts. Naïve female parasitoids did not show a preference towards any of the tested host media. However, the enforced adult experience with the rearing host medium modified the olfactory preference patterns toward non-natal host fruits. These findings provide evidence of associative learning during the adult stage of A. japonica, and demonstrate its plasticity in exploiting the volatiles from various fruits infested by D. suzukii. [ABSTRACT FROM AUTHOR]

It has been proved that the omnivorous predator Nesidiocoris tenuis (Hemiptera: Miridae) is attracted to and can develop successfully on sesame ( Sesamum indicum). In this study, the potential of this plant, compared with Dittrichia viscosa and tomato ( Solanum lycopersicum), to attract the mirid bug was assessed. A Y-tube olfactometer was used to test the olfactory preference of the mirid in dual-choice bioassays comparing healthy tomato, S. indicum, and D. viscosa plants, and tomato plants infested by eggs and larvae of Tuta absoluta (Lepidoptera: Gelechiidae). To understand the biochemical basis of the attraction of the omnivorous predator toward the alternative plants, headspace solid-phase microextraction combined with gas chromatography-mass spectrometry was performed, with the aim of identifying potential volatiles responsible for mirid attraction. S. indicum was the most attractive plant; T. absoluta infestation did not significantly increase N. tenuis attraction. We identified 57 volatiles belonging to the classes of hydrocarbon and oxygenated monoterpenes, sesquiterpenes, C-norisoprenoids, aliphatic aldehydes, esters, alcohols, and hydrocarbons. Sesame plants emitted the lowest amount of hydrocarbon monoterpenes but a higher rate of oxygenated terpenes. Green leaf volatiles, known for attracting mirids, were emitted at higher levels by sesame plants, whereas tomato plants infested by T. absoluta larvae showed the highest levels of monoterpene hydrocarbons. The potential applications of plant volatiles in integrated management of tomato pests are discussed in the framework of mirid ecology. [ABSTRACT FROM AUTHOR]

Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) is an important natural enemy of several key arthropod pests. However, in tomato crop this predator can cause economic damage owing to its zoophytophagous behavior. We investigated in laboratory conditions the influence of two alternative plants, Dittrichia viscosa L. (Asteraceae) and Sesamum indicum (L.) (Pedaliaceae), with or without prey, on N. tenuis damage and its biological control services on Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) eggs. Both D. viscosa and S. indicum, as companion plants in dual-choice bioassays, significantly reduced the damage of the mirid on tomato. S. indicum was more attractive than D. viscosa for feeding and oviposition and its presence did not interfere with the predation on T. absoluta eggs. We also studied the potential of the three plants as preyless rearing substrate for the mirid, and only S. indicum showed to be a suitable host plant for N. tenuis development and oviposition. The potential applications of S. indicum in N. tenuis field management and mass rearing are discussed. [ABSTRACT FROM AUTHOR]

During the past decades, the huge use of pesticides caused several environmental problems, so research investigations moved to find a series of compounds with selective toxicity, of a biodegradable and environment-friendly nature, maintaining a positive action in crop and stored products protection. In this perspective, interesting results in the control of pests and fungal pathogens were obtained using essential oils, which are compounds produced by many species of plants as secondary metabolites. The purpose of this research was to evaluate the fumigant activity of five Citrus essential oils against the confused flour beetle Tribolium confusum Du Val, planning a possible employment in the mill industry. The fumigant effectiveness was evaluated 24, 48, 72 hours and 7 days after the start of exposure and each essential oil was analyzed by means of GC and GC/MS. Further evaluations about the toxicity of these compounds were made by partially filling the glass vials with food matrix, in order to assess the possible interference of this matter on the active compounds. The data obtained indicated that, at a low level of fumigant concentration, essential oils can effectively control stored product pests; in the presence of debris, like flour, the efficacy decreased. Plant extracts caused also increased mortality levels after the end of fumigation. The results obtained from this experimentation confirm the efficacy of essential oils in pest control and, in particular, against stored product pests. [ABSTRACT FROM AUTHOR]

The South American tomato leafminer, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), is a major threat to tomato ( Solanum lycopersicum L.) crops. After its first detection in Spain in 2006, it spread rapidly through the Western Palaearctic region, arriving in Tunisia 2 years later. The aim of this research was to assess whether generalist indigenous parasitoids are adapting to this exotic host in Tunisian tomato crops. For this, we conducted a survey in four Tunisian tomato-growing areas by sampling infested leaves of tomato and solanaceous weeds and exposing artificially infested sentinel plants. Two ectoparasitoid species were found attacking and developing on T. absoluta: Bracon sp. (Hymenoptera: Braconidae) and Necremnus sp. nr artynes (Hymenoptera: Eulophidae), whereas no egg or pupal parasitoids were found. The eulophid wasp was the most abundant with a peak of apparent parasitism rate of 25.5%. It emerged from parasitized T. absoluta young larvae in exposed sentinel plants and in sampled infested tomato leaves, both in greenhouse and open field cultivations. Bracon sp. showed a gregarious development on T. absoluta mature larvae and it was collected only on sentinel plants exposed in the Ragueda (Kiarouan) site, with 10.23% of estimated parasitism. Although further research is still needed to assess properly the ecological role of these parasitoids in the biological control of T. absoluta, this study represents the first step toward establishing the scientific basis for including these parasitoids in the Tunisian IPM and biological programs against this pest. [ABSTRACT FROM AUTHOR]

The South American tomato leafminer, Tuta absoluta Meyrick (Lepidoptera: Gelechiidae), is an invasive Neotropical pest. After its first detection in Europe, it rapidly invaded more than 30 Western Palaearctic countries becoming a serious agricultural threat to tomato production in both protected and open-field crops. Among the pest control tactics against exotic pests, biological control using indigenous natural enemies is one of the most promising. Here, available data on the Afro-Eurasian natural enemies of T. absoluta are compiled. Then, their potential for inclusion in sustainable pest control packages is discussed providing relevant examples. Collections were conducted in 12 countries, both in open-field and protected susceptible crops, as well as in wild flora and/or using infested sentinel plants. More than 70 arthropod species, 20 % predators and 80 % parasitoids, were recorded attacking the new pest so far. Among the recovered indigenous natural enemies, only few parasitoid species, namely, some eulophid and braconid wasps, and especially mirid predators, have promising potential to be included in effective and environmentally friendly management strategies for the pest in the newly invaded areas. Finally, a brief outlook of the future research and applications of indigenous T. absoluta biological control agents are provided. [ABSTRACT FROM AUTHOR]

In the original publication of the article, the authors have inadvertently missed to include a statement in the Acknowledgement section and the corrected version is given below. [ABSTRACT FROM AUTHOR]

Synthetic chemicals are extensively used to limit the substantial crop damage induced by two closely related scale insects, the vine mealybug Planococcus ficus (Signoret) and the citrus mealybug Planococcus citri Risso (Hemiptera: Pseudococcidae). Both organisms are economically important pests occurring in vineyards and/or in citrus orchards worldwide. Synthetic chemicals can be either incorporated in pesticides aimed at directly controlling these pests or used as semiochemicals (i.e., sex pheromones) for monitoring, mass trapping, mating disruption, and/or for kairomonal attraction to enhance parasitoid performances. Growing evidence of both an alarming bee decline and destruction of auxiliary fauna driven by pesticides have stimulated an urgent need for in-depth research clarifying the adverse side effects of pesticides on beneficial arthropods. We have reviewed the current knowledge on mealybug pest control based on insecticides and semiochemicals. We highlight the following major advances: (1) How the active substances of insecticides (four organophosphates, imidacloprid, buprofezin, and spirotetramat) affect target and non-target organisms, (2) in which contexts and how a semiochemical-based strategy could be applied to deal with serious mealybug infestations, and (3) the implications of the appropriate exploitation of these synthetic chemicals for sustainable development. Using selective insecticides with novel modes of action and long-lasting efficacy in combination with eco-friendly semiochemical-based tools is a promising strategy for developing sustainable integrated pest management programs. This would help to maintain biodiversity dynamics and vital ecosystem services, thereby sustaining crop yields. [ABSTRACT FROM AUTHOR]