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The Avian Vampire Fly, Philornis downsi, has invaded the Galapagos Islands, where it causes high mortality of endemic and native landbird species, including most species of Darwin’s finches. Control methods are under development, but key information is missing about the reproductive biology of P. downsi and the behavior of flies in and near nests of their hosts. We used external and internal nest cameras to record the behavior of P. downsi adults within and outside nests of the Galapagos Flycatcher, Myiarchus magnirostris, throughout all stages of the nesting cycle. These recordings showed that P. downsi visited flycatcher nests throughout the day with higher fly activity during the nestling phase during vespertine hours. The observations also revealed that multiple P. downsi individuals can visit nests concurrently, and that there are some interactions among these flies within the nest. Fly visitation to nests occurred significantly more often while parent birds were away from the nest than in the nest, and this timing appears to be a strategy to avoid predation by parent birds. We report fly mating behavior outside the nest but not in the nest cavity. We discuss the relevance of these findings for the adaptive forces shaping P. downsi life history strategies as well as rearing and control measures.

Tetranychus urticae (the two-spotted spider mite) is a phytophagous agricultural pest that affects many economically important crops. Two-spotted spider mites are group-living arachnids that produce silk webbing which is used for protection and dispersal, and also influences settlement behavior of conspecifics. We investigated the effects of conspecific silk and frass on microhabitat selection of these mites and whether these materials are substrates for semiochemicals. Two-choice behavioral assays gave mites the option of settling in the presence or absence of cues produced by conspecifics. Both sexes of mites preferred to settle in the presence of silk produced by conspecific females, and males also responded positively to silk produced by other males. Frass alone had no effect on mite settlement choices, but mites tended to prefer frass in combination with silk over silk alone. Female mites did not respond to conspecific silk after it was washed with methanol, and a crude methanol extract of the silk was sufficient to elicit settlement behavior, confirming that a semiochemical is responsible for the effect. We conclude that silk-bound semiochemicals provide cues used by both male and female mites when selecting a microhabitat, and that frass may also provide relevant social cues.

The ability of female parasitoid wasps, Cotesia kariyai (Hymenoptera: Braconidae), to learn to recognize plant volatiles associated with an oviposition experience was investigated. First, we observed oviposition behavior of female wasps when encountering host larvae (Mythimna separata, Lepidoptera: Noctuidae). On their first encounters with host larvae, 96% of inexperienced female wasps showed oviposition behavior. Immediately afterward, and for 2 h after the first oviposition, wasp oviposition behavior was suppressed. Only 20–30% of wasps showed a second oviposition response, even after several encounters with a new host. Then, oviposition behavior gradually recovered 6 to 24 h after the first oviposition. At 6 h after the first oviposition experience, more than 80% of the wasps showed a second oviposition response when encountering a new host. Next, in a wind tunnel, we investigated the effect of time since first oviposition on wasp responses to host-infested plant volatiles. Female landings in response to volatiles of host-infested maize plants, Zea mays, showed a bell-shaped curve from 0 to 48 h after first oviposition. Eight hours after the first oviposition, the rate of landing by wasps was significantly higher than that of oviposition-inexperienced wasps. The ecological strategy explaining the effect of oviposition experience on olfactory responses of C. kariyai to host-infested plant volatiles is discussed.

Dung beetles of the Scarabaeinae subfamily are present in temperate and tropical ecosystems. Some species of these insects feed on millipede carcasses. The objective of this study was to determine the attraction of Canthon vazquezae to volatiles released by Messicobolus magnificus. The bioassay was performed using a Y-glass tube olfactometer. Canthon vazquezae was significantly attracted to dead M. magnificus, as well as stressed and wounded individuals. In contrast, unstressed M. magnificus did not attract C. vazquezae. The volatiles released by M. magnificus in stressed, wounded, and dead states were analyzed by gas chromatography coupled to mass spectrometry (CG-MS). Six compounds were tentatively identified as 2-methyl-p-benzoquinone, trimethyl-p-benzoquinone, 1,2,4-trimethoxybenzene, 2-methyl hydroquinone, 2,5-dimethoxythiophenol, and 3,4-dimethoxyphenol. Some of these compounds have been identified as attractants to other coleopterans.

In animal taxa, the behavior of choosing a microhabitat determines the context in which individuals engage in all other behaviors and interactions. Microhabitat choice has particularly important implications for animal communication, because the successful transmission of information between individuals is highly context-dependent. Substrate-borne vibrations, which are commonly produced, detected, and used for communication by arthropods, are especially influenced by substrate choice because substrates vary widely in their vibration transmission properties. In this laboratory-based study, we examine vibration transmission properties of substrates commonly encountered in nature by the jumping spider Habronattus clypeatus and also examine whether these spiders exhibit a preference for particular substrates using a choice experiment. We predicted that spiders would prefer substrates that can better transmit vibratory signals. We found that leaf litter minimized the attenuation of vibratory signals, while rocks and sand sharply attenuated the signals. In behavioral trials, more spiders chose leaf litter or rocks as their first substrate over sand. Further, spiders spent more time on, and were more likely to jump to, leaf litter and rocks than sand. These results suggest that substrate preference by H. clypeatus partially matches the choice that would maximize signal transmission efficiency, indicating that the ability to communicate with conspecifics may influence these animals’ choice of microhabitat.

New associations between parasitoid species is common in biological control with interactions ranging from coexistence to competitive exclusion. Spathius agrili and Spathius galinae, native to North East Asia, are two host-specific idiobiont larval parasitoids of the invasive emerald ash borer Agrilus planipennis that do not overlap in their native ranges but have been recently introduced to the United States for biocontrol of A. planipennis. We conducted laboratory experiments to determine the results of competition between these two species. Competition between parasitoid larvae on a single host (intrinsic competition) and competition between adult parasitoids for oviposition sites (extrinsic competition) were evaluated. Successful multiparasitism did not occur in any intrinsic trials. Extrinsic competition favored S. agrili, but S. galinae was not excluded. Competition lowered parasitism rates for both species, but overall parasitism was not lowered. USFS Grant [15-DG-11083150-042]; USDA ARS Grant [58-8010-5-016] Published version This research was funded through USFS Grant 15-DG-11083150-042 and USDA ARS Grant 58-8010-5-016. Public domain – authored by a U.S. government employee

Stink bugs communicate while mating on a plant by means of the substrate-borne component of the species and sex-specific calling, courtship and rival signals, produced by vibration of the abdomen. Courtship conducted over a close visual distance, chemical contact and mechanical exchange of information terminates in copulation. Here we describe characteristics, differences between species, transmission properties and the behavioral context of the stink bugs Chinavia impicticornis, C. ubica and Euschistus heros in relation to their buzzing signals, produced by vibration of lifted wings. Comparison between species reveals their species’ non-specific temporal parameters, characterized by irregular repetition rate and highly variable duration. Frequency spectral bands extend to several kHz above approximately 100 Hz, which is the fundamental frequency and significantly higher in E. heros compared with both Chinavia species. Buzzing signals, recorded predominantly in the very early phase of mating behavior, precede emission of signals produced by abdomen vibration. Males and females emit signals spontaneously when alone on a plant or together with conspecific or alien species mates. Transmission of wing-produced signals along the plant shows characteristics similar to those produced by abdomen vibration. We suggest that amplitudes, measured on distant plants in direct contact or through soil and roots, together with the high sensitivity of relevant vibrational receptors, enable stink bugs to communicate between plants, using substrate-borne vibratory signals outside the limits of the single plant.

The discovery-exploitation tradeoff posits that ant colonies decide between investing in scouts (individual foraging and discovery) or recruits (collective foraging and exploitation) in order to optimize gains. Although this tradeoff has been thoroughly examined through theoretical modelling, research linking model findings to empirical comparative data in ant communities is lacking. We explore the discovery-exploitation tradeoff within an old field ant community in the novel context of a multispecies mutualism with the treehopper Publilia concava. Specifically, we examine the relationship between foraging strategy and ant attentiveness to their treehopper partner, changes in foraging strategy in response to dynamic resources, and how different attendance phenotypes affect partner fecundity. We categorized ants via behavioral assays into “attentive” and “non-attentive” behavioral groups. Foraging strategy differed between ant groups during treehopper oviposition, with “attentive” and “non-attentive” ants favoring collective and individual foraging strategies, respectively. As treehopper nymphs emerged, “non-attentive” Formica subsericea shifted to collective foraging, with a corresponding rapid increase in ant recruitment, while ant recruitment in “attentive” ants remained constant. Treehopper fecundity, however, did not differ when tended by either “attentive” or “non-attentive” ants. We suggest that differences in foraging strategy could be due to residual honeydew left by maternal treehoppers on egg masses, which “attentive” ants exploit. Early recruitment in “attentive” and behaviorally subordinate ants might lead to priority effects, allowing them to persist on host plants and deter invasion from competing ants, which could ultimately lead to species coexistence.

Anthropogenic disturbances, including land use change and exotic species, can alter the diversity and dynamics of ant communities. To examine foraging behavior in an urbanized habitat in northern California, we surveyed the presence of 9 ant species on 876 trees across 4 seasons during both day and night in a 9.5-hectare urbanized oak-exotic woodland. Ants were more likely to be observed on native, evergreen trees, suggesting that native evergreen species may help maintain ant diversity. Species showed clear patterns of temporal partitioning of foraging activity. Ant species varied in their use of native evergreen Quercus agrifolia trees across season and day/night axes. Of the 3 ant species most frequently observed, Camponotus semitestaceus was most active during spring and summer nights, Formica moki was most active during spring and summer days, and Prenolepis imparis was most active during both day and night during fall and winter. Liometopum occidentale was the second most active species during summer day and night, and winter day. Our findings demonstrate that an oak-exotic urban woodland in Northern California was able to maintain a native ant community, and strong temporal partitioning within that community.

The Asian corn borer, Ostrinia furnacalis, is the most notorious corn pest in East Asia and Oceania. The larvae seriously damage crops and lower yields. A previous study found that the O. furnacalis can migrate seasonally. However, the influencing factor on the flight performance of this pest has not yet been investigated. Here, the flight performance and its influencing factors of O. furnacalis were tested using computer-monitored flight mills. The results showed that the longest total flight of an individual was 71.49 km with a mean speed of 6.36 km·h−1 (1.77 m·s−1). Flight performance reached the peak when the moths were 2-days old, with a mean flight distance of 18.89 ± 2.03 km, mean flight duration of 7.34 ± 0.62 h and mean flight speed of 2.47 ± 0.10 km·h−1 (0.69 m·s−1). The flight capability of females was always higher than that of males. Mating status and nutritional status affected partial flight variables. For both sexes, only temperature and relative humidity among the abiotic factors significantly involved flight performance, which was most significant at 25–30 °C and 55–65%. Our study demonstrated that O. furnacalis have a high capability for migration and determined the influencing factors on flight performance. These results provide essential information for forecasting and management of this pest.

The fecundity benefit of sexual cannibalism is a key parameter of models for the evolution and population-level consequences of sexual cannibalism. Previous studies of praying mantids that have attempted to measure the change in egg production following cannibalism have yielded inconsistent results, possibility due to differences in female ages and background diets. We studied the effect of cannibalism on egg production and egg laying in the Chinese praying mantid (Tenodera sinensis), standardizing female age and mating status, and maintaining females on diets that reflect natural rates of foraging. We experimentally assigned females to one of three treatments: cannibal, non-cannibal, or cricket consumers that received an additional diet of crickets (Acheta domesticus) roughly equivalent to the mass consumed by cannibals. We show that cannibalistic females that consume multiple males produced significantly more eggs and laid more eggs in their first ootheca (egg case) compared to non-cannibals. This result supports the hypothesis that sexual cannibalism in T. sinensis is a female foraging strategy that provides resources to increase fecundity. The increase in egg production by cannibals was similar to that of the cricket consumer females suggesting that male mantids are equivalent to other prey, per unit body mass, in terms of their effects on egg production.

This study combines information on the differences in foraging behavior and morphological dimorphism for workers of the termite Constrictotermes cyphergaster. We observed through morphological analyzes that the workers of this species are dimorphic. Through comparisons between major and minor workers signal emissions, we can assume that each of these groups of workers performs different foraging tasks. The crop volumes of minor and major workers were measured, noting it are statistically different and this can be associated to differences in food collection. This study also provides information that during the foraging the major workers may be mistaken for soldiers by having a similar posture and coloring, which reduces their predation and enables a quick predator detection due to their position on the trails’ edges.

Social aggression is a pervasive feature of insect societies. In eusocial Hymenoptera, aggression among females can affect task performance and competition over direct reproduction (egg laying); in most species males participate in social interactions relatively rarely. Males of the independent-founding paper wasp Mischocyttarus mastigophorus are exceptional: they are aggressive toward female nestmates, leading us to explore the function of this unusual behavior. We applied social network analyses to data on M. mastigophorus social aggression to quantify sex differences in giving and receiving social aggression. The network analyses supported the pattern of biased male aggression toward female nestmates; females are relatively rarely aggressive to males. We then asked whether male aggression toward females was biased by females’ relative ovary development. Males were more aggressive toward females with better-developed ovaries, opposite to patterns of aggression among females. Because food brought to the colonies is often monopolized by dominant females, we suggest that males direct aggression toward socially dominant females with better-developed ovaries to obtain food. The implications of biased male aggression for female task performance and physiology are unknown.

Knowledge of the reproductive ecology of insect pests is important for the development of sustainable pest control strategies. Mating behavior studies can provide insights about relevant aspects of intra- or intersexual communication processes, which may lead to sustainable control strategies based on behavioral disruption. The bronze bug, Thaumastocoris peregrinus (Hemiptera: Thaumastocoridae), is an invasive eucalypt specialist that feeds and reproduces in aggregations on eucalypt leaves, causing defoliation and branch dieback in severe infestations. Scant information is available on its mating behavior, so we here report a systematic study of male–female and male-male interactions under controlled experimental conditions. Unmated, sexually mature naive males and females were paired and videotaped from two angles to describe and quantify their behavioral interactions and transitions. Intersexual interactions included mounting, rejection, copulation, antennation and a post-copulatory behavior that we termed smearing and consisted of a rapid backward and forward movement by the male while still on top female. Antennation occurred during copulation, and it may be interpreted as copulatory courtship. Smearing occurred after copulation and positively correlates with total mating time, likely involving mate guarding. Behavioral correlations with size and age showed that female rejection is not affected by male size or age. Intrasexual interactions included two agonistic behaviors that we called sparring and riding, both likely involved in male-male competition and the establishment of male dominance in natural aggregations. Male intrasexual aggressiveness was not related to male size or age either. The results are discussed in relation to the potential functions of these behaviors in the mating system of T. peregrinus.

Metarhizium anisopliae and Beauveria bassiana are commonly used entomopathogenic fungi, but their non-target effects over generalist predatory insects, which can contribute to pest control, are not well known. We studied the capacity of the social wasp Polistes myersi to detect the pathogens in either a powdered form or in Galleria mellonella larvae infected with either of the two pathogens offered as prey. The effects of these treatments were compared considering wasp behaviors such as prey preference, frequency, duration and transitions of both hunting and grooming behaviors. Additionally, the effects of each entomopathogenic fungus on the wasp’s mortality were measured. Wasps seem not to detect the pathogens in powdered form but preferred healthy over infected larvae. Seventeen behavioral units for hunting and 34 for grooming were recognized. There were no differences in grooming frequency but there were significant differences on grooming duration, hunting behaviors and the patterns of transitions. Exposure of wasp colonies to either B. bassiana or M. anisopliae had no detectable impact on the mortality of adults, but mortality of larvae increased. For the first time, this study documented behavioral changes that indicated the capacity of social wasps to detect pathogens before physical contact and the display of hygienic strategies once contact occurs. The study also suggested a potential non-target effect of these entomopathogenic fungi on a generalist predator.

Internal parasites typically are associated with a range of negative effects on their hosts, including reduced energy, which can manifest in behavioral alterations. With this in mind, we examined effects of a naturally-occurring nematode parasite, Chondronema passali, on locomotor activity level in horned passalus beetles, Odontotaenius disjunctus from Georgia, USA. This parasite is not well-studied but can number in the thousands in severely parasitized hosts. Prior study in our lab revealed that parasitized beetles actually consume more wood than unparasitized ones do, leading us to ask here, if parasitized beetles are also more physically active. Beetles were collected from nearby forests and housed individually in our lab. We created a simple tabletop arena to observe beetle locomotor activity, which was gridded and included small stones and paper objects. We allowed individual beetles to traverse the arena for 5 min and recorded the number of grid squares crossed. Then, beetles were dissected to determine parasite presence and level of infection (on a categorical scale). A total of 140 beetles were examined across three collections. Statistical analyses of locomotor activity revealed parasite severity predicted locomotor activity, but paradoxically, lightly-infected beetles were twice as active as those without this nematode. Activity diminished with increasing worm burdens thereafter, but even the group with the most severe burdens did not move less than those with no worms. From these results we conclude that this parasite does not result in overall reduction in activity, but rather it appears to come with heightened locomotion. Alternatively, this result could stem from the fact that more active beetles are simply more likely to contract the parasite.

The role of learning to navigate toward a specific location has been extensively studied in the foraging context of social hymenopteran females, which bring resources to the colony. On the contrary, empirical field studies on learning in other behavioral contexts are scarce, particularly in the context of mating. Apis mellifera males (drones) do not forage for themselves and/or for their colony, but they only return to their colony to refuel if they were unsuccessful in mating with a female. In the present study, to test whether homing in drones results from learning the landscape around their hives, we compared the homing success between drones released at sites that were familiar to them (resident group) and those released at unfamiliar sites (transported group). Drones from the resident group were able to return to their hive, whereas those from the transported group could not, with the exception of a few drones that were released close to the sites that offered direct visual information for the drones to return to the hives. These results indicate that drones learn about their hives and the surrounding landscape during their flights.

Control of the sugarcane borers, Diatraea saccharalis and Diatraea impersonatella (= D. flavipennella) (Lepidoptera: Crambidae), in Brazil, is based on mass release of the larval parasitoid Cotesia flavipes (Hymenoptera: Braconidae). However, this method does not prevent some pupae of these borers from completing development and recolonizing the crop. Thus, additional control is required. This study investigated the parasitoid Tetrastichus howardi (Hymenoptera: Eulophidae) to control pupae of sugarcane borers, especially D. impersonatella. Regardless of larval instar and species, no larval parasitism occurred within 24 h of exposure. Nevertheless, a longer exposure period (ca. 96 h) resulted in parasitism of older larvae. Approximately 90% of pupae of both borers were parasitized by T. howardi within 24 h of exposure, and the parasitoid produced a similar number of offspring with >90% females. The developmental time of T. howardi parasitizing D. impersonatella pupae was delayed ~2 days from that of in D. saccharalis. No-choice trails revealed that parasitoid females took longer to start probing larvae compared to pupae. Likewise, when larvae and pupae were offered simultaneously (choice test), the latter represented the first choice of about 92% T. howardi females. The elapsed time to first attack was less on pupae than on larvae, whereas the number of attacks and probing time was greater on pupae. In addition, parasitism on D. impersonatella pupae was higher than on larvae feeding on artificially infested sugarcane seedlings. These results suggest that T. howardi prefers to parasitize the pupal stage and has the potential to be used as a biological control agent to complement the control of sugarcane bores.

The hemlock looper, Lambdina fiscellaria, is a major defoliator of coniferous forests. As looper larvae are known for their wandering habits, we determined the underlying behavioral mechanisms that enable them to orient in the environment. First, we quantified the response of all larval stages to light or gravity, and to both stimuli tested simultaneously. Second, we evaluated the combined effect of substrate texture and light on the selection of pupation sites by wandering mature larvae (4th instar +10 days). We found that light attracted neonates and newly molted larvae of all stages, but response indices decreased significantly between the second and third larval stages. In a 45° inclined tube, larvae showed a geonegative response that remained relatively constant from one stage to the next. No synergy between the two stimuli was observed when a light source was placed on top of the inclined tube. In contrast, when the light source was placed at the base, the light signal dominated the gravity stimulus. Finally, wandering larvae were indifferent to unidirectional light and reacted positively to gravity. They preferred to pupate in a dark environment, a choice that could be modulated by positive photokinesis. Their final selection of a pupation site also involved physical contact with the substrate, which resembles positive thigmokinesis. The ecological significance of these results is discussed in relation to the spatial distribution of the various larval stages on host trees.

A large accumulation of several hundred actively flight-dispersing spotted lanternflies Lycorma delicatula was found on an isolated single telephone pole in a vineyard in Eastern Pennsylvania, USA. Many of the lanternflies flying across the vineyard very near to the pole turned toward and landed on it in an apparent visually mediated response to the tall vertical silhouette, whereas others flew past it. We video-recorded, digitized, and analyzed 481 tracks, of which there were 188 that were behaviorally classifiable with durations greater than 2 s. We found that lanternflies reacted to the 12.5-m-high pole by turning toward it when they were an average of 2.1 m away from it at an average height of 7.8 m. Those that did not react to the pole by turning toward it were at an average distance of 3.6 m from it at a height of 11.5 m. It appears that the object-vision capabilities of the lanternflies to this vertical structure that were intense enough to elicit a behavioral reaction to it were limited to a mean distance of 2.1 m during in-flight approach.

Morphological variation is widespread, and one case is that of female morphs in damselfly insects. Current knowledge indicates that these female morphs are maintained by a fitness balance whereby male-like, clear-colored females (i.e. andromorphs) are more likely to “escape” from male harassment given their male mimicking compared to dark females (i.e. gynomorph). However, males can learn to distinguish the more frequent morph, leading to a frequency-dependent selection. Alternative to frequency-dependent selection, we tested whether temperature plays a role in driving female morph activity and survival. We used Ischnura denticollis damselflies to test for differences between female morphs and males in: (a) daily activity; (b) time to resume activity following a chilling event (10°C); and, (c) survival at 30, 35 and 40°C. There was no difference in activity among groups after a chilling event. However, gynomorph females were more active early in the day (ca. 17°C) and less active by 1600 hrs (after reaching 32°C), and had lower thermal tolerance than andromorph females. Thus, high temperatures may act against gynomorph females. This implies a role for high temperatures in the maintenance of female polymorphism.

The tobacco whitefly, Bemisia tabaci, is a fast-evolving complex species consisting of more than 35 cryptic species (biotypes). Among these species, the Middle East-Asia Minor 1 (MEAM1) and Mediterranean (MED) are the most widely distributed and often cooccurrent. Field investigations showed that MED has eventually replaced MEAM1in most areas in China, but MEAM1still exists alone or together with MED in some areas. There are several hypotheses for species replacement in B. tabaci, but underlying mechanisms need further investigation. In this study, we focused to compare their adaptability and competitiveness of the two species under insecticide-free conditions by using electrical penetration graph (EPG). Feeding behaviors of the two species were recorded on each other’s pre-infested cotton or cucumber plants to mimic their interactions. Fourteen EPG variables indicated that two B. tabaci species performed remarkably differently on both pre-infested cotton and cucumber plants. Specifically, MEAM1 adults exhibited a shorter pathway for probing and a longer phloem sap ingestion than MED on either healthy or pre-infested plants. Both species had more efficient on its own pre-infested plants than on plants pre-infested by the other B. tabaci species. However, MEAM1 showed an advantage on pre-infested plants than MED under the same conditions. Our results clearly indicated that MEAM1 had stronger adaptability and competitiveness than MED on either cotton or cucumber plants without insecticide stresses.

Inclusive fitness theory predicts that the sex investment ratio should be female biased in social insects with haplodiploidy-generated relatedness asymmetry (between females and males and also among females). However, this ratio should become male biased if related females are competing with each other for resources, as it is predicted by local resource competition hypothesis. This specific situation is expected to occur in ant species that reproduce by fission, where young queens leave their mother colonies on foot to found daughter colonies. We tested this idea using the ant Cataglyphis tartessica in Donana National Park (Spain). This species is monogynous (colonies headed by a single queen), monandrous (queen mate with only one male), and reproduces by fission. Given the similarity between foraging and colony fission distances in this species, a strong local competition for resources should be expected between mother and daughter colonies. In this study, we considered investment in females the sum of the investment in gynes (virgin queens) plus the investment in the worker force that leaves with them to found a new colony. Our results show a male-biased sex investment ratio in C. tartessica of 1:8 (numerical ratio gynes/males 1:56), suggesting queen control over sexual production. In addition, we found that, during its reproductive period, this species exhibits split sex (gyne-male) production as well as split male-worker production, without any evidence of variation in relatedness asymmetry between its colonies, at the population level. An interaction between local resources competition and colony size could explain our results.

Mosquitoes include many major disease vectors and are often controlled in their aquatic larval stage, since they are living in defined habitats. However, non-chemical methods of control are influenced by the female oviposition behavior, and this is affected by many factors. Many mosquito species choose to oviposit on water containing egg raft pheromones (which have thus been used in control), showing another female has selected that pool as being best. However, Culex sitiens did not respond chemically to water previously containing egg rafts, but unlike most species, did strongly respond visually to artificial black egg rafts floating on the surface. Oviposition increased as the number of artificial egg rafts increased up to six, but more rafts gave no further increase. However, even nine egg rafts had no repellent effect, despite the high probability of larval overcrowding and thus starvation. Altering the pattern with which five rafts were interconnected and also altering the size of individual rafts seemed to show that the mosquitoes were responding more to total raft area rather than number. The presence of either 2nd instar or 4th (final) instar conspecific larvae in the water can be detected chemically but did not influence oviposition, either positively or negatively. Conspecific larvae show the water is suitable for oviposition, but they are competitors for the available food and so many studies have shown especially older larvae to be repellent to oviposition. Culex sitiens was thus not responding chemically to either eggs or larvae but unusually had a visual response.

Mountain pine beetle (Dendroctonus ponderosae Coleoptera: Curculionidae: Scolytinae) is a major pest of pine (Pinaceae) in western North America. Mountain pine beetle has an obligatory dispersal phase during which beetles fly in search of new hosts to colonize. Climatic factors may influence dispersal in the expanding geographic range of the mountain pine beetle. This study tests mountain pine beetle flight capacity in the laboratory under different abiotic conditions including temperature, light and wind speed. Beetle flight capacity was tested under different temperatures before and during flight and different light regimes in separate computer-linked flight mill bioassays. A wind tunnel experiment tested the effect of wind speed on beetle flight. Pre-flight temperature and temperature during flight did not affect beetle flight capacity (distance or duration). Beetles do, however, use more energy during flight at high temperatures, which could affect host colonization following dispersal by flight of mountain pine beetle in nature. Beetles fly a greater distance and longer duration during a long (18 h) than short (16 h) photophase, suggesting that increased day length with a northern range expansion could affect beetle flight capacity. Although wind speed does not affect flight probability or duration, it affects the number of flights and flight patterns of mountain pine beetles.

The fruit fly, Drosophila suzukii, is an invasive species that causes widespread crop damage in the United States. We examined a series of basic reproductive behaviors in this species in order to expand our knowledge of the life history of D. suzukii. We also conducted a comparison study using its sister species, D. biarmipes, to determine if the two species shared any similarities in sexual behavior. The behaviors investigated were sexual attractiveness, sexual receptivity, and offspring production. The sexual attractiveness and remating frequency (possibly reflecting sexual receptivity) of both D. suzukii and D. biarmipes females decreased significantly after an initial copulation and did not recover within 14 days. D. suzukii and D. biarmipes females also produced an average of 85.19 ± 6.27 and 104.45 ± 6.90 viable offspring, respectively, over the two weeks following the initial copulation, suggesting that they were able to store sperm over an extended period of time. We also found that the sexual attractiveness of virgin D. suzukii decreased as they aged. This decline may be related to nutrition, as their attractiveness did not diminish when the females were raised on a blueberry as well as standard media and yeast. Our results, coupled with the findings of other studies investigating basic life history and reproductive biology parameters, can aid in the effort to halt the spread of D. suzukii by informing and refining future and current pest management strategies.

Males of many moths possess scent organs, ranging from simple scales and hair-tufts to complex glands. Males of the gregarious beet webworm Loxostege sticticalis (Lepidoptera: Crambidae) display their ventroposterior brushes (VPBs), located on the eighth abdominal sternite, toward adjacent females and usually maintain this posture until sexually receptive females become available, or the arrival of photophase. The peak period of male L. sticticalis VPB display during the scotophase broadly coincides with that of mating. Our experiments revealed that females exposed to male VPB display increased their calling behavior and were more likely to mate than those exposed to males that did not display their VPBs. Volatile chemicals provide the only reliable sensory modality for intersexual communication in L. sticticalis because all behavioral assays were conducted in a sealed darkroom, thereby eliminating a role for visual signals, and no vibratory signals occurred during VPB displaying. Therefore, odors released from the VPB of male L. sticticalis may act as aphrodisiac signals to conspecific females in order to enhance female receptivity and increase his mating success. Our study indicates that chemical communication in these gregarious moths apparently involves mutually stimulating interactions between female attractant and male courtship pheromones.

The ant Odontomachus monticola has a pair of elongated mandibles that can manipulate a variety of objects including food, brood and nestmates. Anatomical and theoretical studies indicate that different tasks may require modification of mandible speed and force which is achieved by modulating the respective activity of three sets of muscles. Despite the advanced investigations on how muscles separately control the mandible movements in trap-jaw ants, real-time visualization of the muscle activity has remained elusive. In this investigation, we developed an approach based on the synchrotron imaging technique to elucidate the real-time topology of the muscles in the head of the ant. Using synchrotron imaging, we described the topology of the living ant’s mandible muscles and calculated area changes in the intracranial muscles, which reflected the respective muscle’s activities in the strike of mandibles. This study provides the first visualization evidence which validates that the mandible strike is facilitated by the contraction of adductor muscles, without the activation of abductor muscles.

Many insects use tactics to protect their eggs from predation, infection, and water loss, among other risks. Some assassin bugs only in the New World tribe Apiomerini are known to use plant substances, such as resin, instead of secretions to protect their eggs. Here, we report a novel storage mechanism and the utilization of plant resin for egg protection in Asian assassin bugs, Velinus nodipes and Agriosphodrus dohrni (tribe: Harpactorini). Adult females of both species were observed to take in plant resin through their genitalia. We reported on the handling of resin by these species and confirmed that A. dohrni adult females stored resin in their subrectal glands and that the substance covering their egg masses was derived from plant resin. This is the first report on the storage of plant resin inside the bodies of assassin bugs and on resin-protected eggs in Harpactorini. Such internal resin storage was not accompanied by external morphological features, as observed in some Apiomerini assassin bugs, thereby suggesting that this tactic has been overlooked and may have evolved in broader tribes of assassin bugs than previously thought.

The leaf beetle Ambrostoma quadriimpressum (Coleoptera: Chrysomelidae) is monophagous on elm trees, Ulmus pumila (Ulmaceae). As this species lives on elm during most of its life but pupates and overwinters as an adult in the soil, the flightless beetle seeks a host plant after emergence from the soil. Previous field experiments showed that the beetle locates host plants via orientation to standing black targets and does not recognize host plant prior to contact it. In order to establish the relationship between preferential vision fixation and host locating behavior, we investigated the visual orientation by placing individuals in the center of an arena and recording their responses to different targets at the perimeter. Responses were compared for a control object - a vertically positioned 10 × 30 cm black rectangle - versus a treatment object that differed from the control in terms of width, height, orientation, edge features, or color. Higher, wider, vertical, and solid black objects were more attractive to the beetle than objects that are shorter, thinner, inclined or have stripes, whereas two altering features (wavy or serrated) of the target’s vertical edge had no effect. The red and black targets were equally attractive, whereas blue, green or yellow objects were less attractive than black ones, and adding a green disk at the top of a black target did no enhance attraction. These visual preferences corroborate that the beetle is attracted to objects that resemble a tree trunk during the field search for a host. The implicated mechanism of vision fixation and host locating pattern of this beetle are discussed.

Paysandisia archon (Lepidoptera: Castniidae) is a pest on palms in Europe. The moth was introduced about twenty years ago, when infected palms were imported from South America. In P. archon, little is known about mate location and the putative activity of the male-produced sex pheromone. The aim of this study was, therefore, to study olfactory responses of P. archon to conspecifics, with and without visual cues, in a wind tunnel and in the field. Results showed that the virgin males exhibiting the scratching behavior, whether they were visible or not, attracted virgin females at long range. Females approached the males, and some landed close to them. In P. archon, the mate location is thus mediated by a long-range pheromone released by males during the scratching behavior. Our findings are providing new insights into the chemical ecology and mate location in P. archon and may serve to further develop efficiency in handling the pest.

Some parasitoids oviposit in nonhosts. Parasitization of nonhosts potentially wastes gametes, risks the death of offspring, and reduces fitness. Associative learning, a strategy for efficient reproduction, has been observed in various parasitoid species. We conducted two types of experiments to reveal whether larval parasitoid wasps, Cotesia kariyai (Hymenoptera: Braconidae), learn associatively by ovipositing in nonhosts. In dissection experiments, we found wasp eggs in both host [Mythimna separata ( Lepidoptera: Noctuidae)] and nonhost [Spodoptera litura ( Lepidoptera: Noctuidae)] caterpillars. However, the mean number of eggs in nonhosts was significantly smaller than in hosts. In oviposition experiments, most naive C. kariyai females attacked both hosts and nonhosts. On the other hand, wasps that had previously attacked nonhosts tended to avoid them thereafter. We conclude that C. kariyai females may be able to detect and identify nonhost metabolites and/or cuticular hydrocarbons. Negative associative learning enhances C. kariyai reproductive success when hunting in complex host habitats.

Adult spotted lanternflies, Lycorma delicatula, launch themselves into the wind from elevated locations such as trees, lamp posts, and buildings. Individuals fly in short, successive bouts along descending trajectories of between 10 and 50 m before landing, crawling upward on a new structure, and again launching upwind. The possible physiological limits to the durations of flight-bouts, if not constrained by their poor ability to generate lift, however, remain unknown. In this study, we observed the behavior of tethered spotted lanternflies known to be prone to flight-dispersing, and recorded the number and durations of their successive flight bouts. Additionally, we recorded the flight distances and durations of similar spotted lanternflies in the field that had spontaneously taken flight or had been manually launched. We found that tethered females can perform >20 successive bouts with only 1 min between bouts when flight durations were limited to 20 s/bout. Bouts averaged 97.9 ± 11.4 s when bout durations were unlimited, with some females flying bouts lasting >400 s. Females could quickly advance upwind a distance >3000 m if the bouts of ~100 s each were performed in quick succession in the field. However, adults spontaneously taking flight in the field flew for an average of only ~13 s and traveled an average of ~29 m before landing on the ground or on nearby objects. This information is important to determine how far a locally dispersing adult can fly before finding a suitable host to finish feeding and attain reproductive maturity.

Hibiscus harlequin bugs (Tectocoris diophthalmus) are Australian jewel bugs known for their maternal care behavior, gregariousness and warning coloration. They feed on plants in the Malvaceae family, although the nymphs will also cannibalize unguarded eggs. Here, I detail observations over 3-year period in Brisbane (QLD), mostly on cultivated Hibiscus and Malvaviscus varieties, to quantify the frequencies at which nymphs and adults occur in groups and the sizes of these groups. I also performed manipulative experiments where I placed individuals together to form groups, or to threaten females guarding a clutch of eggs, and recorded their responses. I observed that harlequin bugs repeatedly colonized a select few individual bushes in sunny locations within the study area. Egg guarding females defended against both conspecific nymphs and adult bugs placed next to the eggs, but rarely responded to the eggs being touched directly with my finger. Nymphs were far more commonly in groups than solitary, and often appeared to aggregate with non-siblings. Further, nymphs inserted into groups mostly remained there. Adults were usually solitary, and typically moved apart if placed together. I suggest that differences in the typical coloration of nymphs (shiny blue) and adults (orange) and possible dual functions as warning and camouflage might explain why nymphs are vastly more social than adult bugs.

The cucumber moth, Diaphania indica (Lepidoptera: Pyralidae), is one of the most destructive pests of cucurbitaceous plants all over the world. Previously, we showed that volatile organic compounds (VOCs) from cucumber plants play a crucial role in guiding gravid D. indica females to oviposition sites, whereas watermelon VOCs did not, and females significantly prefer cucumber over watermelon for oviposition. It remained unclear, however, whether preferred and non-preferred host plants also affect moth reproductive behaviors. In the present study we investigated the effect of preferred and non-preferred host plants on female calling, male attraction to female sex pheromone, and mating behavior in D. indica. In the presence of cucumber, virgin females engaged in significantly more calling on the first night than in either the watermelon treatment or the control. Also, we found that the mean time per bout on the first night in the cucumber plant treatment was significantly higher than that of the other two groups. The combination of cucumber foliage with female pheromone significantly increased the attraction and landing of males compared to either watermelon or the control in the wind tunnel. Furthermore, for one-day-old insects mating occurred only in the cucumber treatment. All insects in the cucumber treatment exhibited their first mating on one of the first three nights, but in the watermelon treatment only by night four had all insects mated. We also found that the duration of first mating in cucumber was significantly greater than in either watermelon or control. Overall, our study provides evidence that preferred and non-preferred host plants affect reproductive behaviors in D. indica.

A honey bee has to visit 3000 flowers to produce one-gram of honey. A honey bee’s hairy tongue dips at an average frequency of 5 Hz, and its glossal hairs erect rhythmically, performing like an opening and closing umbrella to trap the nectar. Dipping by a honey bee tongue is a typical micro-fluidic transport with a low Reynolds number. The high intensify of feeding activities inevitably damage on the fragile tongue structure. We found that that in nature, honey bees with incomplete tongue tips can still load the nectar with hairs erected. Furthermore, the hairs deploy more to form a larger umbrella-like configuration, and the dipping frequency augments when tongues are damaged on the tips, possibly compensating for the nectar intake loss caused by structural damage. Here we examine by experiments and modeling the functional compensation facilitated by the compliant mechanisms in the honey bee tongue. We put forward a fluidic transport model to evaluate nectar intake rate in a damaged tongue, considering variation in hair erection angle and dipping frequency. Theoretical analysis indicates that both mechanisms compensate for nectar intake loss caused by damaged tongue. The findings suggest a new mechanism for functional compensation in flower-visiting insects that may prove useful in engineering applications.

Dulosis is a type of social parasitism in which a parasitic ant has become dependent on captured workers (hosts) of a closely related species. Dulosis can be either facultative or obligate depending on the degree of dependence on host workers. As parasites become more specialized over evolutionary time, their domestic abilities degenerate until they become unable to survive without the host. However, depending on the degree of specialization, the “lost” behaviors may display some degree of recovery when host workers are unavailable to do the tasks. The 12 species of the Formica sanguinea group are all traditionally considered to be facultative parasites. However, recent studies suggest that one member of the group, F. subintegra, has characteristics that are more consistent with obligate parasitism. To explore the degree to which F. subintegra has become obligate, this study examined the degree of recovery of foraging and nest excavation behaviors of parasites when hosts are removed. When parasites were isolated from hosts, they spent more time foraging and feeding regurgitated food to nestmates (oral trophallaxis), and tended to begin feeding sooner following a period of fasting than when hosts were present. Isolated parasites were able to excavate suitable tunnels and engaged in nest building behavior significantly more often than parasites in groups with hosts. These results indicate that F. subintegra demonstrates some recovery of its foraging and nest excavation abilities, and can be considered a less specialized (more primitive) obligate parasite. Formica subintegra and its facultative relatives can be used as models for studying the progression of dulotic evolution within a closely related group of social parasites, and may shed light on which factors contribute to the transition from facultative to obligate parasitism.

The interaction of antlions and ants is postulated to be a predator-prey interaction in which the involved parties coevolve. Here, we investigated two issues of potential significance in terms of antlions and ants imposing selective pressures on one another. First, we determined whether trap-building antlions and sand-dwelling ants closely co-occurred in an area inhabited by both. In the field, we found that ants were the main potential prey items in artificial traps placed inside aggregation zones of antlions and that Formica cinerea workers comprised the majority of these ants. Second, we checked whether rescue behavior, a type of prosocial behavior displayed by F. cinerea workers and performed towards nestmates captured by antlions, reduced the hunting success of the latter. In the laboratory, we found that rescue attempts were very rarely successful. Overall, caution must be used when considering the coevolution of antlions and ants. Clearly, even though these two organisms can closely co-occur, the rescue behavior of ants seems to be unrelated to the predatory threat from antlions.

Host attachment is a necessary behavior in the evolution of parasitism. It is hypothesized that populations pass through a stage of facultative parasitism before the evolution of obligate parasitism. Previous research has revealed the impact of extrinsic factors on the expression of parasitic tendencies, but to our knowledge, the role of individual behavioral variation driving parasitic tendencies remains to be tested. Here, we used repeated behavioral assays to quantify attachment propensity and activity level of individual Macrocheles muscaedomesticae, facultatively parasitic mites of flies, from two different populations. Mites from both populations exhibited repeatability in attachment propensity and mites from one population exhibited repeatability in activity level. We did not find a relationship between an individual’s activity level and attachment propensity. Our data suggest that facultative parasitism may not simply describe a phenotypically plastic strategy that responds to environmental cues, but perhaps that individual differences in parasitic tendencies may appear like facultative parasitism at the population or species level.

Cannibalism is a widespread behavioral phenomenon that is often thought to be an adaptive plastic response to limited environmental resources. However, cannibalism can potentially come at a fitness cost to an individual if one consumes relatives, due to the potential loss of indirect fitness benefits. One way in which this cost could be avoided is by the selective avoidance of cannibalising kin in favour of consuming non-kin conspecifics through the use of kin recognition mechanisms. Here, we examined whether fruit fly (Drosophila melanogaster) 2nd instar larvae differ in their interactions with groups of related and unrelated eggs, and whether this is associated with differential rates of cannibalism. Our experiment revealed that, at this developmental stage larvae appear to be able to distinguish between full-sibling eggs and non-kin eggs, as they behaved differently towards these two groups. Larvae approached groups of unrelated eggs more frequently and spent more time overall associating with them than they did with groups of related eggs. Furthermore, larvae cannibalized unrelated eggs significantly more frequently than kin eggs. These results are consistent with a kin-selection behavioral strategy that maximizes both direct and indirect fitness benefits. We discuss these findings in the context of this species’ natural history, and the potential mechanisms of kin recognition. This study contributes to the growing body of research examining the evolution of social behaviors using this model species.

Female response to male sexual signals is context dependent and influenced by a variety of environmental factors. For instance, females often adjust mating preferences in response to predation risk. Social experiences as a juvenile, such as exposure to conspecific sexual signals, have also been shown to influence female mating preferences as adults. Experiments that examine the influence of both environmental factors and early social experiences on female preferences are needed to understand female mating behaviors in the wild. In Pacific field crickets (Teleogryllus oceanicus), males produce a calling song that females evaluate during mate choice. We examined the influence of both risk perception and juvenile exposure to calling song in shaping adult T. oceanicus female phonotaxis to either a high- or low-quality calling song. We predicted that females raised in song-less conditions would be more responsive to calling song to maximize mating opportunities, and that females would show reduced response to calling in a risky, open area. Females raised in a song-deprived environment were much more responsive to calling song compared to those reared with song. In contrast to our predictions, females raised in song-less conditions were more responsive to the high-quality song in the risky, open arena. These results suggest that juvenile acoustic rearing influences female responsiveness to male calling song, but it has less influence on strength of preference for signal quality.

Leaf cutter ants are model organisms in studies of central place foraging, but these ants carry smaller than optimal leaf fragments for their body size. Laboratory experiments show that load ratios (leaf fragment mass/ant mass) are higher on extreme downhill trails than on extreme uphill trails, which could explain deviations from optimality in the wild. Here we examine how trail gradient affects load size selection in the field for the first time. We measured load ratios on extreme natural gradients in the mountains of Monteverde, Costa Rica. In general, load ratios were found to be higher on downhill trails than on uphill trails as found in laboratory studies. Not all colonies showed this pattern, indicating that other factors may interact with trail gradient to determine load size selection. The results confirm that extreme trail gradients can contribute to determine optimal load sizes in central place foraging in natural conditions.

This review examines visually guided search behavior during walking in different species and developmental stages of insects having contrasting habitat utilization strategies. The discussion focuses on mantises, short-horned grasshoppers and crickets. Although generally short-horned grasshoppers are travelers, whereas mantises are ambush predators, all of these insects exhibit visually guided behavior during walking in the search for food sites and shelter. In crickets, which are central place foragers, visually guided behavior during walking is also important for nest site homing. Despite differences in habitat utilization, these three insect groups all use searches incorporating intermittent locomotion, where the distances traveled and duration of pauses have a distinct functional significance. However, there are also locomotion pattern variations, such as loops, zigzags, spiral patterns and straight lines. Search strategies during walking include searches with and without visual landmarks. The detection and recognition of stationary visual landmarks is based on self-induced retinal image displacement, with differing underlying neuronal mechanisms in the three insect groups. If a visual landmark is identified as a suitable target, a direct approach is elicited under either open- or closed-loop conditions, depending on the situation. In the presence of more than one suitable target object, the behavioral response can be temporarily restricted to stimuli associated with a particular area of the visual field, while information from other areas of the visual field is suppressed. The review concludes that there are gaps in knowledge concerning the various questions and thus further research is needed.

Cockroaches can defend themselves from threats by escape behavior. Although wind-evoked turning in Periplaneta americana is robust, little is known about the turning and translational components of the escape response to looming and localized heat stimuli, especially in other cockroach species. In particular, it has been suggested that the Madagascar hissing cockroach (Gromphadorhina portentosa) lacks an escape response. Our goal was to use high-speed video to explore both the turning and translational components of the escape response of Madagascar cockroaches to looming and heat stimuli. Our results demonstrate that, in contrast to expectations based on previous studies, Madagascar cockroaches do show an escape response that was adapted to looming direction and heat location. Although the escape response to looming stimuli was limited, the response to heat stimulation of their tarsi was unexpectedly robust, especially in translation. The translational responses to both looming and heat were directionally similar (160o and 166o). Our results demonstrate that G. portentosa also exhibits a well-organized escape response and emphasize the need to quantify both turning and translation to obtain a more complete description of an animals’ escape movement.