Journal of Insect Behavior最新文献

Pear psyllid (Cacopsylla pyri) is a persistent pest to the pear industry; with an estimated cost of £5 million per annum in the UK alone. This phloem feeding insect is resistant to a large proportion of approved pesticides, necessitating the use of alternative control strategies. Many pear growers practice integrated pest management (IPM) of pear psyllid, focusing on maximizing natural enemy populations, whilst minimizing the use of agrochemical sprays. The anthocorid Anthocoris nemoralis and the European earwig Forficula auricularia are particularly effective at controlling pear psyllid populations during the summer months. Despite the effectiveness of both natural enemies, there is a lack of understanding on whether both species should be promoted together or separately, due to the risk of intraguild predation (IGP) or interference competition. Furthermore, abiotic factors including temperature may influence both behaviors, altering activity level and niche overlap. Although IGP and interference competition have been documented between multiple species of natural enemies neither have been studied between these two specific predators. Using microcosm experiments, olfactometer assays and survival analyses this study demonstrated whether A. nemoralis and F. auricularia can be used in synchrony to control pear psyllid. Results indicated that IGP is present; F. auricularia will consume A. nemoralis when predators are not spatially separate and in absence of psyllid prey. There was no evidence for interference competition, although both predators consumed more prey at higher temperatures. This confirms that pear growers can encourage both predators for the control of pear psyllid without losing predation efficacy.

Scientists have long studied the unexpected resistance of eusocial insect colonies to pathogen and parasitic threats. Despite having many closely related individuals living in proximity, these colonies have shown the ability to persist for long periods of time without epidemic collapse. Previous studies have theorized a variety of reasons for their ability to withstand chronic infections including the conveyor belt model and task specialization. The impact of each of these different strategies and the synergy between them is unknown. Testing the impact of each strategy experimentally may be difficult and time consuming. This paper examines the impact of five (5) strategies used by Camponotus rufipes to endure a chronic infection from Ophiocordyceps camponoti-rufipedis, a fungal infection which results in “zombie ants.” These five strategies are to avoid areas with increased numbers of spores, prevent completion of the fungal lifecycle within the nest, use specialized workers, separate groups within the nest, and invest less in forager immune response. A full factorial analysis of the strategies is performed through an agent-based model by selectively turning “off” each of the strategies. The contribution of this work is two-fold. First, a conceptual model for C. rufipes is presented. Synthesizing the current literature, the result is a tool for modeling colony behavior. Secondly, the output of the model indicates the role of each strategy in preventing fungal disease propagation in the colony and the interaction effects between the strategies. Analysis includes a 5-way ANOVA with interaction effects, post-hoc testing, and effect size measurements. Significant findings include that the strategy of minimizing the chance of fungal infection and preventing the fungus from completing its life cycle within the nest are the most important. When these strategies were disabled, 100% of colony collapse occurred. Additionally, the use of the conveyor belt approach (the use of older ants to forage) had a negligible effect on colony survival. Interaction effects between the five strategies are also presented. The results of this work highlight the synergies between the strategies used to prevent O. camponoti-rufipedis propagation, guide future experimentation on this species, and provide additional information for those seeking to use this species as a source of biologically inspired design.

In response to physical damage, organisms must balance recovery with adaptive responses to other environmental stressors. Understanding how damage and repair influence adaptive responses to high environmental temperatures is of particular interest in light of global climate change. We investigate the impact of damage and subsequent repair on heat-avoidance behaviors in Cydia saltitans larvae using host seeds (Sebastiania pavoniana) as protective structures (together colloquially known as “Mexican jumping beans”). These larvae perform temperature-dependent “jumping” or “rolling” behaviors to escape extreme heat, which are crucial for larval survival in their native arid and hot subtropical dry forests. Due to possible costs of repair and limited energetic resources, we hypothesized that experiencing damage and investing in subsequent repair to a host seed would reduce larval displacement distance from extreme heat when compared to individuals that experienced damage without repairing the host seed, or the undamaged control group. Results suggest that larvae in control conditions exhibited greater displacement from heat compared to those in either damage treatment group. Contrary to predictions, damage and subsequent repair impaired heat avoidance behavior to same extent as damage without investing in repair. This reduced displacement distance in both damage treatment groups may be linked to energy allocation or an adaptive antipredator response. These findings contribute to our understanding of how environmental stressors interact to shape behavioral responses in insects with “extended architecture.” As global temperatures rise, insights into the flexibility of adaptive behaviors are increasingly crucial.

Death feigning is thought to have evolved primarily as a predator avoidance behavior, and has been reported in 10 of the 31 orders of insects. However, there have been no reports of death-feigning behavior in Mecoptera species. We found that larvae of two scorpionfly species, Panorpa japonica and P. pryeri, showed death feigning in response to external stimuli by brush poking stimulation. First, we examined the frequencies of death-feigning postures. The two species showed two different postures of death feigning, “straight” and “ball.” Most of the 1st instar larvae of P. japonica and P. pryeri adopted the straight death-feigning posture. Next, we examined duration of death feigning. As the larval instar progressed, the death-feigning posture shifted from straight to ball in both Panorpa species. In P. japonica, the longest durations of death feigning were found in the 2nd to 3rd instars, while the longest duration of death feigning was found in the late 4th instar in P. pryeri larvae.

Chironomidae (Diptera) are one of the most abundant aquatic insects in freshwater habitats and play key roles in aquatic ecosystems. Many studies have assessed chironomid longevity under varying conditions to estimate potential consequences of climate change on longevity. However, these studies did not account for behavioral changes that may affect the ability of chironomids to find a mate or return to the water for oviposition. Longevity estimates may therefore underestimate the effects of climate change on chironomids by neglecting behavior-related fitness losses. To better understand how chironomid behaviors relate to survivorship, we used previously identified behaviors to determine how behavior patterns changed as the chironomid Diamesa mendotae aged. We found that D. mendotae exhibited age-related behaviors that correlated with a decrease in mobility over time. Additionally, behaviors performed early post-collection in D. mendotae adult lifespans were predictive of total chironomid longevity. These findings will help improve estimates of chironomid longevity and our understanding of age-related behaviors in other invertebrates. Improved methods for determining longevity and age-specific fitness-linked behaviors will allow us to better understand climate change’s impacts on aquatic insect survival and reproduction, which has broad ramifications for the aquatic ecosystems where they are abundant.

Optimal foraging and individual specialization theories suggest that different properties of the interactions between prey and predators determine foraging strategies. However, none of these theories consider how the nutritional status of the predators and the risk of being attacked by other predators may affect prey foraging strategy. Shelter-building spiders, such as Metazygia laticeps (Araneidae), build webs as dynamic traps to capture prey and may optimize capture efficiency while adopting strategies to minimize their exposure to predators by building a shelter and staying inside it most of the time. Prey capture, however, involves leaving the shelter, which may contribute to an increased risk of predation. Individuals may be more likely to take risks when they are in poor nutritional status. In this study, we conducted field experiments to assess support for the hypotheses that M. laticeps spiders with poor nutritional status (i) expose themselves to greater risk of predation during foraging and (ii) invest more silk in different web structures to increase prey capture success. Nutritional state was unrelated to exposure to predation and did not restrict web investment in M. laticeps. However, spiders left the shelter more quickly at night than during the day, regardless of their nutritional state. We suggest that individual’s nutritional state does not determine foraging, and predation risk can affect general activity of spiders depending on foraging period.

We explored the potential of differences in foraging preferences to contribute to long-term species coexistence in aquatic predatory hemipterans. We hypothesized that predatory hemipterans would have distinct foraging preferences informed by their morphology. We used a prey choice experiment to test whether Belostoma flumineum, Pelocoris biimpressus, and Ranatra australis differed in their relative preferences of amphipod, damselfly naiad, and physid snail prey. We discovered that the predators showed complementarity in their foraging preferences with B. flumineum preferring snails, P. biimpressus damselfly naiads and R. australis amphipods as prey. Our results suggest that the disparate foraging preferences of aquatic hemipterans may facilitate their coexistence in aquatic systems but caution that studies need to explore whether patterns uncovered in the laboratory experiment reflect interactions in nature.

Where a female lays her eggs has strong implications for the survival of her offspring, an impetus that takes on particular significance for species that exhibit highly specific requirements. The preference-performance (optimal oviposition) hypothesis predicts that an individual will place its eggs where the resulting offspring experience their highest success. We assessed the spatial patterns of ovipositioning of the rare, monophagous Harris’ checkerspot butterfly (Chlosyne harrisii: Nymphalidae) and related this pattern to the survival of their early offspring, and the initial foraging-site decisions of the young. Harris’ checkerspots laid their egg masses exclusively on flat-topped white asters (Doellingeria umbellata: Asteraceae), exhibiting a strong preference for tall plants (> 40 cm). However, they frequently laid multiple egg masses on a single plant, seemingly contradicting the preference-performance hypothesis, since even a single brood usually consumed all the leaves of its natal plant, eventually forcing the caterpillars to find another host plant. Larvae in the second instar recruiting to their next aster experienced extremely high losses, though some individuals usually managed to locate the closest site. Accordingly, the average success of single broods on a foodplant significantly exceeded that of multiple ones. We thus found little evidence that plant characteristics associated with oviposition choice benefitted overall survival. Although occasional second broods prevailed over first broods, they typically had fewer food resources than on an unoccupied plant. This study presents an apparent conundrum for the preference performance hypothesis with potential implications for the conservation of this rare butterfly.