Journal of Insect Behavior最新文献

The monarch butterfly is a flagship species and pollinator whose populations have declined by 85% in the recent two decades. Their largest population overwinters in Mexico, then disperses across eastern North America during March to August. During September-December, they return south using two flyways, one that spans the central United States and another that follows the Atlantic coast. Migrating monarchs fly diurnally and roost in groups nocturnally. We sought to determine the criteria this species uses to select roost sites, and the landscape context where those sites are found. We developed species distribution models of the landscape context of Atlantic flyway roost sites via citizen scientist observations and environmental variables that affect monarchs in the adult stage prior to migration, using two algorithms (Maximum Entropy and Genetic Algorithm for Ruleset Prediction). We developed two model validation methods: a citizen scientist smartphone application and peer-informed comparisons with aerial imagery. Proximity to surface water, elevation, and vegetative cover were the most important criteria for monarch roost site selection. Our model predicted 2.6 million ha (2.9% of the study area) of suitable roosting habitat in the Atlantic flyway, with the greatest availability along the Atlantic coastal plain and Appalachian Mountain ridges. Conservation of this species is difficult, as monarchs range over both large areas and various habitat types, and most current monarch research and conservation efforts are focused on the breeding and overwintering periods. These models can serve to help prioritize surveys of roosting sites and conservation efforts during the monarchs’ fall migration.

Abstract

Animals living in social groups often need to conduct certain tasks, such as prey capture or nest maintenance. We might expect individuals to specialize in these tasks, as specialization should increase efficiency and therefore group performance. In groups that vary in sex, morphology, or generation, these factors often determine task participation. However, in social groups where these factors are invariant, persistent individual differences in behavior may drive task specialization. We tested this prediction in groups of the social spider Anelosimus eximius, through experiments conducted on natural colonies in the field. We measured the response to a risky stimulus of individual spiders and then tested whether this predicted their location and/or activity when placed back in a colony. We found the more risk-prone individuals were more likely to be in the more exposed areas of the colony used for capturing prey. Irrespective of the risk-taking behavior, individuals rest and care for young in the protective region of the colony, while in the exposed area of the web individuals are more active and more likely to be walking. Therefore, individual’s responses to risk showed an influence on where an individual would settle within the colony but had no effect on its activity. Our results support previous work that suggests adult A. eximius do not specialize in tasks. Indirect pathways for individual traits, via differences in spatial location or activity levels, may help to explain variation among-individuals in task participation.

Abstract

Herbivorous insects frequently exhibit sexual dimorphism in body size and a variety of other traits. Such differences often lead to distinct behaviors, which may present themselves in insect responses to conspecifics, plant defenses, and feeding. Based on a previous study of a congeneric species, we hypothesized that sexual dimorphism may yield differences in how the host-specific red milkweed beetle Tetraopes tetrophthalmus (Coleoptera: Cerambycidae) deactivates milkweed defenses, a behavior in which beetles cut latex-delivering veins prior to feeding. We also predicted that beetles would display differences in their subsequent feeding patterns and attraction of conspecifics. Although beetles were size dimorphic (females were larger than males), we did not find consistent differences in the rates of vein cutting or initiation of feeding between males and females. Females did, however, cut more milkweed veins per leaf, and attracted more conspecifics than males. Sex differences in size and other traits were thus associated with differential attraction, but not strongly associated with the overall deactivation of plant defense.

The three-cornered alfalfa hopper (TCAH), also known as Spissistilus festinus (Hemiptera: Membracidae), infests legumes and poses a threat to the grapevine industry by acting as a vector for grapevine red blotch virus (GRBV), which causes red blotch disease. Assessing TCAH flight capacity is key for understanding the risk of GRBV transmission. In this study, we examined the flight propensity and flight capacity of male and female TCAH using a flight mill apparatus under laboratory conditions. Our results revealed that sex and age had a significant effect on flight capacity. As insects aged, their flight capacity increased, with two-to-seven-day-old insects flying for shorter durations and covering shorter distances compared to mature insects (≥ eight days). Moreover, male insects exhibited significantly longer and farther flights compared to females, with an average flight capacity of 570.22 m for males and 239.57 m for females. Flight propensity, however, was not influenced by sex or age, as 88% (37/42) of males and 70% (31/44) of females engaged in flight. We observed that female TCAH were heavier and possessed larger wings than males. Nevertheless, wing loading and wing aspect ratio were similar between sexes, suggesting that morphological characteristics were not responsible for the observed differences in flight capacity. Our findings indicate that males have a greater capacity for GRBV dispersal compared to females, thereby providing a foundation for assessing the risk of GRBV spread facilitated by TCAH in vineyards.

Considering recent developments in gene manipulation methods for honey bees, establishing simple and robust assay systems which can analyze behavioral components in detail inside a laboratory is important for the rise of behavioral genetics in the honey bee. We focused on the antennal movements of the honey bee and developed an experimental system for analyzing the antennal responses (ARs) of the honey bee using DeepLabCut, a markerless posture-tracking tool using deep learning. The tracking of antennal movements using DeepLabCut during the presentation of vertical (downward and upward) motion stimuli successfully detected the direction-specific ARs in the transverse plane, which has been reported in the previous studies where bees tilted their antennae in the direction opposite to the motion stimuli. In addition, we found that honey bees also exhibited direction-specific ARs in the coronal plane in response to horizontal (forward and backward) motion stimuli. Furthermore, an investigation of the developmental maturation of honey bee ARs showed that ARs to motion stimuli were not detected in bees immediately after emergence but became detectable through post-emergence development in an experience-independent manner. Finally, unsupervised clustering analysis using multidimensional data created by processing tracking data using DeepLabCut classified antennal movements into different clusters, suggesting that data-driven behavioral classification can apply to AR paradigms. In summary, our results revealed direction-specific ARs even in the coronal plane to horizontal motion stimuli and developmental maturation of ARs for the first time, and suggest the efficacy of data-driven analysis for behavioral classification in behavioral studies of the honey bee.

Dispersal is an important behavior in many animals, with profound effects on individual fitness and the evolutionary trajectories of populations. This is especially true within taxa with particular life-history strategies, for example those that exploit ephemeral habitat. Further, dispersal is commonly seen to be part of behavioral syndromes - suites of traits that covary across behavioral contexts. The red flour beetle, Tribolium castaneum (Coleoptera, Tenebrionidae), is a major post-harvest crop pest responsible for large losses through the infestation of stored grain. In this system dispersal is known to have a strong genetic basis and differential artificial selection on dispersal traits produces strong phenotypic divergence. However, it is unknown which traits are able to rapidly evolve to produce these results, or which behavioral components underlie differences in dispersal. Using replicate lines of T. castaneum previously selected for divergent dispersal behavior, we test for correlated activity and movement patterns, morphology and substrate surface use. We find robustly repeatable associations between the dispersal phenotype and higher activity, straighter paths, larger body size (but not relative leg length) and increased tendency to remain at the surface of fodder. Together our results suggest that dispersal is part of a syndrome of traits in T. castaneum, and must be treated as such when considering the evolution of dispersal in this system, and in attempting to predict and control its spread.

Supplementary information: The online version contains supplementary material available at 10.1007/s10905-024-09862-x.

In the multimodal communication of Schizocosa ocreata wolf spiders, males respond to chemical signals from females with visual and substrate-borne vibratory signals for courtship. We examined the effect of wet vs. dry leaves on transmission of male courtship signals, responses of male spiders to female chemical cues, responses of courting males to bird calls indicating predator presence, and mating success. Laser Doppler vibrometry showed that spider stridulation and percussive signals maintain higher amplitude over distance on dry leaves than on wet leaves. Male response to chemical cues (courtship latency and rate) declined after leaves with female silk became wet. In response to predatory bird calls (Blue Jays) transmitted through leaf surfaces, courting male spiders on dry leaves responded with anti-predator “freeze” behaviors more often and with longer duration than those on wet leaves, and with longer latency to return to courtship on wet leaves. Laser Doppler vibrometry confirmed that bird calls on dry leaves had significantly greater average amplitude and different spectral profiles than those on wet leaves. Males courted females on wet and dry leaves with equal frequency, but subsequent mating success was significantly greater on dry leaf litter. Interestingly, visual signals increased on wet leaves, suggesting compensatory behavior in response to moisture. Given a predicted change in precipitation in parts of North America because of global climate change, these results suggest potential for impact on behavior of invertebrates at the microhabitat level.

Egg-laying decisions by female insects should balance aspects related to immature survival and foraging profitability of emerging larvae. Using field-captured individuals, we characterized the egg distribution of Istocheta aldrichi (Diptera: Tachinidae) on the body of its adult host, the Japanese beetle Popillia japonica (Coleoptera: Scarabaeidae). We determined whether the pattern varies as a function of host sex and the number of eggs laid on a given host. Out of the 5667 eggs observed, 95.9% were located on the host pronotum. Furthermore, eggs on the pronotum were mostly positioned in the center of this sclerite and oriented perpendicular to the host body axis. The proportion of eggs placed on other parts of the host body increased with the number of eggs per host (superparasitism). Successful development of I. aldrichi into pupae was maximum for eggs laid on the host pronotum than for eggs laid on other parts of the host. Oviposition decisions in I. aldrichi are likely shaped by trade-offs between vulnerability to grooming by the host and foraging profitability of neonate larvae (i.e., their capacity to penetrate the host cuticle), but also by the mating and defensive behaviors of the Japanese beetle.

Sternochetus mangiferae (Coleoptera: Curculionidae) is an important pest of mango trees around the world. This work aimed to investigate the reproductive behavior, stridulatory communication and describe the stridulatory apparatus and basic mechanism of signal emission in this species. This knowledge may facilitate the development of monitoring and control tactics. Reproductive behavior was observed in experimental arenas where stridulatory emissions of males and females were recorded. Stridulatory signals were analyzed in two different behavioral contexts, stress and reproductive behavior. Scanning electronic microscopy and stereoscopic microscope images were analyzed to describe the stridulatory apparatus and mechanism of signal production. Reproductive behavior of S. mangiferae showed some basic behaviors, described previously in other Curculionidae, including rapid movements and encounter of pairs and mounting of females by males together with emission of stridulatory signals. In response to these stridulatory signals, females interrupted their movement which facilitated copulation. Stridulatory signals emitted in the two different behavioral contexts showed specific temporal and spectral differences and could be characterized as stress signals, male courtship signals and female rejection signals. Stress signals were emitted in higher rate than courtship or rejection signals. Stress signals were produced almost continuously while the stress factor was present. The stridulatory apparatus had a different structure of pars stridens and plectrum in males and females and an inversion of the location of these components. The basic stridulatory mechanism consisted of an antero-posterior movement of the abdomen that, when in contact with the inner surface of elytra, scraped the plectrum on the pars stridens.