The common grass mantid, Brunneria borealis Scudder, is well known as perhaps the only completely parthenogenetic species among the more than 2,400 named mantid species. An abundant mantid within its broad geographic range, it has long been considered a native North American endemic; however, all other known species in the genus Brunneria (and in its family, Coptopterygidae) are South American. We were able, for the first time, to perform a genetic comparison between B. borealis and a congeneric South American species, B. subaptera. We sequenced a standard segment of the mitochondrial cytochrome oxidase I (COI) gene for which there is no variation among different populations among localities throughout the range of B. borealis, and compared this sequence with haplotypes from different South American populations of B. subaptera.The single B. borealis haplotype falls within the genetic variation of populations of B. subaptera, suggesting that the North American mantid is really a colonist from this South American species.

Insects have evolved remarkably complex social systems. Social wasps are particularly noteworthy because they display gradations in social behaviors. Here, we sequence the genomes of two highly diverged Vespula wasps, V. squamosa and V. maculifrons Buysson (Hymenoptera: Vespidae), to gain greater insight into the evolution of sociality. Both V. squamosa and V. maculifrons are social wasps that live in large colonies characterized by distinct queen and worker castes. However, V. squamosa is a facultative social parasite, and V. maculifrons is its frequent host. We found that the genomes of both species were ∼200 Mbp in size, similar to the genome sizes of congeneric species. Analyses of gene expression from members of different castes and developmental stages revealed similarities in expression patterns among immature life stages. We also found evidence of DNA methylation within the genome of both species by directly analyzing DNA sequence reads. Moreover, genes that were highly and uniformly expressed were also relatively highly methylated. We further uncovered evidence of differences in patterns of molecular evolution in the two taxa, consistent with V. squamosa exhibiting alterations in evolutionary pressures associated with its facultatively parasitic or polygyne life history. Finally, rates of gene evolution were correlated with variation in gene expression between castes and developmental stages, as expected if more highly expressed genes were subject to stronger levels of selection. Overall, this study expands our understanding of how social behavior relates to genome evolution in insects.

This study comprehensively explored the ecological roles, behaviors, and adaptive strategies of the enigmatic nocturnal hornet species Vespa binghami du Buysson, 1905 (Hymenoptera: Vespidae), in South Korea. Using time-series analysis, we identified the hornet's peak activity to be between 23:00 and 00:00, consistent with its dietary preference for species of the order Lepidoptera as identified through cytochrome c oxidase I metabarcoding. Metabarcoding revealed a specialized diet that predominantly consists of moths belonging to the family Noctuidae, suggesting a co-evolutionary predator-prey relationship. However, our sample size was limited; therefore, this observation should be considered preliminary. Our findings also provide evidence of opportunistic predation on bees, indicating adaptive flexibility in foraging behavior. Spatiotemporal analysis showed that the hornets exhibited peak activity during late summer and that they are mainly found at elevations between 100 m and 400 m. Despite their adaptability, sightings are regionally limited within South Korea. Observations indicated that the hornets prefer nesting in tree cavities, which have architectural features uniquely adapted to their nocturnal lifestyle. Taken together, these findings offer a multidimensional understanding of the nocturnal behaviors, specialized adaptations, and ecological significance of V. binghami. Moreover, they highlight the need for further multidisciplinary research to fully elucidate the role of this hornet in its ecosystem and its potential as a bioindicator of environmental stability and habitat quality.

Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) is a polyphagous pest impacting numerous economic crops. This impact is facilitated by its long-range dispersal capacity, which can lead to the colonization of new cultivated areas in the agricultural landscape and the potential spread of insecticide-resistant populations. Despite these negative implications, it is unclear how ecological and morphological factors influence H. zea flight capacity. Here, we investigated the dispersal capacity and morphophysiological determinants of the flight performance of H. zea. Tethered flight mill experiments were conducted to examine the impact of mating status, age [young (2-day-old), middle-aged (3- to 6-day-old), or old (7- to 9-day-old)], and sex on the flight capacity of moths under controlled conditions. We found that the flight capacity was not influenced by mating status or the number of mature eggs. Males flew faster than females, and middle-aged moths' flight had higher performance (speed, time, and distance) than young and old moths. Body size and wing-to-thorax ratio negatively influenced the moth flight time. Male's body size was larger than females, but they had a smaller forewing area and smaller wing-to-thorax ratio. Middle-aged moths exhibited the highest likelihood of engaging in migratory movements (> 10 km). Finally, oogenesis-flight syndrome was not detected, confirming the hypothesis of facultative migration in this species. Our results enhance our understanding of the factors influencing the flight behavior of H. zea, which can be used to predict the long-range capacity of infestation of this species, and the spread of resistance genes to management tools, such as insecticides and Bacillus thuringiensis (Bt) toxins expressed in transgenic crops.

Larvae of the diamondback moth (DBM), Plutella xylostella (L.) (Lepidoptera: Plutellidae) wriggle vigorously backward when physically stimulated. To explore whether this behavior is effective against ant attacks on their host plants with three-dimensional structures, we experimentally observed DBM larval movements and consequences thereof when attacked by Formica japonica (Hymenoptera: Formicidae) ants on the upper and lower surfaces of host plant leaves. On the upper surfaces of leaves, DBM larvae wriggled backward in response to ant attacks, and most larvae hung from leaf edges by spinning silk threads. On the lower surfaces of leaves, DBM larvae did not wriggle backward but immediately hung from the lower surface in response to attacks. No ants were able to pursue hanging larvae. We conclude that wriggling backward by DBM larvae belongs to a sequence of evasive movements against ant attacks on upper leaf surfaces. To our knowledge, this is the first report of combined wriggling and hanging behaviors by Lepidopteran larvae that are effective against ants in three-dimensional habitats.

Graphical Abstract

Defensive behaviors of DBM larvae on upper and lower leaf surfaces.

Coloration is a multifaceted trait that serves various functions, including predator defense, thermoregulation, and immune response, among others. We investigated pupal color variation in Chlosyne lacinia pupae, focusing on identifying the cue that influences variation in melanization. Through laboratory experiments, we demonstrated that pupae reared on black backgrounds exhibited significantly higher melanization compared to those on white backgrounds. Additionally, black pupae experienced longer developmental periods, suggesting a trade-off between defense and developmental time. Our findings support crypsis as a likely evolutionary driver for increased melanization in response to substrate color. We discuss potential implications for predator avoidance, immune response, and developmental costs associated with melanization. This study provides insights into the adaptive significance of pupal melanization in response to environmental cues, shedding light on the complex interplay between life history traits in butterflies.

Knowledge of insect dispersal and long-distance migratory flight capacity and patterns represent key factors needed for risk assessment of invasive pest species, insecticide resistance management, and more effective pest control. Having operative tools to both mark and track insect pest movement is therefore critical to achieving such goals. Here, we describe a new procedure for marking Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), one of the most economically important crop pests in the United States. Adult H. zea moths were effectively marked using the liquid fluorophore cartax green, a persistent UV-fluorescent pigment, both directly by topical application and indirectly by briefly submerging pupae in the marking solution prior to adult emergence. Regardless of the application method, the cartax mark was retained on the moths throughout their entire adult lifespan. No mortality differences were observed between cartax green-marked and water-marked (control) moths. Additionally, using rotary flight mills, we found no significant differences in several flight parameters, including total number of flights, flight speeds, flight distances, or flight durations between unmarked and cartax-marked moths. Under laboratory conditions, we did observe the lateral transfer of different colored fluorophores between moths, indicating that undesirable marking could potentially occur. Moreover, we found that not all fluorophores were equally retained on H. zea moths, with cartax green remaining intact on moths longer than did a corresponding magenta fluorophore. The results show that cartax green fluorophore could be a practical marker for H. zea and other holometabolous species targeted for large-scale mark-release-recapture research.

Genetic linkage maps are valuable resources for investigating chromosomal structure, quantifying karyotype, estimating recombination rates, and improving preexisting genome assemblies. Comparative linkage mapping, in turn, broadens our understanding of the phylogenetic history of these genomic features. Through an assessment of synteny (the conservation of gene order on homologous chromosomes in different species) and variation in recombination rate, we can begin to understand how genomic features change during the evolution of distinct species. Here, we construct high-density genetic linkage maps for 3 Vespidae wasp species from the Vespula genus: Vespula consobrina, Vespula pensylvanica, and Vespula vidua to investigate shared genomic architecture between these 3 yellowjacket wasp species. We show that these species exhibit high levels of collinearity, often in chromosome-length blocks of synteny, with some evidence for small interchromosomal rearrangements. We also identify 2 “inversions” in all 3 species that are likely artifacts from the genome assembly process. In addition, we map genome-wide recombination rates and reveal the recombination landscape to be highly variable on intrachromosomal, interchromosomal, and interspecific scales. Genome-wide recombination rates are high for all three Vespula species, (V. pensylvanica: 22.7 cM/Mb, V. consobrina: 24.3 cM/Mb, and V. vidua: 24.7 cM/Mb), which is consistent with findings of high recombination rates for other eusocial species. Our high-quality linkage maps will be resources for ongoing evolutionary genetics studies interested in the genome evolution of social wasps.

The performance of various life processes in arthropods is greatly influenced by temperature. The survival of arthropods is temperature-dependent, which must be accounted for when predicting and simulating outbreaks of pest population under global warming scenarios. However, mathematical models for describing temperature-dependent arthropod survival are still lacking.The 5-parameter performance equation (PE), which was originally proposed to describe the influence of temperature on the jumping distance of the green frog, can generate symmetrical and asymmetrical inverted U-shaped curves, and thus is applicable to modeling a broad variety of thermal performance relationships. However, prior studies have not assessed its validity in describing the temperature-dependent survival of arthropods. In this study, we used 16 data sets of insects and mites to test the validities of this PE and its generalized version with 7 parameters (GPE) in fitting temperature-dependent survival data. The PE and GPE were both found to be valid for use in fitting the observed data. However, the estimated values of the PE's parameters were more robust than those of the GPE.The goodness of fit of the GPE was better than that of the PE for each data set; however, the GPE tended to overfit the data when observations at threshold temperatures were lacking. Overall, the PE is better than the GPE.The present work further confirmed that the temperature-dependent survival of arthropods is an inverse U-shaped curve and provided a useful tool for quantifying the effect of temperature on the survival of arthropods.