Ecological Entomology

O_LIBiological invasions threaten global ecosystems and economies, prompting the need for sustainable management approaches such as releasing natural enemies from the native range (i.e., classical biological control; CBC). While the release of multiple natural enemies can enhance the effectiveness of CBC, interactions between these agents and their host plants defenses are poorly understood. C_LIO_LIThis study explored the interactions between two congeneric specialist herbivores introduced for the control of Dioscorea bulbifera (air potato) in Florida, USA: Lilioceris cheni (Coleoptera: Chrysomelidae), which feeds primarily on leaves and L. egena, which feeds primarily on the aerial reproductive structures (i.e., bulbils). Specifically, we investigated whether foliar herbivory by L. cheni or induced defenses by jasmonic acid (JA) or salicylic acid (SA) influenced L. egenas feeding behavior and performance on bulbils. C_LIO_LIWe conducted feeding assays to measure bulbil consumption and its relationship to pupal mass and adult eclosion as indicators of beetle performance. Additionally, we performed dose-dependent feeding assays to test how varying concentrations of saponins, a key defense compound in air potato, influenced feeding and survival of L. cheni and L. egena. C_LIO_LIOur results indicated no significant differences in bulbil feeding by L. egena across treatments; however, SA-treated plants produced significantly heavier pupae and adults compared to controls. Dose-response assays revealed non-linear, hump-shaped, feeding and survival patterns in L. cheni, while L. egena experienced reduced feeding and survival with increasing saponin concentrations. C_LIO_LIThese findings suggest that the two beetles respond differently to plant defenses while occupying distinct feeding niches, likely allowing for additive impacts on D. bulbifera. This study provides insights into the role of plant defenses in CBC and informs strategies to optimize biocontrol programs for invasive species management. C_LI

The phoretic mite assemblage of the Douglas-fir beetle, Dendroctonus pseudotsugae Hopkins (Coleoptera: Curculionidae) has not been as thoroughly documented as that of some other ecologically and economically important bark beetle species. Phoretic mites can impact individual fitness and population dynamics of their hosts and documenting the mite assemblage associated with a bark beetle may provide information on their ecological and interactive roles. We caught Douglas-fir beetles over two summers in central British Columbia, Canada and sorted the associated mites into morphospecies. Representatives of the morphospecies were DNA barcoded (cytochrome oxidate I barcode region) which indicated at least nine distinct Operational Taxonomic Units (OTUs). There was a mean of 50.5 {+/-} 4.7 mites per beetle with both females and males carrying similar numbers of most mite species. However one OTU (Sarcoptiformes: Hemisarcoptidae) was found in substantially higher numbers than all other OTUs, and was always clustered in large aggregations in an anterior pocket on the sub-elytral surface. When B1 was removed from the mean, there were only 1.3 {+/-} 0.2 mites per beetle. The consistent high numbers of that OTU in conjunction with its consistent anatomical aggregation suggests an important interaction between that mite species and the Douglas-fir beetle.

While the Japanese rhinoceros beetle Trypoxylus dichotomus typically feeds on the sap of the oak Quercus acutissima and the crape myrtle Lagerstroemia subcostata during the night, it exhibits feeding activity both during the day and night when it utilizes the ash tree Fraxinus griffithii. However, the mechanisms underlying the variations in temporal activity patterns remain unknown. We compared feeding rates (measured as body mass increments) and sap exudation rates among F. griffithii, Q. acutissima, and L. subcostata. We found that beetles feeding on L. subcostata and Q. acutissima exhibited significantly higher feeding rates than those feeding on F. griffithii. No significant differences in feeding rates were observed between L. subcostata and Q. acutissima. The sap exudation rate was significantly higher for Q. acutissima than for F. griffithii. However, there were no significant differences in the sap exudation rates between F. griffithii and L. subcostata or between Q. acutissima and L. subcostata. These findings suggest that lower feeding rates on F. griffithii prolong the feeding duration, resulting in daytime activity. While the low sap exudation in L. subcostata seems inconsistent with high feeding rates on this host, this apparent contradiction could be related to the extended duration of sap exudation.

Mate choice is a fundamental aspect of sexual selection where the chooser chooses a courter by assessing a variety of traits that communicate potential fitness. However, the influence of interspecific interactions, such as symbiosis, on mate choice remains underexplored. We addressed this shortcoming with experiments on burying beetle Nicrophorus nepalensis and their interactions with phoretic mites Poecilochirus carabi. The mites can act either as mutualists or parasites depending on the presence of competitors and mite densities, thus potentially influencing mate choice. In a laboratory experiment, we presented female N. nepalensis with a range of natural mite densities: 0, 5, 10, or 20, with males carrying either 0 or 10 mites in an olfactory-based mate choice assay. Subsequently we allowed females to breed with their chosen male and all their mites before evaluating the fitness effects of the varying mite densities. We found that females across all mite densities had no preference for males with or without mites. In line with this, the mite densities had no effect on the brood size or the averaged larva mass. However, the mite densities per breeding cohort did positively affect the number of mite offspring. Our results suggest that mites act as benign passengers, not directly affecting mate choice or fitness.

The Japanese knotweed (Fallopia japonica) is considered as highly invasive in Europe and is largely widespread in France, without any established predator. This short study first characterized the herbivory of Fallopia by the black vine weevil (Otiorhynchus sulcatus), a commonly encountered coleopteran in France. Through an experimental design of leaf choices, between Fragaria spp. and Fallopia spp., our results show that the insects prefer Fallopia, even if it is presented for the first time. Even if this simple observation may appear as trivial, it highlights a novel plant-insect interaction and may start new insight in plant control or invasion management.

O_LISeveral polyphagous moths are severe crop pests. Diet breadth patterns and mechanisms among polyphagous insects provide an excellent system to study ecological and evolutionary processes in herbivores, driving dietary specialization. However, studies of diet breadth on more than a handful of crops are scarce. C_LIO_LIHere, we estimated the diet breadth in two species of lepidopteran herbivores from the genus Spodoptera: S. littoralis (SL), with host range including both mono- and dicotyledonous plants and S. frugiperda (SF) Corn strain, primarily adapted to different grass species. C_LIO_LILarval performance on 23 crop and wild plant species from 17 families from terrestrial and wetland habitats was compared to an artificial diet in no-choice feeding bioassays. SL survived and performed better on most tested plants, particularly on the family level, except on two monocot plants (maize and leek), where SF performed well. There were five wild non-host plants where both generalists failed to survive. Nutrition indices assay corroborates the findings on a subset of plants. C_LIO_LIIn a subset of plants, larval feeding preference correlated partly, and larval attraction correlated well with larval performance. Female oviposition choice showed a weak correlation with larval performance. This weak correlation implies that these traits are decoupled, and other factors are crucial for female host plant selection. C_LIO_LIDuring larval dispersal greenhouse experiments, SL and SF larvae strongly tended to migrate onto their suitable host plants, indicating that this is one factor that modulates female host plant selection. C_LIO_LIIn summary, SL has a broader diet breath compared to SF, surviving on wild plants with no previous exposure. The present study provides the first comprehensive data on the diet breadth of two range-expanding and highly invasive polyphagous herbivores. C_LI

The ability to use small molecule alkaloids as defensive chemicals, often acquired via trophic interactions, has evolved in many organisms. Animals with diet-derived defenses must balance food choices to maintain their defense reservoirs along with other physiological needs. Poison frogs accumulate skin alkaloids from their arthropod diet, but whether they show preference for specific prey remains unexplored. Here, we explore the role of leaf litter prey availability and diet preferences in shaping poison frog chemical defenses along a geographic gradient. We examined skin alkaloid composition, stomach contents and leaf litter ants in aposematic diablito frogs (Oophaga sylvatica) at five sites in northwestern Ecuador, and in sympatric, cryptic Chimbo rocket frogs (Hyloxalus infraguttatus) at one site. We found that differential availability of leaf litter ants influenced alkaloid profiles across diablito populations, and low levels of alkaloids were observed in the sympatric, undefended Chimbo rocket frog. Ants were the primary dietary component of the defended species, while undefended species ate other prey categories including beetles and larvae in addition to ants. A prey selection analysis suggested that defended and undefended frogs both feed on a high proportion of specific small ant genera that naturally contain alkaloids, suggesting that selectivity for toxic prey is not restricted to classically aposematic and highly toxic species. These findings suggest that poison frogs use of feeding resources relative to availability may be an understudied and important selection factor in the evolution of acquired defenses. ResumenLa capacidad de usar alcaloides como productos quimicos defensivos ha evolucionado en muchos organismos, a menudo a traves de interacciones troficas. Los animales con defensas que se derivan de la dieta deben balancear la seleccion de los alimentos para mantener sus reservas defensivas junto con otras necesidades fisiologicas. Las ranas venenosas acumulan alcaloides en la piel procedentes de su dieta de artropodos, pero aun no se ha explorado si muestran preferencia por presas especificas. En este estudio, investigamos el papel de la disponibilidad de presas en la hojarasca y las preferencias dietarias en la configuracion de las defensas quimicas de las ranas venenosas a lo largo de un gradiente geografico. Examinamos la composicion de alcaloides en la piel, el contenido estomacal y la presencia de hormigas de la hojarasca en ranas aposematicas diablito (Oophaga sylvatica) en cinco sitios del noroeste de Ecuador, asi como en la especie criptica y simpatrica rana cohete de Chimbo (Hyloxalus infraguttatus) en un sitio. Encontramos que la disponibilidad diferencial de hormigas en la hojarasca influyo en los perfiles de alcaloides en las poblaciones de diablito, y se detectaron niveles bajos de alcaloides en la rana cohete de Chimbo, previamente considerada indefensa. Las hormigas fueron el componente principal de la dieta en la especie defendida, mientras que la especie indefensa consumio otras categorias de presas, incluidos escarabajos y larvas, ademas de hormigas. Un analisis de seleccion de presas indico que tanto las ranas defendidas como las indefensas prefieren ciertos generos de hormigas pequenas que contienen alcaloides de forma natural, lo que sugiere que la preferencia por presas toxicas no esta restringida a especies clasicamente aposematicas y altamente toxicas. Estos hallazgos sugieren que las preferencias de comportamiento pueden ser un factor de seleccion poco estudiado, pero crucial, en la evolucion de las defensas adquiridas.

Understanding how resource availability shapes herbivore competitive interactions is crucial for predicting pest dynamics under changing agricultural practices. Interspecific competition among herbivorous insects is mediated by host plant quality, yet mechanisms underlying competitive outcomes under varying nutrient conditions remain unclear. We investigated how fertilization affects population dynamics and competitive interactions between the legume-specialist Megoura crassicauda and the generalist Aphis craccivora on pea shoots (Pisum sativum) under fertilized and unfertilized conditions. Aphid population dynamics were monitored for 30 days in single-species and mixed-species treatments, and plant survival and biomass changes were assessed. Unexpectedly, fertilization reduced aphid population growth in both species, challenging conventional assumptions about nutrient effects on herbivores. Fertilization significantly affected M. crassicauda population growth but not that of A. craccivora. In mixed treatments, A. craccivora consistently excluded M. crassicauda by day 25, regardless of nutrient status. Plant mortality occurred in all aphid treatments except M. crassicauda under fertilized conditions. Our findings demonstrate that nutrient enrichment reduced herbivore performance but did not alleviate interspecific competition. The consistent competitive dominance of the generalist suggests that intrinsic species traits, rather than resource availability, determine competitive hierarchies. These findings have implications for pest management under changing agricultural practices.

Supplemental lighting, such as with LED lamps, allows greenhouse producers to maintain yields when natural light levels are low. Since both insect pests and their natural enemies are sensitive to light, both the duration and spectrum of LED daylength extensions could affect biological pest control in greenhouses. Longer days could allow for extended periods of reproduction for pests or foraging activity of biological control agents, possibly depending on the spectra used for these extensions. However, the effects of lengthening days with different LED spectra on the behaviour of biological control agents has mostly been studied in short-term experiments to date, and has not always included the context of the lights effect on their hosts reproduction. In growth chambers, we examined the locomotor activity of the parasitoid biocontrol agent Aphidius matricariae (Hymenoptera : Braconidae) as a predictor for foraging activity and the fecundity of its aphid host Myzus persicae (Hemiptera : Aphididae) over multiple days under different daylength extension regimes representative of those used in greenhouse vegetable production. We compared the effects of 14, 16, 18, and 20 h photoperiods, and 12 h days extended by 6 h with three different spectral qualities. The parasitoids adjusted how their activity was distributed throughout the lit period of the day (i.e., its total duration and peak timing) without changing the total amount of daily activity, regardless of the photoperiod or the light spectrum used for daylength extension. The aphids peak fecundity was not affected by photoperiod or spectral quality. Our results suggest that at least some behavioral and reproductive traits of these insects can be resilient to even drastic changes in their light environment.

Local temperatures can shape the ability of introduced species to flourish and disrupt novel environments. The emerald ash borer (EAB), Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is an invasive beetle that threatens ash trees in North America and Europe. To assess the role of temperature on EAB reproduction, we reared groups of adult beetles at one of four temperatures (12, 15, 18, and 21 {degrees}C) and measured reproductive success (laying fertilized eggs and egg hatching). There was no effect of rearing temperature on EAB female lifespans but no eggs laid at 15 or 18 {degrees}C hatched, suggesting these temperatures disrupt the reproductive process of EAB. Females reared at 21 {degrees}C, however, consistently laid eggs that hatched. We then used these results to assess the likelihood of reproductive success over the previous ten years in eight cities in Canada that host EAB. All locations experienced temperatures of [≥] 21 {degrees}C, but the number of hours and the number of days above this critical temperature were highly variable. There were ample opportunities in all locations for EAB to reproduce, but EAB in cooler cities would experience thermal limitations thus slowing the spread of EAB populations.

Insect-induced galls are novel structures that serve as habitat to whole communities of associate arthropods that include predators, parasitoids and inquilines. Galling insects are generally under-described, but their associate communities, which can include many specialist organisms, are virtually unknown, particularly in the southwest United States. Aciurina bigeloviae (Cockerell 1890) and Aciurina trixa Curran 1932 are unusually common and abundant galling flies in New Mexico. The 2 species are sister and occur in sympatric areas but have distinct gall morphologies. We reared all arthropods from 3800 galls from 14 sites in the northern and central regions of the state and as a result characterized the complete communities of both species, including barcode sequences and eclosion phenology. We also investigate interactions of A. trixa galls with the abundant inquiline weevil Anthonomus cycliferus Fall 1913 and find no measurable effect of inquiline abundance on the size of the emerged adult fly or gall. The total species count is 24 and includes 6 guilds; both A. bigeloviae and A. trixa communities are richer and more complex than other documented Tephritidae-Asteraceae galling systems. This study highlights the potential of galling insects as ecosystem engineers to maintain large, rich and multi-trophic communities.

Age-specific patterns of nectar and pollen use by insect pollinators may reflect behavioral or physiological changes over the insects lifespan, and may also influence flower visitation rate. Studying Heliconius charithonia (Lepidoptera: Nymphalidae) and Psiguria umbrosa (Cucurbitaceae), we showed that honey-water (as a nectar substitute) intake increases over the first ten to twelve days of females life, while decreasing over the same age period for males, when individuals were fed ad libitum. Intake then remains stable at least through 28 days of age. Mean intake is higher for females than for males, and is not significantly affected by body size. Intake patterns for honey-water and pollen did not change with age in a similar manner. Pollen feeding increased significantly with age for both sexes, with females showing a two week delay in the increase when studied in a free-flying greenhouse population with competition for pollen. Under both ad libitum and pollen competition conditions, females collected more pollen than did males. Body size did not significantly affect the amount of pollen collected for either sex. Within each sex, butterflies with ad libitum pollen collected more pollen than those in a free-flying greenhouse population with more restricted pollen availability. These results suggest that two resources obtained from the same source, pollen and nectar, are not treated identically by the insect pollinator, and that the demography of the insect population may affect flower visitation rates in some cases. Further, foraging patterns for pollen and nectar are likely driven by physiological demand for different resource types.

Two species of larval parasitoids of the globally invasive fruit pest, Drosophila suzukii (Diptera: Drosophilidae), Leptopilina japonica and Ganaspis brasiliensis (both Hymenoptera: Figitidae), were detected in British Columbia, Canada in 2019. Both are presumed to have been unintentionally introduced from Asia, however; the extent of their establishment across different habitats with diverse host plants used by D. suzukii was unclear. In addition, there was no knowledge of the temporal dynamics of parasitism of D. suzukii by these two parasitoids. We repeatedly sampled the fruits of known host plants of D. suzukii over the entire 2020 growing season in British Columbia. We documented the presence of L. japonica and G. brasiliensis and estimated the apparent percentage of D. suzukii parasitized. Across a large region of southwestern British Columbia, both L. japonica and G. brasiliensis were found to be very common across a variety of mostly unmanaged habitats over the entire course of the season (May-October) in the fruits of most host plants known to host D. suzukii larvae. The two parasitoids were responsible for more than 98% of D. suzukii larval parasitism and usually co-existed. Parasitism of D. suzukii was variable among hosts plants and sites (0-66% percent parasitism) and appeared to be time-structured. Our study demonstrates that the close association between the two larval parasitoids and D. suzukii that exists in Asia has evidently been reconstructed in North America, resulting in the highest parasitism levels of D. suzukii yet recorded outside of its area of origin.

Sarracenia insectivorous plants show a diversity of visual features in their pitchers but their perception by insects and their role in attraction, have received little attention. They also vary in prey composition, with some species trapping more flying Hymenoptera, such as bees. To test the hypothesis of a link between visual signal variability and prey segregation ability, and to identify which signal could attract flying Hymenoptera, we characterised, the colour patterns of 32 pitchers belonging to four taxa, modelled their perception by flying Hymenoptera, and examined the prey they trapped. The pitchers of the four taxa differed in colour patterns, with notably two long-leaved taxa displaying clear areoles, which contrasted strongly in colour and brightness with the vegetative background and with other pitcher areas in the eyes of flying Hymenoptera. These taxa trapped high proportion of flying hymenoptera. This suggests that contrasting areoles may act as a visual lure for flying Hymenoptera, making plants particularly visible to these insects. Prey capture also differed according to pitcher stage, morphology, season and visual characteristics. Further studies on prey visitation are needed to better understand the link between prey capture and attraction feature.

Interactions between flowers and flower-visiting insects play central roles in ecosystem functioning. In addition to ensuring pollination, flower-visiting insects are also crucial for numerous other biotic interactions, using floral resources as fuel in their search for prey, hosts, breeding sites, and other resources. Studying insect-flower interactions may thus be strategic to conserve and restore biotic interactions in ecosystems heavily degraded by intensive land use and climate change, such as the arid savannas of the northern Sahel. We aimed to document for the first time the diversity of flower-visiting insects in this region and to examine whether restoration efforts of the Great Green Wall initiative have affected insect abundance and diversity. Using two capture methods, hand netting and pan traps, we inventoried insects visiting flowers of Balanites aegyptiaca. This is the most abundant tree species in the region and is also of economic importance. We sampled three sites in a single locality: a "Restored" site from which livestock are excluded, an "Unrestored" site in intensively grazed rangeland, and a topographical "Depression" site in a grazed area but with high tree density. Each site was sampled at three different periods to examine variation in this extremely harsh and seasonal environment. The open-access flowers of Balanites aegyptiaca are produced in multiple flowering events each year. We found a surprisingly high diversity of insects visiting its flowers, comprising 371 morphospecies from 10 insect orders, with a predominance of Hymenoptera and Diptera. Insect abundance, diversity and species composition differed markedly between seasons. Bees appear to be important pollinators, particularly solitary bees of the family Halictidae, which were abundant in all seasons. Diptera, in particular several families of small flies, were also frequent visitors and were especially abundant and diverse in the wet season. Ants were especially abundant at flowers in the dry season, when few resources other than flowers and flower-visiting insects were likely available to them. Insect abundance and observed diversity differed only little between sites, but estimated total diversity (Chao1 richness) was highest in the Depression site. Insects visiting flowers of B. aegyptiaca included herbivores, decomposers, and parasitoids and predators of diverse arthropods, underlining the role of these floral resources in numerous facets of ecosystem functioning. The floral resources of B. aegyptiaca and other trees, which can flower throughout the year, are likely critical to assure the persistence of numerous insect species. Integrating biotic interactions into ecosystem management is crucial for conservation and restoration in Sahelian ecosystems.

Phoretic mites have been found attached to different body parts of the red palm weevil (RPW), Rhynchophorus ferrugineus (Olivier, 1790), to disperse. However, the question of how the patterns of attachment sites are formed remains intriguing. Here, we conducted the first study of RPW-associated phoretic mites in Portugal, particularly in the districts of Viana do Castelo, Braga, Porto and Aveiro in Northern Portugal (macrohabitat), and investigated the patterns of mite distribution on six body parts of RPW (microhabitat). At the macrohabitat level, we detected seven phoretic mite taxa actively using the RPW host in each of the four studied districts, all documented for the first time in association with this invasive exotic species in Portugal. However, their relative abundance (species evenness) varied between districts, as did species diversity. All examined weevils carried mites, and the prevalence of the different taxa did not differ between districts or sex of weevils. Measured by mean abundance and degree of aggregation, Centrouropoda sp. proved to be the common dominant taxon, while Acarus sp. And C. rhynchoporus were considered common subordinate taxa and Uroovobella sp., Mesostigmata, N. extremica and Dendrolaelaps sp. sparse taxa. At the microhabitat level, all taxa were present in all body parts of the RPW; the highest abundance was in a region encompassing the inner surface of the elytra and the membranous hind wings (subelytral space). Analysis of niche overlap revealed that the distribution patterns of phoretic mite taxa on the RPW were not randomly structured. In the subelytral space, interspecific coexistence of mites increased as a function of body size difference with the dominant Centrouropoda sp. We conclude that the distribution patterns of RPW-associated phoretic mites show body size-dependent effects that resulted in the dominant taxon displacing similar size taxa and accepting taxa with which it has the greatest size difference as co-habitants.

The fungus Fusarium xyrophilum produces flower-like structures (i.e., pseudoflowers) that were recently discovered on yellow-eyed grasses (Xyris spp.) in Guyana. It is unknown whether these pseudoflowers, which are composed entirely of fungal tissue, are true mimics that attract insects as a means of fungal dispersal. We evaluated the potential of F. xyrophilum to affect insect visitation patterns to flowers and pseudoflowers by 1) documenting insect visitation to X. surinamensis in Guyana, 2) measuring the presence of F. xyrophilum DNA on insects, and 3) evaluating fluorescence and volatile production on flowers and pseudoflowers. We report for the first time Vespidae, Formicidae, Salticidae, Acrididae, and Tetrigidae visiting Xyris. Diverse insects, including Conocephalini spp. (meadow katydids; Tettigoniidae), Camponotus spp. (carpenter ants; Formicidae), and a Geometridae sp. (geometer moths) were found to visit flowers and pseudoflowers. Fusarium xyrophilum DNA was detected on 3/12 (25%) of captured insect bodies using conventional and quantitative PCR. Volatiles produced in the field by pseudoflowers and flowers were similar, except for the presence of a sesquiterpene, putatively identified here as -gurjunene, which was detected both in F. xyrophilum pure cultures and field-collected pseudoflower samples, but not from flowers. The production of this sesquiterpene by F. xyrophilum and the fluorescence of X. surinamensis peduncles represent potential signals involved in insect attraction for this system. These observations, along with the overlap in insect visitors of flowers and pseudoflowers and the detection of F. xyrophilum DNA on insect bodies, are consistent with insect visitors being vectors of Xyris pollen and F. xyrophilum propagules between host plants.

Istocheta aldrichi (Diptera: Tachinidae) is a specialist parasitoid of the invasive Japanese beetle, Popillia japonica (Coleoptera: Scarabaeidae). Research and releases for biological control depend on field collecting parasitized hosts and rearing the parasitoid through diapause to obtain I. aldrichi adults. This study investigated how rearing practices before, during and after the seasonal overwintering period affected the proportion of I. aldrichi pupae that emerged as adults, the timing of parasitoid emergence, and their longevity. Increasing cold exposure duration during overwintering increased adult I. aldrichi emergence from puparia and reduced development time after transfer to warm conditions. Adult I. aldrichi emergence from overwintered puparia depended on interactions between overwintering environment (indoors vs. outdoors), spring thermal regime, and the timing of host collection in the previous season. Burying puparia in the soil in late summer/early fall resulted in higher subsequent adult I. aldrichi emergence. Manipulating spring temperatures in controlled environments allowed parasitoid emergence to be staggered over several weeks without reducing emergence success. Emergence under outdoor spring conditions was unreliable. Adult longevity was affected by temperature and diet: cooler conditions extended lifespan, honey-water increased longevity relative to pollen alone or honey-water and pollen together. These results provide a foundation to further improve I. aldrichi rearing techniques for use in experimental research and applied biological control of P. japonica.

Communal breeding is a reproductive system in which more than a single pair of individuals share parental care duties. Burying beetles (genus Nicrophorus) breed on small vertebrate carcasses, which is used as a food source for their young. On larger carcasses, burying beetles will breed communally, forming multiple male-female associations. A significant and costly component of parental investment by burying beetles is the preservation of the carcass with secretions containing immune molecules. Because this immune investment is for the benefit of the offspring, the behavior is a form of social immunity. We test the hypothesis that communal breeding in burying beetles evolved as a mechanism to increase the social immune investment on larger carcasses, which are more difficult to preserve. We used N. defodiens, a communal breeding burying beetle species to test the hypothesis. There were two experimental treatments wherein, the females either bred communally or non-communally. Our results show that the combined immune activity in the secretions were higher in communally breeding pairs than in the immune contribution of single male-female pairs. However, subordinate females were rarely observed on the carcass, and the level of social immune activity of dominant females was lower than females breeding singly. These data suggest that communal breeding in N. defodiens decreases the level of investment in social immunity. Our results demonstrate that the presence of multiple females, which is common under natural conditions, can greatly complicate patterns of social immunity investment in burying beetles.

Arachis pintoi (Fabaceae) is a common relative of the cultivated peanut, and folds its four leaflets up to look like one at night. The adaptive significance of this behavior (foliar nyctinasty) is unknown. To test the hypothesis that leaflet folding alone can deter herbivores, a leaf preference experiment was performed on Chromacris trogon grasshoppers. Small oval cutouts were made from leaves of the grasshoppers preferred food source, Iochroma arborescens (Solanaceae), and were combined with small pieces of tape and dry grass to construct artificial leaves resembling the day and night form of A. pintoi. In the experiment, groups of three grasshoppers were starved for 24 hours and then placed in petri dishes containing one closed and one open artificial leaf. After 30 six-hour trials, the average herbivory of open leaves was 12.3%, while closed leaves was 5.2% (p = 0.00145), indicating a significant preference for open leaves. This suggests that the folded configuration of A. pintoi leaves can be a defense against herbivory.