Ecological Entomology

Xylosandrus crassiusculus (Motschulsky), the granulate ambrosia beetle, was one of the first highly-destructive ambrosia beetles introduced into the southern U.S in the 1970s where it was found in South Carolina (Kovach 1986). The Redbay ambrosia beetle, Xyleborus glabratus Eichhoff, was first detected in the U.S. in South Georgia in 2002. This beetle and its associated fungi, the laurel wilt fungus Raffaelea laurelensis and others have caused substantial destruction to native redbay (Persea borbonia) in GA, SC, FL and elsewhere. This beetle-pathogen complex also poses a threat to commercial avocado production in the U.S., Central and South America as well as to valuable other Persea spp. and related plants (Laureacea) that are known hosts. As an addition here, 10 years of the spring appearances (Fig.1) of X. crassiusculus in North Florida is offered for future comparisons. A second unusual appearance is the finding and working with UV mulch and ethanol, as a surprising attraction of X. crassiusculus and other ambrosia beetles including X. glabratus. It was also found that the ambrosia beetles do not respond to yellow and green as expected by most. Also, adding burlap was found to be attractive (increases dead and dying appearing trees) as is silver metallic like UV mulch, while camouflage (camo) was found to work like yellow and green. These occurrences led to the invention and development of UV mulch with new traps to better monitor ambrosia beetles. New traps led to new uses for yellow, green and camo to monitor and decrease damage and losses from ambrosia beetles. The data are presented as evaluated and appear in the figures, discussion and a supplemental section. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=139 SRC="FIGDIR/small/733798v1_fig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@1006101org.highwire.dtl.DTLVardef@1e0a3d6org.highwire.dtl.DTLVardef@1244d1borg.highwire.dtl.DTLVardef@423cb7_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFigure 1:C_FLOATNO Relative timing of annual emergence of Xylosandrus crassiusculus in north Florida. Collected over 10 years using 5 Baker traps with a 10% ethanol/water solution. Data are from years as marked. Note: data from year 2003 was not collected. C_FIG

Frugivorous insect larvae are dependent on fruiting plants for development, leading to complex host-parasite interactions that may be influenced by many factors at various scales. We compared the relative effects of factors at the individual, neighborhood, and landscape scales in forest patches. Our results suggest that in areas like upstate New York, where agricultural land uses are dominant, individual scale factors are the most influential. Specifically, parasitism increased with host fruit crop size, but was not associated with host species richness or proximity to forest edge. Notably, the most parasitized hosts were non-native species, including Frangula alnus Mill. (Glossy Buckthorn), indicating a potential role of invasive species to shape host-parasite interactions in our system. Our results underscore the importance of host-specific traits in structuring parasitism patterns and suggest management could consider both the ecological context of host traits and the influence of invasive species at multiple scales.

Artificial light at night (ALAN) can alter the movement of nocturnal pollinators such as moths, with potential consequences for pollination services. However, most studies have focused on the presence or properties of lights, while the role of spatial lighting configuration remains poorly understood. We conducted a small-scale field experiment to test how different lighting configurations affect pollination success in moth-pollinated plants, using low-intensity LED garden lights. Potted phytometer plants of three moth-pollinated species were exposed to one of three treatments: no-light control, isolated LED point lights, or 25 m linear arrays of multiple LED lights. We quantified pollination success as both the probability of seed set and reproductive output through seed and capsule production. Experimental lighting affected plant reproductive success, with light arrays increasing seed-set probability, seed and seed capsule number relative to unlit controls, whereas point lights showed no clear effect. These results provide preliminary evidence that the spatial configuration of artificial lights may influence nocturnal pollination outcomes. Future work combining phytometer assays with direct tracking of moth movement is needed to assess whether light arrays facilitate or redirect the dispersal of nocturnal pollinators.

Invasive ambrosia beetles and fungal pathogens threaten forest ecosystems worldwide, exemplified in Hawaii by the widespread loss of keystone species [o]hia (Metrosideros polymorpha), due to Rapid [O]hia Death (ROD). A unique occurrence of five ambrosia beetle species (one native, four introduced) that vary in their symbiotic relationships with two introduced fungal pathogens provide an opportunity to test hypotheses of how opportunistic symbioses facilitate disease dynamics involving dominant forest trees. ROD is caused by two novel Ceratocystis fungal pathogens whose spores can spread via association with ambrosia beetles as they bore into [o]hia trees. We examined beetle-pathogen interactions of all five ambrosia beetle species in three ROD-affected regions on Hawaii Island, and used quantitative PCR (qPCR) to provide the first molecular confirmation of the two ROD pathogens associated with the exterior, mycangia, and gut of each beetle species. Results from generalized linear models and correlation networks show that pathogen acquisition and transport, including the potential for consumption and the presence of the pathogens, are determined by beetle invasion status and mycangia morphology. A niche construction framework suggests that both varying symbioses and opportunism facilitate disease spread, with the three invasive Xyleborus species emerging as key disease vectors. Identifying the beetle species that are more likely to contribute to disease spread, and understanding their biology as vectors, can inform targeted conservation strategies for [o]hia and for insect-pathogen threats in forests worldwide, and illustrates the potential ecosystem-level impacts of novel and opportunistic symbioses between globally distributed invasive vectors and pathogens.

Objectives identified as critical for effective management of brown marmorated stink bugs, Halyomorpha halys Stal (BMSB), were addressed in the overwintering life stage. Research was conducted on a 675-acre farm in western Maryland, U.S.A. Developing and testing were done during September - October of each of the years 2013 - 2020. Traps and related materials were developed. Four invented traps plus the development and use of "weed beater" polyethylene plastic in combination with the other traps were used as attractions to BMSB during the overwintering testing periods. Overwintering BMSB showed very little interest other than to find a place to hide that was dry, dark, easy to get into and safe over the winter months (Nielson et al. 2016). Placement of traps show effect of cardinal directions due to heat and light were north = east > west = south of numbers of BMSB. These data were affected by the vegetation, type of buildings such as silos, cabins, houses, etc., around BMSB prior to the en masse flight. Silos were used as attractants from long range during the en masse flight. Five trap types were invented and tested for use against overwintering BMSB found various places such as buildings of any type, pathways in the woods and other habitats present. Trap #1 was made of plastic out of special plant pots, turned upside down with a plastic lid and entry holes top and bottom that allowed the BMSB to reach the hexcel inside and stay there. Trap #2 was made of white, rectangular coroplast and pressed into 0.5 x 0.5 x 7.32 m (5" x 5" x 24") box also holding hexcel. Traps #1 and #2 are useful for attachment to most anything with BMSB such as the eaves in houses, other buildings, vegetation, crevasses, etc. They can be placed as horizontal or vertical with other ways that enhance efficacy. Both #1 and #2 are cheap and easy to make and use. Trap #3 is made of a cardboard tube, as a fake or "faux" tree (dead and/or dying) in vegetation 20 cm (6-8") diameter and 1.22 m (3 or 4) long. The tubes are placed on tomato stakes, have hexcel and holes made as do the others and are placed vertically in the ground. The tubes are covered with small widths of white, black and or burlap around them. Lids of plastic are on top and the trap appears as a dead and/or dying tree. The fourth trap is a "mechanism" or resembling some kind of "Haven" if you will, made of "weed beater" plastic materials 1.98 m (66") wide in brown or black. The materials are placed on trees by wrapping them around 3-4 trees near 4.6 m (10-15 long). Traps 1 and 2 can then be placed on the outside of the plastic walls and the #3 fake trees can be added around the outside areas. Around 60,000 BMSB were collected and counted in these experiments by the author, and several different factors were raised and addressed to better understand the BMSB behavior during the overwintering stage. The results provide several new tools as well as understanding of approaches to address BMSB management better.

In search of recurrent patterns of postzygotic hybrid incompatibility, we investigated the Holarctic 'Old World Swallowtail' (Papilio machaon Linnaeus) butterfly complex, whose members can easily be crossed in the laboratory. How many species this model system comprises remains unclear, as taxa with highly distinctive larvae but uncertain status come into contact with authentic P. machaon subspecies in Southern parts of the Palearctic region. By determining mitochondrial and ITS2 haplotypes within and away from contact zones, we found that these neighboring populations do exchange genes, as expected from F1 hybrids being generally fertile in our laboratory crosses. Nevertheless, recurrent instances of dysregulation of diapause were uncovered in hybrid progenies. In keeping with Haldane's Rule, pupae of the heterogametic (female) sex were either unable to enter diapause or, in reciprocal crosses, unable to resume development after having initiated diapause, whereas F1 males experienced normal, photoperiod-regulated diapause, but passed on abnormal diapause regulation to part of their female offspring when backcrossed. Comparing male and female pupal weights in hybrid progenies provides estimates of parental incompatibility that allow to rank taxa and predict quantitatively the outcome of additional crosses, as expected if the same regulatory system were involved. A survey of the entomological literature confirms that diapausing pupae that cannot resume development ('perpetual nymphs') are a recurrent feature of interspecific lepidopteran crosses. Moreover, of the two parent species of a perpetual nymph, the paternal one generally has fewer broods per year. These observations are discussed in the light of models of the speciation process.

Animals fight for resources to obtain fitness benefits; most contests are intrasexual, and males tend to fight more than females. Although the genetic basis of male aggression is well studied, we know little about the genetic variation of female aggression. Female aggression varies with reproductive status and is potentially influenced not only by her genotype, but also by the genotype of her mate. Here we measured both male and female aggression in a set of Drosophila melanogaster inbred lines by competing each line against a standard competitor. Aggression varied among lines for both sexes, but male and female aggression were not correlated. Female aggression for many lines increased with mating, as expected, but not all lines changed aggression. However, when females were mated to males of different lines, male genotype did not affect the post-mating change in aggression, suggesting that ejaculate-mediated effects do not vary across these lines. The aggression level of the standard opponent was positively correlated with that of focal individuals indicating that individuals modulate their behavior according to the genotype of their opponent.

The honey bee (Apis mellifera) gut microbiome plays a central role in host health, yet its variation across agricultural landscapes remains poorly resolved. This study investigates how major environmental stressors, particularly pesticide exposure and RNA virus loadings, shape the honey bee gut microbiome in a large-scale field study conducted across Canada, spanning diverse agroecosystems from British Columbia to Quebec. We identify consistent associations between specific bacterial taxa and major RNA viruses, including enrichment of Serratia marcescens with SBV and depletion of Bombella intestini with BQCV. Pesticide exposure is likewise linked to reproducible shifts in key microbial taxa. Together, these findings reveal that interacting stressors jointly shape the bee gut microbiome and enable prediction of microbiome responses in agroecosystems. HighlightsDistinct associations identified between gut bacteria and major bee RNA viruses (BQCV, SBV, LSV, IAPV) Pesticide exposure is linked to reproducible shifts in key microbial taxa Combined virus-pesticide effects form coordinated clusters that predict microbiome variation and specific bacterial responses Integrated modeling demonstrates that environmental stressors can jointly explain microbiome structure beyond crop effects Graphical abstractSchematic overview of potential links between pesticide exposure and RNA virus infection and their effects on the bee gut bacterial community. Solid arrows indicate associations supported by the present study, whereas dashed arrows indicate hypothesized or unresolved interactions. Associations between the presence of specific bee RNA viruses (left) or pesticide residues (right) and changes in the relative abundance of particular gut taxa (pink {uparrow}, increased; blue {downarrow}, decreased). The pesticide subtype is indicated by the icon in the cell (leaf - herbicide, hyphae - fungicide and insect - insecticide). Several bacterial taxa showed reproducible associations with specific viral or pesticide variables, including Bombella intestini, Serratia marcescens, Melissococcus plutonius, Paenibacillus alvei, Apibacter sp. wkB309, and Gilliamella sp. A7. Abbreviations: BQCV Black queen cell virus; LSV, Lake Sinai virus; SBV, Sacbrood virus; IAPV, Israeli acute paralysis virus. (p/n/b) indicate the sample matrix in which the pesticide was detected, namely pollen, nectar, and bee tissue, respectively. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=133 SRC="FIGDIR/small/731697v1_ufig1.gif" ALT="Figure 1"> View larger version (40K): org.highwire.dtl.DTLVardef@cb92a4org.highwire.dtl.DTLVardef@1087045org.highwire.dtl.DTLVardef@102cabforg.highwire.dtl.DTLVardef@4ce2f1_HPS_FORMAT_FIGEXP M_FIG C_FIG

Surges in food availability create localized but intense foraging opportunities, often attracting multi-species consumer groups. Agricultural practices can trigger these surges, prompting bird associations. However, the strength and duration of the association, as well as its drivers, remain unclear. This study examines waterbird association with harvesting and ploughing events in rice fields. The duration and magnitude of these associations were determined and three hypotheses addressed to explain them: (1) increased food availability, (2) enhanced foraging success and (3) reduced time allocated to vigilance. Waterbird counts and GPS tracking revealed strong associations with management events. Bird numbers spiked during events but declined within one to two days. Food availability (and soil penetrability) increased significantly during events - crayfish and rice during harvesting, worms and soil penetrability during ploughing - supporting Hypothesis 1. However, this did not improve foraging performance (intake rate, foraging success), rejecting Hypothesis 2. Higher competition, interference or kleptoparasitism in these large mixed-species flocks may offset increased food availability benefits. Alternatively, functional responses of target species may limit prey intake due to physiological or behavioural constraints. Hypothesis 3 was also unsupported, as birds did not reduce vigilance. It is plausible that birds may be drawn to events by the perception of a feast, not actual benefits. Gregariousness and foraging behaviour by local enhancement may explain such associations. Results highlight the complexity of bird responses to food surges while suggesting waterbirds in rice fields maintain stable foraging performance during agricultural management events and otherwise, indicating resilience to agricultural timing shifts.

Due to climate change, extreme weather events such as droughts are becoming more frequent and intense. This has a profound impact on plant performance and ecological interactions, including those involving herbivorous insects. The combined impact of drought stress and insect herbivory on plant metabolism has rarely been studied, particularly in woody plants. In this study, we investigated the influence of varying degrees of drought, both alone and in combination with herbivory by the leaf beetle Chrysomela tremulae, on the morphological and chemical characteristics of black poplar (Populus nigra) trees using a full factorial experimental design. We quantified morphological traits, volatile organic compound (VOC) emissions, phytohormone and amino acid concentrations, and phenolic profiles. Drought conditions increased the concentrations of salicylic acid (SA) and abscisic acid (ABA), while feeding induced ABA and SA. Amino acid profiles shifted significantly under drought conditions, particularly in beetle-infested plants. In contrast, salicinoids, which are the most important phenolic defense compounds in poplars, remained relatively stable. We also observed significant compound-specific effects on both constitutive and herbivore-induced VOC emissions. Our results demonstrate that drought and insect herbivory exert a joint influence on the chemical responses of P. nigra across multiple metabolic pathways. These findings highlight how the interaction between abiotic and biotic stresses can influence the defense chemistry of trees, which will consequently affect ecological interactions in forest ecosystems in the face of climate change.

Predator satiation is an understudied topic among vertebrate organisms, especially avian species. In Anderson, South Carolina, a species of migratory black bird, Euphagus carolinus (Rusty Blackbird) was observed roosting seasonally in a patch of Phyllostachys aurea (Golden bamboo) in large numbers. A resident avian predator, Buteo lineatus (Red-shouldered Hawk was seen preying on these roosting blackbirds; however, when this hawk would attack, pin down, and eat a blackbird, the rest of the flock would not react or fly away. Upon initial observation, we questioned if these roosting blackbirds exhibited predator satiation as a protection mechanism against avian predation. When E. carolinus flocked to roost, their numbers were visually counted and compared between at least two members of the research team. After allowing the birds to settle between fifteen seconds and one minute, a B. lineatus call was played with speakers to the flock. Simultaneously, a regulation-sized football was tossed to simulate the hawk attacking a member of the flock. The number of birds that flew away was recorded. Results between roosting numbers and flight numbers upon disturbance were analyzed to see if roosting group size correlates with evasiveness in birds. Results indicated that as blackbird group size increased, the total percentage of escaping birds decreased. Statistical analysis showed the leaving percentage versus the natural logarithm of group size was highly statistically significant (p < 0.001) and had a moderately negative overall correlation (rs = -0.62). Our results suggest that these blackbirds feel safer in large groups instead of small groups during predation events when roosting in dense brush. LAY SUMMARYO_LIThere is little research involving predator satiation tendencies in birds. C_LIO_LIPredator satiation is a strategy developed by prey animals to cope with predators, relying on sheer numbers to avoid predation instead of fight or flight. C_LIO_LIWe observed roosting Rusty Blackbirds in Anderson, SC displaying predator satiation-linked tendencies under avian predation stress when in large groups. C_LIO_LIWe tested the behavior of Rusty Blackbirds by simulating a hawk attack, noting the group size and the number of birds escaping. C_LIO_LIOur results showed that as group size increased, flight percentage decreased under a simulated predator attack. C_LIO_LIRusty Blackbirds seem to use the predator satiation strategy when roosting. C_LI

Arctic and Boreal raptor communities will continue to be affected by borealization and other climate change related processes, providing a challenge for ecologists predicting future sates. However, by using community assembly theory and species traits, future communities may be predictable. In this study, we analyzed variation in reproduction traits as a consequence of diet specialization for 29 raptors, 2 skuas and 3 corvids. We assessed and implemented foraging traits for specialists and generalists into predator-prey models from which successful invasion conditions were derived. Specialist raptors produced larger clutch sizes, had a higher proportion of fledged per clutch and also expressed more variation compared to generalist raptors. These results suggest a relationship between diet specialization and reproductive traits which was also observed within phylogenetic orders. Specialist owls (Strigiformes) produced higher clutch sizes with a larger clutch range compared to generalist owls. The same pattern was observed for falcons (Falconiformes). No clear difference in reproduction was observed for specialist and generalist hawks, kites and eagles (Accipitriformes). Corvids expressed clutch sizes similar to that of specialist raptors while having the lowest proportion of fledged per clutch. Differences in foraging traits between specialists and generalists could be distinguished using functional response curves. A predator-prey model parameterized with foraging trait data showed that a generalist can coexist with a resident specialist if it has access to prey unavailable to the resident specialist. Otherwise, the native specialist outcompetes the invading generalist due to foraging efficiency. The combined empirical and theoretical findings in this study show how diet specialization affects both reproduction and the potential invasion success of raptors.

O_LIFloral nectar plays a critical role in shaping the ecology and evolution of plant-pollinator interactions. Effective and efficient methods that allow for broad-scale sampling of nectar volume and sugar concentration across a diversity of taxa are needed to improve our understanding of many dimensions of mutualistic plant-pollinator interactions--including their basic ecology and evolution, their responses to environmental change, and their conservation and restoration. C_LIO_LIDespite the key importance of nectar for mediating plant-pollinator interactions, quantifying floral nectar in the field from many different plant species is challenging because there is often no one-size-fits-all sampling method that is effective across a diversity of floral structures and nectar traits. Different methods require different preparation, and sampling from many species involves a variety of logistical challenges. C_LIO_LIHere we provide a methodological roadmap for sampling floral nectar in the field from many different plant species. We describe our nectar collection methods in detail, including necessary equipment, calculations, and approaches appropriate for different floral morphologies. We also provide a troubleshooting guide for common problems encountered while collecting nectar in the field. To demonstrate the utility and effectiveness of our methods for collecting nectar from many different species, we present results on nectar trait variation from 53 species in an ecosystem. C_LIO_LIOur method illustrates that nectar traits vary considerably within and among plant species, indicating that large-scale nectar sampling projects are an important consideration for many basic and applied questions in pollination ecology and evolution. We hope that across many plant communities and ecosystems, our paper provides a practical roadmap for how to navigate the complexities of quantifying floral nectar traits. C_LI

Climate change is expected to alter plant populations not only through direct environmental shifts but also via changes in biotic interactions, such as with herbivores and pathogens. As plant species are also expected to differ in their responses to both climate and antagonists, plant responses to both factors are expected to be variable and species-specific. To assess whether interactive effects of climate and antagonists on plant population dynamics are common and whether the strength and direction of plant responses vary across species, we conducted a multi-year field experiment that manipulated realistic climate change and experimentally reduced insect herbivores and fungal pathogens. We measured responses of plant vital rates, such as survivorship, growth, and reproduction across six grassland species. Using Integral Projection Models (IPMs) and Life Table Response Experiments (LTREs), we quantified changes in population growth rate across experimental treatments and the contribution of each vital rate to that observed change. Two of the study species declined so drastically over the course of the experiment that demographic quantification of population growth rates was not possible. From the remaining species, Bromus erectus and Plantago lanceolata show significant interactive responses of climate and antagonist reduction on population growth rates. In contrast, Dianthus carthusianorum and Tragopogon orientalis showed limited responses to experimental treatments. Notably, our results indicate that in some species biotic interactions may amplify the effects of climate change: the presence of plant antagonists exacerbates the negative effects of the future climate treatment on plant population dynamics. Our findings highlight the complexity in predicting plant population responses to climate change and provide insights for grassland management under future environmental conditions.

Fat accumulation and use is critical for sustaining life. Most insects show a typical response to feeding where fat is accumulated when sufficient sugars and other carbohydrates are consumed. Parasitoid insects are an exception, because most species do not accumulate fat when feeding on a sugar-rich diet. Studies on fat metabolism generally measure fat content early in life without considering lipid metabolism as a dynamic process that is expected to change as life progresses. In this paper, we compared fat accumulation and use throughout the lives of adult female Drosophila melanogaster and females of 5 inbred lines of the parasitoid wasp Leptopilina heterotoma. We expected that fat accumulation would take place irrespective of teneral fat content in D. melanogaster. We found that fat D. melanogaster initially used fat reserves, while lean flies economized on fat stores. Both lean and fat flies started accumulating fat after 7 days of life, indeed showing a typical response for insects. Unlike other parasitoids, L. heterotoma populations differs in fat accumulation patterns that we expected to observe also between inbred lines. In none of the inbred lines, however, did fat accumulation take place. Our results did reveal that inbred lines differed in the rate at which fat was used mainly later during life. We further confirmed that D. melanogaster pupal size was highly correlated with adult female size for both D. melanogaster and L. heterotoma. Overall, our findings for L. heterotoma provide strong evidence that genetic background has a major impact on the rate at which fat is used over a lifetime.

Ectomycorrhizal (EM) fungi are vital to forest ecosystems, supporting tree growth and survival. However, their inclusion in conservation policy and action remains limited and little is known about the status of their genetic diversity, which is essential for their long-term survival and adaptation. The Global Biodiversity Framework adopted a genetic indicator based on the effective population size, Ne, to monitor genetic diversity in all species. To date, it is still uncertain how Ne, a key parameter, can be reliably assessed in species with complex life history traits. Ectomycorrhizal fungi are a highly diverse group of taxa displaying haplodiplontic life cycles with partially clonal reproduction. Here, we review the literature to understand how these life history traits might affect Ne and its estimation in six species of EM fungi. We estimated Ne in 19 populations using eight genetic and genomic datasets from selected studies. We compared Ne estimates using Linkage Disequilibrium (LD) and Sibship Frequency (SF) methods. We tested how Ne estimates change due to partial clonality and genetic structure gradients and whether the number of genetic markers influence the precision of the estimates. We show a systematic bias in Ne estimations when large clones are present and when populations are not correctly delimited. We found both methods are not robust to these factors, which makes them unreliable for conservation assessment purposes in EM fungi. This study provides new perspectives for further research into the links between life history traits and the effective population size of ectomycorrhizal fungi.

Nutritional symbionts can be essential for their animal hosts. The bacterial symbiont of the leaffooted bug, Leptoglossus zonatus, Caballeronia, is acquired from the environment each generation in the 2nd instar. The symbiont is critical for L. zonatus: aposymbiotic bugs are unable to reproduce. We hypothesized that symbiotic bugs excrete Caballeronia where juveniles might find and consume them. We inoculated L. zonatus with GFP-labelled Caballeronia and examined feces of each life stage. We found that Caballeronia is excreted almost exclusively in the adult stage. We then asked if 2nd instar nymphs could acquire Caballeronia from feces. Nymphs were provided with a) feces from adults fed GFP-labelled Caballeronia, b) GFP-Caballeronia in culture, or c) water only. We found that feces-fed bugs had similar rates of symbiont acquisition to those fed Caballeronia in culture, indicating that feces can be a source of Caballeronia for L. zonatus. However, compared to culture fed individuals, bugs fed feces had reduced survivorship and required longer to develop, and surviving adults had reduced mass. Bacterial motility assays showed that in contrast to cultured Caballeronia cells, Caballeronia in feces were non-motile. These results show suggest that feces can be a source of Caballeronia, at least in some environments, however transmission mode can influence success of the offspring.

Bees and wasps are ecologically vital, but many species are declining due to anthropogenic stressors. Social bees harbour host-specific and dense gut microbiomes that affect their resilience to stress. However, there are tens of thousands of other bee and wasp species that vary in sociality and diet (including pollen-feeding and predatory guilds), traits known to influence host-microbe symbioses. The role of gut microbes in the biology of these species is largely unknown. Here, we measured the composition and absolute abundance of bacterial communities in adult abdomens across 61 genera and 14 families of field-collected bees, predatory wasps, and pollen wasps. We found that solitary bees and both wasp guilds harbor distinct bacterial taxa and lower bacterial abundances as compared with social bees. Bacterial abundances also varied extensively among and within genera of solitary bees, with little variation explained by body size, diet breadth, or nesting ecology. Further, microbiome composition was only weakly differentiated among solitary bees and the two wasp groups, even comparing herbivorous (pollen-feeding) and carnivorous taxa. We suggest that the sparse and somewhat stochastic microbiomes of solitary bees and wasps reflect weak host dependence on microbially mediated functions, a trait that may influence their responses to environmental change.

The Eurasian spruce bark beetle Ips typographus, a major forest pest on Norway spruce (Picea abies), forms intimate associations with several types of microbial symbionts. While previous research has focused primarily on filamentous fungi, yeasts have remained largely unexplored. Here, we show that yeasts associated with I. typographus may contribute to host tree colonization by providing defensive benefits. Dominant yeasts (Yamadazyma, Kuraishia, Nakazawaea, and Wickerhamomyces), which are phylogenetically related to other insect-associated Saccharomycotina, significantly attract adult beetles. Moreover, several yeasts inhibit the growth of the pathogenic fungus Trichoderma harzianum in vitro, and beetle eggs benefit from the presence of Kuraishia capsulata by reduced fungal infection under semi-natural conditions. Strikingly, these effects are mediated by the yeasts' transformation of the tree's defensive stilbene glycosides into antimicrobial aglycones and phenolic acids that accumulate in beetle galleries. These findings reveal a previously unrecognized role of symbiotic yeasts in converting spruce defensive stilbene glycosides into antimicrobial aglycones and oxidative cleavage products that accumulate in beetle galleries, and might contribute to the survival of their bark beetle host.

Aims: Species' distributions are determined by the interplay between ecological niche and dispersal ability, constrained by biogeographical barriers. Bald-headed uakaris (Cacajao spp.) are highly specialized primates often associated with seasonally flooded forests. In this study, we used ecological niche models to assess changes in habitat suitability and geographic distribution of uakari species under future scenarios. Location: Western Amazonia. Methods: We integrated ecological niche models, current deforestation data, and dispersal ability to estimate habitat suitability under two Shared Socioeconomic Pathway (SSP) scenarios: intermediate (SSP2-4.5) and very high (SSP5-8.5) greenhouse gas (GHG) emissions. Results: Our models project shifts in suitable conditions for all species. Three of the five species are projected to experience substantial reductions ([&ge;]62%) in suitable habitat conditions within their current ranges by 2050 under both future scenarios. Across the western Amazonia, up to 219,189 km2 and 211,276 km2 of land are projected to be unsuitable within the uakari ranges under the intermediate and very high emissions scenarios, respectively. This is particularly relevant for C. calvus, C. rubicundus, and C. ucayalii. At the species level, the uakaris may lose between 343 km2 and 84,531 km2 of their ranges in the intermediate scenario and 858 km2 and 76,216 km2 in the very high scenario. Shifts in suitability due to climate change are expected to vary from 6 to 191 km in the intermediate scenario and from 5 to 168 km in the very high scenario. Furthermore, the uakaris may lose between 0.5% and 8% of their current ranges due to deforestation in all scenarios. Main conclusions: Our findings reveal a high sensitivity of the uakaris to climate change impacts. It is projected that all species may experience contractions in the suitable areas and spatial suitability within their ranges by 2050, underscoring climate change as a relevant threat to these taxa.