Amy Toth

Iowa State University | ISU · Department of Ecology, Evolution and Organismal Biology

Background The common Eastern bumble bee Bombus impatiens is native to North America and is the main commercially reared pollinator in the Americas. There has been extensive research on this species related to its social biology, applied pollination, and genetics. The genome of this species was previously sequenced using short-read technology, but...

This article describes a genome assembly and annotation for Bombus dahlbomii, the giant Patagonian bumble bee. DNA from a single, haploid male collected in Argentina was used for PacBio (HiFi) sequencing and HiC technology was then used to map chromatin contacts. Using Juicer and manual curation, the genome was scaffolded into 18 main pseudomolecul...

Wasps are understudied in their contribution to pollination services. In order to better understand the ecological contribution of wasp communities to plant pollination, we conducted three studies to compare bees and wasps by (1) the plant communities visited in agricultural and prairie environments, (2) body pollen composition as an indirect measu...

Eusocial insect societies are fundamentally non-egalitarian. The reproductive caste "wins" in terms of resource accumulation, whereas non-reproductive workers "lose". Here, we argue that division of labor among workers is also organized by nutritional inequalities. Across vastly different social systems and a variety of hymenopteran species, there...

Balancing demand for food while supporting biodiversity and ecosystem services in landscapes committed to crop production may require integrating conservation with agriculture. Adding strips of diverse, native, perennial vegetation, through the recently created prairie strips practice of the U.S. Conservation Reserve Program, into annual cropland r...

Social insects have provided some of the clearest insights into the origins and evolution of collective behaviour. Over 20 years ago, Maynard Smith and Szathmáry defined the most complex form of insect social behaviour—superorganismality—among the eight major transitions in evolution that explain the emergence of biological complexity. However, the...

The north central state of Iowa is heavily dominated by agriculture, with limited nesting and foraging habitat for wild and managed pollinators. This region has been identified as critical for pollinator conservation for bees and non-bee species (e.g., monarch butterfly [Danaus plexippus]). Pollinator sustainability (i.e., wild bee conservation and...

The evolution of eusociality requires that individuals forgo some or all their own reproduction to assist the reproduction of others in their group, such as a primary egg-laying queen. A major open question is how genes and genetic pathways sculpt the evolution of eusociality, especially in rudimentary forms of sociality – those with smaller cooper...

Large scale agricultural production can lead to a reduction in availability of habitat used by wild bees for nesting and forage and has been implicated in worldwide bee population declines. There is growing concern that further declines in wild bee populations will occur because of continued transformations of natural or seminatural landscapes into...

Extreme weather events, like high temperatures and droughts, are predicted to become common with climate change, and may negatively impact plant growth. How honey bees (Apis mellifera L. [Hymenoptera: Apidae]) will respond to this challenge is unclear, especially when collecting pollen, their primary source of protein, lipids, and micro-nutrients....

Nourishment can have profound effects on social behaviour, including aggressive interactions between individuals. The prevailing theoretical and empirical understanding is that when nutritional resources are limited, inter‐individual competition and aggression will increase. Alternatively, studies from some group‐living species suggest limited nutr...

The consequences of early-life experiences are far reaching. In particular, the social and nutritional environments that developing animals experience can shape their adult phenotypes. In honeybees, larval nutrition determines the eventual social roles of adults as reproductive queens or sterile workers. However, little is known about the effects o...

Ecosystems are interconnected and complex, but conservation has often focused on rehabilitating individual species. A systems-ecology approach aims to support overall ecosystem structure and maintain ecological functions, and may be especially pertinent for mutualistic plant-pollinator communities. This approach focuses on species interactions as t...

Honey bee colonies have a yearly cycle that is supported nutritionally by the seasonal progression of flowering plants. In the spring, colonies grow by rearing brood, but in the fall, brood rearing declines in preparation for overwintering. Depending on where colonies are located, the yearly cycle can differ especially in overwintering activities....

While it is well known that the genome can affect social behavior, recent models posit that social lifestyles can, in turn, influence genome evolution. Here, we perform the most phylogenetically comprehensive comparative analysis of 16 bee genomes to date: incorporating two published and four new carpenter bee genomes (Apidae: Xylocopinae) for a fi...

Prairie was a dominant habitat within large portions of North America before European settlement. Conversion of prairies to farmland resulted in the loss of a large proportion of native floral resources, contributing to the decline of native pollinator populations. Efforts to reconstruct prairie could provide honey bees (Apis mellifera) a source of...

Hygienic behavior is a social defense mechanism against parasites and pathogens in honeybees. We studied the genetic basis of hygienic behavior in African-derived Apis mellifera by performing RNA sequencing on brains of individual honeybee workers observed performing hygienic behavior, in order to identify expression changes linked with this behavi...

Populations of wild and managed pollinators are declining in North America, and causes include increases in disease pressure and decreases in flowering resources. Tallgrass prairies can provide floral resources for managed honey bees (Hymenoptera: Apidae, Apis mellifera Linnaeus) and wild bees. Honey bees kept near prairies may compete with wild be...

In 2006, the full complement of DNA sequence information (or ‘genome’) of the Western honey bee, Apis mellifera , was published. This important resource was one of the most important advances in the history of honey bee research, with seemingly limitless applications to unlocking the secrets of honey bee biology and social life and for improving he...

To study how honey bees utilize forage resources and guide pollination management plans in crops, a multitude of methods have been developed, but most are time consuming, costly, and require specialized skills. Colored pan traps for monitoring activity-density are a simple, efficient, and cost-effective alternative; however, their usefulness for st...

Identifying the genetic basis of behavior has remained a challenge for biologists. A major obstacle to this goal is the difficulty of examining gene function in an ecologically relevant context. New tools such as CRISPR/Cas9, which alter the germline of an organism, have taken center stage in functional genomics in non-model organisms. However, ger...

Anthropogenic changes create evolutionarily novel environments that present opportunities for emerging diseases, potentially changing the balance between host and pathogen. Honey bees provide essential pollination services, but intensification and globalization of honey bee management has coincided with increased pathogen pressure, primarily due to...

Intensified agriculture reduces natural and seminatural habitats and plant diversity, reducing forage available to honey bees (Apis mellifera L. [Hymenoptera: Apidea]). In agricultural landscapes of Iowa, United States, we studied the impact of extrinsic agricultural intensification on the availability of pollen for honey bees by placing colonies n...

In the last century, a global transformation of Earth's surface has occurred due to human activity with extensive agriculture replacing natural ecosystems. Concomitant declines in wild and managed bees are occurring, largely due to a lack of floral resources and inadequate nutrition, caused by conversion to monoculture-based farming. Diversified fr...

Native pollinators are important for providing vital services in agroecosystems; however, their numbers are declining globally. Bees are the most efficient and diverse members of the pollinator community; therefore, it is imperative that management strategies be implemented that positively affect bee community composition and health. Here, we test...

Significance Industrial-scale production of crops through monocultures has resulted in “green deserts” of reduced biodiversity in many areas worldwide. Such simplified landscapes may impact ecosystem services such as pollination. Here, we present a large-scale, longitudinal study of managed honey bee colonies in the context of corn and soybean mono...

Hormones are often major regulators of complex behaviors, such as mating and reproduction. In insects, juvenile hormone (JH) is integral to many components of reproductive physiology and behavior, but its role in female sexual receptivity is not well understood. To investigate the influence of JH on receptivity, we utilized the social wasp Polistes...

Eusociality, a form of animal social organization involving sterile and reproductive castes, is a rare, but highly ecologically successful form of life. There are striking examples of eusocial species with populations that are ecologically dominant in their native ranges, as well as remarkably successful globally as invasive species; prominent exam...

Background Parts of Europe and the United States have witnessed dramatic losses in commercially managed honey bees over the past decade to what is considered an unsustainable extent. The large-scale loss of bees has considerable implications for the agricultural economy because bees are one of the leading pollinators of numerous crops. Bee declines...

Foraging decisions of social animals occur in the context of social groups, and thus may be subject to considerations of not only an individual's nutritional state and nutrient input, but those of the social group in which they live. In eusocial insects, which live in colonies containing workers that forage for food that is mostly consumed by other...

Although social behavior can have a strong genetic component, it can also result in selection on genome structure and function, thereby influencing the evolution of the genome itself. Here we explore the bidirectional links between social behavior and genome architecture by considering variation in social and/or mating behavior among populations (s...

Honeybee population declines have been linked to multiple stressors, including reduced diet diversity and increased exposure to understudied viral pathogens. Despite interest in these factors, few experimental studies have explored the interaction between diet diversity and viral infection in honeybees. Here, we used a mixture of laboratory cage an...

We develop a transdisciplinary deliberative model that moves beyond traditional scientific collaborations to include nonscientists in designing complexity-oriented research. We use the case of declining honey bee health as an exemplar of complex real-world problems requiring cross-disciplinary intervention. Honey bees are important pollinators of t...

Animal nutritional state can profoundly affect behaviour, including an individual's tendency to cooperate with others. We investigated how nutritional restriction at different life stages affects cooperative behaviour in a highly social species, Apis mellifera honeybees. We found that nutritional restriction affects a worker's queen pheromone respo...

Despite a strong history of theoretical work on the mechanisms of social evolution, relatively little is known of the molecular genetic changes that accompany transitions from solitary to eusocial forms. Here we provide the first genome of an incipiently social bee that shows both solitary and social colony organization in sympatry, the Australian...

Cooperative breeding decreases the direct reproductive output of subordinate individuals, but cooperation can be evolutionarily favored when there are challenges or constraints to breeding independently. Environmental factors, including temperature, precipitation, latitude, high seasonality and environmental harshness have been hypothesized to corr...

Eusociality has independently evolved multiple times in the hymenoptera, but the patterns of adaptive molecular evolution underlying the evolution and elaboration of eusociality remain uncertain. Here, we performed a population genomics study of primitively eusocial Polistes (paper wasps), and compared their patterns of molecular evolution to two s...

Cooperation and aggression are ubiquitous in social groups, and the genetic mechanisms underlying these behaviours are of great interest for understanding how social group formation is regulated and how it evolves. In this study, we used a candidate gene approach to investigate the patterns of expression of key genes for cooperation and aggression...

Hymenoptera is the second-most sequenced arthropod order, with 33 publically archived genomes (52 with ants, reviewed elsewhere), however these genomes do not capture the breadth of this very diverse order (Figure 1, Table 1). These sequenced genomes represent only 15 of the 97 extant families. Although at least 55 other genomes are in progress in...

RNA-interference (RNAi) is a useful tool to assess gene function by knocking down expression of a target gene, and has been used successfully in domestic and laboratory organisms. However, RNAi for functional genomics has not fully extended into ecological model organisms in natural environments. Assessment of gene function in the wild is important...

The social and nutritional environments during early development have the potential to affect offspring traits, but the mechanisms and molecular underpinnings of these effects remain elusive. We used Polistes fuscatus paper wasps to dissect how maternally controlled factors (vibrational signals and nourishment) interact to induce different caste de...

The specialized ability to learn and recall individuals based on distinct facial features is known in only a few, large-brained social taxa. Social paper wasps in the genus Polistes are the only insects known to possess this form of cognitive specialization. We analyzed genomewide brain gene expression during facial and pattern training for two spe...

In social species, there is a fundamental trade-off between ‘me’ and ‘we’; that is, should I reproduce, or should I work to help others to reproduce? In this issue of Molecular Ecology, Okada et al. (2017) delve into the evolution and genetic mechanisms of this core question, focusing on social caste formation in insects. The authors take advantage...

Parasites can manipulate host behaviour to increase their own transmission and fitness, but the genomic mechanisms by which parasites manipulate hosts are not well understood. We investigated the relationship between the social paper wasp, Polistes dominula, and its parasite, Xenos vesparum (Insecta: Strepsiptera), to understand the effects of an o...

The evolution of eusociality is a perennial issue in evolutionary biology, and genomic advances have fueled steadily growing interest in the genetic changes underlying social evolution. Along with a recent flurry of research on comparative and evolutionary genomics in different eusocial insect groups (bees, ants, wasps, and termites), several mecha...

Evidence of inter-species pathogen transmission from managed to wild bees has sparked concern that emerging diseases could be causing or exacerbating wild bee declines. While some pathogens, like RNA viruses, have been found in pollen and wild bees, the threat these viruses pose to wild bees is largely unknown. Here, we tested 169 bees, representin...

List of site names and descriptions for field sites used for bee collections with latitude and longitude and percent of total bees collected that were honey bees. (DOCX)

Summary table of all the wild bees collected across field sites: a) List of each specimen collected, with family, genus, and species noted, as well as whether specimen was used for virus quantification. b) Counts and proportion detected for each virus by genus and family. (DOCX)

Comparison of DWV, IAPV, and SBV g.e. in M. rotundata and C. inaequalis samples collected at 1 and 5 days post treatment exposure (d.). ANOVA, Tukey HSD p<0.05 (S5 Table); sample sizes indicated, * denotes significantly different from field-collected honey bees, ⁺ denotes significantly different from apiary-collected honey bee samples. (EPS)

χ2 report statistics for virus incidence in each wild bee bee family compared to a) field-collected honey bees and b) apiary samples. Data used to generate Fig 1A. (DOCX