Body size is a universal property affecting biological structure and function, from cell metabolism to animal behavior. The nervous system, the physical generator of behavior, is also affected by variations in body size; hence potentially affecting the way animals perceive, interpret and react to the environment. When animals join to form groups, such individual differences become part of the structure of the society, even determining social roles. Here, I explore the association between body size, behavior and social organization in honeybees and bumblebees. Focusing on bumblebees, I explore the link between body size, brain allometry and learning and memory performance, within the context of task specialization. I show that body size goes along with brain size and with learning and memory performance, and that foraging experience affects such cognitive and neural features. Next, I explore the association between body size and foraging task specialization in honeybees. Previous evidence showed a link between specialization on pollen or nectar foraging and sensory sensitivity, further associating sensitivity to the quality and/or quantity of resource exploited. I hypothesize that, as in solitary bees, larger body size is associated with higher sensory sensitivity. I test this hypothesis by comparing body size and the quality and quantity of the resource exploited by wild Africanized and European honeybees. I show that nectar foragers are smaller and have fewer olfactory sensilla, which might underlie their lower sensitivity to odors. Also, larger bees collect more pollen (within pollen foragers) and more dilute nectar (within nectar foragers). To further test this `size hypothesis', I compare strains of bees selected to store large ("high strain") or small ("low strain") amounts of pollen surplus. As these strains differ in sensory sensitivity, I predict that the more sensitive high strain bees are larger and have more sensory sensilla. I show that high strain bees are generally bigger, but have fewer sensory sensilla than low strain bees. These results show that in bees, body size is associated with an individual's sensory, neural and cognitive features, further suggesting that body size plays a more important role in the organization of bee societies than generally assumed.

Animals in general vary immensely in body size, which greatly affects their morphology, physiology, survival, and nutritional requirements. The nervous system is also affected by variation in body size, which, in turn, shapes the perception of environmental stimuli and the behavior of animals. Comparative studies of vertebrates suggest that larger brains and their integrative centers comprise more and generally larger neurons (Jerison, 1973; Kaas, 2000), but much less is known about brain - body size relations in invertebrates. Closely related social bee species are well suited to study correlations between body size and brain composition. Different honey bee species vary in body size yet differ little in their ecological requirements and behavior and bumble bees feature a large range of body sizes even within a single colony.

The honeybees Apis cerana and Apis mellifera are derived from the same ancestral base about two million years ago. With speciation and evolution, they have acquired many advanced living skills in common, but have also evolved very different living strategies due to different distributions. This thesis is an intensive study of the biology of the mixed-species colonies of these species, the aims of which were to investigate their behavioural relationships and uncover the evolutionary conserved features of their behaviours subsequent to speciation. The results show that the two species can form a stable society to perform normal tasks. First, workers of both species in the mixed-colonies could form the typical retinue behaviour to hetero-species queens, thus indicating that queen pheromones could be spread to and by both species. Secondly, both species did not show significantly different ovarian activation under hetero-species queens, suggesting that the queen pheromones more likely play a role of "honest signal" rather than a "repression" substance in the honeybee colonies. Thirdly, both species could mutually decode each other‘s waggle dances, with unexpectedly low misunderstanding; revealing that the dance language in a dark environment is quite adaptive for cavity-nesting honeybees. Fourthly, workers of both species could cooperate with each other in comb construction, although the combs they built contain many irregular cells. Interestingly, A. cerana workers could be stimulated by A. mellifera workers to perform this task, thus confirming self-organization theory in the colony. Fifthly, A. mellifera workers behaved more "defectively" in thermoregulation, but perhaps because A. cerana workers are more sensitive to changes in hive temperature. Given these differences in strategy, A. mellifera workers‘ performance might in fact reduce conflicts. Lastly, when faced with threats of predatory wasps, both species engaged in aggressive defence. Although they did not learn from each other‘s responses, species-specific strategies were adopted by each of them so that the defence of the mixed-colonies is very effective. I conclude that the two species can adapt to each other‘s efforts and task allocation is reasonably organized allowing mixed-species colonies to reach stability. These results suggest that all of the social behaviours discussed here were highly conserved following speciation. This thesis could provide some clues for the study of honeybee evolution from open-nesting to the transition of cavity-nesting.

Brazil is the country with the second-largest number of cataloged bee species in the world, about 2,000. Among these we have stingless bees, with around 250 different species; these live in society, produce honey, and unlike the European Apis Mellifera, do not sting. Sadly, most Brazilians only know of the existence of a single bee species, which is the invasive European bee. Native bees are not only the most important pollinators of our native flora but are also part of an intricate and fragile web of life that is currently under threat. For each bee species that go extinct, there are far-reaching consequences for the entire ecosystem it belongs to, therefore it’s imperative to protect and care for our native bees.In this project, I've worked alongside the Terra Mirim foundation. I’ve compiled information on native bees, their biology, the native history of beekeeping, societal behavior, their importance, risks, etc. I started this work in collaboration with Terra Mirim, a foundation that works on the recovery of the Atlantic Forest and has over 60 native beehives under their care, they also receive many visitors throughout the year who are looking for closer contact with nature. I believe awareness, knowledge, and proximity are important starting points for developing empathy towards other forms of life, so along with the photographs I’ve been taking, I am transforming the information I compiled into signboards to promote awareness among Terra Mirim’s visitors.

The health of pollinators, especially bees, is of the utmost importance to success of many agricultural ecosystems. Microorganisms can cause diseases in bees; such microbes are pathogenic. The ability of a pathogen to cause harm to its host (such as a bee) is termed its virulence. Studying the evolution of different levels of virulence can lead researchers to a better understanding of pathogens, and potentially predict how much harm a pathogen can cause in the future. We studied the evolution of virulence levels for a fungal disease of bees. This group of fungi is composed of 28 species, and some cause a disease in bees called chalkbrood while others do not. Using what we know about virulence evolution we wanted to see if the pathogens could infect all bees, if the pathogens varied in virulence when infecting at the same time as another pathogen, and if solitary bees had any behavioral adaptations that might increase or decrease chalkbrood infection. By using DNA sequences, the relationship between the genetic structures of each of the fungal species was studied, and we found that pathogens of solitary bees grouped together while pathogens of social bees (honey bees) were not part of this group. We then found that a solitary bee pathogen did not infect honey bees very well, and vice versa. The nuances of the relationship between two solitary bee pathogens were examined more closely to determine how the two pathogens interact in this bee. In this case, under varying conditions of infection, one pathogen always maintained a similar level of virulence and spore production, while the other pathogen varied in these measures. In addition, when doses of these fungi were fed to bee larvae at different times, more bees survived than when the doses were given at the same time, suggesting that bee immune responses are very important. Finally, we found no evidence of any specific behaviors of solitary bees exposed to infective spores that would suggest these bees have behaviors that are evolved to alter chalkbrood levels in populations.

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Repeated cold exposures and warmer winter temperatures might negatively affect insects by depleting stored fuel reserves. I researched the effects of fluctuating thermal regimes on two species of solitary mason bees (Osmia albiventris and O. lignaria) by quantifying mass loss and reserves of lipids, free sugars, and glycogen after experimental temperature treatments during early spring. In a second season, I quantified mass loss, time to emergence, and time to recover from chill coma after bees had been exposed to one of two spring-time temperature regimes. I found that warmer temperatures in combination with greater temperature variability increases mass loss and the depletion of fuel reserves. Additionally, my results suggest that accelerated bee emergence helps to mitigate mass loss. Overall, these bees appear resilient in the face of changing spring temperatures. Résumé: On sait peu sur la façon dont la variabilité environnementale affecte les abeilles solitaires sauvages. Ma recherche a étudié la façon dont les régimes thermiques fluctuants affectent la vigueur de deux espèces d'abeilles solitaires (Osmia albiventris et O. lignaria) en quantifiant la perte de masse ainsi que les réserves métaboliques (lipides, sucres libres, et glycogène) des abeilles suite à des manipulations expérimentales de la température printanière. Dans une deuxième saison, j’ai quantifié la perte de masse, le temps de l'émergence et le temps pour récupérer du coma froid après que les abeilles avaient été exposées à l'un de deux régimes de températures printanières. Mes résultats indiquent que les températures plus chaudes ont tendance à augmenter la perte de masse et des réserves métaboliques lorsqu'elles sont combinées avec une plus grande variabilité. De plus, mes résultats suggèrent que ces abeilles sont résilientes face aux températures printanières changeantes.

Processes structuring bee communities in agricultural landscapes are well-documented compared to those in other anthropogenic landscapes, like production forests. Forests across the temperate zone have historically been under-sampled, in part due to the perception that they provide little habitat to support diverse bee communities. While research suggests that early successional habitats support high levels of bee species richness and abundance, little empirical evidence exists to support the notion that forests, in turn, do not. To understand the relationship between forest successional age and major elements of the bee community, I sampled bees in a southern production pine forest in Hancock County, MS across 2012 and 2013. I found that while bee abundance declines with successional age, species richness does not. Combining this work with other recent research, I propose a generalized framework for understanding the role of disturbance and forest structure in structuring bee communities of southern forests.

Increases in agricultural intensification over the past century have resulted in significant alterations to the rural landscape across the Midwest. Pollinators are essential to sustain natural and managed ecosystems. They are vital for food production and their declines have been linked, in part, to a rise in intensive agricultural practices. There is a recognized need among numerous stakeholders to build sustainability into the management of agroecosystems to protect both the biotic and abiotic resources of these systems. The use of cover crops is gaining interest among agricultural producers for benefits such as improving water quality and soil health. Cover cropping systems have the potential to provide floral resources to pollinators and suppress problematic driver weeds. The overall objective of this study was to quantify the effects of cover crops on plant and pollinator biodiversity within agricultural systems. This study aimed to characterize the pollinator diversity indicative of the patchwork mosaic forest-agroecosystem of Crab Orchard National Wildlife Refuge; evaluate the roles cover crop treatments play in supporting pollinator diversity and weed suppression benefits in a conventionally managed system; and provide the basis of recommendations for sustainable weed suppression tactics and for enhancing the quality of pollinator habitat within agricultural systems.

A comunidade de insetos visitantes de flores de clones do eucalipto urograndis (Eucalyptus grandis x E. urophylla) foi estudada em um plantio localizado na Fazenda Areão, em Piracicaba, SP (22° 41 41 S e 47° 38 5 3 W ) por meio de levantamentos semanais com rede entomológica, durante os florescimentos de 2007 e de 2008 com a finalidade de caracterizar seu potencial apícola com a determinação de sua apifauna associada, e das características de néctar produzidos por suas flores. A comunidade antófila nos dois anos do levantamento foi representada por 29.492 indivíduos pertencentes a 6 ordens, 21 famílias, 43 gêneros e 52 espécies. A apidofauna foi representada por 24.882 indivíduos pertencentes a 11 gêneros e 10 espécies. A abelha africanizada Apis mellifera, o visitante mais efetivo em todo o levantamento (80,96%), seguida do sirfídeo Ornidia obesa (5,29%) e do mantispídeo Zeugomantispa virescens (4,26%). Os índices de diversidade (H) e equitabilidade (E); foram distintos nos dois levantamentos indicando distribuição de espécies mais uniforme na coleta de 2007 em relação à de 2008. Dentre as demais espécies predominantes, destacaram-se as abelhas Trigona spinipes (irapuá), Tetragonisca angustula (jataí), e Nannotrigona testaceicornis (iraí). As concentrações médias encontradas por clones foram inferiores ao relatado na literatura, sendo os valores máximos variando entre 13 e 14%. As diferenças encontradas entre alguns clones possivelmente foram influenciadas pela altura de algumas plantas. / The community of insect flower visitors of eucalyptus urograndis clones (Eucalyptus grandis x E. urophylla) was studied in an plantation located at Areão farm, in Piracicaba, São Paulo state, Brazil (22° 41 41 S e 47° 38 53 W ). Weekly collections were conducted using hand net during the bloom periods of 2007 and 2008 in order to characterize the potential for beekeeping by determining the associated apifauna and the nectar characteristics produced by the flowers.The anthophilous community in the two-year survey was represented by 29,492 individuals belonging to 6 orders, 21 families, 43 genera and 52 species. The apidofauna was represented by 24,882 individuals belonging to 11 genera and 10 species. The Africanized honey bee Apis mellifera. This species was the most effective visitor throughout the survey (80.96%) followed by the syrphid Ornidia obesa (5.29%) and the mantispid Zeugomantispa virescens (4.26%). The diversity (H\') and equitability (E) indices were different between the two surveys showing that species distribution was more uniform in the collecting of 2007 when compared to the 2008. Among the other dominant species, the bees Trigona spinipes (Irapuá bee), Tetragonisca angustula (jataí bee), and Nannotrigona testaceicornis (Iraí bee) were the main ones. The differences found between some clones were possibly influenced by the height of some plants.