Genetic Basis of Thermal Tolerance influence both dynamic plastic responses to thermal stress and preparatory processes that improve thermal resistance. These results also have utility for directly comparing GWAS and transcriptomic approaches for identifying candidate genes associated with thermal tolerance.

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In this study we test one central prediction from sociogenomic theory--that social and non-social taxa share common genetic toolkits that regulate reproduction in response to environmental cues. We exposed Drosophila females of rover (for(R)) and sitter (for(s)) genotypes to an ovary-suppressing pheromone derived from the honeybee Apis mellifera. Surprisingly, queen mandibular pheromone (QMP) affected several measures of fitness in flies, and in a manner comparable to the pheromone's normal effect on bee workers. QMP-treated sitter flies had smaller ovaries that contained fewer eggs than did untreated controls. QMP-treated rover flies, by contrast, showed a more variable pattern that only sometimes resulted in ovary inhibition, while a third strain of fly that contains a sitter mutant allele in a rover background (for(s2)) showed no ovarian response to QMP. Taken together, our results suggest that distinctly non-social insects have some capacity to respond to social cues, but that this response varies with fly genotype. In general, the interspecific response is consistent with a conserved gene set affecting reproductive physiology. The differential response among strains in particular suggests that for is itself important for modulating the fly's pheromonal response.

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Detailed social and phenological data collected from nesting aggregations exist for relatively few sweat bee species because nesting aggregations are rarely found in large numbers, even when local populations are highly abundant. This limits researchers’ abilities to assess the social status of many species, which in turn, limits our ability to trace the sequence of evolutionary steps between alternative social states. To address this problem, we demonstrate the utility of rehydrated, pinned specimens from pan trap and netting collections for generating inferences about the phenology and social status of a well-studied sweat bee species, Lasioglossum (Dialictus) laevissimum. A detailed comparison of phenology and reproductive traits, between pinned specimens and those in a previous nesting study, produced similar results for bivoltine foraging activity and eusocial colony organization typical in this species. We then used pinned specimens from monitoring studies to describe, for the first time, the foraging phenology and social behaviour of two additional Dialictus species, L. hitchensi and L. ellisiae. Both L. hitchensi and L. ellisiae each exhibited two peaks in abundance during their breeding seasons, indicating two periods of foraging activity, which correspond to provisioning of spring and summer broods. Differences in body size, wear, and ovarian development of spring and summer females indicated that L. hitchensi is most likely eusocial, while L. ellisiae is either solitary or communal. This study demonstrates that analyses of specimens obtained from flower and pan trap collections can be used for assessing the phenology and social organization of temperate sweat bees in the absence of nesting data. The phenological and social lability of many sweat bee species make them ideal for studying geographic and temporal variability in sociality, and analyses of pan trap collections can make these studies possible when direct observations are impossible.

Reproductive division of labour is based on biased expression of complementary parental behaviours, brood production (egg-laying) by queens and brood care (in particular, brood-provisioning) by workers. In many social insect species, queens provision brood when establishing colonies at the beginning of a breeding season and reproductive division of labour begins with the emergence of workers. In many social insect species, the expression of foraging (for) mRNA is associated with the intensity of foraging behaviour and therefore brood-provisioning. However, only two studies have compared queen and worker for expression levels and neither accounted for transcript splice variation. In this study, we compare the expression level of the for-α transcript variant across four life stages of the queen caste, two behavioural groups of workers, and males of a eusocial sweat bee Lasioglossum laevissimum (Smith, 1853). Foundresses collected prior to the onset of the foraging season and males had the highest for-α expression levels. All active (post-hibernatory) queens and workers had similar for-α expression levels independent of behaviour. These results suggest that the for gene in L. laevissimum acts as a primer before foraging activity and that caste-specific expression patterns correlate with the timing of foraging activity in queens and workers.

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