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Emerging evidence suggests that insect populations may be declining at local and global scales, threatening the sustainability of the ecosystem services that insects provide. Insect declines are of particular concern in the Neotropics, which holds several of the world’s hotspots of insect endemism and diversity. Conservation policies are one way to prevent and mitigate insect declines, yet these policies are usually biased toward vertebrate species. Here, we outline some key policy instruments for biodiversity conservation in the Neotropics and discuss their potential contribution and shortcomings for insect biodiversity conservation. These include species-specific action policies, protected areas and Indigenous and Community Conserved Areas (ICCAs), sectoral policies, biodiversity offsetting, market-based mechanisms, and the international policy instruments that underpin these efforts. We highlight that although these policies can potentially benefit insect biodiversity indirectly, there are avenues in which we could better incorporate the specific needs of insects into policy to mitigate the declines mentioned above. We propose several areas of improvement. Firstly, evaluating the extinction risk of more Neotropical insects to better target at-risk species with species-specific policies and conserve their habitats within area-based interventions. Secondly, alternative pest control methods and enhanced monitoring of insects in a range of land-based production sectors. Thirdly, incorporating measurable and achievable insect conservation targets into international policies and conventions. Finally, we emphasise the important roles of community engagement and enhanced public awareness in achieving these improvements to insect conservation policies.

Developmental conditions can strongly influence adult phenotypes and social interactions, which in turn affect key evolutionary processes such as sexual selection and sexual conflict. While the implications of social interactions in phenotypically mixed populations at the individual level are increasingly well known, how these effects influence the fate of groups remains poorly understood, which limits our understanding of the broader ecological implications. To address this problem we manipulated adult phenotypes and social composition in Drosophila melanogaster – by experimentally manipulating the larval density of the group-members – and measured a range of group-level outcomes across the lifespan of groups. Adult groups composed of exclusively low larval-density individuals showed high courtship levels, and low early reproductive rates, group growth rates, offspring mass and offspring eclosion success, relative to high larval-density or mixed larval-density groups. Furthermore, high larval-density groups had lower survival. Offspring mass increased with time, but at a reduced rate in groups when male group members (but not females) were from a mixture of larval-densities; peak reproductive rates were also earlier in these groups. Our results suggest that that variation in developmental conditions experienced by adult group members can modify the reproductive output of groups.

Sexual selection is responsible for the evolution of formidable adaptations across the tree of life. Traditionally, sexual selection research has focused on male sexual displays and female choice. However, this approach ignores important social and environmental factors that can influence the operation of sexual selection. In this thesis, I aim to contribute to our knowledge of the effects of social and environmental factors, particularly those related to nutrition, on sexual selection. I investigate how the sexual behaviour of females and the nutritional and social environments of both sexes during larval and adult stages modulate sexual selection in the fruit fly Drosophila melanogaster. First, I assess how female promiscuity ("polyandry") affects the strength of sexual selection and patterns of assortative mating in freely interacting populations. There is no current consensus for the conflicting results of previous studies showing that polyandry can have positive, negative or have negligible effect on the opportunity for sexual selection. Using a genetic knockout that increases female sexual receptivity, I show that increasing polyandry reduces the opportunity for sexual selection and shifts the relative role of sexual selection from pre- to post-copulatory in males without affecting assortative mating patterns in freely interacting populations. Next, I consider how plastic responses to nutritionally poor larval environments and adult social environments modulate sexual selection, an area that has been considerably ignored. I find that although nutritionally poor larval environments reduce individuals' mating and reproductive success, plastic responses to social environments might mitigate against these disadvantages. Moreover, I show that plastic responses to larval and social environments influence the relative role of pre- and post-copulatory sexual selection in males, regulate offspring traits through trans-generational effects and determine population fate. Finally, I consider whether male reproductive traits have distinct macronutrient (protein and carbohydrate) requirements, and whether males can regulate their feeding to attain a diet that satisfies the requirements for these traits. I find that both a high short-term rate of offspring production when males mate with virgin females, and a high total number of offspring sired when males mate with previously mated females, require carbohydrate-rich diets, whereas male attractiveness requires a balanced (1:1) macronutrient diet. Furthermore, I show that male protein intake can negatively affect female long-term reproduction when males mate with virgins, but not with previously mated females, revealing a novel intersexual effect of male nutrition. Thus, this thesis deepens our understanding of key evolutionary processes by revealing the negative effects of high polyandry and nutritionally poor larval environments on the operation of sexual selection as well as uncovering male nutritional compromise in the expression of reproductive traits.

Glycated albumin (GA) is a marker of glycemic control that reflects postprandial plasma glucose levels and glycemic excursions better than HbA1c. However, no reports have examined correlations between diabetes duration and the ratio of glycated albumin to HbA1c (GA/HbA1c ratio) in patients with autoimmune type 1 diabetes (T1AD) or type 2 diabetes (T2D). We conducted a cross-sectional study involving 219 patients with T1AD and 141 patients with T2D. We evaluated correlations between diabetes duration, the GA/HbA1c ratio and fasting serum C-peptide immunoreactivity (CPR), index of insulin secretion capacity. The GA/HbA1c ratio was significantly correlated with diabetes duration in both T1AD and T2D patients (T1AD; R=0.139, p