Deconstructing superorganisms and societies to address big questions in biology

Social insect societies are long-standing models for understanding social behaviour and evolution. Unlike other advanced biological societies (such as the multicellular body), the component parts of social insect societies can be easily deconstructed and manipulated. Recent methodological and theoretical innovations have exploited this trait to address an expanded range of biological questions. We illustrate the broadening range of biological insight coming from social insect biology with four examples. These new frontiers promote open-minded, interdisciplinary exploration of one of the richest and most complex of biological phenomena: sociality

Effects of the neonicotinoid pesticide thiamethoxam at field-realistic levels on microcolonies of Bombus terrestris worker bumble bees

Copyright © 2013 Elsevier. Notice: this is the author’s version of a work that was accepted for publication in Ecotoxicology and Environmental Safety. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Ecotoxicology and Environmental Safety, 2014, Vol. 100, pp. 153-158 at: http://dx.doi.org/10.1016/j.ecoenv.2013.10.027Neonicotinoid pesticides are currently implicated in the decline of wild bee populations. Bumble bees, Bombus spp., are important wild pollinators that are detrimentally affected by ingestion of neonicotinoid residues. To date, imidacloprid has been the major focus of study into the effects of neonicotinoids on bumble bee health, but wild populations are increasingly exposed to alternative neonicotinoids such as thiamethoxam. To investigate whether environmentally realistic levels of thiamethoxam affect bumble bee performance over a realistic exposure period, we exposed queenless microcolonies of Bombus terrestris L. workers to a wide range of dosages up to 98 μg kg−1 in dietary syrup for 17 days. Results showed that bumble bee workers survived fewer days when presented with syrup dosed at 98 μg thiamethoxam kg−1, while production of brood (eggs and larvae) and consumption of syrup and pollen in microcolonies were significantly reduced by thiamethoxam only at the two highest concentrations (39, 98 μg kg−1). In contrast, we found no detectable effect of thiamethoxam at levels typically found in the nectars of treated crops (between 1 and 11 μg kg−1). By comparison with published data, we demonstrate that during an exposure to field-realistic concentrations lasting approximately two weeks, brood production in worker bumble bees is more sensitive to imidacloprid than thiamethoxam. We speculate that differential sensitivity arises because imidacloprid produces a stronger repression of feeding in bumble bees than thiamethoxam, which imposes a greater nutrient limitation on production of brood.Natural Environment Research Council (NERC

Migration control: A distance compensation strategy in ants

©The Author(s) 2016. This article is published with open access at Springerlink.com. Migratory behaviour forms an intrinsic part of the life histories of many organisms but is often a high-risk process. Consequently, varied strategies have evolved to negate such risks, but empirical data relating to their functioning are limited. In this study, we use the model system of the househunting ant Temnothorax albipennis to demonstrate a key strategy that can shorten migration exposure times in a group of social insects. Colonies of these ants frequently migrate to new nest sites, and due to the nature of their habitat, the distances over which they do so are variable, leading to fluctuating potential costs dependent on migration parameters. We show that colonies of this species facultatively alter the dynamics of a migration and so compensate for the distance over which a given migration occurs. Specifically, they achieve this by modulating the rate of ‘tandem running’, in which workers teach each other the route to a new nest site. Using this method, colonies are able to engage a larger number of individuals in the migration process when the distance to be traversed is greater, and furthermore, the system appears to be based on perceived encounter rate at the individual level. This form of decentralised control highlights the adaptive nature of a behaviour of ecological importance, and indicates that the key to its robustness lies in the use of simple rules. Additionally, our results suggest that such coordinated group reactions are central to achieving the high levels of ecological success seen in many eusocial organisms

Cross tabulation for effect of manipulation on final nest choice.

<p>Best choice: chose the better new nest, or split between the two new nests; moderate: chose the worse new nest; impaired: remained in starting nest or split between starting and worse new nests (nest destruction from previously published data).</p><p>Cross tabulation for effect of manipulation on final nest choice.</p

Mean percentage of total colony workers in nests of each quality over time for (a) control; (b) nest predation, (c) peripheral predation groups, and (d) when the original nest was destroyed (from previously published data).

<p>The mean represents n = 10 colonies for each time point in (a)–(c) and n = 11 colonies in (d). Error bars indicate 95% confidence intervals.</p

The range of nest types used in the experiment: (a) clear cover, 1mm wall height, 4mm entrance width; (b) red filter cover, 2mm wall height, 4mm entrance width; (c) red filter cover, 2mm wall height, 1mm entrance width; (d) clear cover, 1mm wall height, 4mm entrance width, acetate film with holes for ant removal and second acetate layer to act as a cover; (e) clear cover, 1.8mm wall height, 4mm entrance width; (f) red filter cover, 1.8mm wall height, 2mm entrance width. (g) Experimental arena, starting nests were of poor quality and were not destroyed, allowing voluntary emigrations to occur.

<p>A similar arena was used for the nest destruction treatment, measuring 800x165mm [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0141012#pone.0141012.ref015" target="_blank">15</a>].</p