Abstract
Competition among queens in polygynous societies may result in queen executions or conflicts over personal reproduction. Understanding the factors that mediate the executions of ant queens should provide insight into how queen numbers are regulated in polygynous insect societies. The Argentine ant is a widespread invasive species that displays secondary polygyny, and workers execute 90% of their nestmate queens each spring. In this study, we investigated: (1) whether ambient temperature, queen number, and protein deprivation have an effect on queen executions and (2) whether workers select the queens slated for execution based on their cuticular hydrocarbon (CHC) profiles. We found that the percentage of queens executed was positively correlated with temperature and queen number but that protein deprivation did not play a role. As for queen fate, the levels of some CHCs were higher in surviving queens. One of these CHCs is associated with queen productivity (i.e egg-laying rate and ovarian index) suggesting that workers execute the least productive queens. Our findings suggest that chemical cues related to fertility signaling may mediate queen executions in Argentine ants.
Highlights
Among social insects, ants stand out as a group in which polygyny may be the predominant social structure[1]
This study has revealed new information about how queen numbers are regulated in the Argentine ant, a globally invasive species that displays secondary polygyny
We found that higher queen numbers and higher temperatures resulted in a greater percentage of queen executions
Summary
Ants stand out as a group in which polygyny (i.e., the presence of several queens in the same colony) may be the predominant social structure[1]. Primary polygyny can occur when multiple queens accompanied by workers found a new colony after budding from larger colonies[2]. In contrast, there is a decrease in queen fecundity as queen numbers increase[13,14,15,16,17]. The Argentine ant, (Linepithema humile, Mayr), an invasive species found across the globe, displays secondary polygyny and carries out a dramatic number of queen executions. Www.nature.com/scientificreports key role in regulating queen numbers, especially in highly polygynous species such the Argentine ant. Deslippe and Guo (cited in28) found that, in fire ants, the mortality rate of queens was positively correlated with queen number, which could suggest that workers execute supernumerary queens to regulate the level of queen pheromones circulating in the colony
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