Mating Status Influences Cold Tolerance and Subsequent Reproduction in the Invasive Ladybird Harmonia axyridis

Benoit Facon,Ruth A Hufbauer,Arnaud Estoup,Ashraf Tayeh,Julien Foucaud

doi:10.3389/fevo.2017.00108

Abstract

Among arthropods, ability to survive cold conditions may be instrumental for species invading temperate or colder climatic zones. Cold tolerance can be influenced by multiple environmental and physiological factors. We experimentally investigated the effects of mating status (unmated, mated, or mated and reproductive) on cold tolerance of the invasive harlequin ladybird Harmonia axyridis and subsequent reproduction. We found that unmated adults survive cold better than mated ones. Among mated individuals, those that had not reproduced survived better than those that had reproduced. After cold stress, formerly unmated females were mated, and we evaluated ability to reproduce in females from all three treatments. Females that reproduced prior to cold stress were less likely to reproduce after cold stress than females from both other treatments. We discuss what these results mean for the proportion of unmated females in H. axyridis aggregates at overwintering sites. This study highlights the importance of investigating how physiological status can affect cold tolerance of invasive arthropods.

Highlights

Temperature constitutes one of the main environmental factors explaining the geographic distribution of ectotherm species (Andrewartha and Birch, 1954)
We tested the prediction that mating experience would impact cold tolerance and subsequent reproduction in the invasive ladybird H. axyridis
We measured survival and subsequent ability of individuals exposed to a sub-zero temperature stress to reproduce, and evaluated whether survival and reproduction depended upon mating status

Summary

Introduction

Temperature constitutes one of the main environmental factors explaining the geographic distribution of ectotherm species (Andrewartha and Birch, 1954). Species from temperate and polar regions have to cope with cold conditions during winter. Insects have evolved several mechanisms allowing the persistence of populations including diapause, dispersal toward protective microclimate locations or production of antifreeze compounds (Graham et al, 2000; Denlinger, 2002; Hahn and Denlinger, 2011; Lee and Leskey, 2015). The ability to pass through cold conditions may be instrumental for the establishment of species introduced into a temperate or polar region (Dalin et al, 2010). Several studies have shown that ability to survive cold conditions in invasive species evolves to better match novel environmental conditions in the introduced areas (Hsiao, 1985; Sadakiyo and Ishihara, 2011; Lehmann et al, 2014)

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Conclusion