Reproductive arrest and stress resistance in winter-acclimated Drosophila suzukii

Citation

Toxopeus, J., Jakobs, R., Ferguson, L.V., Gariepy, T.D., Sinclair, B.J. (2016). Reproductive arrest and stress resistance in winter-acclimated Drosophila suzukii. Journal of Insect Physiology, [online] 89 37-51. http://dx.doi.org/10.1016/j.jinsphys.2016.03.006

Plain language summary

In order for insects to survive the winter in cold climates, they often have to adapt. Here we investigate the strategies that have been developed by the invasive pest, Spotted Wing Drosophila (SWD). When the immature (larval) stage of SWD is reared under short-day length and low temperatures (simulating winter conditions), they are slower to develop but are able to remain active under lower temperatures, and are more tolerant of environmental conditions, which increases their survival. These strategies likely contribute to the survival of SWD in Canada during the winter.

Abstract

Overwintering insects must survive the multiple-stress environment of winter, which includes low temperatures, reduced food and water availability, and cold-active pathogens. Many insects overwinter in diapause, a developmental arrest associated with high stress tolerance. Drosophila suzukii (Diptera: Drosophilidae), spotted wing drosophila, is an invasive agricultural pest worldwide. Its ability to overwinter and therefore establish in temperate regions could have severe implications for fruit crop industries. We demonstrate here that laboratory populations of Canadian D. suzukii larvae reared under short-day, low temperature, conditions develop into dark 'winter morph' adults similar to those reported globally from field captures, and observed by us in southern Ontario, Canada. These winter-acclimated adults have delayed reproductive maturity, enhanced cold tolerance, and can remain active at low temperatures, although they do not have the increased desiccation tolerance or survival of fungal pathogen challenges that might be expected from a more heavily melanised cuticle. Winter-acclimated female D. suzukii have underdeveloped ovaries and altered transcript levels of several genes associated with reproduction and stress. While superficially indicative of reproductive diapause, the delayed reproductive maturity of winter-acclimated D. suzukii appears to be temperature-dependent, not regulated by photoperiod, and is thus unlikely to be 'true' diapause. The traits of this 'winter morph', however, likely facilitate overwintering in southern Canada, and have probably contributed to the global success of this fly as an invasive species.

Publication date

2016-06-01

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