Effect of the frequency and magnitude of extreme temperature on the life history traits of the large cotton aphid, Acyrthosiphon gossypii (Hemiptera: Aphididae): implications for their population dynamics under global warming

Abstract

Models of global climate change predict a greater frequency and magnitude of extreme temperature events and this will have biological consequences. Aphids are vulnerable to climate warming because ambient temperature strongly affects their life history traits. We used the large cotton aphid (Acyrthosiphon gossypii M.) as a model insect to provide insights into the responses of mid-latitude (temperate zone) aphids exposed to high temperature events. The developmental time, survival and fecundity of individual A. gossypii were measured under five temperature regimes. Even though the mean daily temperature was the same (24 degrees C) for all temperature regimes, the impact of temperature fluctuations to extreme levels (36 degrees C) on aphid fitness was clearly different to the impact of constant temperature. Negative effects on the aphid's life history traits occurred under all four fluctuating temperature regimes. Our study shows that cooler intervals may help the insect to tolerate potentially lethal high temperatures under naturally occurring conditions. The results will help us to understand the changes to aphid population dynamics likely to be associated with global warming in the future, and to design management practices for this pest species in cotton-growing areas in mid-latitudes such as central Asia.