Abstract

Tetranychus ludeni Zacher is a spider mite that has invaded all continents except Antarctica and become an economically important pest around the world. Understanding the plasticity of its life history traits as a response to temperatures provides critical information for its risk analysis and management. Here we tested its response to temperatures ranging from 15 to 30ºC over two generations. We found that there was no difference in the egg hatch rate and immature survival rate across temperatures in the first generation. However, the egg hatch rate was lower and immature survival rate was higher at 30ºC in the second generation. The sex ratio (proportion of females) of resultant adults was consistent under all test temperatures in both generations except for 30ºC in the second generation which was lower. Higher temperature accelerated development in both generations but the development at the lower temperatures was faster in the second generation. Adult body size in both generations generally decreased with the increase of temperature, with females being more likely than males to adjust body size in response to temperature changes they first experienced. Temperature-dependent body size was not translated into fecundity, but larger adults lived longer. The thermal threshold was lower and degree days (DD) were greater in the second generation than in the first generation. Our findings indicate that life history traits of T. ludeni are highly flexible and adaptive to dynamic thermal environment in successive generations. Furthermore, increasing temperature elevated the intrinsic rate of increase (rm) but shortened the generation time (T) and the time to double the population size (Dt). The net population growth rate (R0) was higher at 20 and 25ºC as compared to lower and higher temperatures.