Effect of temperature on development and reproduction of Proprioseiopsis asetus (Acari: Phytoseiidae) fed on asparagus thrips, Thrips tabaci.

Abstract

Thrips tabaci Lindeman (Thysanoptera: Thripidae) is one of the most important pests of asparagus in China. In this study the effects of five constant temperatures (15, 20, 25, 30 and 35°C) on the growth, survivorship and reproduction of Proprioseiopsis asetus (Chant) (Acari: Phytoseiidae) fed on T. tabaci was examined under laboratory conditions. Development time of immatures decreased with increasing temperature. The lower egg-to-adult developmental threshold (T 0) and thermal constant (K) of P. asetus were estimated at 15.2°C and 75.8 degree days by means of a linear model. Fertilized females fed on T. tabaci produced offspring of both sexes, whereas the offspring sex ratio [♀/(♀+♂)] of P. asetus at 20-35°C was female-biased (0.68-0.78) and not significantly influenced by temperature. Survivorship during immature development was significantly influenced by temperature, and was especially low at 15°C. Pre- and post-oviposition periods of fertilized females shortened with the increase in temperature. The longest oviposition period was 20.4days, at 25°C, whereas at 15°C the mites did not reproduce. Maximum average life time fecundity and mean daily fecundity was recorded at 25 and 35°C, respectively; the intrinsic rate of increase ranged from 0.05 (20°C) to 0.17 (35°C). The results indicate the capability of P. asetus to develop and reproduce at a broad range of temperatures, especially above 25°C, which can be used for better management of T. tabaci in asparagus.