Effects of Temperature on the Development and Reproduction of Oligonychus litchii Lo and Ho (Acari: Tetranychidae) when Reared on Litchee

Oligonychus litchii Lo and Ho (Arachnida: Acari: Tetranychidae) is one of the primary pests in the litchi orchard and causes serious damage. We studied the effects of temperature on development and reproduction of O. litchii and constructed experimental population life tables at 5 constant temperatures (20, 23, 26, 29, and 32 °C) under laboratory conditions. The results showed that development, reproduction, and life table parameters of O. litchii were significantly affected by different temperatures. The egg stage had the longest period of development, and survival or development time decreased significantly with rising constant temperatures. Duration of the larva, protonymph, and deutonymph stages, and total generation time, tended to decline as the temperature increased, but development time at 26, 29, and 32 °C did not differ significantly. The longest generation time (egg to death of the adult) was 34.3 d at 20 °C, followed by 21.9 d at 23 °C, and it was shortest at 32 °C (10.7 d). There is a positive linear correlation between the temperature (T) and developmental rate (V). The developmental threshold temperature and effective accumulated temperatures for the entire generation were 13.4 °C and 172.41 degree-d, respectively. The highest number of eggs laid per female was 77.2 eggs at 26 °C, while the lowest was 30.0 eggs at 20 °C. The maximum population growth rate (rm) values increased from 20 °C (0.04) to 29 °C (0.17), then decreased at 32 °C (0.12). The finite rates of increase (λ) were over 1.00 at all 5 constant temperatures. Temperature had a great effect on the development and reproduction of O. litchi, and the optimal temperature for the mite is around 26 °C.