Temperature-dependent development and life history of Oligonychus litchii (Acari: Tetranychidae), on wax apple

Abstract

The litchi spider mite Oligonychus litchii Lo & Ho is one of the major pests of fruit crops in Taiwan. This study investigated the life history of the litchi spider mite on wax apple (Syzygium samarangense Merr. & Perry) at five constant temperatures (16, 20, 25, 30, and 32°C) under 70±5% RH and a 12L:12D photoperiod. Ninety-five percent of the eggs hatched at 20, 25, and 30°C, respectively. The entire developmental period was 40.3days at 16°C and only 9.3days at 32°C. The low developmental threshold temperature for development from egg to adult was 10.1°C, and the effective accumulated temperature was 197.5degree–days (DD). Unmated female mites had the longest life span although the oviposition period shortened as temperature increased. Mated female mites produced significantly more eggs than unmated females. At most, a mated female could produce an average of 3.5 eggs per day at 25°C and a maximum of 60.3 eggs over the entire oviposition period at 20°C. Unmated females exclusively produce male offspring, indicating that litchi spider mites are arrhenotokous. At 25°C, the intrinsic rate of increase (r) was 0.1610day−1, the net reproductive rate (R0) was 19.58 offspring, the finite rate of increase (λ) was 1.1747day−1, and the mean generation time (T) was 18.50days. The results obtained in this study provide useful information to aid in the development of phenological models for pest monitoring programs of O. litchii in Taiwan.