Effect of relative humidity on population growth of Apolygus lucorum (Heteroptera: Miridae)

Apolygus lucorum (Meyer-Dur) (Heteroptera: Miridae) is a significant insect pest of cotton, Chinese dates, grapes and many other crops in China, and its populations typically increase after heavy rains. However, the intrinsic mechanism of the rainfall-dependent outbreak is not yet fully understood. In our study, the effect of different relative humidity (RH), 40, 50, 60, 70, and 80% RH, on population growth of A. lucorum was evaluated in the laboratory. High humidity (e.g. 70 and 80% RH) was observed to significantly increase egg and nymph survival, prolong adult life longevity, and improve female fecundity. However, low humidity (e.g. 40 and 50% RH) led to unfavorable effects on survival and fecundity. As a result, the intrinsic capacity for increase (r (m)), net production (R (o)), and the finite rate of increase (lambda) of A. lucorum population greatly increased with increasing relative humidity. Additionally, the relationships between r (m) and R (o) and relative humidity were good fits to the logistic models y = 36.82/(1 + Exp(10.76 - 0.19x)) (p < 0.001) and y = 0.10/(1 + Exp(9.26 - 0.19x)) (p = 0.003), respectively. This study provides insight into the phenology of A. lucorum, and may contribute to modeling of its population dynamics.