INFLUENCE OF RELATIVE HUMIDITY ON SURVIVAL OF THE CITRUS LEAF‐MINER, PHYLLOCNZSTZS CITRELLA STAINTON (LEPIDOPTERA: PHYLLOCNISTIDAE)

Abstract The relationshLps between relative humidity (RH) and survival rates of eggs, all larval stages and pupae of the citrus leaf‐miner, Phyllooiistis citrella Stainton, were determined by laboratory experiments. The survival of the citrus leaf‐miner was observed at seven levels of relative humidity from 35% RH to 95% RH at intervals of 10% RH, with 12 L: 12 D photoperiod and temperatiure (29±0.5) C. The relative humidity was controlled by saturated solutions of MgCl2 6H2O, K2CO3 2H2O, C6H12O6, NaNO2, NaCl, KCl, and Pb(NO3)2. The results showed that lower relative humidity is unfavorable for incubation of the eggs, survival of the larvae and eclosion of the pupae. The survival rates increased generally with rising of relative humidity within the range of 35% ‐ 85% RH, and the maximum survival rates occurred at 85% RH for different life stages. The variations in hatching rates of the eggs, survival rates of the larvae and emergence rates of the pupae were great, but unimodal at different relative humidity. The effect of relative humidity on survival rates of the citrus leaf‐miner could be simulated by regression analysis, using a polynomial function of three orders, and the results of fitting the model to the observed data are presented and discussed.