Influence of daily temperature maximums on the development and short-distance movement of the Asian citrus psyllid

Abstract

Temperature is a key factor in insect biology and ecology. Climate change is driving insect exposure to temperature extremes and understanding the effect of extreme temperatures on the biology of invasive agricultural pests will be key to predicting the effect of temperature increases. Here, we simulated diurnal cycles with different lengths of exposure times to maximum temperatures experienced in summer in different locations of California on the survivorship and development of the Asian citrus psyllid (ACP) (Diaphorina citri Kuwayama). ACP is the invasive vector of Huanglongbing disease (HLB), a lethal bacterial pathogen of citrus which is currently spreading in the Los Angeles, California basin. We also tested the effect of high or low humidity at high temperatures on ACP survival and development and the effect of high temperatures on short-distance dispersal. ACP were able to complete their life cycle in all temperature treatments (28-43 °C) except in daily cycles when 43 °C was maintained for 6 h. Temperature and exposure time significantly decreased adult emergence above 40 °C. High temperatures significantly increased development time with longer development as exposure times to high temperatures increased. The interaction between low humidity and high temperature increased the number of emerging adults and decreased developmental times. ACP short-distance dispersal increased over time but was not affected by temperature. These results indicate that ACP are capable to develop in temperatures higher than previously reported, suggesting that increasing temperatures may reduce the invasive capacity of ACP in regions where maximum daily temperatures are increasing along with the duration of such temperatures throughout the day.

Keywords: Climate change; Heatwave; Huanglongbing; Invasion ecology; Temperature tolerance; Thermal stress; Vector dispersion.