Asian Citrus Psyllid (Hemiptera: Liviidae) Tolerance to Heat

Abstract
The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is an important citrus pest because it vectors bacteria responsible for a serious citrus disease known as huanglongbing (also called citrus greening disease). We conducted research on Asian citrus psyllid heat tolerance, with special emphasis on identifying heat treatments lethal to adult Asian citrus psyllid. Working with an Asian citrus psyllid colony maintained at 27°C, we assessed survival of adult Asian citrus psyllid exposed to temperatures of 43–60°C for various durations in a laboratory oven. We found under our experimental conditions that adult Asian citrus psyllid cannot survive at 50°C for more than ≈10 min and that death occurred faster at higher temperatures; males tended to be more heat-tolerant than females; young adults were less tolerant of high temperatures than older adults; adult Asian citrus psyllids predisposed to warmer temperatures were more heat-tolerant than those predisposed to cooler temperatures; and heat treatments lethal to adult Asian citrus psyllids were lethal to eggs and usually lethal to nymphs. Adult Asian citrus psyllids were less tolerant of heat treatments in the oven when the humidity level was high than when it was low. A number of heat treatments lethal to adult Asian citrus psyllid in an oven situation can be identified from the results of this research and would be useful to regulatory agencies interested in eliminating adult Asian citrus psyllids from shipments of citrus leaves destined for culinary or medicinal markets. Among a number of candidate treatments, 60°C for at least 10 min would be effective against all Asian citrus psyllid life stages and faster killing than lower temperatures.