Effect of Candidatus Liberibacter asiaticus on detoxifying enzymes and insecticide susceptibility of Asian citrus psyllid, Diaphorina citri

Infection of Asian citrus psyllid (ACP) Diaphorina citri Kuwayama with Candidatus Liberibacter asiaticus (Las) may affect the physiology of this plant disease vector. We investigated the effect of Las infection on susceptibility of ACP to selected insecticides. Furthermore, general esterase, glutathione S-transferase and P450 activities were quantified in Las-infected and uninfected ACP to gain insight into the possible mechanism(s) responsible for altered susceptibility to insecticides due to Las infection. LC50 values were significantly lower for Las-infected than in uninfected ACP adults for chlorpyriphos and spinetoram. There was a general trend for lower LC50 values in Las-infected than control ACP for three other insecticides tested; however, the differences were not statistically significant. General esterase, glutathione S-transferase and P450 enzyme activities were significantly lower in Las-infected than uninfected ACP.