Effect of plant species on insecticidal response of Asian citrus psyllid, Diaphorina citri Kuwayama

Diaphorina citri (D. citri) is a vector of citrus disease-causing bacterium, ‘Candidatus’ Liberibacter asiaticus, and has seriously impacted the citrus industry in Florida since it was first reported in 1998. Diaphornia citri can feed and reproduce on several different plant species, each of which produces a battery allelochemicals to defend against herbivory. In addition, these chemicals can induce the same detoxification enzyme systems as insecticides, and it has been shown that in some insects, the plant species and cultivar on which they are reared can have significant impact on the response of the insect to insecticidal treatment. Upon routine insecticidal screening of D. citri sub-cultures reared on different plant species of the Rutaceae family, it was noted that there was differential response in the LD₅₀ estimate to the pyrethroid, fenpropathrin. To determine if this difference could have an enzymatic basis, we determined the activity levels of the three main detoxification enzyme systems, general esterases, glutathione S-transferase, and cytochrome monooxygenase P450, in insects reared on the three plant species Citrus sinensis, Murraya paniculata and Bergera koenigii. Finally, to investigate if insects reared on the different plants varied in body size, we conducted biometric studies. For some parameters examined, differences between plants were observed. This system could serve as a model to investigate differential insecticidal response in D. citri, as well as have implications for integrated pest management strategies.