CHEMICAL ECOLOGY Responses of the Asian Citrus Psyllid to Volatiles Emitted by the Flushing Shoots of Its Rutaceous Host Plants

Diaphorina citriKuwayama (Hemiptera: Psyllidae) carriesCandidatus liberibacter spp., the putative causal agents of Huanglongbing. D. citri reproduces and develops only on the ßushing shoots of its rutaceous host plants. Here we examined whetherD. citri is attracted to host plant odors and a mixture of synthetic terpenes. Tests conducted in a vertically oriented Y-tube olfactometer showed that both males and females preferentially entered the Y-tube arm containing the odor from the young shoots of Murraya paniculata (L.) Jack and Citrus limon L. Burm. f. cultivar Eureka. Only males exhibited a preference for the odor of C. sinensis L., whereas the odor of C. paradisi MacFadyen cultivar Rio Red was not attractive to both sexes. The volatiles emitted by young shoots of grapefruit cultivar Rio Red, Meyer lemon (Citrus limon L. Burm.f.), and M. paniculata were analyzed by gas chromatographÐmass spectrometry. The samples were comprised of monoterpenes, monoterpene esters, and sesquiterpenes. The number of compounds present varied from 2 to 17, whereas the total amount of sample collected over 6 h ranged from 5.6 to 119.8 ng. The quantitatively dominant constituents were (E)-ocimene, linalool, linalyl acetate, and -caryophyllene. The attractiveness of a mixture of synthetic terpenes, modeled on the volatiles collected fromM. paniculata, was evaluated in screened cages in a no-choice test. At three observation intervals, signiÞcantly more individuals were trapped on white targets scented with the mixture than on unscented targets. These results indicate the feasibility of developingD. citri attractants patterned on actual host plant volatiles.