Comparative behavioral responses of two parasitoid species of the Asian citrus psyllid to host-related cues

The invasive Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae) is the vector of the bacterium, Candidatus Liberibacter asiaticus that causes the devastating huanglongbing (citrus greening) disease. Two parasitoid species, Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae) and Diaphorencyrtus aligarhensis (Shafee, Alam and Argarwal) (Hymenoptera: Encyrtidae) have been introduced into the US for the classical biological control of D. citri. In Florida, more attention has been focused on T. radiata compared with D. aligarhensis, arguably because the later has failed to establish in the target area. This study compared host location strategies in the two parasitoid species. The movement of female parasitoids relative to the position of D. citri nymphs (hosts), host plus citrus leaf, infested citrus leaf without host, and cotton leaf (non-host plant) was recorded in a petri dish arena and analyzed with a behavioral tracking software. Further, the attraction of each parasitoid species to control (no plant) versus host-infested citrus, uninfested citrus or non-host plant was tested in Y-tube olfactometer bioassays. Comparative behavioral responses of the two parasitoid species may reveal key similarities and differences in their host location strategies. This knowledge will help improve their recruitment and effectiveness in the field, especially for D. aligarhensis which is lagging T. radiata. The ecological significance of the results is discussed.