Comparison of the effect of endo- and ectoparasitoid venoms on the physiology of the Asian citrus psyllid Diaphorina citri

Abstract :

Yellow dragon disease threatens global citrus production. Also known as HLB due to its Chinese name Huanglongbing, or ‘citrus greening’ in English, it first manifests itself as yellowing leaves, then fruit deformation, before killing the trees. To date, no treatment appears to be effective. Over the past fifteen years, the bacterium has been detected in seven of the ten leading orange-producing countries and has decimated plantations in Asia, Brazil, the Dominican Republic and the United States. The disease is transmitted by psyllids, which are piercing/sucking insects. In Asia, Diaphorina citri Kuwayama (Hemiptera: Psyllidae) and in Africa, Trioza erytreae (Hemiptera: Psyllidae). Both psyllids are currently present in the Mediterranean region. Biocontrol solutions have been implemented, in particular the use of the parasitoids Tamarixia radiata (ectoparasitoid; Hymenoptera: Eulophidae) and Diaphorencyrtus aligarhensis (endoparasitoid; Hymenoptera: Encyrtidae). These have proven to be very effective in controlling psyllid vectors. In collaboration with the Nanchang University, we have undertaken a study on the interactions between parasitoids and the Asian psyllid Diaphorina citri, focusing in particular on the effects of their venoms on the insect's behaviour and immune response.