Two Parasitoids of Diaphorina citri (Hemiptera: Liviidae) have Shared, Stage-Specific Preference for Host Nymphs that does not Impact Pest Mortality Rates

Abstract

Assessing the oviposition preference and offspring performance of 2 parasitoid species being used to establish classical biological control of Diaphorina citri Kuwayama (Hemiptera: Liviidae) infesting citrus may provide important insight into their potential coexistence in California, USA. Tamarixia radiata (Waterston) (Hymenoptera: Eulophidae), an ectoparasitoid, preferred fourth and fifth instar D. citri nymphs for oviposition in both choice and no-choice experiments. Larval development and adult longevity of T. radiata offspring were positively correlated to female oviposition preference. Oviposition preferences of T. radiata were unaffected by conspecific and heterospecific competitors. Diaphorencyrtus aligarhensis (Shafee, Alam & Agarwal) (Hymenoptera: Encyrtidae), an endoparasitoid, preferred third and fourth instar hosts in choice experiments and fourth instar hosts in nochoice experiments. Parasitoid larvae that developed in these instars performed better than larvae that developed in second and fifth instars. The oviposition preferences of D. aligarhensis were unaffected by competitors in choice arenas, but were affected in no-choice experiments. Populations of T. radiata and D. aligarhensis from Pakistan, where they exist in sympatry and used in the experiments reported here, demonstrated a shared preference for fourth instar D. citri nymphs, which has not been documented previously for populations of D. aligarhensis from other geographic regions. This shared preference did not affect D. citri mortality rates, but it may affect the ability of D. aligarhensis to establish in areas of California where T. radiata is currently present.