Foreign exploration for natural enemies of Rastrococcus iceryoides (Hemiptera: Pseudococcidae) and climatic matching to guide introduction of promising parasitoids into Africa

Rastrococcus iceryoides Green (Hemiptera: Pseudococcidae) is a devastating alien invasive pest of several horticultural crops in Africa, mostly Tanzania, Kenya and Malawi. Although several indigenous parasitoids have been found attacking the pest, they are unable to keep the pest populations below economically damaging levels. Rastrococcus iceryoides is believed to have originated from India and as an invasive species in Africa; it is an excellent target for classical biological control. Exploration for natural enemies of this pest was conducted in nine districts across the state of Tamil Nadu, India. The survey yielded 14 species of parasitoids from two families; Aphelinidae and Encyrtidae. Based on field surveys and initial laboratory studies, the most promising parasitoids were Praleurocerus viridis Agarwal (Hymenoptera: Encyrtidae) and Anagyrus chryos Noyes & Hayat (Hymenoptera: Encyrtidae). Ten species of predators from 7 families were also recorded. The result of the exploration indicated that R. iceryoides population in India is kept at extremely low level by the action of the coevolved natural enemies, therefore, a predictive model using maximum entropy method (Maxent) was used to identify climatically suitable areas in Africa that are agro-meteorologically similar to the pest aboriginal home. The model parameters derived from India fitted well with the original introduced distributional range of the pest in Africa, and suggest that the humid tropical coastlines of Kenya and Tanzania are climatically appropriate for introduction. The result suggests that the prospects for establishment of P. viridis and A. chryos for classical biological control of R. iceryoides in Africa is promising.

Key-words: Exploration, Rastrococcus iceryoides, Natural enemies, Climate matching, Classical biological control.