Parasitic efficiency of Encarsia guadeloupae (Hymenoptera: Aphelinidae) on symbiotic and antibiotic treated invasive whitefly, Aleurodicus rugioperculatus (Hemiptera: Aleyrodidae)

Abstract

Abstract Rugose spiraling whitefly, Aleurodicus rugioperculatus Martin (Hemiptera: Aleyrodidae) is an invasive pest on coconut and other horticultural crops found in India during July 2016. A nymphal parasitoid, Encarsia guadeloupae Viggiani (Hymenoptera: Aphelinidae) is a potential natural enemy of A. rugioperculatus. Insect-associated bacteria with whiteflies are reported to influence the efficacy of parasitoids. Hence, the present study investigated the parasitization efficiency and biological parameters of E. guadeloupae on symbiotic (untreated) and antibiotic-treated A. rugioperculatus nymphal stages reared on four host plants viz., coconut, banana, sapota, and guava. The molecular identification of E. guadeloupae and A. rugioperculatus were confirmed using the mtCOI gene. Combination of Carbenicillin 100 µg ml− 1 + Ciprofloxacin 5 µg ml− 1 antibiotics was provided to the A. rugioperculatus by direct feeding in a parafilm feeding chamber method and the resultant populations (cultivable bacteria eliminated) were subjected to parasitoid efficiency experiments for F4, F5, and F6 generations of A. rugioperculatus. Higher parasitism (74.70%), lower emergence rate (59.70%), and longer developmental time (21.00 days) of E. guadeloupae were observed in the antibiotic-treated population than in untreated A. rugioperculatus population of the F6 generation. Elimination of insect associated bacteria through antibiotics might have reduced the nutritional status of the whiteflies and led to more susceptibility towards parasitoid attack and poor parasitoid emergence and longer developmental time in the initial generations (F4) and the parasitoid coevolve to counteract the effect with the generational exposure.