Population Biology of Begomovirus Viruliferous Whiteflies (Bemisia tabaci) and Its Associated Endosymbionts in the Cucurbitaceous Ecosystem of Tamil Nadu, India

Abstract

The sweet potato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) is a polyphagous, phloem sap-feeding pest of highly economically important crops. This pest infests more than 600 horticultural and agricultural crops. It is thought to be a complex of physically similar cryptic species with variations in their genetic, physiological and biological characteristics. In the present study, the incidence of the cryptic species B. tabaci and the viruliferous nature of whiteflies with begomovirus in cucurbitaceous crops from seven agroclimatic zones of Tamil Nadu were assessed. Based on the available sequence data, we report the occurrence of four major cryptic species of whiteflies recorded in Tamil Nadu. The identified cryptic species of B. tabaci, viz., Asia I, Asia II (5), Asia II (7) and Asia II (8) were observed in all 22 locations in Tamil Nadu. The predominant occurrence of B. tabaci Asia I was recorded in three agroclimatic zones, viz., the western, north western and high-rainfall zones of Tamil Nadu. Asia II (5) was detected in all six agroclimatic zones, while Asia II (8) was detected in the western, north western and southern zones of Tamil Nadu. Asia II (7) was the only cryptic species recorded in the western zone of Tamil Nadu. Studies on endosymbiont associations with these whiteflies revealed the presence of Portiera (PP593660), Fritchea (PP600138), Cardinium (PP600148), Hamiltonella (PP593664), Wolbachia (PP593662) and Rickettsia (PP590220) in the reported cryptic species of B. tabaci. Hap_2, hap_14, hap_35, hap_42, hap_79 and hap_80 were the haplotypes of B. tabaci on cucurbitaceous crops in Tamil Nadu. Asia II (5) exhibited the highest haplotype diversity, and Asia I showed a high level of nucleotide diversity. These results will be useful for understanding outbreaks of B. tabaci and developing efficient management strategies for viruses that are transmitted by B. tabaci.