Exotic whiteflies and Conservation Biological Control in Coconut System

Abstract

Exotic pests upset biotic balance, threaten biodiversity and distort the livelihood security of the nation. In coconut, five exotic whiteflies viz., spiralling whitefly, Aleurodicus dispersus Russell, rugose spiralling whitefly, Aleurodicus rugioperculatus Martin, Bondar’s nesting whitefly, Paraleyrodes bondari Peracchi, non-native nesting whitefly, Paraleyrodes minei Iaccarino and palm whitefly, Aleurotrachelus atratus Hempel were reported from India. Morphological and molecular identification of these invasive whiteflies were established by puparium and (or) adult taxonomy and cytochrome c oxidase subunit 1 (COI) gene, respectively. Co-existence of nesting whiteflies with other exotic whiteflies regulated population explosion and warranted correct diagnosis of whiteflies in coconut system. Weather parameters viz., precipitation, temperature and humidity play an important role in the gradient outbreak of exotic whiteflies. The aphelinid parasitoids (Encarsia guadeloupae Viggiani, Encarsia dispersa Polaszek), predators (Apertochrysa sp., Cybocephalus sp. coccinellids viz., Jauravia pallidula Motschulsky, Serangium parcesetosum Sicard, Cheilomenes sexmaculata (Fabricius) and entomopathogenic fungus Aschersonia sp. reduced the incursion potential by exotic whiteflies. A sooty mould scavenger beetle, Leiochrinus nilgirianus Kaszab (Tenebrionidae: Coleoptera) that devours sooty mould encrusted on palm leaflets during monsoon phase was reported for the first time from Kerala, India. Pesticide holiday approach, conservation biological control using the aphelinid parasitoids, predators and entomopathogenic fungus as well as in situ habitat conservation of L. nilgirianus through crop-habitat diversification strategy subdued the invasive potential of exotic whiteflies in coconut system by 60%-80% gaining economic benefit to the tune of 17.59 billion rupees. Strict quarantine and systematic surveillance are the need of the hour to combat the biosecurity risks entering the country.