Identification of whitefly species (Hemiptera: Aleyrodidae) of coconut palms in Colombo and Gampaha districts

Abstract

The Whitefly (Hemiptera: Aleyrodidae) has become a key pest in many crops in the world. Since 2019, whiteflies have been reported as significant pests in coconut plantations in Sri Lanka. The whiteflies have spread to the major coconut growing areas of the country and therefore, causing yield reductions mainly in king coconut palms. Therefore, management of the whitefly infestations in coconut plantations is of paramount importance. The whiteflies and their related arthropods in coconut plantations have not been extensively studied in Sri Lanka. Hence, the current study represents the first effort to identify the species of whiteflies, associated arthropods, and alternative host plants in the Colombo and Gampaha districts. Between February and June 2022, a random survey was carried out to gather coconut leaf samples infested with whiteflies and document alternative host plants from five distinct geographical locations in the Colombo and Gampaha districts. Pupal stages of whiteflies from the collected samples were prepared for taxonomic identification at the Crop Protection Division of the Coconut Research Institute of Sri Lanka. The diversity of whitefly species in the sample locations was calculated using the Shannon-Weaver diversity index. A total of four whitefly species were identified from both districts, with three species being common, namely Aleurodicus dispersus, Aleurodicus aff. cocois, and Paraleyrodes minei, while Aleurotracheulus atratus was the fourth species. Among these, Aleurodicus aff. cocois was found to be exclusively associated with coconut palms. The locations of Katunayake and Kaduwela had the highest diversity of whiteflies. Besides whiteflies, several other arthropods like scale insects, ants, caterpillars, spiders, mealybugs, and mites were identified in association with whiteflies. The locations of Uswetakeyiyawa and Peliyagoda had the highest diversity of these arthropods. The most commonly found alternative host plants for whiteflies in coconut plantations were Indian almonds (Terminalia catappa) and bananas (Musa paradisiaca).