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).
