REVIEW ARTICLES CURRENT SCIENCE, VOL. 119, NO. 7, 10 OCTOBER 2020 1101 *For correspondence. (e-mail: joecpcri@gmail.com) Diagnosis of invasive whitefly species co-occurring on coconut A. Josephrajkumar 1, *, Chandrika Mohan 1 , Merin Babu 1 , P. S. Prathibha 2 , Vinayaka Hegde 2 and V. Krishnakumar 1 1 ICAR-Central Plantation Crops Research Institute, Regional Station, Kayamkulam 690 533, India 2 ICAR-Central Plantation Crops Research Institute, Kasaragod 671 124, India As many as four exotic whiteflies of Neotropical origin have been reported from different coconut-growing regions in India in rapid succession in the last four years. The spiralling whitefly, Aleurodicus dispersus Russell was the earliest reported invasive species on coconut from Kerala in 1996. The rugose spiralling whitefly, Aleurodicus rugioperculatus Martin was first reported in 2016 followed by three species (Paraley- rodes bondari, Paraleyrodes minei and Aleurotrachelus atratus) in 2019. At present, all are found to coexist on coconut in South India. In such combined incidences, one species occupies the breeding and feeding niche of another under optimum weather parameters and attempts to displace one or more of its competitors. The Bondar’s nesting whitefly, P. bondari is associated with rugose spiralling whitefly in most districts of Kerala and Tamil Nadu, whereas the nesting whitefly P. minei is interlinked with A. rugioperculatus in Kasaragod, Kerala, and also found to co-occur with the palm whitefly, A. atratus in Mandya, Karnataka. In Kayamkulam, Kerala, P. bondari, P. minei and A. rugioperculatus co-lived for a brief period during 2018. Due to the incursion and subsequent coexistence of these exotic whiteflies which share more or less the same niche with similar habits on coconut, it is imper- ative to identify them correctly for carrying out fur- ther studies on their bioecology, population dynamics and management. Hence an illustrated diagnostic account of these exotic whiteflies is given here to faci- litate their visual identification by economic entomo- logists and field workers. The COI sequences of these exotic whiteflies are also given to enable rapid confir- mation of the field diagnosis. Keywords: Bioinvasion, coconut, coexistence, exotic whiteflies, field diagnosis. Management of non-native pests in a new environment poses great challenges as they upset indigenous biodiver- sity, and usually multiply and spread rapidly in the absence of natural enemies. With the liberalization of in- ternational trade, introduction of planting material from different countries has paved the way for accidental entry of several exotic pests in the recent past, and the coconut system is no exception for such incursion. As many as four exotic whiteflies of Neotropical origin have entered India in just four years, starting with the rugose spiralling whitefly (Aleurodicus rugioperculatus Martin), which was reported in 2016 initially from Pollachi, Tamil Nadu and Palakkad, Kerala, and later expanded to all coconut- growing regions in peninsular and North East India with- in a short span 1 . This incursion has been kept in check by the combined action of the exotic aphelinid parasitoid, Encarsia guadeloupae and in situ habitat conservation of the sooty mould scavenger beetle, Leiochrinus nilgiria- nus 2,3 . Entry of two exotic nesting whiteflies (Paraley- rodes bondari and Paralyerodes minei) into Kerala in 2018 (refs 4, 5) and their coexistence with A. rugiopercu- latus have reduced the population density of A. rugioper- culatus. Recently, in Mandya, Karnataka, palm whitefly (Aleurotrachelus atratus), another exotic species, has been reported; it was observed to be in consistent associa- tion with the Neotropical nesting whitefly (Paraleyrodes minei). Co-occurrence of these four exotic whiteflies with similar habits has often caused confusion in their identifi- cation, and further studies on their bioecology, natural enemies and management are hampered in the absence of accurate diagnostic support. Therefore, in this article, we provide a pictorial guide to all exotic whiteflies infesting coconut for their field-level identification by economic entomologists and extension workers supported by taxo- nomic characters. The COI sequences of these whiteflies are also given to enable rapid confirmation of their identi- ties. Methodology Life stages of the exotic whiteflies were collected from three locations, viz. Kayamkulam, Pollachi and Mandya in the coconut-growing regions of South India. Molecular characterization Molecular characterization of the five whiteflies (Aleuro- dicus dispersus, A. rugioperculatus, P. bondari, P. minei and A. atratus) was done to facilitate their rapid identifi- cation by non-entomologists. Genomic DNA was isolated