GUWAHATI, Aug 6 - Whitefly attack has been reported in several villages of Kamrup district, with agriculture scientists claiming it to be the first such phenomenon in the State in which vast stretches of vegetation has turned brownish-black.
The pest was first reported in coconut in Belize in 2004, then in Florida in 2009 and later in some south Indian states in 2016.
�During the month of July, the pest infested coconut, arecanut, betelvine, banana, mango, guava, ornamental plants, etc., in several villages of Kamalpur agriculture circle. It was observed that almost all the leaves of coconut and other plants beneath and nearby it have turned brownish-black due to severe growth of sooty mould. All the leaves of the plants were found to be full of whitefly,� Dr Samiran Pathak, principal scientist (entomology) at the Kahikuchi-based Horticultural Research Station told The Assam Tribune.
Such type of wide coverage of sooty mould was observed for the first time in Assam.
While some normal whiteflies exist in small numbers in the State, such an epidemic-like attack by Rugose Spiralling Whitefly (Aleurodicus rugioperculatus) has been detected for the first time in the region.
Initially, villagers thought the phenomenon could be due to industrial pollution in the nearby areas, but that has been ruled out by scientists.
Although whiteflies are not normally considered coconut pests, these insects can damage crops and other plants directly by sucking the sap, which weakens the plant. Indirect damage may be caused by sooty mould formation over the excreted honeydew and by the transmission of pathogens.
Dr Pathak said the nymphs and adults suck the sap from underside of coconut leaflets and the heavy infestation leads to yellowing of the leaves, drying of the leaves and finally death of the plants. Excessive feeding by the whiteflies leads to excretion of honeydew which is deposited on the upper surface of the leaf resulting in growth of sooty mould. The growth of sooty mould causes disfigurement of hosts affecting the photosynthetic efficiency of the plants.
Scientists say the immediate cause of the massive population build-up of the pest is due to the hot humid weather condition with deficit rainfall and insufficient number of natural enemies of the pest.
The scientists� team which investigated the epidemic has given a report to the district agriculture officer, suggesting management strategies like removal of the heavily infested leaves, installation of yellow sticky traps for the pests, spraying of mild soap water and starch solutions, etc.
Scientists also suspect that the pest could have come through coconut saplings brought to the State from south India. There are fears that it could spread to other contagious areas.