Scientists at an awareness programme recently opposed the use of insecticides to control whitefly menace in coconut plantations. It should be controlled through parasitoids, they said.
K. Selvaraj, Scientist (entomology) of National Bureau of Agricultural Insect Resources (NBAIR), said the infestation of ‘Rugose Spiraling Whitefly’ (Aleurodicus rugioperculatus) has been recorded in coconut and banana plantations in southern India. He said use of any insecticide may affect parasitoids that are the natural enemies of this whitefly.
A.N. Shylesha, Principal Scientist (entomology), NBAIR, said the most commonly recorded natural enemies are two parasitoids – Encarsia guadeloupae and Encarsia dispersa. Both these parasitoids were found more predominant in all the locations affected by whitefly, helping in reducing the number of such whiteflies.
Spray water on sooty mould
Explaining other modes of control of Rugose Spiraling Whitefly, he said farmers can spray water on sooty mould. They can also spray starch at 2% to remove the sooty mould.
In severe cases, farmers can spray neem oil at 2% or neem seed kernel extract at 5%. The use of chemical insecticides should be avoided strictly. Asking farmers not to panic, he said despite heavy incidence of whitefly on coconut, it is not causing crop loss.
H.R. Nayak, Deputy Director of Horticulture Department, Mangaluru, said NBAIR is planning mass production of parasitoid for Dakshina Kannada and Udupi districts on a pilot basis.
Whitefly siphons out coconut sap by selective feeding on the under-surfaces of the leaflets. Extensive feeding of the insect leads to the excretion of honey dew-like substance. This substance gets deposited on the upper surface of the leaves positioned down beneath or even on other under storey crops. This honey dew-like substance, being sweet and watery, attracts ants and encourages growth of the fungus. This causes disfigurement of host plant like black tinge (sooty mould) on leaves affecting photosynthetic efficiency of the plant.
