A comparative survey of the pest prevalence and chemical control practices in the tea gardens of Sonitpur district of Assam

The aim of this investigation was to go for a comparative study of the pest prevalence in the tea gardens of Tezpur and Gohpur sub-divisions of Sonitpur district of Assam with reference to the chemical control measures adopted in those gardens. From survey, it was found that the overall infestation in the seventeen surveyed tea gardens of the district was shown by eight types of pests, namely Tea Mosquito bug (Helopeltis theivora), Red spider mites, two species of Looper caterpillars, Red slug, Green fly, Thrips, Aphids and Bunch caterpillars. The maximum numbers of TRA approved pest control agents used in the gardens of Tezpur and Gohpur sub-divisions of the district were 22 and 25 respectively. Helopeltis was found to develop resistance against adverse climatic conditions while Looper caterpillar became resistant to Deltamethrin (Decis), a commonly used synthetic pyrethroid pesticide. Deltamethrin has also caused an increase in the resurgence of red spider mites because of the impact of the chemical on the non target natural predators of the latter. As a deterrent, systemic bio-pesticides are frequently used as they pose no threat to the predators. With a view to tackling the overall biotic stress and impact of pesticides, discovery of suitable plant extract with antifeedant effect becomes an urgent need at the moment.