Pesticide differentially affects natural predators causing pest build up: a case study in Brinjal
Keywords:Pesticide, Pest, Natural predator, Whitefly, Spider, Non target impact.
Pesticide application aimed at pest regulation in agricultural field can have unintended differential and negative impacts on non-target species.Therefore, its continuous and uncontrolled usage can disturb the balance of agricultural ecosystem. The objective of the present study was to assessrelative impacts ofpesticideson pest and predator populations in an agricultural ecosystem. We chose brinjal farm as our focal system as it is an economically important crop that has high pest vulnerability and therefore requires heavy pesticide usage. Whitefly is a major pest of brinjal.Spiders are important natural predators that is known to control pests by active predation. We explored the impacts of pesticide on whitefly and spider populations in brinjal farming system. Thirty farms were selected in the coastal agro-climatic zone in southern West Bengal. Whitefly abundance increased significantly with increasing usage intensity of pesticides used by farmers. Spider abundance decreased as pesticide intensity increased. Decreasing spider density resulted in increased whitefly population. These results show how non-target impact of pesticide impedes natural pest regulation