Impact of global warming on the insect pest status on plants

Abstract

Green house gases capture the heat radiation from the sun and maintain an average global temperature of 15°C in the lower most atmospheric layer, the troposphere, which supports the life of our planet. Increase in the concentrations of green house gases in the atmosphere due to anthropogenic, animal and microbial activities, creates an enhanced global green house effect in the recent time, causing Global Warming. This phenomenon affects various climatic and natural processes that also include adverse changes in the insect pest status on the agricultural, horticultural and forest plants. Under the elevated ambient temperature and concentrations of green house gases like CO 2 , the pest species exhibit increased herbivory, longevity, voltinism, reproductive cycles, fecundity, population size, and pesticide resistance. The plant's natural phytochemical defense mechanism against insect attack also decreases under raised green house effect. This induces over damage to plants by enhancing the longevity and fecundity and population of the pest species. Plants also shift their other chemical defense mechanisms from nitrogen-based chemicals to carbon-based chemicals under high CO 2 environment. The high level of carbohydrate in relation to nitrogen in plants produced under elevated ambient CO2 amount also accounts for over herbivory by the insects to satisfy their nitrogen requirement. Hence, increased pest status of insects, besides necessitating costlier control measures, definitely inflicts an irreversible damage to the plant lives of our planet.