Impact of Climate Variability on the Use and Exposure of Pesticides in Sugarcane Production in Malawi

Abstract

It is widely accepted that climate change will affect sugarcane production and its associated pests. The aim of this chapter is to review the impact of climate variability on factors and processes affecting environmental exposure of pesticides used in sugarcane production in Malawi. We indicate that changes in temperature and rainfall will have a dual effect on pesticide risk. Temperatures higher than 30--35 {\textdegree}C affect pesticide toxicity, though effects will vary with pesticide-pest combination. Rapid degradation of pesticides such as acetamiprid and atrazine is expected at temperatures above 30 {\textdegree}C. Higher temperature may increase the incidence and severity of pests such as red spider mites, prompting farmers to use more pesticides. On the other hand, the amount and timing of rainfall in relation to pesticide application are important determinants on the amount of pesticide residue remaining in the environment. There is a higher likelihood of pesticide transport to surface (through runoff) and percolating to groundwater at higher rainfall intensity. A higher soil water content will result in increased pesticide degradation. There is a need to determine the occurrence of pesticide residue in sugarcane cropping and aquatic systems surrounding sugarcane plantations. We highly recommend building capacity in this sector, particularly in biological control of pest species using microbial agents such as insect pathogenic fungi pathogens.