Microbial Degradation of Pesticides in Tropical Soils

Abstract

Although their use is at least as essential in tropical as in temperate zones, pesticides remain little studied as regards their fate and microbial degradation in tropical soils. To contribute to closing this gap, this review examines to what extent results from studies on pesticide microbial degradation in temperate zones can be extrapolated to the tropics. It is concluded that geographical distances or barriers are not expected to create profound differences between tropical and temperate soil microbial communities, although fine-tuning adaptation might exist. This suggests that environmental conditions, mainly temperature and humidity, are the principal factors contributing to a difference between pesticide degradation phenomena as they occur in soils from tropical and temperate zones. According to this hypothesis, the kinetics or metabolic pathways of microbial pesticide degradation would be similar in temperate and tropical environments that would themselves be similar with respect to temperature, humidity, and other parameters. The hypothesis also predicts that in the hot humid tropics, pesticide degradation is expected to occur faster than in temperate zones, whereas in cool tropical highlands or in arid tropical zones the degradation rate would be reduced to a level comparable to or even lower than that in temperate zones. Finally, it is proposed there that pesticide degradation rate in the tropics can be predicted by models developed in temperate climates, insofar as these models have been validated as applying to tropical countries.