Accelerated biodegradation of pesticides: An overview of the phenomenon, its basis and possible solutions; and a discussion on the tropical dimension

Accelerated microbial degradation is the name commonly given to the phenomenon associated with a significant increase in the rate of degradation of a pesticide in soil following a previous application of the same pesticide and also to the closely related phenomenon involving an unexpectedly rapid degradation of a pesticide following a previous application of another pesticide, usually of similar chemical structure. It apparently is caused by an adaptation of one or more species of microorganism present to metabolize the pesticide. In the late 1940s it was recognized that repeated applications of 2,4-D accelerated its degradation. Studies done in the 1970s and 1980s revealed that many pesticides in use were susceptible to the phenomenon and that it was reducing the efficacy of a number of commercial products especially those for which applications at seeding time were expected to provide prolonged pest control. Further work since that time has shown the dynamic nature of the phenomenon as a number of pesticides which were previously shown to be unaffected are now susceptible. The phenomenon can result in significantly reduced crop yields and coping with it usually involves additional costs. In the following manuscript we give an overview of this phenomenon, its basis and possible solutions; and attempt to predict how should biogeography factors and tropical conditions influence the phenomena.