The Boll Weevil
The boll weevil (Anthonomus grandis) is a beetle which feeds on cotton buds, flowers and bolls. Its larvae also develop within these plant structures rendering the cotton lint un-usable for textile production. While protected in the buds and bolls, these immature stages are also very difficult to control with insecticides.
In their attempts to control the boll weevil, growers have to use 10–15 sprays per season and sometimes up to 30 in cases of severe infestations, often with unsatisfactory results. The pest has contributed greatly to the reduction in the area of cotton grown in Brazil from 2 m ha down to 1 m ha, the greatest occurring in the North East of the country where farms are generally small and cotton growing is marginal due to the high need for pesticide. The overuse of pesticides leads to contamination of streams and groundwater directly associated with the cotton fields. The health of operators and wildlife is also jeopardised.