BENEFICIAL INSECT POPULATION AFFECTED BY PESTICIDES IN IPM AND CONVENTIONAL COTTON SYSTEMS

ABSTRACT

Aiming to study the impact of insecticides on beneficial insects in the cotton crop, we conducted an experiment in the western region of state of Bahia, Brazil, in the 2002/2003 season. Two management systems were compared: the Integrated Pest Management (IPM) and the conventional system, conducted at the farm where the experiment was installed. The populations of Orius spp, Chrysoperla externa, syrphid flies (Diptera: Syrphidae) and coccinellids (Coeloptera: Coccinellidae) were monitored for 19 consecutive weeks, using a beat cloth, beat 100 times per week at each cropping system. The evaluation was made based on linear regression for each species monitored in each system, taking “time,” the number of weeks, as the independent variable, and, as the dependent variable, the insect population, represented by the average of the counts of the 100 beat cloth points in each survey. For these species, it was found that the growth rates given by the slopes of regression lines were always higher in the IPM.

KEY WORDS
Gossypium hirsutum L; natural enemies; integrated pest management