INDIRECT AND DIRECT EFFECTS IN A TROPICAL AGROECOSYSTEM - THE MAIZE-PEST-ANT SYSTEM IN NICARAGUA

Population levels of fall armyworm Spodoptera frugiperda and corn leafhopper Dalbulus maidis were monitored among 4 treatments: 1) carbofuran, a systemic insecticide; 2) chlorpyrifos, a broad-spectrum insecticide; 3) carbofuran + chlorpyrifos; and 4) a control (no insecticide). Ant foraging activity also was monitored. Carbofuran reduced ant foraging activity and increased population levels of fall armyworm. Ant predation was apparently responsible for a higher pupal removal rate in the plots with no insecticides. Chlorpyrifos significantly reduced ant foraging activity as well as densities of fall armyworm, but it resulted in higher levels of corn leafhopper. Results are discussed in light of developing integrated pest management programs in which ants may play an important role as agents of biological control, and ant susceptibility to chemical insecticides should be considered. -from Author