Ants as biological control agents in the maize agroecosystem in Nicaragua

The potential of ants as agents of biological control of maize pests in the Pacific plains of Nicaragua was investigated. A series of experiments in which ants were excluded and populations of Spodoptera frugiperda and Dalbulus maidis were monitored showed that ants significantly reduced populations of these two pests. In the work reported herein it is claimed that (1) ants can reduce the attack of these two major pests in maize production in Nicaragua, both under rainfed and irrigated conditions, (2) the ant community in the maize agroecosystem exhibits a relatively complicated pattern of succession associated with the disturbing effect of land preparation, and (3) insecticides, perhaps those applied to control the pests in the first place, can have the effect of dramatically reducing ant foraging, thus possibly countering whatever desired effect they may have on the pests. Taken together these results suggest that there is great potential for the use of ants as generalist predators in Integrated Pest Management programs.;Of the ant species found during the study, Ectatomma ruidum and Solenopsis geminata seem to be the most promising ones for controlling pest populations both because of their high abundance and predatory habits. An experiment with E. ruidum demonstrated that this species preys upon larvae and pupae of S. frugiperda and that it has a preference for intermediate instar larvae. Solenopsis geminata was found to have a significant effect on numbers of adult corn leafhoppers, D. maidis. Pheidole radowszkoskii, the third most abundant ant species found in the study site, along with E. ruidum, can significantly reduce numbers of S. frugiperda. In areas not affected by insecticide application, almost 100% of the baits were occupied by ants and at the same time pupae mortality by predation was very high. Predation rate on pupae was clearly correlated with ant foraging activity. In areas where P. radowszkoskii and other ants were effectively removed by insecticides, damage by S. frugiperda was higher than in adjacent areas. (Abstract shortened with permission of author.).