Further laboratory and field evaluations of experimental baits to control leaf-cutting ants (Hymenoptera: Formicidae) in Brazil

Abstract

Four features concerned with the baiting of leaf-cutting ants were studied. A liquid concentrate containing attractive and arrestant substances together with a toxicant was developed for the production on site of cheap baits for leaf-cutting ants in Brazil by addition to suitable locally available particulate carrier materials (matrices). The five non-organochlorine insecticides that performed best in previous baiting trials were further tested in Brazil at slightly higher concentrations against Atta cephalotes (L.), which had been shown to be the most difficult species to eradicate; two of these showed promise as substitutes for the well-proven but persistent organochlorine insecticide mirex. Other tests showed that bait widely scattered over a nesting site containing colonies of A. sexdens (L.), in simulation of a broadcast application from aircraft or ground dispensers, was as effective as that placed by hand at entrance holes of nest mounds. Weathering tests in a forest area showed that spoilage by rain and fungal growth, not loss of insecticide, were the main factors governing the effective life of dried citrus pulp baits under wet or humid conditions.