Influence of Selected Weedy and Weed-free Sugarcane Habitats on Diet Composition and Foraging Activity of the Imported Fire Ant (Hymenoptera: Formicidae)

Abstract

Imported fire ant (IFA), Solenopsis invicta Buren, diet composition and foraging activity investigations in selected weedy sugarcane habitats showed that the most frequent foraging occurred in grass habitats, which also had the greatest vegetation density and above-ground biomass. Predation observed on immature leafhoppers, adult dipterans, phytophagous insects (collectively), and on foliage-associated fauna was greater ( P < 0.05) in grass than in broadleaf or weed-free habitats. Sweep net counts of foliage-associated arthropods revealed highest relative abundance in grass ( n = 828) versus weed-free ( n = 141) habitats. Greatest species diversity (H' = 3.464) occurred in broadleaf habitats. IFA prey capture efficiency was lower in broadleaf than in weed-free habitats, possibly due to pollen and nectar foraging, and was lower in grass habitats, probably as a result of predator satiation. Based on the results obtained, broadleaf plants are expected to provide more prey per amount of dry biomass (g/m ² ) than grasses or sugarcane alone. These data show that IFA population levels can be enhanced through judicious vegetation management. This enhancement would result in increased ecological stability of the sugarcane crop protection system.