Effects of soil types and cultural practices on the fire ant, Solenopsis invicta, in sugarcane

Abstract

A two-year study (1984, 1985) conducted in South Louisiana sugarcane fields to investigate the effects of selected soil types and cultural practices on the abundance of the fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), showed that the highest S. invicta populations were present in clayey fields. There was a several-fold difference in the number of S. invicta mounds between the early-harvested fields and late-harvested or plant fields. Additionally, S. invicta mounds were more abundant in fields where there was a greater amount of ground cover (weeds and crop residues). During the 1984 study, foraging by S. invicta on clayey soils was somewhat lower in harvested than in planted fields. However, there was a trend for higher foraging in harvested than in planted fields in 1985. Significantly higher amounts of phosphorus, potassium, calcium, magnesium, sodium and percent organic matter were found in clayey than in sandy fields during 1984 and 1985. The significantly higher moisture content and the lower bulk density in clayey than in sandy soils seemed potentially conducive to greater S. invicta abundance through elimination of the risk of colony desiccation, as well as enhancement of subterranean foraging tunnels and deeper colony expansion.