Reduction of immature Ixodes scapularis (Acari: Ixodidae) in woodlots by application of desiccant and insecticidal soap formulations

Abstract

The efficacy of two commercially available formulations of a desiccant and insecticidal soap were compared with chlorpyrifos wettable powder (0.6 kg [AI]/ha) against the immatures of Ixodes scapularis Say in a woodlot in Westchester County, New York. The desiccant formulation (Drione) was applied at 61.04 kg/ha and an insecticidal soap (Safer's) was applied as a mixture (39 ml concentrate per liter of water) at 107 liters/ha. By 1 wk after application, all treatments significantly reduced the density of nymphs in comparison to untreated plots. Only plots treated with chlorpyrifos had significantly reduced nymphal densities 2 wk after application. By 6 wk after application, there were no differences in nymphal density between treated and untreated plots, which was likely the result of a decline in overall nymphal populations. None of the treatments against nymphs affected larval densities sampled 6 wk after application. Larval density was significantly lower 1 wk after application in plots treated with chlorpyrifos and Safer's insecticidal soap than in untreated plots. By 2 wk after treatment, only plots treated with chlorpyrifos had lower larval densities than untreated plots. Results indicate that the desiccant Drione and Safer's insecticidal soap are good for short-term control of immature I. scapularis.