SUSCEPTIBILITY OF IMMATURE IXODES-SCAPULARIS (ACARI, IXODIDAE) TO DESICCANTS AND AN INSECTICIDAL SOAP

Efficacy of commercially available formulations of desiccants (Drione, Dri-die, diatomaceous earth) and insecticidal soap (Safer's) comprise d of active ingredients were evaluated against Ixodes scapularis Say i mmatures in petri dish and grass turf bioassays. In petri dish bioassa ys at label rate, all products, except diatomaceous earth, provided a high degree of control by 24 and 48 h (71-100% mortality). Mortality o f larvae exceeded 94% by 4 h after treatment with Drione (10X label ra te held at 85% RH), Dri-die (label rate held at both 85% and 98% RH) a nd Safer's insecticidal soap (10X label rate held at 98% RH). Nymphal mortality was highest by 4 h after treatment with Safer's insecticidal soap (up to 96%). Larvae were mote susceptible than nymphs to desicca nts, however, nymphs were more susceptible than larvae to Safer's inse cticidal soap. Immature ticks treated with Safer's insecticidal soap e xhibited sublethal effects with significantly decreased attachment to hosts and no engorgement. In grass turf bioassays, mortality of nymphs was equivalent (85-95%) between treatments of chlorpyrifos (0.6 kg [A I]/ha, Safer's insecticidal soap, and Drione. In the same bioassays, n ymphal mortality was moderate after treatment with Dri-die (23-29%) an d low following application with diatomaceous earth (l6%) and for untr eated controls (6%).