Enhancement of permethrin efficacy in acaricide-attractant mixtures for control of the fowl tick Argas persicus (Acari: Argasidae)

Three acaricides, permethrin, propoxur and diazinon, were tested against Argas persicus ticks in a test of susceptibility and in a multiple choice test in bioassay. A mixture of guanine hydrochloride and diatomaceous earth in saline was used as an attractant in bioassays, causing 53.1-95.7% assembly. The attractant was mixed with acaricides to reduce their repellency and enhance their efficiency in bioassays. Permethrin was the most toxic (LC95 at day 7=0.5-1.4 mg m(-2) depending on the developmental stage) and most repellent acaricide. The mortality of males in the bioassay was significantly higher (76.7-94.3%, p < 0.01) when acaricide in amounts of 16 and 160 mu g of active ingredient per filter paper disc were mixed with attractant (0.5 mg per filter paper disc) instead of acaricide alone (20-45.7% mortality only). The mean permethrin residue on the lick body at the end of bioassay with the acaricide-attractant mixture was significantly higher (13.62 +/- 11.64 ng) than in experiments without the attractant (less than 1 ng). Propoxur was less toxic (LC95 at day 7=0.9-1.9 mg m(-2)) and diazinon the least toxic (LC95 at day 7=2-9.4 mg m(-2)), both being not or only slightly repellent. Males and females also assembled on filter paper discs treated with propoxur without an attractant. Diazinon displayed significant mortality only in amounts of 0.1 and 1 mg of active ingredient per filter paper disc with or without the attractant. Therefore, the repellency of permethrin can be reduced and its effectiveness enhanced when used in a mixture with an attractant. No similar effect was observed with propoxur or diazinon.