LABORATORY TESTS OF ARTHROPOD REPELLENTS AGAINST LEPTOTROMBIDIUM DELIENSE - NONINFECTED AND INFECTED WITH RICKETTSIA-TSUTSUGAMUSHI - AND NONINFECTED L-FLETCHERI (ACARI, TROMBICULIDAE)

Laboratory tests were conducted to compare the response of noninfected Leptotrombidium deliense Sambon and Leptotrombidium fletcheri (Womers ley & Heaslip) and L. deliense naturally infected with Rickettsia tsut sugamushi, the etiologic agent of scrub typhus, to 8 chemical repellen ts and toxicants. Low concentrations of permethrin, dimethylphthalate, diethyl methylbenzamide, benzyl benzoate, di-n-propyl 2,5-pyridine-di carboxylate, 1-(3-Cyclohexen-1-yl-carbonyl)-2-methylpiperidine (AI3-37 220), 2-hydroxymethyl-cyclohexyl acetic acid lactone, and a high conce ntration of dibutylphthalate (DBP) were toxic for noninfected larvae o f both species tested. The median effective knockdown time for all che micals, except 1% AI3-37220 and 5% permethrin, were longer against inf ected L. deliense than uninfected larvae of the same species. However, the results indicate that low concentrations of all chemicals, except DBP, should be effective against 2 important vectors of scrub typhus.