PYRIPROXYFEN EFFECTS ON NEWLY ENGORGED LARVAE AND NYMPHS OF THE LONE STAR TICK (ACARI, IXODIDAE)

Newly engorged larvae and nymphs of the lone star tick, Amblyomma amer icanum (L.), were exposed to 9 treatments of pyriproxyfen in glass via ls consisting of dosages of 4, 8, and 16 mu g/cm(2) for 7 d, 14 d, and continuous exposure periods at each concentration. Treatment of newly engorged larvae resulted in decreased molting, altered postmolt defec ation, and nymphal survival with results being dose and exposure depen dent. Molting inhibition ranged from 35.9 to 68.4%. Successfully molte d nymphs were lethargic, exhibited altered defecation patterns, and we re short-lived compared with untreated adults. By 65 d after treatment , cumulative inhibition of molting and hastened mortality of molted ad ults resulted in 82.6-100% control, depending on dosage and exposure. Treatment of newly engorged nymphs showed minimal to no effect on molt ing; however, adults were lethargic and displayed altered postmolt def ecation patterns. Subsequent adult longevity was most dramatically aff ected with 87.9-100% control achieved by 82-84 d after treatment. Feca l patterns and survivorship were dose and exposure dependent. Estimate s of subsequent feeding success of adults treated as engorged nymphs, show reduced capacities of attachment, engorgement and reproduction.