Wa. Donahue et al., PYRIPROXYFEN EFFECTS ON NEWLY ENGORGED LARVAE AND NYMPHS OF THE LONE STAR TICK (ACARI, IXODIDAE), Journal of medical entomology, 34(2), 1997, pp. 206-211
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.