Effect of high concentrations of lufenuron, pyriproxyfen and hydroprene on Rhipicephalus (Boophilus) annulatus

The activity of high doses of three insect growth regulators (IGRs), lufenuron (MATCH®), pyriproxyfen® and hydroprene (Gentrol®), were tested on Rhipicephalus(Boophilus) annulatus adult females, eggs and larvae. Different concentrations of the IGRs were tested on eggs, larvae and adult ticks through immersion, larval packet and adult immersion bioassays, respectively. The tested IGRs did not show adulticidal activity against female ticks even at very high concentration. However, both hydroprene and pyriproxyfen caused a significant decrease (P<0.05) in the reproductive indices of adult female ticks. Both lufenuron and pyriproxefen showed considerable ovicidal activity delaying the hatchability of the treated eggs until the 21st day and decreasing the hatchability percentages to 37.7% and 60.6% at concentrations ≥10X and ≥4X, respectively. Lufenuron (≥10X dose), hydroprene (≥4X dose) and pyriproxyfen (≥4X dose) induced highly significant larvicidal activity as they caused 100% mortality after 72 h of exposure. The oxidative profile of the hydroprene treated ticks had decreased glutathione peroxidase and increased malonaldehyde in comparison to the other IGR- treated and control untreated ticks. It is concluded that the IGRs did not show R. annulatus adulticidal effect, however, the deposited egg mass and its hatching percent decreased significantly when treated with hydroprene and pyriproxyfen. The tested IGRs showed larvicidal activity against R. (B.) annulatus.