Hyalomma dromedarii is the predominant tick species infesting camels.
Consequently, the aims of the present study were to compare the photodynamic
efficacy of rose bengal (RB) to that of ivermectin (IVR) against the engorged
females of H. dromedarii through in vitro immersion bioassays and to test the
effect of the applied materials on the reproductive potential of the survived
females. RB has been tried as acaricides for the first time, to the best of our
knowledge. Different concentrations of RB (0.01, 0.03, 0.13, 0.5 and 2%) and
IVR (0.02, 0.08, 0.6, 2.5, and 10%) were freshly prepared in distilled water. The
minimal lethal concentrations that cause 100% acaricidal effect were 2%, 8 h
post treatment (PT) with RB, and 2.5%, 24 h PT with IVR. Eight hours PT with
RB and IVR, the LC50 (lethal concentration, 50%) values were 0.08 and
0.35%, respectively, whereas those for LC95 were 1.45 and 30.07%,
respectively. At the levels of LC50 and LC90, RB was 4 and 15 times more
potent than IVR. The median lethal time, LT50, values of 2% RB and 2.5%
IVR were 0.92 and 2.63 h, respectively. Treatment with the lowest
concentrations of RB and IVR induced reduction in the number of survived and
ovipositing females, eggs per female, ticks laid hatched eggs, and hatched eggs
(48.98, 93.33, 1854.53±45, 97.5 and 93.64%) and (26.53, 86.67, 7661.27±377,
87.80 and 89.40%), respectively. The low cost of RB, together with the
availability of inexpensive low-power light sources or sunshine, suggests that
this approach is of great potential as an interesting alternative to chemical
acaricides.
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