Effect of Temperature on the Oviposition Capacity of Engorged Adult Females and Hatchability of Eggs of Dog Ticks: Rhipicephalus sanguineus and Heamaphysalis leachi leachi (Acari: Ixodidae)

Abstract

Effects of temperature on the oviposition capacity of engorged adult females of Rhipicephalus sanguineus and Haemaphysalis leachi leachi and on the hatching pattern of their eggs were investigated under laboratory conditions. The temperatures of maintenance were 15⁰C, 20⁰C, 25⁰C, 30⁰C and 37⁰C at 85% relative humidity (R.H). The pre-oviposition periods of engorged adult females of R.sanguineus and H. leachi leachi increased as the incubation temperature became low from 30⁰C to 15⁰C. There was a significant difference (p < 0.05) in the pre-oviposition periods of R. sanguineus and H. leachi leachi at all the maintenance temperatures. The number of eggs oviposited by adult females of R.sanguineus and H. leachi leachi decreased as the incubation temperature dropped from 30⁰C to 15⁰C. The mean numbers of eggs produced respectively by 0.06g and 0.12g R. sanguineus female ticks at 37⁰C were 278.00 + 3.46 and 955.33 + 4.90 while no egg was laid by the same weights of female H. leachi leachi at the same temperature. The eggs of both species did not hatch at 15⁰C. At 37⁰C the eclosion period of R. sanguineus was 17 days while the eggs of H. leachi leachi did not hatch. The mortality rates of eggs of H. leachi leachi, (56.2, 16.8 and 16.6%) were higher than those of R. sanguineus, (17.6, 10.3 and 10.2%) at 20⁰C, 25⁰C and 30⁰C respectively. It is concluded that R.sanguineus has greater resistance to the deleterious effect of extreme temperatures than H. leachi leachi

Keywords: Dog tick, temperature, Rhipicephalus sanguineus, Heamaphysalis leachi leachi, oviposition, hatchability