On the sterile male release technique: sterilization by γ-radiation (60Co) in Amblyomma variegatum (Fabricius, 1794), Hyalomma anatolicum excavatum (Koch, 1844), and Rhipicephalus appendiculatus (Neumann, 1901)

Nymphal stages (2-3 days before moulting) and adult male ticks (one week after moulting) of Amblyomma variegatum, Hyalomma a. excavatum, and Rhipicephalus appendiculatus were exposed to irradiation with gamma-rays in the range of 0-8 krad. All ticks irradiated with a dose of 2 krad or more became 100% sterile. There was found no significant difference in engorged weight, time of engorgement, and egg weight in control-ticks and female partner-ticks of Amblyomma variegatum, males of which had received an irradiation dose of 2 krad as nymphs or adults. The same result was obtained in Hyalomma a. excavatum and Rhipicephalus appendiculatus when the males were irradiated as adults with 2 krad. However, significant differences occured when males of Hyalomma a. excavatum and Rhipicephalus appendiculatus were irradiated as nymphs with 2 krad. This applied also when males of all 3 species of ticks (nymphs or adults) were irradiated with higher doses. Since it was found that parthenogenesis occured in different degrees in all 3 species of ticks the practical application of the sterile-male-release-technique appears doubtful at least in the 3 investigated strains. (orig.)