Gamma Irradiation and Male Glossina austeni Mating Performance

SIMPLE SUMMARY: African animal trypanosomosis, also known as nagana, is a neglected disease in South Africa, transmitted by tsetse flies. It has been proposed to manage this disease through the eradication of Glossina austeni, one of the vectors of this disease in South Africa. The strategy would be an integration of various control tactics and the release of sterilised colonised males (sterile insect technique) to eliminate relic pockets. The irradiated colonised males must be able to compete with wild males. In preparation of the technique, the mating performance of colony-reared male flies was assessed. Factors that can influence male mating performance, such as radiation dose, and the development stage that is exposed to radiation were evaluated in the laboratory and under semi-field conditions. Radiation doses of 80 Gy and 100 Gy induced 97–99% sterility in colony females that mated with colony males treated as adults or pupae. Walk-in field cage assessments indicated that a dose of up to 100 Gy did not adversely affect the mating performance of males irradiated as adults or late stage pupae. This study indicated that the colonized G. austeni males irradiated as adults or late stage pupae will be suited for the sterile insect technique. ABSTRACT: An area-wide integrated pest management (AW-IPM) strategy with a sterile insect technique (SIT) component has been proposed for the management of African animal trypanosomosis (AAT) in South Africa. In preparation for the SIT, the mating performance of colony reared Glossina austeni males under influencing factors such as radiation dose and the development stage that is exposed to radiation, was assessed under laboratory and semi-field conditions. The radiation sensitivity of G. austeni colonized 37 years ago when treated as adults and late-stage pupae was determined. Radiation doses of 80 Gy and 100 Gy induced 97–99% sterility in colony females that mated with colony males treated as adults or pupae. Males irradiated either as adults or pupae with a radiation dose of 100 Gy showed similar insemination ability and survival as untreated males. Walk-in field cage assessments indicated that a dose of up to 100 Gy did not adversely affect the mating performance of males irradiated as adults or late stage pupae. Males irradiated as adults formed mating pairs faster than fertile males and males irradiated as pupae. The mating performance studies indicated that the colonized G. austeni males irradiated as adults or late stage pupae will still be suited for SIT.