PhD research fellow, Pretoria


Determination of chemical cues used by gravid female stable fly to locate suitable oviposition sit

Due to their blood-feeding habit, the stable fly, Stomoxys calcitrans Linnaeus (Diptera: Muscidae), are an economically important vector of domestic animal diseases (camel, cow, goat, sheep, horse…). Stomoxys calcitrans mechanically transmit helminths, protozoans, bacteria, and viruses. During outbreaks, S. calcitrans can reduce weight gain in cattle by up to 19%, and lead to a 40-60% reduction in milk yields. Surra disease, caused by the protozoan T. evansi, can cause morbidity of up to 30% and mortality of around 3.0% in camels. In the USA, the economic losses attributed to S. calcitrans infestation are estimated to be around $2.211 billion per year. To ensure the survival of their offspring, S. calcitrans adults deposits their eggs in decaying organic matter. It is well known that insect use chemical odour to locate a suitable breeding site for oviposition; however, in S. calcitrans, information about the oviposition site preference and the precise chemical cues and associated olfactory sensory neurones that govern egg laying are still unknown. In this PhD project, I am investigating the olfactory basis of oviposition in S. calcitrans under field and laboratory conditions. To achieve this objective, I use chemical, electrophysiological and behavioural techniques. At the end of this study, the information obtained will serve to establish the chemosensory mechanisms that stable flies use to locate and select a suitable oviposition site. Furthermore, the knowledge generated from this PhD thesis will have a practical application by identifying and developing novel attractants that will enhance the trapping of gravid females for surveillance and reduction S. calcitrans populations, and thereby limit the diseases they transmit.