Trapping of flies to identify seasonal or other variation in abundance. Multivariate and GIS analysis to relate abundance to specific environmental features. Pteridine fluorescence analysis to determine the age of flies collected. Identification of visual characters responsible for fly attraction using a lab colony of S.calcitrans. Investigation of fly trap design and evaluation of their use in the field.
To develop a simple, easily managed, inexpensive trap to catch biting flies and reduce biting fly nuisance for donkeys.
Stable fly abundance increased over the course of the summer with peak numbers occurring in September. A high degree of variation in abundance was observed between different trapping sites. Multiple factors appear to affect their local abundance including availability of breeding sites, weather and availability of hosts. Through pteridine flourescence analysis it was established that there appears to be a continuous emergence of adults throughout the season rather than discrete age-related cohorts. Population peaks reflected overlapping generations. Mass trapping for fly population control was not an effective method for supressing the stable fly population.
The continuous emergence of adult stable flies throughout the summer which results in a continual replenishment of the population makes suppression very difficult. Environmental factors that affect fly abundance should therefore be given careful consideration, such as limiting available breeding sites. Dung heaps should not be maintained near to where donkeys live and, where possible, dung should be moved off site or stored away from donkey housing.
Trapping, in the form used in this study, is not likely to be an effective management strategy against S.calcitrans as the number of traps needed to make a sustained impact on the fly population would likely be cost prohibitive and very labour intensive.
The present study used sticky-traps without an attractive odour bait though and relied on visual stimulus alone for attraction. Future work could investigate the use of chemical attractants as an approach to boosting trap catches, which would potentially make the traps more cost-effective to use. Further investigation into the optimum spatial arrangement for deployment of traps might also be useful.