A MODEL OF OVINE CUTANEOUS MYOSIS USING THE PREDICTED ABUNDANCE OF LUCILIA-SERICATA AND A PATTERN OF SHEEP SUSCEPTIBILITY

A simulation model of ovine cutaneous myosis (blowfly strike) was deve loped to investigate the potential for forecasting the pattern of dise ase and to explore a range of control options, The model was developed from an understanding of the population dynamics of Lucilia sericata and the proposed interaction between flies and sheep. Fly abundance pa tterns were simulated from daily maximum and minimum temperatures usin g the weighted development fraction technique. The pattern of sheep su sceptibility was based on the seasonal incidence of faecal soiling of the perineum-an important risk factor for strikes in that area. The pr evalence and incidence of blowfly strike were estimated from the mean density of female gravid blowflies per susceptible sheep using a negat ive binomial distribution. The effects of two control strategies on th e incidence of blowfly strike and fly abundance were examined and comp ared with field survey data. We concluded that the model provided a po tentially useful system for developing and testing control options and for the prediction of high-risk periods.