Development, Validation and Use of a Simulation Model to Deliver National Predictions of Ovine Cutaneous Myiasis Risk in the British Isles
Forecasting systems represent an important approach to the sustainable control of a wide variety of insect pests and parasites. A computer model that simulates the seasonal pattern of ovine cutaneous myiasis (strike), by the blowfly Lucilia sericata (Meigen) was developed. The model is based on two sub-components. The first simulates the seasonal pattern of abundance of the insect pest, L. sericata, using quantified temperature-dependent development, mortality and oviposition rates. The second uses the range of key factors known to increase the susceptibility of ewes and lambs, to estimate the proportion of a flock at risk from strike. The two components are integrated to estimate a predicted strike rate per day. Key drivers in the model are the seasonal patterns of temperature and rainfall. However, parasitic nematode burdens and husbandry practices such as shearing and lambing dates, which are known to affect strike incidence, are also included. To validate the model, it was parameterized using average regional climate data and averaged regional patterns of lambing, shearing and insecticidal treatment. Its predictions were then compared with patterns of lamb and ewe strikes recorded over a year on 370 farms. The results showed that the model was able to account for the start of seasonal blowfly strike for both ewes and lambs and to explain a significant percentage of the variance in lamb strike incidence. To provide a national strike-risk warning system for the British Isles, a web site "strikewise.com" was established and run for three years. The web site carried basic information about strike and a regionalized map of England, Wales and Scotland. At the start of each month, the model was run using the accumulated weather data for each region and an expected strike incidence risk forecast generated and displayed graphically on the web site. Regular news releases in the sheep farming press were used to highlight the web site predictions.
KEYWORDS blowfly, Lucilia sericata, disease incidence, forecast, model, ovine cutaneous myiasis, simulation, weather, web site, strike
KeywordsSeasonal Pattern British Isle Life Cycle Stage Oviposition Site Parasite Abundance
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