EFFECT OF WEATHER CONDITIONS ON THE FLIGHT ACTIVITY OF NIGERIAN BLACKFLIES (DIPTERA, SIMULIIDAE)

A vehicle-mounted net was used to make hourly catches of blackflies at 700-1000 m altitude in the River Assob valley, central Nigeria, on 20 days during the dry season. Pearson Correlation Matrix analysis of th e collection data and meteorology showed that the main factors affecti ng flight activity of each of the four most abundant blackfly species were primarily light intensity and secondly wind velocity, whereas rel ative humidity was the least important factor. Flight activity showed a negative linear regression against wind, with some activity occurrin g in wind speeds up to 15 km/h. Distance-weighted least-squares (DWLS) regressions showed little correlation of temperature with activity fo r Simulium hargreavesi and S. adersi, but S. squamosum and S. vorax ha d small peaks at 28 degrees C and 31 degrees C, respectively. DWLS reg ression against light intensity showed an activity peak at 6000 lux, e xcept in Simulium adersi.