Expected effects of reducing Oestrus ovis L. mature larval weight on adultpopulations

In order to estimate the effects of eventual reductions in larval weight (L W) of Oestrus ovis L. as a measure of control, the correlation between matu re LW and adult fly length (AL) in laboratory specimens (n=150) was calcula ted. The regression equation AL=5.62+10.65LW (r(2)=0.76) was obtained. This equation was then applied to estimate the mature LW of wild larvipositing females (n=51) to predict the minimum mature LW at which fly viability woul d be compromised. The critical weight, 0.28 g (standard error limits 0.235, 0.323), was obtained from a small fly measuring 8.6 mm in length. Data fro m 383 mature third instars were used to estimate, by statistical analysis, the expected effects of decreasing the mature LW on subsequent fly populati on size. A considerable mean reduction (38%) in adult populations might be achieved by a 40% reduction of mature LW, but this eventual reduction may b e temporary due to the high reproductive rate in this species. Sex differen ces in mature LW and fly size are also reported. (C) 2000 Elsevier Science B.V. All rights reserved.