Estimation of Leafmine Density of Liriomyza trifolii (Diptera: Agromyzidae) in Cherry Tomato Greenhouses using Fixed Precision Sequential Sampling Plans

Abstract

This study was conducted to develop sequential sampling plans to estimate leafmine density by Liriomyza trifolii (Burgess) at three fixed-precision levels in commercial tomato greenhouses. The within-greenhouse spatial patterns of leafmines were aggregated. The slopes and intercepts of Taylor's power law did not differ between greenhouses and years. A fixed-precision level sampling plan was developed using the parameters of Taylor's power law generated from total number of leafmines in a tomato leaf (consisted of 7 leaflets) at three precision levels (D) of 0.20, 0.25, and 0.30. The resulting sampling plans were tested with sequential bootstrap simulations (n = 500) using 9 independent data sets for validation. Bootstrap simulation within a wide range of densities demonstrated that actual D′ values at desired D = 0.30 averaged < 0.29 in all cases. even at the lowest density of leafmine (0.16 mines per leaf), the actual mean D′ value was 0.24 at D = 0.30. This result shows that the sampling plan developed in this study is effective and reliable for estimating the mine densities in tomato greenhouses. © 2005 Korean Society of Applied Entomology, Taiwan Entomological Society and Malaysian Plant Protection Society.