Citrus leafminer (Lepidoptera : Gracillariidae) density: Effect on yield of 'Tahiti' lime

The relationship between damage by citrus leafminer, Phyllocnistis citrella Stainton, and Tahiti' lime yield were investigated in a 15-yr-old and a 5- yr-old lime orchard. Citrus leafminer population densities were controlled by insecticide applications of abamectin plus FC 435 oil, abamectin plus FC 435 oil plus imidacloprid. and methomyl. The control was not treated. To en sure adequate citrus leafminer densities, adult citrus leafminer were perio dically released in the experimental plots during fall and winter. For the 15-yr-old trees, the least amount of leaf area damage occurred in the abame ctin plus FC 435 oil plus imidacloprid (1.9%) and the abamectin plus FC435 oil (2.3%) treatments compared with the control treatment (10-21%). In the 5-yr-old orchard, the least amount of leaf area damaged occurred in the aba mectin plus FC435 oil plus imidacloprid (0.4%) and the imidacloprid (0.1%) treatments compared with the control (20.85%). The percentage of leaf area damaged was linearly correlated with the average number of mines per leaf, average mine days, and cumulative mine days in both orchards. In both orcha rds, the percentage of leaf area damaged and cumulative mine days was linea rly correlated with the number of fruit per tree and total fruit weight per tree. Calculating the economic injury levels indicated that 16-23% and 18- 85% of leaf area damaged caused significant yield reductions in 15-yr-old a nd 5-yr-old trees, respectively.