SPECIES COMPOSITION AND DENSITY FLUCTUATION OF THE CITRUS LEAFMINER PHYLLOCNISTIS CITRELLA STAINTON (LEPIDOPTERA: PHYLLOCNISTIDAE) ON XOAN ORANGES IN DONG PHU DISTRICT, BINH PHUOC PROVINCE

The study on the composition of insect pests on Xoan Orange trees in Dong Phu District, Binh Phuoc Province, identified 28 species belonging to 25 families and 7 orders. Among these, the order Hemiptera (true bugs) had the highest number of species, with 8 species (28.57%), while Lepidoptera (moths and butterflies) and Diptera (flies) each had only 1 species (3.57%). Thirteen natural enemy species were recorded, belonging to 8 families and 4 orders. The order Hymenoptera (wasps and bees) accounted for the highest number of species (6 species, 46.16%), while Hemiptera contributed the least (1 species, 7.69%). The density of citrus leafminer (Phyllocnistis citrella) varied with the season and type of orchard. In nurseries, the highest density was observed in August (4.56±0.02 larvae/leaf) and the lowest in January (1.42±0.03 larvae/leaf). In young orchards, the peak density occurred in April (3.68±0.01 larvae/leaf) and the lowest in January (1.38±0.02 larvae/leaf). In mature orchards, the highest density was recorded in April (2.61±0.02 larvae/leaf) and the lowest in January (0.78±0.04 larvae/leaf). The percentage of damaged leaves was highest in April across all three orchard types: Nurseries: 28.55±0.02%; Young orchards: 26.05±0.23%; Mature orchards: 25.38±0.02%. The lowest damage rates were observed in January, with corresponding values: Nurseries: 13.59±0.01%; Young orchards: 10.65±0.05%; Mature orchards: 8.67±0.03%. Keywords: Citrus leafminer; Phyllocnistis citrella; Xoan Orange