author(s)
Tran Thi My Hanh and Nguyen Trinh Nhat Hang

abstract
Determining the composition of fruit flies damage to jackfruit and effect of some plant extracts to prevent fruit fly egg laying was carried out from January to November 2022 at Southern Horticultural Research Institute (SOFRI) and the jackfruit farms at Tan Lap and Tan Thanh communes, Tan Thanh district, Long An province. The results of determining the composition of “Changai” jackfruit fruit fly species in 15 orchards revealed that there were two fruit fly species, Bactrocera dorsalis and B. umbrosa with a frequency of occurrence of 80.0% and 26.67%, respectively. The lab trial to study efficiency of five plant extracts Allium sativum (Garlic), Allium cepa (Onion), Wedelia trilobata (Wedelia), Artemisia absinthium (Mugwort), Azadirachta indica (Neem) to prevent egg laying of B. dorsalis was conducted; the results showed that two treatments of plant extracts A. indica and W. trilobata were highly effective against B. dorsalis with rates of 82.22% and 71.50% at 7 days after treatment. In laboratory conditions, 0.9% concentration neem seed extract was effective in preventing fruit fly oviposition on jackfruit fruits by 83.19%. In field conditions, the results of spraying neem seed extracts at a concentration of 0.9% with 8 times/fruit crop and 6 times/fruit crop (5 and 7 days/time, respectively) reduced the damage of fruit flies with the damage rate of 41.67% and 50.33%, respectively. The experimental results have an initial significance in contributing to the integrated pest management process of fruit fly damage on jackfruit.