A Bio-rational Management Strategy Using Insect Growth Regulators Against Conopomorpha sinensis (Bradley) and Quality Assessment of Litchi Fruit

Abstract

The litchi fruit borer, Conopomorpha sinensis (Bradley) (Lepidoptera: Gracillariidae), is one of the major destructive and main pest of litchi fruits in Southeast Asia, including Bangladesh. This experiment was carried out in three different litchi orchards to develop a bio-rational management strategy using insect growth regulators (IGRs) to control the population of C. sinensis. The effectiveness of emamectin benzoate 5%, buprofezin, lufenuron, lufenuron (5%) + emamectin benzoate (5%), and abamectin were evaluated on the basis of fruit damage, yield of undamaged fruit and size, % fallen fruit, and total number of larvae in fallen fruits in three different litchi orchards. In our results, treatment with buprofezin showed the lowest (13.3%) level of fruit damage, followed by lufenuron + emamectin benzoate, abamectin, emamectin benzoate, and lufenuron, all of which were statistically significant compared with the untreated control. Furthermore, the highest number of undamaged fruits rate and mean fruit length were 86.7% and 17.8 mm, respectively, for buprofezin treatment compared to control (75.5 and 16.2). A large number of damaged, fallen fruits were found in the control plots (11.3%), while their number was lowest in buprofezin-treated orchards (4.1%). The chemical composition of litchi fruits was not affected by the application of IGRs. Indeed, levels of vitamin C, sugars, and titratable acidity increased in IGR-treated fruits compared with fruits from the control plots. Moreover, IGR treatments had a positive effect on total phenol (except lufenuron + emamectin benzoate) and flavonoid content of litchi fruits, improving their quality and as a source of antioxidants. Therefore, buprofezin can be used to manage the litchi fruit borer in organic litchi orchards.