M. A. Taher, M. M. Uddin and K. S. Islam
Lychee is damaged by the litchi fruit borer (LFB), Conopomorpha sinensis severely reduces the yield and marketable quality of the fruits, and farmers face a substantial financial loss. An experiment was conducted for two consecutive years in the commercial litchi orchard. The study evaluated the efficacy of some insecticides under the group of pyrethroids, such as cypermethrin (Ripcord 10 EC), deltamethrin (Decis 2.5 EC), and fenvalerate (Fenfen 20 EC), neonicotinoids as imidacloprid (Imitaf 20 SL), thiamethoxam (Actara 25 WG), and pre-formulation of chlorantraniliprole+thiamethoxam (Voliam flexi 300 SC) and organophosphate (Hilthion 57 EC). All insecticides are used with recommended doses against C. sinensis to develop an appropriate management strategy. Among the treatments, spraying of voliam flexi 300 SC observed the maximum reduction of infestations over the control trees (99.47%), followed by imitaf, actara, decis, ripcord, fenfen, and hilthion. The highest benefit-cost ratio was obtained from the treated fruit trees with voliam flexi (12.11:1) and near about in fenfen and decis. Considering the effectiveness, spraying of voliam flexi at the rate of 0.5 ml per litre of water, followed by two sprays, first at ten days after the fruit set and then 20 days after the first spray. It is the most promising insecticidal approach for managing C. sinensis and may reduce the health risk to humans and save desirable components of the environment.
Keywords: Lychee; Fruit borer; Pyrethroid; Neonicotinoid insecticides.