The bagging of fruits is widely used to provide a physical barrier between the fruits and insect pests. Litchi can easily be bagged to keep them safe from oviposition of litchi fruit borer, Conopomorpha sinensis Bradley (Lepidoptera: Gracillariidae). Efficacies of different bagging alone or in combination with insecticides were evaluated against the control trees in a commercial litchi orchard in Bangladesh. The study consisted of five treatments: mosquito net sheets, mosquito net bags, white waxed-paper bags, mosquito net bags combined with Novastar 56 EC (bifenthrin + abamectin) and mosquito net bags combined with neem leaf extracts. Treatments were set at 10, 20 and 30 days after fruit settings (DAFS). Regardless of the bagging method and setting times, all the treatments significantly reduced C. sinensis infestations compared to the control trees. Earlier bagging of fruits (within the 10 days of fruit settings) provided the best protection (100%) from C. sinensis infestations. In the cases of later bagging of fruits (at 20 and 30 DAFS), better defences against C. sinensis were found from the white waxed-paper bagging and mosquito net bags + Novastar 56 EC treatments. Irrespective of the bagging times, higher pest-free fruits (>95%) and benefit-cost ratios (BCR) were achieved from the bagging with white waxed-paper bags (8.25:1) and the mosquito net bags + Novastar 56 EC (5.18:1). Among the treatments, the mosquito net bags, or sheets were less effective. However, mosquito net bags combined with neem leaf extracts provided better outcomes. Therefore, bagging fruits within 10 days of fruit settings can be recommended for better protection. For the delayed bagging, white waxed-paper bags or the mosquito net bags in combination with Novastar 56 EC (preferred) or neem leaf extracts might be suggested.
Key words: Litchi, netting, Novastar 56 EC (bifenthrin + abamectin), neam leaf extracts, benefit-cost ratios (BCR)
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