Moth pests collected in light traps of tea plantations in North East India: species composition, seasonality and effect of habitat type

摘要

Light trap has often been used in the ecological studies of lepidopteran insect pests in agroecosystems. However, the light trap in Indian agricultural systems is rarely adopted either to monitor the population size or to study the migration of moth pests. In the present study, we have installed light traps in shaded and unshaded tea plantations of North East (NE) India to study (-1-) the species composition, (2) effect of shade on moth pests, (3) seasonality of major pests and (4) to learn the sex proportion of major pests captured in light traps. The two-year catches in light traps suggested that Hyposidra talaca (Geometridae) is a major pest of tea in NE India. It peaks in number during winter months, with relatively few moths caught in the later parts of the year. Eterutia magnifera (Zygaeni-dae) is the second major pest of tea that peaks in number during summer months. Hyposidra infixaria, Buzura suppressaria, Ectropis obliqua, Ascotis sp. (all Geometridae) and Arctornis submarginata (Lymantridae) were caught in the light traps, but in low numbers. The catches also suggested that shade status has an important role on moth pest population in tea agroecosystems; shaded plantations received significantly higher number of moths of all major pests. The difference in the catches of H. talaca moths was significant among years. Pair-wise analysis suggests that the difference in the catches of H. talaca in corresponding standard meteorological weeks (SMWs) of two years was not significant for most of the SMWs, which confirms the inter-annual consistency in the life cycle and generations. Male moths constitute more than 77% of the overall catches of H. talaca. Overall, our results highlight that light trap is an effective, bias-free monitoring tool of moth pests of tea, which also captures the variability due to habitat type.