Egg-laying pattern of Hyposidra talaca (Lepidoptera: Geometridae) in Northeastern Indian tea plantations: implications for pest management

Abstract

Hyposidra talaca (Walker) is a recent host range-expanded major insect pest of tea in Northeastern India. We studied the egg-laying pattern of H. talaca in tea plantations with an aim to take suitable measures to disrupt egg hatching and to manage the pest. Egg clutch distribution in different heights (0–8 m) of 49 shade trees of seven species was studied. Stems and foliage of a total of 400 tea plants growing close to the shade trees were also subjected to the survey. Female moths deposited eggs underneath the scales of shade tree bark, lichen cover and the root mantles of parasitic plants that are growing on all shade tree plants, except Melia azaderach L. The shade tree bark of M. azaderach and tea plants had no egg deposits. Overall, 1785 egg clutches, comprising 84–302 eggs/clutch (average 258 eggs), were located. An average of 45.77 ( ± 7.06 SD, range 0–183) egg clutches was found per tree. The mean number of egg clutches was high in Acacia lenticularis Buch.-Ham. (95.4 ± 24.78 SD, range 40–183), and was low in Lagerstroemia speciosa (L.) Pers. (23 ± 6.42 SD, range 4–46). Overall, the number of egg clutches reduced with the height of shade trees. This study suggests that the oviposition of H. talaca is typical for an outbreak species and that the management of shade trees, including the choice of species, has an important role in controlling the pest in tea plantations.