Host-based life cycle traits and detoxification enzymes of major looper pests (Lepidoptera: Geometridae) of tea from Darjeeling Terai,India

Three polyphagous looper caterpillars, Buzura suppressaria Guenée, Hyposidra talaca Walker and Hyposidra infixaria Walker, have established themselves as severe pests of tea Camellia sinensis (L.) Kuntze] in the plantations of sub Himalayan West Bengal (Terai region). Schima wallichii (DC.) Korth. is a naturally occurring alternative host of all these looper species. To gain an insight into looper and host plant relationships, the present work contemplates studies on host preference, host-based life cycle traits and levels of detoxification enzymes, such as general esterases (GEs) and glutathione S-transferases (GSTs). From the study, host-induction of feeding preference was evident in all the three looper species. Hyposidra spp. exhibited similar post-embryonic development periods both on tea and S. wallichii, whereas B. suppressaria reared on tea needed a longer development period than on S. wallichii. Tea-reared caterpillars of Hyposidra spp. were significantly heavier, having higher quantities of GEs and GSTs than S. wallichii-reared ones. B. suppressaria, however, exhibited similar body weights on tea and S. wallichii. While GST level was higher in tea-reared B. suppressaria, its GE quantity was higher on S. wallichii. Although tea was found to be a more suitable host for Hyposidra spp., the host S. wallichii proved marginally better than tea for supporting B. suppressaria. However, all the three looper species could utilize the foliage of tea and S. wallichii successfully. So S. wallichii trees can act as a sylvan reservoir of the looper species, prompting their possible invasion of tea plantations and thus making management of looper pests in tea more difficult.