Comparison of life cycle traits of a Helopeltis theivora Waterhouse (Heteroptera: Miridae) population infesting organic and conventional tea plantations, with emphasis on deltamethrin resistance

The tea mosquito bug, Helopeltis theivora (Waterhouse), is an important economic pest of tea in India. The development of resistance in H. theivora populations obtained from a conventional plantation as compared with a strain from an organic plantation was studied in the laboratory for five generations, and associated changes in life cycle traits were assessed. Selection using sublethal concentrations of deltamethrin resulted in a 5.19-fold increase in insecticide resistance ratio from the F1 to the F5 generation in the H. theivora population from the conventional plantation. By the F5 generation, nymphal duration and total developmental duration and adult longevity were higher and fecundity was lower in the deltamethrin-selected strain than in the non-selected strain from a conventional plantation and the susceptible strain from an organic plantation. These findings have practical implications for insecticide resistance management of this important sucking pest of tea.