Effect of host plants on fitness traits and detoxifying enzymes activity of Helopeltis theivora, a major sucking insect pest of tea.

摘要

Helopeltis theivora Waterhouse (Heteroptera: Miridae) is a major sucking insect pest of tea (Camellia sinensis) which feeds on a wide variety of alternative host plants. Feeding biology and fitness traits of H. theivora, on two alternative host plants, viz., Mikania micrantha (Asteraceae) and Psidium guajava (Myrtaceae), besides C. sinensis (Theaceae), were studied along with corresponding levels of xenobiotic defense enzymes. C. sinensis is the preferred host of H. theivora. The development time of H. theivora is significantly shorter on C. sinensis (13.3+or-0.16 days) than on the two other hosts, M. micrantha (14.2+or-0.22 days) and P. guajava (14.7+or-0.23 days). Similarly, the fecundity (C. sinensis: 172.6+or-4.5 eggs/female, M. micrantha: 128.6+or-4.4 eggs/female, P. guajava: 118.7+or-3.3 eggs/female), oviposition period (C. sinensis: 24.1+or-0.7 days, M. micrantha: 22.5+or-0.6 days, P. guajava: 21.7+or-0.8 days) and hatchability (C. sinensis: 80.9+or-1.9%, M. micrantha: 69.4+or-1.6%, P. guajava: 64.1+or-1.7%) are recorded to be significantly higher on C. sinensis. The age at reproductive maturity and egg incubation periods were lower on C. sinensis than on the two other host plants. Host-based variation in H. theivora fitness traits is interpreted in light of differential activity of three principal xenobiotic detoxifying enzymes, the general esterases (GEs), glutathione S-transferases (GSTs) and cytochrome P450 monooxygenases (CYPs). The activities of these enzymes in H. theivora were significantly enhanced when the insect fed on M. micrantha and P. guajava as compared with on C. sinensis.