Effects of bifenthrin and indoxacarb on the midgut cell structure and hemolymph detoxification enzyme of Ectropis obliqua Prout (Lepidoptera: Geometridae)
Author of the article:LI Liang-De;LIU Feng-Jing;WANG Ding-Feng;WU Guang-Yuan
Author's Workplace:Tea Research Institute, Fujian Academy of Agricultural Sciences;Tea Research Institute, Fujian Academy of Agricultural Sciences;Tea Research Institute, Fujian Academy of Agricultural Sciences;Tea Research Institute, Fujian Academy of Agricultural Sciences
Key Words:Ectropis obliqua Prout; bifenthrin; indoxacarb; midgut structure; hemolymph; detoxification enzyme
Abstract:
[Objectives] To investigate the
effects of bifenthrin (BIF) and indoxacarb (IND) on the midgut cell structure and hemolymph detoxification enzyme
of Ectropis obliqua Prout, a pest of tea plantations. [Methods] The tail
immersion method was used to expose 5th instar larvae of E. obliqua to the median lethal
concentration (LC50) of bifenthrin and indoxacarb and subsequent
changes in structure in midgut cells were observed with transmission electron
microscopy. The activities of detoxification enzymes in hemolymph, including glutathione-S-transferase (GSTs), acetylcholinesterase (AChE) and
carboxylesterase (CarE), were also quatified. [Results] The LC50s of BIF and IND for 5th instar E. obliqua larvae were 5.884
mg.L-1 and 0.268 mg.L-1, respectively.
Transmission electron microscopy revealed that BIF and IND induced disintegration of the microvilli in columnar
cells, which became scattered in the intestine. In addition, intracellular
organelles were transferred to the top cytomembrane and became obviously
deformed. BIF induced an obvious increase
in AchE and CarE activity but no
significant change in GSTs activity,
whereas IND significantly inhibited GSTs,
AchE and CarE activity in hemolymph. [Conclusion] Bifenthrin and indoxacarb damaged the structure of midgut columnar cells in E. oblique by destroying the
microvilli and disrupting organelle function. In addition, the detoxification
of bifenthrin in hemolymph is related to esterase (AChE and CarE), but not
transferase (GSTs) activity, whereas the detoxification of indoxacarb is related to both esterase (AChE and CarE) and transferase (GSTs)
activity.