Mortality and physiological impacts of the tea saponin against Ephestia kuehniella Zeller (Lepidoptera: Pyralidae)

Abstract

The toxicity of a tea saponin (TS) was investigated on mortality, digestive system, detoxifying and antioxidant enzymes of Ephestia kuehniella Zeller. The larvae were fed on a diet containing different concentrations of TS (5, 10, 20, 40, and 80 mg/mL) to determine the lethal dose and the lethal exposure time. The LC₅₀ of TS was calculated as 28 mg/mL while the LT5 value was found to be 4.14 days following the bioassay experiment. The activities of all enzymes except for lipase decreased in the TS-fed larvae, while the activities of general esterase and glutathione S-transferases as the detoxification enzymes significantly increased contradictory. Moreover, the larvae fed on TS demonstrated the higher activities of antioxidant enzymes including superoxide dismutase, peroxidase, and catalase in addition to the content of malondialdehyde. These findings indicated the significant toxic effects of TS on inhibition of digestive activities and induction of antioxidant enzymes which developed our knowledge on physiological disruptions due to TS treatment.

Keywords:

• Ephestia kuehniella
• tea saponin
• biopesticide
• bioassay
• digestive physiology
• antioxidant system

Acknowledgement

The authors would like to thank University of Guilan (Rasht, Iran) for supporting our research.

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.