# Mechanisms of Aphids (Myzus persicae (Sulzer)) Response to Insecticides and Drought Stresses on Cabbage (Brassica rapa L. ssp. Pekinensis)

## TL;DR

This study explores how green peach aphids respond to insecticides and drought stress on cabbage plants, revealing how these factors affect aphid survival and plant health.

## Contribution

The study identifies how drought and insecticides interact to influence aphid performance and detoxification enzyme activity.

## Key findings

- Flonicamid-treated plants showed higher aphid survival and reproduction under drought and well-watered conditions.
- Thiacloprid-treated plants had better photosynthetic efficiency and lower transpiration rates.
- Flonicamid increased specific enzyme activities in aphids compared to thiacloprid.

## Abstract

Drought stress and insecticide exposure are two significant environmental factors that can impact the physiology and behaviour of aphids, a major agricultural pest. An understanding of the mechanisms of green peach aphids’ response to insecticides under drought stress is a critical area of research that needs urgent attention. In view of this, we conducted this study to determine the impact of drought and insecticides on the activity of detoxification enzymes in green peach aphid. A 2 × 2 × 3 factorial experiment involving two levels of water treatments (drought and no drought), two levels of aphids infestation (aphids and no aphids), and three levels of pesticides applications (thiacloprid, flonicamid and no pesticide) was conducted. The treatments were arranged in a randomized complete block design with three replications. The results showed that there was a significant (p < 0.01) interaction effect of drought × insecticides on the green peach aphid performance under drought or no drought conditions. Generally, the highest aphids host acceptance, survival rate, colonization success, and average daily reproduction under drought and well-watered conditions occurred on flonicamid-treated plants, whereas thiacloprid-treated plants had the least. However, the thiacloprid-treated plants had higher photosynthetic rate, water use efficiency, lower stomatal conductance, and decreased transpiration rate. Moreover, flonicamid treatment increased the accumulation of glutathione–S-transferase, acetylcholinesterase, butyrylcholinesterase, 1-napthyle acetate, and 1-napthyle butyrate activities in aphids, compared to the thiacloprid treatments. The thiacloprid pesticide, which demonstrated higher efficacy against green peach aphid, can be used in areas where green peach aphids and drought stress are major concerns.