Effects of Sitobion avenae Treated with Sublethal Concentrations of Dinotefuran on the Predation Function and Enzyme Activity of Harmonia axyridis

TL;DR

This study shows how sublethal doses of dinotefuran affect ladybugs' ability to hunt aphids and their enzyme activity, impacting pest control strategies.

Contribution

The study reveals how sublethal pesticide exposure alters ladybug predation and enzyme activity, offering insights for integrated pest management.

Findings

Ladybug predation on aphids decreased with higher pesticide concentrations, following the Holling II disc equation.

Detoxification enzymes like GST and MFO were significantly upregulated in ladybugs after consuming pesticide-treated aphids.

Handling time increased while attack rate and predation efficiency decreased in ladybugs exposed to treated aphids.

Abstract

This work investigated the effects of aphids treated with sublethal concentrations of dinotefuran on the predation function and enzyme activity of Harmonia axyridis. This study assessed the pesticide’s toxicity to aphids and H. axyridis using the leaf dipping method and residual film in glass tubes. The results demonstrate that the ingestion of insecticide-treated aphids led to changes in the predatory performance of H. axyridis, as well as modulation of the detoxification enzyme activities, which were either upregulated or downregulated. These findings highlight the impact of control strategies using dinotefuran to manage aphid behavior based on natural enemies and establish a foundation for the integrated application of chemical and biological control methods.

This study investigated the impact of sublethal concentrations of dinotefuran on the predatory behavior and detoxification enzyme activity of Harmonia axyridis, aiming to establish a theoretical foundation for the conservation and utilization of natural enemies and the effective management of wheat aphids. This study treated wheat aphids with sublethal concentrations (LC20 and LC30) of dinotefuran via the leaf dipping method and subsequently used them as prey for the fourth-instar larvae of H. axyridis. The predation amount, instantaneous attack rate, handling time, daily maximum predation amount, and detoxification enzyme activity of H. axyridis were statistically analyzed. The results indicated that the predation of H. axyridis on wheat aphids conformed to the Holling II disc equation. Moreover, in comparison to the control group, the handling time of H. axyridis on wheat aphids was extended, and at the same time, the instantaneous attack rate, maximum daily predation amount, and predation efficiency were all diminished. After the ingestion of LC20- and LC30-dinotefuran-treated aphids, the carboxylesterase levels in H. axyridis were not significantly different from the control, with levels 0.97-fold and 0.94-fold that of the control, respectively. Glutathione-S-transferase (GST) demonstrated an induction impact compared to the control, reaching 1.96- and 1.47-fold higher than the control, respectively. The activity of mixed-functional oxidase (MFO) demonstrated an induction effect compared to the control, measuring 1.98- and 3.04-fold higher than that of the control, respectively. Consequently, the predation function and detoxification enzyme activity of H. axyridis were influenced when consuming wheat aphids treated with sublethal concentrations of dinotefuran, with significant variations across different concentrations, potentially reflecting the survival strategy of insects under dinotefuran stress.

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