What is it about?

Drosophila suzukii is an insect of global economic importance, including in the Neotropical region. Due to the difficulty in controlling this insect pest with conventional insecticidal molecules, it is necessary to search for novel alternatives. Here, we present the potential of synthetic lactone-based insecticides to control D. suzukii. Additionally, we demonstrate molecular predictions regarding the actions of these molecules on the nervous system of the target pest and on the nervous system of its parasitoid, Trichopria anastrephae. By using in silico approaches, we demonstrate that the lactone derivatives (rac)-8 and compound 4 predominantly affect the TRP channels of D. suzukii (TRPM) and exhibit less stable interactions with the TRP channels expressed in T. anastrephae.

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Why is it important?

Drosophila suzukii, an invasive insect pest, poses a significant threat to various fruit crops. The use of broad-spectrum insecticides to control this pest can reduce the effectiveness of biological control agents, such as the parasitoid Trichopria anastrephae. Here, we evaluated the toxicity of newly synthesized lactone derivatives on D. suzukii and their selectivity towards T. anastrephae. We used in silico approaches to identify potential targets from the most promising molecules in the D. suzukii nervous system and to understand potential differences in susceptibilities between D. suzukii and its parasitoid. Of the nine molecules tested, (rac)-8 and compound 4 demonstrated efficacy against the fly. Exposure to the estimated LC90 of (rac)-8 and compound 4 resulted in a mortality rate of less than 20% for T. anastrephae without impairing the parasitoid’s functional parasitism. The in silico predictions suggest that (rac)-8 and compound 4 target gamma amino butyric acid (GABA) receptors and transient receptor potential (TRP) channels of D. suzukii. However, only the reduced interaction with TRP channels in T. anastrephae demonstrated a potential reason for the selectivity of these compounds on the parasitoid. Our findings suggest the potential for integrating (rac)-8 and compound 4 into D. suzukii management practices.

Perspectives

Drosophila suzukii is a bug that's causing big problems for fruit crops. Using strong bug killers to get rid of it can mess up the good bugs that help control it, like Trichopria anastrephae. So, we tested some new chemicals to see if they work on D. suzukii without hurting the good bugs too much. Out of nine chemicals we tried, two called (rac)-8 and compound 4 did the job against the fly. Even when we used a lot of (rac)-8 and compound 4, the good bug's death rate stayed low, and it kept doing its job. Interestingly, these affect these receptors less in the good bug, which might explain why they're safer for it. So, it looks like (rac)-8 and compound 4 could be part of a plan to deal with D. suzukii without harming the helpful bugs.

Professor Elson Santiago Alvarenga
Universidade Federal de Vicosa

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This page is a summary of: Novel Lactone-Based Insecticides and Drosophila suzukii Management: Synthesis, Potential Action Mechanisms and Selectivity for Non-Target Parasitoids, Insects, August 2023, MDPI AG,
DOI: 10.3390/insects14080697.
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