# Autophagy is involved in the toxicity of the biocontrol agent GC16 against Tetranychus pueraricola (Acari: Tetranychidae) based on transcriptomic and proteomic analyses

## TL;DR

This study shows that the pesticide GC16 kills spider mites by triggering autophagy, a cellular process linked to increased calcium levels.

## Contribution

The study reveals that autophagy is a key molecular mechanism in GC16's toxicity against Tetranychus pueraricola.

## Key findings

- GC16 treatment increased autophagosome and autolysosome numbers in mites.
- LC3 protein expression was significantly elevated in GC16-treated cells.
- GC16 disrupted calcium homeostasis, with a 2.30-fold increase in intracellular calcium.

## Abstract

GC16 is a novel pesticide with acaricidal properties against the spider mite Tetranychus pueraricola (Ehara & Gotoh). Its physiological mechanisms have been described previously, but its molecular mechanisms of action remain unclear. Thus, we aimed to explore the acaricidal mechanisms of GC16 through transcriptomic and proteomic analyses. The results were verified using transmission electron microscopy (TEM), immunofluorescence assay, and western blotting.

Transcriptomic and proteomic analyses revealed 2717 differentially expressed genes (DEGs) and 374 differentially expressed proteins (DEPs) between the GC16-treated and control mites. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis indicated that the DEGs and DEPs were enriched in the autophagy pathway. TEM showed that the number of autophagosomes and autolysosomes was higher in the GC16-treated mites than in the control mites. Immunofluorescence assay and western blot results consistently indicated that GC16 treatment significantly enhanced the relative expression of the autophagy protein LC3 in insect Sf9 cells. The intracellular calcium concentration in the GC16-treated Sf9 cells was 2.30 times higher than that in the control cells, suggesting that GC16 disrupted calcium homeostasis and potentially acted as a calcium-driven nerve agent.

Autophagy is involved in the toxicity of GC16 against T. pueraricola and may be activated by elevated Ca2+ levels. This study reveals the molecular insecticidal mechanisms of GC16 and provides rationale for the field application of GC16 to control pest mites.

The online version contains supplementary material available at 10.1186/s12864-025-11312-7.