# Silicon-mediated defence response in chilli against yellow mite infestation

## TL;DR

This study shows that applying silicon to chilli plants can reduce yellow mite infestations and boost fruit yield in an eco-friendly way.

## Contribution

The study introduces silicon as an effective, environmentally safe method to enhance chilli plant resistance against yellow mites.

## Key findings

- Silicon application significantly reduced mite infestation and increased fruit yield in chilli plants.
- Silicon treatment increased leaf epidermis thickness and stress hormone levels, correlating with reduced mite infestation.
- Calcium silicate at 0.1% concentration was most effective in reducing mite infestation and improving plant health.

## Abstract

Chilli yellow mite is a major pest of chilli, which causes significant damage to both leaves and fruits. Synthetic acaricides, though widely used for control, pose environmental risks and often give unsatisfactory results due to pest resistance. Therefore, this study aimed to enhance the resistance of chilli plants against mite by applying silicon (Si), a natural element, in two forms- CaSiO₃ and K₂SiO₃, at concentrations of 0.1%, 0.5% and 1.0%. Results showed that Si application significantly reduced mite infestation while having no effect on their natural predator, the ladybird beetle. CaSiO₃ at 0.1% Si led to the lowest leaf infestation rates (7.6 ± 1.5%, 4.4 ± 0.4% and 2.4 ± 0.4% after the first, second and third sprays, respectively), and produced the highest number of healthy fruits at both the first and second harvests (345.8 ± 5.3 g/plant and 335.0 ± 4.2 g/plant, respectively). Si treatment increased the thickness of both the upper and lower leaf epidermis, especially with CaSiO₃ and K₂SiO₃ at 1.0% Si. It also elevated the levels of the stress-responsive hormones salicylic acid and jasmonic acid relative to the control, particularly with CaSiO₃ at 0.1% Si. Principal component analysis revealed that mite infestation was negatively correlated with both acid levels and leaf epidermis thickness. Thus, Si application presents a promising, eco-friendly strategy for managing mite infestations in chilli plants.

The online version contains supplementary material available at 10.1007/s10493-025-01079-7.