# Silencing Attempts of Bombyx mori Odorant Receptors Potentially Associated with Oviposition Behavior

## TL;DR

This study shows that reducing a specific odor receptor gene in silk moths increases their egg-laying behavior when mulberry leaves are present.

## Contribution

The study identifies BmOr54 as a key odorant receptor gene influencing oviposition behavior in Bombyx mori.

## Key findings

- Knockdown of BmOr54 increased oviposition rates on mulberry leaves.
- BmOr44 and BmOr63 knockdown had no significant effect on oviposition behavior.
- BmOr gene expression levels were restored after fertilization.

## Abstract

We employed dsRNA technique to knock down three Bombyx mori odorant receptor genes (BmOrs), BmOr44, BmOr54, and BmOr63, to investigate their roles relating to the oviposition behavior of silk moth. Our results revealed that the reduction in the BmOr54 expression level could increase the oviposition rates of silk moth.

The silkworm, Bombyx mori (Bm), is an insect that contributes to industries such as silk production, cosmetics, medicine, and food, as well as to scientific research. A previous study showed that Bm odorant receptor (BmOr) genes, BmOr44, BmOr54, and BmOr63, may play a major role in oviposition. This research aimed to investigate the function of these three genes using a double-stranded RNA (dsRNA) technique to knock down their expression levels. Our results revealed that the gene-specific dsRNAs could moderately reduce the expression levels of BmOr44, BmOr54, and BmOr63 in the silk moth antenna. Silk moths were injected with 50 nM dsRNABmOr54 and 100 nM dsRNABmOr63 and showed relative oviposition rates under the mulberry leaves condition at 111.45% and 109.58%, respectively, when compared to those with dsRNAlacZ injection. The reduction in expression levels of these three genes showed no effect on the oviposition rates of the silk moths without mulberry leaves treatment. The expression levels of these BmOr genes were restored after fertilization, suggesting the temporary effects of the dsRNAs. Our findings suggested that variation in BmOr54 expression level was correlated with changes in oviposition behavior in Bombyx mori.