# Impact of Brood Cell Cocoons on Metal Accumulation and CYP450 Detoxification Gene Expression in Apis cerana cerana

## TL;DR

This study shows that cocoons in multi-generation brood cells increase metal accumulation and gene activity in honey bees, harming their health.

## Contribution

The study reveals how multi-generation brood cell cocoons negatively affect honey bee health through metal accumulation and gene expression changes.

## Key findings

- Cocoons in multi-generation brood cells had higher levels of metals like Cr, Cd, Pb, Mn, Ni, and As.
- Metal accumulation led to increased expression of four CYP450 detoxification genes in larvae and newly emerged workers.
- These findings suggest that multi-generation brood cells negatively impact honey bee health.

## Abstract

Honey bees play a critical role as pollinators. However, their reproduction success and survival face severe threats due to the deterioration of their living environment. Notably, environmental conditions during their preimaginal stage inside brood cells can influence their immune capabilities and overall health after emergence. During the in-cell developmental stage, workers are in close contact with cocoons, which can become a source of stress due to accumulated metals. To investigate this potential threat, experiments were conducted to examine the impact of cocoons in brood cells used to rear different generations on the metal content and detoxification gene expression levels in Apis cerana cerana. Our findings indicated significant differences in the layers, weight, base thickness, and metal contents like Cr, Cd, Pb, Mn, Ni, and As of cocoons in multi-generation brood cells compared to single-generation brood cells. These increases led to significant elevations in metal levels and upregulations of the four CYP450 detoxification genes in both six-day-old larvae and newly emerged workers. In conclusion, this study highlights the negative impact of cocoons in multi-generation brood cells on bee health and provides evidence supporting the development of rational apiculture management strategies for ecosystem stability.