Transcriptome Analysis Provides Insights into Water Immersion Promoting the Decocooning of IOsmia excavata/I Alfken

Osmia excavata Alfken is an excellent pollinator. A variety of factors affect the rate of O. excavata release from its cocoon. However, rapid improvement of the concentrated decocooning of O. excavata has not been sufficiently investigated. In this study, we examined the effect of water immersion on the decocooning rate of O. excavata. Our results showed that water immersion significantly improved O. excavata decocooning. This will provide technical support to improve effective application of O. excavata. Illumina Novaseq™ 6000 transcriptome sequencing showed muscle-related functions play important roles in O. excavata decocooning in response to water immersion. The timing of decocooning and nesting during the flowering period are crucial for the reproduction and pollination activities of Osmia excavata. In order to improve the pollination efficiency of O. excavata, it is crucial to find a way to break the cocoon quickly. Our results showed that the decocooning rates at 6, 12, 24, 36, 48, and 72 h after 30 min of water immersion (WI) were 28.67%, 37.33%, 37.33%, 41.33%, 44.33%, and 53.00%, respectively. The decocooning rate fold of 6 h was 14.33 compared with the control group. Transcriptome sequencing resulted in 273 differentially expressed genes (DEGs) being identified between the WI and control groups. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that muscle-related functions play important roles in O. excavata decocooning in response to WI. Cluster analysis also showed that DEGs in cardiac muscle contraction and adrenergic signaling in cardiomyocytes were up-regulated in response to WI-promoted decocooning. In conclusion, the rate of decocooning can be improved by WI in a short time. During WI-promoted decocooning, muscle-related pathways play an important role. Therefore, the application of this technology will improve the pollination effect of O. excavata.