Transcriptome analysis of Callosobruchus chinensis: insight into the biological control using entomopathogenic bacteria, Bacillus thuringiensis

Abstract

Bacillus thuringiensis based microbial pesticide is a potential alternative to fumigants. However, the effect of this entomopathogenic bacteria on stored-product pests, and the molecular mechanisms of insect response remain to be investigated. In this study, we showed that B. thuringiensis exhibited toxicity against Callosobruchus chinensis (L.) larvae. The 50% and 95% lethal concentrations in response to B. thuringiensis were 1.08 × 10⁷ and 4.27 × 10⁷ spores, respectively. We established a transcriptome to identify differential expressed genes. The predicted unigenes were categorized into 62 GO terms. A total of 187 DEGs were identified according to RNA-seq analysis, which 73 were downregulated and 114 were upregulated. And we preformed RT-qPCR assays to validate RNA-seq results. Both RNA-seq and RT-qPCR indicated that L-lactate dehydrogenase and glycoside hydrolase were inhibited in response to B. thuringiensis, while antimicrobial peptide, GST, and heat shock 90 were induced, suggesting that these genes might be involved in B. thuringiensis insecticidal effect for storage pests. A better understanding of molecular response to B. thuringiensis will facilitate us to develop a viable strategy method to control stored-product pests.

Keywords:
adzuki bean weevil; biological control; Bacillus thuringiensis; transcriptome analysis