Resistance mechanism of energy canes developed from Saccharum spontaenum and Erianthus arundinaceus against sugarcane borer pests

• Saccharum spontaneum and Erianthus arundinaceus introgressed canes are Type I & II. • The incidence of sugarcane borers was significantly lower in Type II energy canes. • Type II energy cane-fed sugarcane borers reduced larval and pupal survivability. • Silicon and trypsin inhibitors negatively correlated with sugarcane borer biology. • SBIEC14006, 11004, 11001 (Type II) and SBIEC 13010 (Type I) showed borer tolerance. A total of 26 newly developed energy canes including Type I having Saccharum spontaneum as immediate parent and Type II having as immediate parent Erianthus arundinaceus were screened for resistance against sugarcane early shoot borer (ESB), Chilo infuscatellus and internode borer (INB), Chilo sacchariphagus indicus. Field and lab screening study results indicated that ESB and INB incidence was much lower in E. arundinaceus energy canes, with no discernible impairment to internode morphology than in S. spontaneum energy canes. Furthermore, Type II energy canes-fed ESB and INB showed adverse effects on growth and development by reducing their larval and pupal survivability. Besides, ESB and INB larval durations were 22 to 34 days and 39 to 52 days in Type I and Type II energy canes, respectively. A significant increase in secondary metabolites, such as phenols, silicon content, polyphenol oxidase and proteinase inhibitors, as well as a decrease in positive nutritive compounds in E. arundinaceus, indicated the antibiosis mechanism of resistance. Furthermore, E. arundinaceus PIs effectively inhibited the midgut proteases of ESB and INB compared to S. spontaneum PIs. Proteinase inhibitors, silicon and phenolic content showed a significant negative correlation with the incidence and development of sugarcane borers. The study identified three borer-tolerant Type II energy canes (SBIEC 14006, SBIEC 11004, SBIEC 11001) and one Type I cane (SBIEC 13010), which could be utilized for biofuel production. In addition, these elite clones can serve as genetic stocks for developing borer-tolerant varieties in future energy cane breeding programmes.