Characterization of resistance to the Mexican rice borer (Lepidoptera: Crambidae) among Louisiana sugarcane cultivars

Authors: SALGADO, LEONARDO - Louisiana State University Agcenter; WILSON, BLAKE - Louisiana State University Agcenter; Penn, Hannah; Richard, Randy; WAY, MICHAEL - Texas A&M Agrilife

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/27/2022
Publication Date: 9/30/2022
Citation: Salgado, L.D., Wilson, B.E., Penn, H., Richard, R.T., Way, M.O. 2022. Characterization of resistance to the Mexican rice borer (Lepidoptera: Crambidae) among Louisiana sugarcane cultivars. Insects. 13(10):890. https://doi.org/10.3390/insects13100890.
DOI: https://doi.org/10.3390/insects13100890

Interpretive Summary: The Mexican rice borer (MRB) is an insect pest in Texas sugar cane and is becoming a problem in Louisiana. The MRB bite holes into the plant stems and eat the plant from the inside, making plants lose sugar. One way to control this pest is by planting sugar cane varieties that are not attractive to MRB or that can deal with higher levels of damage. We looked at which sugar cane varieties had the most damage and some of the reasons why MRB might choose some over others. We found that the sugar cane varieties L 01-299 and HoCP 85-845 had the lowest amount of MRB damage, but HoCP 00-950 and L 12-201 had the highest levels; but the level of MRB damage changed with the field site and weather. In the lab, when we looked at the reasons why plants may have had different MRB damage levels we found that it was not related to where adults laid eggs but with larval growth. MRB that ate plants that had less damage in the field had smaller bodies and took more time become adults. This shows that plant types that have less pest damage help control pests like MRB.

Technical Abstract: Cultivar resistance can be an essential management strategy for Eoreuma loftini (Dyar) in Louisiana’s sugarcane, but mechanisms of resistance are not well understood. E. loftini resistance was evaluated among commercial sugarcane cultivars and experimental clones through a series of field screenings, greenhouse trials, and a diet incorporation assay. Cultivars L 01-299 and HoCP 85-845 were among the cultivars with the lowest borer injury levels, while cultivars HoCP 00-950 and L 12-201 were among the most heavily injured in field and greenhouse trials. The variability of results from field trials suggests that a genotype × environment interaction and a pest abundance effect might affect the expression of resistance levels in cultivars. While oviposition did not differ among evaluated cultivars in the greenhouse choice study, suggesting these cultivars do not influence adult preference, results from the no-choice greenhouse experiment revealed up to 3-fold differences were present among cultivars in neonate establishment. In a diet incorporation assay, all cultivars reduced larval weight by 59.2–86.5% and increased days to pupation by 1.8-fold relative to the artificial diet control. These results suggest a range of resistance levels remains present in sugarcane breeding germplasm and highlight the importance of screening cultivars before commercial release. Future studies of stem borer resistance should attempt to determine the influence of environmental factors and species composition in resistance expression.