Submitted to: International Society of Sugar Cane Technologists Proceedings
Publication Type: Proceedings
Publication Acceptance Date: June 30, 2000
Publication Date: June 30, 2000
Citation: White, W.H. 2000. Stalkborer bioassays: Experiences in Louisiana. In: Allsopp, P.G., Suasa-Ard, W., editors. Sugarcane Pest Management in the New Millennium, IV Sugarcane Entomology Workshop, Khon Kaen, Thailand, Proceedings of the International Society of Sugar Cane Technologists. p. 28-33. Interpretive Summary: The "built-in" protection of plant-resistance, effective throughout a crop plant's life, offers a compelling alternative to insecticides in controlling damaging infestations of insects. However, among the world's sugarcane industries, host-plant resistance remains an under utilized tactic. The absence of examples of genetic sources that confer insect resistance may explain why plant-resistance has not been more fully exploited by sugarcane plant breeders. Efforts to import genetic sources of resistance that may be utilized are frequently hindered by quarantine considerations. The risk of introducing a new disease or insect may be too great. I report here an assay procedure that may provide a solution to the problem of importing live plants and thus the possible introduction on new diseases or insects. This assay is conducted in the laboratory, utilizes prepared sugarcane tissue, and resistance is measured by reduced larval growth at 14-days. We have used this assay to look for resistance to the larvae of our most important insect pest in Louisiana (and all the Americas), the sugarcane borer. The assay is useful in comparing tissue among several different genetic sources. Sugarcane entomologists and plant breeders should benefit from our procedure as it would facilitate the importation and testing of promising genetic material from around the world. Ultimately, releasing resistant plants will lead to less insecticide use in sugarcane fields and this would be a tremendous benefit to both farmers and the non-farming communities.
Technical Abstract: One reason that host-plant resistance has not been more fully exploited by the world's sugarcane industries is the absence of insect resistant germplasm for use in breeding programs. However, efforts to import and characterize exotic germplasm that may provide that needed resistance can be hindered by quarantine consideration. The threat of introducing a new disease or insect can negate the potential benefits that may be derived from new germplasm sources. A possible solution to this dilemma may be to employ a bioassay procedure that uses prepared cane tissue. This would obviate the need to exchange living plants and may be more acceptable to quarantine authorities. I report a bioassay that uses freeze-dried cane, but does not require the tissue to incorporated into a semi-defined diet. Using this procedure we evaluated population of 33 Sacccharum spontaneum L. lines. Three were found to produce larvae significantly smaller when feed on sheath and internode tissue for 14-days than when feed the same tissue from commercial standards. In this paper I review the inherent limitations of bioassays using excised tissue. I also suggest that our bioassay serve as a model for developing a cooperative project among interested entomologist to evaluate promising germplasm lines from around the world for resistance to important stalk-borers.