November 2000. PNG was asked by NAQS Scientific, AQIS, Queensland for information about the weevil borer, Rhabdoscelus obscuru Boisduval, a native to New Guinea, but which is now present in Fiji, Hawaii, Solomon Islands and Queensland. It is a serious pest of sugarcane, but this damage is usually associated with cane damaged through other means, such as rat damage, cane knife cuts, splits in stalks and other stem borers. In Papua New Guinea, damage by Sesamia grisescens (Lep. Noctuidae) is far more serious than that from weevil borer. There is also a strong correlation between S grisescens damage and the incidence of weevil borer.
In the last 4-5 years, PNG has been concentrating in controlling the moth borer from an IPM perspective. This involves the use of insecticides (lambda-cyhalothrin/ permethrin, acephate and terbufenozide – Mimic), variety resistance, inundative releases of Cotesia flavipes and Pediobius furvu and through cultural methods such as time of planting and planting of high risk areas to resistant varieties. A pheromone is used to monitor moth populations and using this information to guide all insecticide spraying. This has prove very successful, not only in controlling S grisescens but also weevil borer, Chilo terenellus and Scripophaga excerptalis (both pyralids). At present, weevil borer is not a proplem in cane on the commercial estate; however, it still is a major one in village gardens.
This has been reported in the proceedings of a recent ISSCT entomologyl workshop (Kuniata, 2000). Eds. P.G. Allsopp & W. Suasa-ard.
Apart from damage and population monitoring, there is currently little work done on weevil borer control. n the past we have tried to introduce the tachinid fly parasite to the estate but this did not establish.