Borer damage and estimation of losses caused by Sesamia grisescens Walker (Lepidoptera: Noctuidae) in sugarcane in Papua New Guinea

Sesamia grisescens Walker (Lepidoptera: Noctuidae) is a serious pest of sugarcane in Papua New Guinea. Field studies on borer damage and potential crop losses were carried out at Ramu Sugar estate between 1986 and 1996. Apart from the direct losses in cane weight (cane yield) due to boring from the larvae, cane juice quality is also adversely affected, resulting in lower recovery of sucrose in the factory. Estimated cane losses were 0.82 tonnes cane ha- 1 and sugar losses were 0.13 tonnes sugar ha- 1 for every 1% bored and rotting stalks. In 1987 losses of up to 32 tonnes cane or 3 tonnes sugar ha- 1 valued at more than US$ 1800 were observed. Other indirect losses are also discussed