Assessment of natural parasitism of sugarcane moth borers Sesamia spp. by Telenomus busseolae

Sugarcane moth borers are a diverse group of species occurring in several genera, and are mainly polyphagous pests of gramineous crops including corn, sugarcane, rice and sorghum. They cause economic loss in sugarcane and other crops through damage to stem by larval boring. The pink stem borer Sesamia spp. is the most destroying pest of sugarcane in South-west of Iran where it has been managed largely through the planting of resistant cultivars, cropping practices and biological control. Telenomus busseolae Gahan is the most important egg parasitoid of sugarcane stem borers in Iran and this biological control agent can periodically reduce the damage of moth borers in sugarcane cultivars. In this study, we investigated the natural parasitism of this tiny wasp in five commercial cultivars; CP57-614, CP48-103, CP69-1062, IRC99-01 and SP70-1143. Samplings for eggs were carried out in both plant cane and ratoon with four replicates. In each replication, 20 stalks were cut and leaf sheaths were examined for moth borer eggs whether they are healthy or parasitised. All eggs were placed separately in glass-tubes for 2 weeks until adult emergence. The results showed that the highest percentage of parasitism was associated with CP48-103 variety. As a result, T. busseolae has a significant effect on moth borer eggs and can be considered as a key component of borer control in the sugarcane fields. (Résumé d'auteur