Cotesia flavipes Cameron

Cotesia flavipes is a principal larval endo-parasitoid of Chilo pariellus on maize and sorghum. C.flavipes has also been recorded from sugarcane tissue borers but the parasitism is generally very low. Recently an Indonesian strain from sugarcane ecosystem has been introduced and evaluation is in progress.

The rearing jar (25x12cm) is painted black from outside and a column of water (about 1 cm high) is maintained at the bottom. A circular piece of fine wire gauge about 12 cm in diameter is placed horizontally inside the jar about 5 cm above the bottom. The mouth of the jar is secured with a piece of muslin cloth on which anesthetized borer larvae are placed for parasitisation. A glass sheet is placed over the mouth of the jar to keep the larvae in position. Boiled raisins are kept over the wire gauge. The freshly emerged adults are confined between the wire gauge and muslin cloth where feeding, mating and oviposition takes place. The female deposits a mass of eggs in the body cavity of the host larva. The exposed larvae are replaced every 24 hrs with fresh ones. The eggs hatch in about 4 days. The parasitized larvae are reared either on semisynthetic diet or on cane pieces until they pupate. When fully fed, they leave their host and spin snow-white cocoons near the host. The larval period is completed in 8-14 days and the adults emerge from cocoons after 7 days. Each female parasitizes 6-8 larvae in an oviposition period of 6 days and about 70 eggs are deposited. Upto 40 adults can emerge from each host.

It is advisable to rear the selected strain on Chilo infuscatellus at least for one generation before field release. The parasitoid could also be multiplied on either sugarcane tissue borers and/or on field collected diapausing larvae of C. partellus in North India. Presence of host frass acts as a kairomone and improves parasitism.