Chelonus heliopae Gupta

Chelonus heliopae the egg-larval parasitoid has been reared from Heliothis peltigera (Denis and Schiffermuller), Spodoptera litura (Fabricius), Scorbipalpa heliopa (Lower), Earias spp. and Spodoptera exigua (Hübner). It is an important parasitoid described from tobacco stem borer Scorbipalpa heliopa from Gujarat. In the field the parasitoid is active from July to February with maximum parasitism during July and August. The parasitoid has been successfully reared on Helicoverpa armigera (Hübner), Achaea janata Linnaeus, Corcyra cephalonica Stainton and Plodia interpunctella (Hübner).

The culture of Chelonus heliopae is started from large number of egg masses and small larvae of Spodoptera litura and Spodoptera exigua. The parasitoid pupae are held in plastic containers till the emergence of adults. The adults are transferred in 30 cm x 30 cm x 30 cm wooden cage with muslin cloth on the side and glass at the top.

The adults emerging on first lot are stored at 10°C because of the disproportionate sex ratio and are mixed with the adults emerging after 3-4 days. One of the sides is fitted with a sleeve to introduce the adults in the cage. A moistened urethane foam sheet, 1.25 cm in thickness, is kept on the bottom to maintain humidity inside the cage. Cotton-wool pads or plugs dipped in 5.0 per cent honey solution are hung with the help of pins from the sides of the cage and also placed in small polythene cap at the bottom to feed the parasitoids.

A piece of paper carrying Spodoptera litura eggs is stuck under the glass top of the cage containing the parasitoids with the help of cellophane tape. The eggs are exposed to the parasitoids until parasitized. The larvae hatching out of these eggs are reared on castor leaves or the semisynthetic diet consisting chickpea flour, agar, vitamins, antimicrobial solution and other precautions as described for rearing Helicoverpa armigera. When the parasitized larvae begin to enter the soil for pupation the soil for the cage is not disturbed. The unparasitised larvae which grow rapidly are picked up and destroyed. The parasitized larvae are allowed to enter the soil for about 4 days and the remaining larvae are transferred to another cage. The cage is left open on the rack for 2 days to allow cocoon formation. The soil is then sifted through suitable sieves to separate the parasitoid pupae, which are then held in a plastic bowl lined with moistened sponge for emergence of adults, the bowl is placed in a cage.

The parasitoid is produced at 26.7°C, the parasitoid lays 562.64±306.65 eggs which hatch in 20.2 hrs (18 to 21.5 hrs). The egg larval duration on Spodoptera litura is passed in 13.75 days, the cocoon stage of males lasts 6.04± 0.73 days and females 7.32± 0.84 days. The male live for -4.84 ±2.45 days and the females for 6.38 ±2.49 days, unmated females live for 5.38±2.54 days. The females outnumber males 14:1.