Earias insulana (Boisdual)

Earias insulana is found in drier regions. The newly hatched larvae after wandering for few hours bore into tender shoot, flower bud or bolls. The larvae do not confine their feeding to just one plant or boll. As a result, partial damage is seen at many of their favorite feeding sites.

The initial culture is started either by rearing field collected larvae or the moths are collected from light traps. Hundred freshly emerged male and hundred female moths are placed in the breeding cage. For adult feeding, one cotton swab dipped in drinking water and another in 10% honey solution are provided in twin plastic containers placed inside the breeding cages. For obtaining eggs, corrugated butter paper or folded tissue papers or 20-30 okra fruits are placed in the cage. The top lid of the cage which has nylon net for aeration is screwed properly. The eggs are collected daily or on alternate days. The adult food is also replaced while collecting the eggs.

The eggs of each collection are kept in separate rearing containers. In most laboratories, freshly hatched larvae are introduced to okra pods by making incision with the help of a knife. The top of the black rearing container is secured with lid with plastic mesh. The rearing is normally carried out at room temperature or at 28°C and 70% RH.

The food is changed on alternate days and the entire assembly i.e., the rearing container and its contents is replaced with a fresh one. The used container is sterilized and dried to be used again.

The life stages on okra i.e., the egg, larval, pupal and adult are completed in 3-5, 12-18, 6-9 and 8-15 days, respectively. It takes about one to one and half months to complete one cycle. Each mated female produces about 150-200 eggs in its egg laying period of 8-10 days.

Earias insulana is being successfully reared on a semisynthetic diet based on cotton seed flour and chickpea flour. The diet is composed of the following ingredients.

Fraction A is added to 200 ml of water and heated to 60- 70°C, cooled, stirred well and transferred to a blender and mixed thoroughly. Fraction B i.e., agar-agar is boiled in 400 ml of water and then added to the blender and mixed well. Fraction C is added to the blender and again mixed. The diet is placed in petridishes to a depth of 2 cm or in glass vials (7.5 cm x 5 cm). Sterilized cotton wool is used to plug the rearing tubes. From the eggs which hatch in 3-5 days 20 newly hatched larvae are placed in each glass vial. The larvae which are fullfed in 12-18 days prefer to pupate on the side of cotton plug. The pupae formed are collected after two days of their formation when they become hard. The pupae are surface sterilized with 0.2% hypochlorite, neutralized with 10% sodium thiosulphate and then washed with distilled sterile water and rolled over a dry blotting sheet.

The pupae are placed in adult emergence cage which is similar to the egg laying cages. The adults emerge in 6-9 days and are fed on 10% honey soaked and water soaked cotton swabs. They live for 8-15 days. The females lay 150 to 200 eggs. If hygienic conditions are maintained, over 90% of the eggs laid by the moths give rise to healthy larvae.