Among the insect pests that attack silkworm, the most formidable one is a dipteran parasitoid, Uzifly. If the parasitisation occurs after the middle of the fifth instar the parasitized worms mature two days earlier and construct poor quality cocoons. Such cocoons become stained and are unfit for seed purpose and for silk reeling due to the death of worms and emergence of maggots from the cocoons by piercing it. This has drawn the attention of several research workers in the past, who suggested different approaches such as providing fly proof wire mesh and nylon net to prevent the entry of Uzi fly into the site, spray of Uzicide to kill the eggs laid on silkworms, use of Uzi trap to attract and kill the adults and releasing of natural enemies to destroy the Uzi puparia. Though recommended preventive and control measures are being followed by farmers, the Uzi fly menace is still persisting. Considering the importance of botanicals in the silkworm pest management as an eco-friendly approach, neem oil and petroleum ether leaf extract of Vitex negundo has been tried to control Uzifly in the present study. Fifth instar silkworm larvae were reared in the wire mesh cage and one pair of two day old Uzifly were released into the cage for oviposition. Sixty Uzifly eggs on the body of the fifth instar silkworm larvae were selected (Silkworm larvae having minimum one egg and maximum two Uzifly eggs were selected) and treated with 0.5, 1 and 1.5 µl of neem oil / 1µl of acetone with help of automizer to record the egg hatchability. Controls and Carrier controls were maintained to compare the results and the experiments were replicated six times. Treated silkworms carrying Uzifly eggs were observed for their hatchability. The influence of 0.5µl, 1µl and 1.5 µl of neem oil/1µl of acetone on the egg hatchability of Uzifly recorded on an average was as 41.00 ± 0.541, 28.88 ± 0.611 and 24.72 ± 0.898 while in the control and carrier control it was recorded as 60.00±0.000 and 56.33± 0.881.5211 respectively. Treating the Uzifly eggs on fifth instar larvae of silkworm with neem oil reduced the egg hatchability when compared to the control.
Keywords : Neem oil, Uzifly (Exorista bombycis), Egg hatchability.