Abstract:

The branches of Broussonetia papyrifera Linn. were treated with neem extracts(Neem EC) as the food of the beetle (Apriona germari Hope), the effects of neem extracts on the oviposition and egg hatch of the beetle were investigated. The testing pair beetles were put into the plastic containers with a diameter of 25 cm and of a height 25 cm and covered with iron screen. During 15 days' testing period, the average egg number laid per pair beetles per day in treated group (7 pairs), which were fed on branches treated by neem extracts containing 50×10^-6g/mL azadiractin was 2.00±1.56 and that in the control group (7 pairs) was 10.33±3.33. T-test showed significant difference in the values of the average egg number laid between treated and control groups. In the test with a dosage of the neem extracts containing 100×10^-6g/mL azadirachtin, in the treated group (7 pairs), the beetles began to die on the fifth day and all the beetles were died on the eighth day, their average egg number laid per pair for the living beetle pairs per day, was 1.00±1.41 and that for the control group was 13.73±2.90. T-test showed the difference between the two values was significant. The hatching rate of the eggs laid by the beetles, which had fed on the treated branches with a dosage of neem extracts containing 50×10^-6g/mL azadirachtin, reached 33.3% at the nineteenth day. However, that of eggs laid by the control beetles was 98.9% on the ninth day. During a 24 days' choice test of feeding, the branches were treated with a dosage of the neem extracts containing 100×10^-6 g/mL azadirachtin and the average food taken by the beetles in the treated group (7 pairs) was 3.53±0.38g per pair per day and that on the control group(7 pairs) was 3.42±0.60g per pair per day. T-test showed that the difference between the two values was insignificant. It indicated that the beetle could not distinguish the food treated with neem extracts, that is, neem extracts is not an antifeedant for the beetle. Based on the above results a new way using neem extracts to control the beetle was put forward and discussed.

Key words: Neem extracts, Apriona germari Hope, Oviposition, Egg hatching rate, Broussonetia papyrifera Linn