Insecticidal Toxicology Of Bacillus Thuringiensis HBF-1 Strain On Anomala Corpulenta Larvae And A.exoleta Larvae

A specific HBF-1 strain from Bt which showed high toxicity to Anomala corpulenta and A. exoleta was isolates by Shuliang Feng in 1998 and the cry8Ca gene was cloned. The aim of this study is to get more information on the toxicology of HBF-1 strain to Scarabaeid larvae and its interaction with chemical pesticides. After a series of experiments, the following results were got.1. The survival rate of A. corpulenta larvae and A. exoleta larvae was decreased, the antifeeding and growth inhibition of A. corpulenta larvae were increased, the feeding selectitity to feedstuff of A. corpulenta larvae enhanced as the concentration of HBF-1 strain was increased and the time of infected with HBF-1 strain was prolonged. The A. exoleta larvae LC50 was 64.16 μ g · g-1 for seven days and decreased 13.98 μ g · g-1 for fourteen days infected by HBF-1 strain; The A.exoleta larvae LC50 reduced from 79.69 μ g · g-1 to 19.14 μ g · g-1 treated with HBF-1 strain. When the A. corpulenta larvae treated with HBF-1 strain at the concentration of 10 μ g/g soil for seven days, the antifeeding rate and growth inhibition rate were 4.74% and 9.84%, 30.75% and 73.87% for fourteen days. When the A. corpulenta larvae treated with HBF-1 strain at the concentration of 160 μ g/g soil for seven days, the antifeeding rate and growth inhibition rate were 39.01% and 83.61%, 86.10% and 97.75% for fourteen days. A. corpulenta larvae were more repellent to the feedstuff containing HBF-1 strain of high concentration.2. The sensitivity of A. corpulenta to the chemical insecticides increased gradually with increasing exposure time and concentration to HBF-1 strain. When the larvae were pretreated with HBF-1 strain at the concentration of 20 μ g/g soil for three days, its sensitivity to Phoxim and Chlorpyrifos increased 1.96 and 3.28 times respectively, and increased 6.71 and 16.14 times when pretreated for five days by comparing to the larvae without pretreatment with HBF-1 strain. The sensitivity of the larvae to Phoxim increased 10.22 and 27.10 times after...