Studies On Chemical Control Of Blattella Germanica

German cockroach {Blattella germanica) has been regarded as one of the most important and the hardest to control city pests in the world. In this paper, the effect of sublethal dosage of insecticides on target enzyme activity of German cockroach and the attracting effect of foods and feces crude extracts on German cockroach were researched. The results were as follows:The results of toxicity test showed that KT50S of deltamethrin and cypermethrin to the 5th instar larvae were 14.16 and 24.60min, respectively. LC₅₀s of phoxim and dichlorvos were 827.26 and 592.65 mg/L, respectivley. The resistance of 5th instar larvae was higher than any other instar larvae. Compared with 1th instar larvae, the relative resistance ratios were 1.97, 2.46, 20.72 and 17.86, respectively. The resistance of male adults was higher than that of female. Insecticde mixture test showed that the co-toxicity coefficient of cypermethrin and phoxim (1:5) was 188.29. The co-toxicity coefficient of cypermethrin and dichlorvos (1:5), deltamethrin and dichlorvos (1:5) was 152.05 and 130.94, respectively. But mixture of deltamethrin and phoxim (1:5) did not show obvious synergism with the co-toxicity coefficient of 119.41.Enzyme activity results showed that activitives of both CarE and AChE decreased with the growth of larvae, and the difference was significiant. As for CarE, the activity of male adults was 1.74 times higher than that of female adults. But the activity of AChE had no obvious difference. The activity of GST had no difference among 1st, 3rd, 5th instar larvae and male, female adults when expressed asμmol/mgpro·min, but the activity increased with the growth of larvae when expressed asμmol/insect·min.After treated with sublethal dosage LC₁₅ (5.90 mg/L) of deltamethrin, the activity of CarE decreased gradually in the first 72h, 28.02% lower than before treatment. The activity of AChE had a little increase in 24h, 19.79% higher than before, then declined gradually. After treated with sublethal dosage LC₂₀ (203.77 mg/L) of phoxim, the activity of CarE decreased to the lowest in 24h, the activity of AChE decreased gradually and 96h after treatment, it was 27.27% lower than before treatment. The activity of GST declined to the lowest 72h after treatment. Roast soybean powder had the best attracting effect, the attraction rate was 45.66%. Banana was the second, with attraction rate of 25.83%. The attraction effect of pakchoi juice was lower and glucose was the lowest, with attration rate of 11.67%. When mixed roast soybean powder and banana with deltamethrin and phoxim, banana bait had the best attraction and killing effect.The results of experiment of attraction effect of feces extraction showed that ethanol was the best solvent. Ethanol extract of low instar larvae feces had the best attraction effect. The attraction rates to low instar larvae, high instar larvae, female adults and male adults were 39.72%, 40.56%, 38.33%and 34.17%, respectively. When added a certain amount of ethanol extract of low instar larvae and high instar larvae feces to bait, the attraction and killing percent increased significantly, and the effect of low instar larvae extract was better than that of high instar larvae.