Preliminary Studies On The Bioactivity And Mechanisms Of Octadecyl Trimethyl Ammonium Chloride Against Pieris Rapae

Bioactivity of octadecyl trimethyl ammonium chloride (1831) against larvae of Pieris rapae were systematically studied in this paper. The results showed that 1831 had contacting and stomach poison against the 5th instar larvae of Pieris rapae, the regression equation of contact toxicity of 48 h and 72 h after treatment were y= -0.461 2+1.768 5 x (r=0.998 9) and y= - 0.335 2+1.824 6 x (r=0.989 5), LC50 were 1 224.73 mg/L and 839.53 mg/L, respectively; the regression equation of stomach poison of 48 h and 72 h after treatment were y=0.4238+1.5352 x (r=0.9883) and y=2.966 5+0.740 8 x (r=0.988 1), LC50 were 956.86 mg/L and 555.91 mg/L, respectively. 1831 also showed strong antifeedant effects against the 5th instar larvae of Pieris rapae. the regression equation of antifeedant effects of 24 h and 48 h after treatment were y=3.992 4+0.909 4 x (r=0.987 8) and y=4.760 0+0.741 6 x (r=0.985 8), the medium antifeedant concentrations AFC50 were 12.82 mg/L and 2.11 mg/L, respectively. The growth inhibition rates gradually decreased with 1400, 700, 350, 175, 87.5 mg/L dosage of 1831, were 98.43%, 93.68%, 88.60%, 84.59%, 67.71% for each treatment after 24 h. The average pupal weights of treatments with 1831 were significant lower than that of control. The rates of eclosion were 20.00%, 26.67%, 33.33%, 66.67%, 80.00% for each treatment. It was obvious that the growth inhibitory effects of 1831 against the 5th larvae of Pieris rapae were notable.Action mechanisms of 1831 against the 5th larvae of Pieris rapae were researched in this thesis. The results showed that the effects of 1831 on the cuticle weights of 5th larvae of Pieris rapae were notable, but the chitin content in cuticle were from 28.44% to 31.75% and not significantly different from that of the control (32.82%) . 24 h after treatment, the reduced rate of total weights of haemolymph were from 14.34% to 28.49% for each treatment with 25-400 mg/L dosage of 1831, the reduced rate of total weights of haemolymph reached 51.59% of 48 h after treatment. The total weights of haemolymph of each treatment were significant lower than that of control, were significantly different at control by Duncan's multiple range test (DMRT). Effects of 1831 on the contents of protein in haemolymph and the...