东莨菪内酯与双脱甲氧基姜黄素对朱砂叶螨毒力的温度效应

为明确植物性杀螨活性物质东莨菪内酯与双脱甲氧基姜黄素对朱砂叶螨Tetranychus cinnabarinus雌成螨毒力的温度效应， 采用玻片浸渍法测定了两者不同温度下的杀螨活性。结果表明： 在8～26℃的温度范围内， 东莨菪内酯和双脱甲氧基姜黄素对朱砂叶螨雌成螨的毒力呈正温度系数； 在26～34℃的温度范围内两者对朱砂叶螨雌成螨的毒力呈负温度系数。其中26℃下东莨菪内酯和双脱甲氧基姜黄素表现出较好杀螨活性， 处理后48 h的致死中浓度(LC₅₀)分别为0.1884和0.3376 mg/mL； 23℃下的毒力次之。致死中浓度(y)与温度(x)关系的拟合方程为： 东莨菪内酯: y₁= 0.006x₁²-0.278x₁+3.403； 双脱甲氧基姜黄素: y₂=0.007x₂²-0.354x₂+4.826。对y求最小值得出， 东莨菪内酯和双脱甲氧基姜黄素对朱砂叶螨雌成螨的最高毒力温度分别为23.2℃和25.3℃， LC₅₀分别为0.1828和0.3504 mg/mL。据此认为， 在一定的温度范围内， 随着温度的升高， 这两种植物性杀螨活性物质对朱砂叶螨的毒力与温度先呈正相关， 到达最佳毒力温度后再呈负相关。

Effect of temperature on toxicities of scopoletin and bisdemethoxycurcumin against Tetranychus cinnabarinus(Acari:Tetranychidae)

The toxicities of botanical acaricides scopoletin and bisdemethoxycurcumin(BDMC) were investigated for their acaricidal activity against female adults of the carmine spider mite,Tetranychus cinnabarinus,by slide-dip bioassay at different temperatures in order to ascertain the temperature effect of scopoletin and BDMC.Both scopoletin and BDMC displayed a positive temperature coefficient at temperatures from 8 to 26℃ and a negative temperature coefficient at temperatures from 26 to 34℃.At 26℃,48 h after treatment,scopoletin and BDMC showed the strongest acaricidal activity against T.cinnabarinus with the LC50 values of 0.1884 and 0.3376 mg/mL,respectively.The mathematical models of the relationship between LC50(y) and temperature(x) were simulated:for scopoletin,y1=0.006x12-0.278x1+3.403;for BDMC,y2 =0.007x22-0.354x2+4.826.Based on the differential coefficients of above models,the optimal acaricidal activities of scopoletin and BDMC were obtained at 23.2 and 25.3℃,respectively,with the LC50 values of 0.1828 and 0.3504mg/mL,respectively.It is so concluded that the toxicities of scopoletin and BDMC exhibit a positive temperature coefficient first and then exhibit a negative temperature coefficient with increasing temperature.