Resistance risk assessment: realized heritability of resistance to methrin, abamectin, pyridaben and their mixtures in the spider mite, Tetranychus cinnabarinus.

The heritability of resistance has an important bearing on the management of pest resistance, especially for evaluating the sustainability of a chemical on a particular pest population. The susceptibility of pests to insecticides may change depending on the selection pressure of these compounds on populations. Tetranychus cinnabarinus , a very important mite pest of many crops in China, was continuously selected with methrin, abamectin, pyridaben and mixtures of pyridaben and abamectin (pyidaben:abamectin = 7.4:0.1 m/m), and methrin and abamectin (methrin:abamectin = 8.9:0.1 m/m). After 16 generations, the resistance increased to 25.8-, 3.7-, 1.3-, 4.0- and 2.5-fold to methrin, abamectin, pyridaben, pyridaben + abamectin and methrin + abamectin, respectively. The more generations selected, the higher was the resistance level, except in the case of the strain selected with pyridaben. The realized heritabilities of resistance to methrin, abamectin, pyridabe, pyridaben + abamectin and methrin + abamectin were: 0.20, 0.15, 0.03, 0.18 and 0.08, respectively. Higher values of heritability occurred during the second eight generations selected than through the first eight generations except in the case of the strain selected with the mixture pyridaben + abamectin. [ABSTRACT FROM AUTHOR]