| As many advanced scientific techniques, the application of pesticide also has the both benefit and side effect to human beings. Among these, the pest resistance is one of the great challenges when we try to control the infestation of plant diseases, insect pests, and weeds, etc. Therefore people have to study the pest resistance, and insect pests resistance to insecticides is the most active study in this area.Due to stronger reproductive ability, shorter generation time, smaller movement area, higher cross rates of near relatives, more acaricides contact opportunity, the problem of mite resistance is more dominant than other crop insect pests. Tetranychus cinnabarinus is widely distributed in China, and often infests seriously, but difficult to control in cotton and many vegetables. This mite has developed significant resistance in many areas in China. Particularly in recent years, through the extension of transgenic cotton, the infestation of cotton bollworm is effectively inhibited, but the infestations of cotton aphid and mite are more serious. Such situation has caused the great attention to scientists in plant protection field. Investigation of the resistance development of T. cinnabarinus to common used acaricides, analysis of the resistance inheritance, clarification of resistance mechanisms, comparison of the ecological fitness, estimation of the resistance realized heritability and assessment of the resistance risk would have theoretical and practical senses for protocol designing of resistance management and enriching the research contents of pest resistance. This study was supported by National Natural Science Foundation of China (39970493), and after 3 years study, the main results are as follows.1. Resistance Selection and Development in T. cinnabarinus 1.1 Resistance selectionThe three novel acaricides, fenpropathrin (pyrethroid), abamectin (bioinsecticide), and pyridaben (heterocylic acaricide), were used to select the resistance to T. cinnabarinus. The stock colony of T. cinnabarinus was collected from cowpea in the field in Beibei, and reared under pesticide free conditions in insect-rearing room for 5 years (about 100 generations). This colony was regarded as susceptible strain. Before experiment, seven batches were separated from the susceptible strain. Among these seven batches, three of them were sprayed with fenpropathrin, abamectin, and pyridaben, respectively, and named as FeR, AbR, and PyR, accordingly. Two of them were treated with mixture of fenpropathrin + abamectin, and pyridaben + abamectin,respectively, and named as Fe-AbR and Py-AbR accordingly. The last two batches were selected with the sequence of fenpropathrin followed by abamectin, and the sequence of pyridaben followed by abamectin, respectively, and named as Fe/AbR and Py/AbR accordingly. After 40 generations selection, the different selection responses were occurred to different acaricides treatments in T. cinnabarinus.Single acaricide selection. After 40,42, and 48 generations selection with fenpropathrin, abamectin, and pyridaben, respectively, Tetranychus cinnabarinus developed 68.5, 8.7, and 0.8-fold resistance to these three acaricides, respectively. This suggested that the resistance developmental rate of T. cinnabarinus to fenpropathrin (pyrethroid) was the fastest, followed by the bioinsecticide, abamectin. Tetranychus cinnabarinus did not develop significant resistance to pyridaben (heterocylic acaricide), and the response was only the decrease of susceptibility. Based on the slope (b) value of log-probit regression line, the resistance of T. cinnabarinus to fenpropathrin could continue develop to a higher level, but the developmental rate would be slow. The response to pyridaben would still stay the stage of susceptibility decreasing.Mixture selection. After 40 generations selection with the mixture of pyridaben and abamectin, Tetranychus cinnabarinus developed 6.7-fold resistance to the mixture, but this strain did not develop the obvious resistance to two single acaricide, and the res... |
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