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引言鉴别剂量法是贮粮害虫抗药性常规试验的一种有效方法。这种试验方法是将昆虫暴露在大约相当于已知敏感品系99.9％致死的浓度下,如果没有任何昆虫对这种试验产生反应,这就说明可能存在抗性,然后进一步进行确证试验。如果样品全部反应,则该种群就应归类于敏感的品系。但是,在某些条件下,这种试验不能决定样品中抗性基因的存在。当被抽样的种群中抗性基因频率很低时,样品中可能包含有些抗性为杂合的昆虫,但是,纯合抗性的个体的频率可能更低,以至在样品中不能出现。如果抗性以隐性基因存在,杂合的个体将对鉴别剂量产生反应,因此,试验就指出杀虫剂的敏感度。面临基因所赋予的抗性,在杀虫剂处理的原始种群中,抗性可能发生,因而抗性将产生选择作用。但是,如果抗性以很低的频率检出,这
Introduction Differential dosimetry is an effective method to routinely test pest resistance in stored grain. This test method exposes insects to a lethal concentration of about 99.9% of the known susceptible strain. If no insects react to this test, this indicates possible resistance and further confirmatory testing. If all the samples react, the population should be classified as sensitive. However, under certain conditions, this test does not determine the presence of resistance genes in the sample. When the frequency of resistance genes in sampled populations is low, some of the samples may contain heterozygous insects, however, homozygous resistant individuals may be less frequently present in the sample. If the resistance exists as a recessive gene, the heterozygous individual will react to the discriminating dose and, therefore, tests indicate insecticide sensitivity. Faced with gene-conferring resistance, resistance may occur in the original population of pesticide treatments, and thus resistance will have a selective effect. However, if resistance is detected at a very low frequency, this is