【摘要】 <正> 一、引言 在培养昆虫抗性的过程中,逐代的施用药剂,昆虫即发生抗性,并且在一定程度上随着培养代数的增多而杭性强度逐渐增加。昆虫的抗性从前一代可以影响到后一代,因此,目前大家公认昆虫的抗药性是可以遗传的。但产生抗性的原因,国际上尚有不同的看法,国内在1961年全国昆虫学会学术讨论会上亦有不同意见的争论。形成抗性遗传的不同更多还原

【Abstract】 One type of selection was carried out without insecticide pressure. Twenty indivi-duals of mated female houseflies were selected and separated in twenty vials from anormal strain. After laying eggs, each female fly was tested in a small glass box, de-posited with γ-BHC, to determine its resistance. The eggs, either laid by the most tole-rant or the most sensitive individual, were allowed to hatch out, and the larvae well rearedseparately in two different cages. The sensitive ones of the offspring from the sensitiveindividual were always selected on subsequent generations by the above procedure, andthe tolerant ones of the offspring from the tolerant individual were always also selected.At the end of these selections, the KD₅₀ for the tolerant line is much higher, while theKD₅₀ for the sensitive line is much lower than that for the original normal strain. The biotic potential of houseflies weakens gradually after some generations of single-pair mating, but the weakness of the biotic potential does not influence the resistance ofsensitive lines, since there is no increase of resistance after intercrossing between twosensitive lines. Another type of selection was carried out with insecticide pressure. When a lowconcentration of γ-BHC solution （0.005%） was sprayed to a normal strain, some sensitiveflies showed signs of poisoning and were reared after recovery. These were treated with0.005% γ-BHC on subsequent generations. Then, a higher concentration of 5% γ-BHCwas sprayed to the same normal population. Those tolerant individuals that showed nosign of knockdown were selected in the above manner on subsequent generations. After23--26 generations, the KD₅₀ for the resistant line is much higher while the KD₅₀ forthe sensitive line is lower than that for the original normal population. Evidence from the present study favourably substantiates the pre-adaptation view ofhousefly resistance.更多还原