延迟交配对山楂叶螨繁殖的影响

为了探索雌螨延迟交配对整个种群的负面效应, 采用叶碟饲养法, 在室内条件下研究了延迟交配对山楂叶螨Tetranychus viennensis Zacher繁殖及种群增长的影响。结果表明: 雌螨延迟交配主要影响寿命、产卵量, 进而影响种群增长率; 随着雌螨交配时间的延迟, 影响的程度逐渐加剧。交配延迟达到或超过7 d, 雌螨的寿命比对照延长20.17%, 产卵量比对照下降26.74%, 但对后代的孵化率、存活率无明显影响。对生命表参数的分析结果表明, 雌螨交配延迟达到或超过7 d, 会导致净生殖率显著下降、平均世代周期历期显著延长, 而内禀增长率则在交配延迟3 d时显著降低。未经交配的雌螨只能营孤雌生殖, 寿命延长了31.14%, 产卵量减少了30.08%。营孤雌生殖的雌螨可以通过与其后代回交而实现两性生殖。结果提示延迟交配会导致山楂叶螨的繁殖力降低。

Effects of delayed mating on the reproduction of the hawthorn spider mite, Tetranychus viennensis Zacher (Acari: Tetranychidae)

In order to explore the negative effects of delayed mating on the population of the hawthorn spider mite, Tetranychus viennensis Zacher, a leaf disc bioassay was employed to investigate the effects of delayed mating on the female longevity, fecundity, and the intrinsic rate of increase of T. viennensis in the laboratory at the conditions of 25 ± 1℃, RH 60% ± 7%, and photoperiod of 16L- 8D. Life tables were constructed in each experiment. The parameters, including the intrinsic rate of increase (r_m), the finite rate of increase (λ), the net reproduction rate (R_0), mean generation time (T) and doubling time (Dt) were calculated and analyzed using Jackknife method. The results showed that delayed mating had negative effects on the longevity and fecundity of female adults, depending on the period of delay, but had no effect on the hatchability and survivorship in the offspring. These negative effects strengthened with increasing of mating age of females. Significantly reduced fecundity (26. 74%) and significantly prolonged longevity (20. 17%) were found in females whose mating was delayed by 7 d or more. Meanwhile, the net reproduction rate (R_0) was reduced significantly and mean generation time (T) prolonged significantly. As the result of the decreased net reproductive rate and prolonged mean generation time, the intrinsic rate of increase decreased sharply in females whose mating was delayed by 3 d or more. Unmated female mites had a significant lower fecundity (decreased by 30. 08%) and a significant longer longevity (increased by 31.14%) than inseminated ones. The increased longevity of unmated females combined with a lower oviposition rate tended to increase the probability of an encounter with a male at some point in the productive life of a female. In the extreme case, the parthenogenetic producing female could shift to sexual reproduction by mating with one of her mature sons, and this was proved by backcross test. These results suggest that delayed mating has adverse impacts on the fecundity of T. viennensis.