›› 2009, Vol. 52 ›› Issue (12): 1312-1318.

• RESEARCH PAPERS • Previous Articles     Next Articles

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

  

  • Online:2009-12-20 Published:2009-12-20

Abstract: 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 (rm), the finite rate of increase (λ), the net reproduction rate (R0), 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 (R0) 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.

Key words: Tetranychus viennensis, delayed mating, reproduction, fecundity, hatchability, longevity, life table parameters, parthenogenesis