赤眼蜂寄生行为研究(Ⅰ)——过寄生与子代分配

STUDY ON PARASITISING BEHAVIOUR OF TRICHOGRAMMA(Ⅰ)—SUPERPARASITISM AND PROGENY ALLOCATION

寄生蜂的过寄生现象是经常发生的。Ullyett(1949)认为,一种有效的昆虫寄生蜂,往往以蜂卵在寄主上的分布这种方式来使其达到最高存活率。Smith(1916)指出,由于蜂卵在寄主上的分布不同,形成了过寄生。关于过寄生对寄生蜂种群繁殖率的影响。

Study on the relationship between superparasitism and ovipositional behavi- our as well as superparasitism and progeny survive of Trichogramma japonicum on Corcyra cephalonia was reported in this paper.Three experiments about superparasitism,affect of the density of female wasp on the number allocation and sex ratio of progeny,affect of the distribution of wasp-eggs in parasitized host egg on progeny survive,and affect of the frequency of ovipositing or pro- ding of female wasps on the distribution of their progeny in host egg were con- ducted in the laboratory. The experimental results showed that(1)the affect of the density of female wasps on the number of their progeny was obvious,the number of effective offsprings decreased with the increase of female wasps;the density of female wasp could cause the change of sex ratio of next generation in some extent,but no regularity had been found in this change,(2)overmuch ratio of female wasp to host egg,much long time of exposure,repeatedly encountering and proding or ovipositing the same host resulted in serious superparasitism,and(3)if one rice grain moth egg had been proded by female wasp over 3 times or the number of wasp-eggs contained in one such host egg was more than 3,the wasps could not develop to prepupal stage. According to the experimental results,we suggest that for avoiding serious superparasitism in mass production of Trichogramma,the number of trichogra- mmatid eggs contained in each small host egg such as C.cephalonia should be controlled at 1-2 individuals and the frequency of the proding and ovipositing of female wasp on one host egg should be kept at 1-2 times.For this purpose, the optimum ratio of female wasps to host egg is 1:20-1:10 and the available exposure time is 24 hours.