| The 12 geographic populations of Trichogramma ostriniae used in the study are Jilin Nong'an population, Liaoning Tieling population, Liaoning Heishan population, Liaoning Shenyang population, Beijing population, Hebei Langfang population, Hebei Baoding population, North Korean Pyongyang population, Shandong Jinan population, Shandong Rizhao population, Guangdong Guangzhou population and Pyongyang of North Korea population, all of which originally collected from the parasitized egg masses of the Asian corn borer, Ostrinia furnacalis (Guénee), in corn field, and then reared and kept on eggs of Corcyra cephalonica. The sequences of mtDNA fragments, the response to the different temperature and humidity combinations, the adaption to extreme temperature and humidity, and the reproductive compatibility of different geographic population were studied. The results are as follows:1. There were 20 variable sites, which contained 7 parsimony-informative sites of the mtDNA COI gene of experiment population. The content of A+T was 73.4%, nucleotide diversity was 0.01416, average number of nucleotide differences was 7.33333, and the evolutionary distance was among 0.2%~2.6% of the COI gene of experiment population. There were 10 variable sites, which contained 3 parsimony-informative sites of the mtDNA COII gene of experiment populations. The content of A+T was 76.9%, nucleotide diversity was 0.01155, average number of nucleotide differences was 3.52381, and the evolutionary distance was among 0.0%~3.0% of the COII gene of experiment populations. There were 21 variable sites, which contained 4 parsimony-informative sites of the mtDNA Cytb gene of experiment populations. The content of A+T was 75.3%, nucleotide diversity was 0.01433, average number of nucleotide differences was 6.95238, and the evolutionary distance was among 0.2%~3.4% of the Cytb gene of experiment populations. Due to the the value of Tajima's D test were not significant of the 3 genes, we concluded that mtDNA evolution probably followed neutral models, which meant the results of sequence evolution was random genetic drift of the natural population. The value of Fu's Fs test was all negative so that the population of T. ostriniae was likely to expand. Based on Fst value, there's significant genetic divergence of Trichogramma population.2. Compared with the inbred among geographic populations, no significant difference were observed in the female progeny of both cross and backcross. Though the fecundity between the cross and backcross was partly significantly different, the differences were no clear regularity. In addition that the index of reproductive compatibility were among 0.9348~1.0573(IRC>0.75), so there was no reproductive isolation among the tested geographic populations of T. ostriniae.3. The emergence rate, female longevity, fecundity, emergence of progeny and female progeny of Guangzhou population were significantly higher than other population at 16℃,and 75% RH combination. While the emergence, female longevity, fecundity, emergence of progeny and female progeny of Beijing population were significantly higher than other population at 33℃,and 75% RH. So Guangzhou population was adaptable to lower temperature and Beijing population was adaptable to higher temperature. The parasitism potential and female ration of progeny at low temperature of 16℃,and 75% RH combination were more much higher than at high temperature of 33℃,and 75% RH. When the humidity kept in 75% RH, the fecundity of the different geographic populations of T. ostriniae were clearly higher at 25℃and 28℃than at 16℃. The life index at 25℃and 75% RH combination was better than at 28℃and 75% RH combination.4. Longevity of female, fecundity and sex ration of different geographic populations of Trichogramma ostriniae were investigated when reared on eggs of the Asian corn borer, at low temperature with low humidity (19℃, 45% RH) and high temperature with low humidity (31℃, 45% RH). Results showed that the Beijing and Rizhao population parasitized 17.60±1.70 and 17.44±1.46 eggs per female, respectively, significantly higher than other populations at 31℃, RH45%. Guangzhou population parasitized 26.65±2.17 eggs per female, significantly higher than others at 19℃, RH45%. These populations would be as candidate for control Asian corn borer at low temperature with low humidity or high temperature with low humidity conditions.The genetic differentiation of COI and COII gene of T. ostriniae was significant; mtDNA evolution probably followed neutral models;the population of T. ostriniae was likely to expand;there's significant genetic divergence of Trichogramma populations;there was no reproductive isolation among the tested geographic populations of T. ostriniae;Guangzhou population would be as candidate for control Asian corn borer at low temperature with low humidity, and Beijing population and Rizhao population would be as candidate for control Asian corn borer at high temperature with low humidity conditions.
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