利用肿瘤DNA创建生物标记追踪癌症

国际蚜虫基因组联盟已成功对农业害虫蚜虫进行基因组测序，根据对蚜虫基因信息的解读，研究人员期冀将来能开发出防治蚜虫的有效方法。     

食蚜瘿蚊研究进展

<正> 食蚜瘿蚊Aphidoletes aphidimyza(Rond.)是蚜虫的一种专一捕食性天敌,可以取食61种不同作物上的蚜虫(Harris,1973),其中包括许多种重要的农业害虫。早在1916年,Davis就指出食蚜瘿蚊是蚜虫的一种具有很大潜在价值的生防控制因子。70年代初,联邦德国、苏     

Sublethal effects of imidacloprid and pymetrozine on population growth parameters of cabbage aphid, Brevicoryne brassicae on rapeseed, Brassica napus L.

Efficiency of imidacloprid and pymetrozine on population growth parameters of cabbage aphid, Brevicoryne brassicae L. （Homoptera： Aphididae） was determined using demographic toxicology by leaf dip method. At first, bioassay tests were performed. The LC50 value and confidence limit for imidacloprid and pymetrozine were 1.61 × 10^-5 mol/L （0.74 × 10^-5-2.66 × 10^-5） and 2.14 × 10^-4 mol/L （1.24 × 10^-4-3.40 × 10^-4）, respectively. To evaluate the sublethal effect of two insecticides on population growth parameters of cabbage aphid, LC30 concentrations of imidacloprid and pymetrozine were used at 5 mol/L and 30 mol/L. The experiments were carried out in a incubator at 20±1℃, 60% ± 5% RH and 16：8 （L：D） photoperiod on canola seedlings, Brassica napus L. var. ＇PF＇. Net fecundity rate decreased in both insecticide-treated populations. Intrinsic rates of increase （rm） were lower in imidacloprid and pymetrozine treatments than in controls. Intrinsic birth rates also decreased in treated populations. There was a relative increase in intrinsic death rates of treated populations. The mean generation times and doubling time were also lower in populations treated with insecticides than in controls. There was a considerable reduction in the average numbers of nymphs reproduced per female as compared with the control. The average longevity of female adults in the control was significantly different from those treated with imidacloprid and pymetrozine. However, there was no significant differences in aphid life-table parameters between the two insecticide-treated populations （P 〉 0.01）.     

Fitness traits and underlying genetic variation related to host plant specialization in the aphid Sitobion avenae

Sitobion avenae （E） is an important cereal pest worldwide that can survive on various plants in the Poaceae, but divergent selection on different host plants shouldpromote the evolution of specialized genotypes or host races. In order to evaluate their resource use strategies, clones of S. avenae were collected from oat and barley. Host-transfer experiments for these clones were conducted in the laboratory to compare their fitness traits. Our results demonstrated that barley clones had significantly lower fecundityand tended to have longer developmental times when transferred from barley to oat. However, oat clones developed faster after they were transferred to barley. Clones fromoat and barley had diverged to a certain extent in terms of fecundity and developmental time of the nymphs. The separation of barley clones and oat clones of S. avenae was alsoevident in a principal component analysis. Barley clones tended to have higher broad-sense heritabilities for fitness traits than oat clones, indicating the genetic basis of differentiationbetween them. Barley clones showed significantly higher extent of specialization compared to oat clones from two measures of specialization （i.e., Xsp and Ysp）. Therefore, barleyclones were specialized to a certain extent, but oat clones appeared to be generalized. The fitness of S. avenae clones tended to increase with higher extent of specialization. Theevolution toward ecological specialization in S. avenae clones, as well as the underlying genetic basis, was discussed.     

THE ROLE OF BACTERIAL SYMBIONTS IN AMINO ACID COMPOSITION OF BLACK BEAN APHIDS

To evaluate the role of bacterial symbionts ( Buchnera spp. ) in the black bean aphids ( Aphis craccivora Koch), the aphids were treated with the antibiotic, rifampicin, to eliminate their intracellular symbiotic bacteria. Analysis of protein and amino acid concentration in 7-day-old of aposymbiotic aphids showed that the total protein content per mg fresh weight was significantly reduced by 29 %, but free amino acid titers were increased by 17% . The ratio of the essential amino acids was in general only around 20% essential amino acids in phloem sap of broad bean, whereas it was 44% and 37% in symbiotic and aposymbiotic aphids, respectively,suggesting that the composition of the free amino acids was unbalanced. For example, the essential amino acid,threonine represented 21. 6% of essential amino acids in symbiotic aphids, but it was only 16.7% in aposymbiotic aphids. Likewise, two nonessential amino acids, tyrosine and serine, represented 8.9% and 5.6% of total amino acids in symbiontic aphids, respectively, but they enhanced to 21.1% and 13.6% in aposymbiotic aphids. It seems likely that the elevated free amino acid concentration in aposymbiotic aphids was caused by the limited protein anabolism as the result of the unbalanced amino acid composition.     

暇夷翠雀蚜Delphiniobium yezoense Miyazaki

蚜虫类Aphidinea是同翅目昆虫中一个较大的类群，世界已知4500余种，我国有1000余种。成虫体长约0．5-7．5mm，多为1．0-4．0mm。体多椭圆形，体色丰富。吸食植物汁液。具有复杂多样的生活周期、孤雌生殖、多型现象、转主寄生、分泌蜜露、蚁访等特性，绝大多数是农林牧业的重要害虫。