| Aphids,which belong to Hemiptera,are widely distributed around the world.Many kinds of aphids can do serious harm on a variety of plants,including crops,vegetables,fruits and grasses.Aphids can also transmit numerous plant viruses,which are recognized as one of the most common vector pests in agriculture and forestry.Current control of aphids mainly relies on chemical pesticides,due to the long-term and extensive application of pesticides,which caused a steady arising of aphids' resistance to pesticide.Therefore,it is urgent to explore new methods for aphids control.In recent years,the development of RNAi technology has shown great potential in pest control,and RNAi-based crop protection technology has also suggested potential advantages in aphid population control.The appropriate target gene is the primary condition for the development of RNAi anti-aphid technology,so it is of great importance to the screen lethal gene against aphids for the development of RNAi technology for pest control.In addition,current studies have indicated that it may be difficult to control pests effectively in the field by RNAi technology alone.Exploring a combination of RNAi and traditional aphid control methods will help solve this problem,and may also reduce in the use of conventional chemical pesticides.To answer above questions,we used pea aphids(Acyrthosiphon pisum)as the study object,screened the lethal genes by feeding RNAi,and applied ds RNA relating lethal genes in combination with the chemical pesticide imidacloprid,and obtained the following results:(1)Three candidate lethal genes were identified: ApCactus,ApCoa,and Ap Cmb4 b,which resulted in 100% mortality in the green morph of pea aphids within 7 days with the final ds RNA dose of 1000ng/?L.And ds RNA concentration gradient experiment showed that there was a positive correlation between aphid RNAi efficiency and ds RNA concentration,and the minimum effective concentration of lethal gene ds RNA on pea aphid was about 300ng/?L.(2)In order to further verify the universal of the lethal genes,we also carried on the study in the red morph of pea aphids feeding experiment,similar mortality was found that can be induced by Ap Cactus,Ap Coa and Ap Cmb4 b ds RNA against red morph of pea aphids,separately.However,the RNAi efficiency of 3 genes was different between the red and green morph of pea aphids.For example,ds RNA was feed to pea aphids with final concentration of 800ng/?L or below,the mortality rate of red morph of pea aphids was generally higher than that of green.(3)In the combined application test of lethal gene ds RNA and imidacloprid,we found that Ap Cmb4 b,Ap Cactus and Ap Coa with the final concentration of 600ng/?L and imidacloprid with final concentration of 0.05mg/L had a serious impact on the survival and body weight of pea aphid,with the mortality rates of 93.33%,70.00% and 53.23%,respectively.Our study suggested that Ap Cmb4 b,Ap Cactus and Ap Coa genes could be used as candidate genes for RNAi-based technology for aphid control.Ds RNA induced different mortality in green and red morphs of pea aphid,and aphids mortality exhibited a direct ds RNA dose response relationship.The combined method of ds RNA and conventional chemical insecticide imidacloprid can effectively control aphids.Our current study provides novel candidate genes for RNAi-based aphid control method,in addition,will contribute to a theoretical basis for exploring the method of reducing traditional pesticides,which will be helpful for establishing and promoting green and efficient technologies for aphid control. |
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