| Phyllotreta striolata(Fabricius)belongs to Coleoptera,Chrysomelidae,which is an important pest of cruciferous of vegetables.P.Striolata adults feed on leaves of host plant,cause small holes on the leaves,and affect the quality of vegetables.P.striolata larvae feed on the roots,which will cause the plant poor growth,even death.The main method to control P.striolata of cruciferous vegetables is chemical control.However,long-term use of chemical pesticides not only makes P.striolata resistance to pesticides,less natural enemies,increases more harm to environment,but also causes excessive pesticide residues and pollutes the ecological environment and affects people's healthy life.So it is very important to take the control methods without chemicals.In order to find a new way to control P.striolata and elongate its resistance,the effects of bio-control bacterium,plant extract and the planting pattern of vegetables to P.striolata were carried out.The results will provide a theoretical basis and technical support to establish the theory system without chemicals to control P.striolata.1.Screening a highly pathogenic strain of Metarhizium against P.striolata and its infection mechanism.The pathogenicity of 8 Metarrhizium anisopliae against P.striolata was tested.The results showed that the strains Ma6,Ma2,Ma8 and ZPTP had higher virulence than the other strains,and the strain Ma6 exhibited the highest virulence.Under the condition 25? 8.0 × 108 spore ˇmL-1,the LT50 of the strain Ma6 was 4.09 d,and showed a 100%cumulative mortality for 7 d.We also studied the characteristics of Ma6 and found the optimal growth conditions of Ma6 was PDA medium,in 25?30?,pH= 6.0,and first 6 days darkness and later 8 days light.The result of scanning of electron microscopy indicated that the strain Ma6 infected P.striolata from the abdomen,internode membrane and hind legs,etc.2.The repellency of plant extracts against P.striolata.The deterrence effect and the anti-feedant function of Melaleuca leucadendron and Cymbopogon citratus against P.striolata adult were measured.The results showed that the choice of P.striolata were 15%and 40%on the extracts of M.leucadendron and C.citratus,respectively.The extracts of M.leucadendron and C.citrates had deterrence effect on the P.striolata,and the deterrent rate was 14.89%?45.95%and 8%?35%,respectively.The anti-feedant rates of P.striolata against M.leucadendron reached 84.21%?98.25%,and the anti-feedant rates of P.striolata reached 25.30%?47.59%against C.citratus.3.Effects of planting patterns on the populations of P.striolata.From June,2015 to June,2016,the population dynamics of P.striolata adult with different planting patterns were studied and investigated.The result indicated that in?Brassica campestris field intercropping other vegetables,the population of P.striolatain the field was intercropping Apium graveolens>intercropping Lactuca sativa>intercropping Lactuca sativa var.longifoliaf>intercropping Sonchus oleraceus.In different mode of rotation,rotating of Momordica charantia,Sonchus oleraceus,Cucumis sativus,Lycopersicon esculentum Miller with Brassica campestris spp.could suppress the population of P.striolata effectively,while rotating of Capsicum annuum and Lactuca sativa could not control the population of P.striolata in the whole growth period,it only reduced the population of P.striolata at the early growth stage of cruciferous vegetables. |
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