Studies On Host Selection And Its Mechanism Of Phyllotreta Striolata Fabricius

In this paper, the host range of the striped flea beetle (SFB),Phyllotreta stiolata (Fabricius) in Fuzhou was investigated.The host selection of SFB among common species of Cruciferae was studied. The relationship between host selection of SFB and the amount of epicuticuliar wax and glucosinolate content of vegetables were analyzed to enunciate the mechanism of the host selection of SFB. Based on the research results , advices on controlling this pest were given.It was observed that the host range of SFB was confined to Cruciferae .The cruciferous vegetables cultivated widely in Fuzhou such as Brassica campestris L.ssp.pekinensis Olsson,Brassica campestris L.ssp.chinensis(L.) Makino var. utilis Tsen. et Lee , Raphanus sativus L., Brassica parachinensis Bailey, Brassica juncea cosson var. foliosa Bailey, Brassica alboglabra Bailey , Brassica oleracea L.var. botrytis L., Brassica oleracea L.var. capitata L.,and Brassica campestris L.ssp.chinensis(L.) Makino v&r.rosularis Tsen. et Lee were host plants of SFB.It was found that SFB can feed on Tropaeolum majus L. (Tropaeolaceae).Laboratory research and field investigation were conducted to study the host selection of SFB among different species of Cruciferae. The results showed that SFB preferred B.campestris ssp.pekinensis,B. campestris ssp.chinensis var. utilis , Raphanus sativus , B. parachinensis and B. juncea , ate less B. alboglabra , B. oleracea var. botrytis and B. oleracea var. capitata . The same result was achieved in the field investigation.The epicuticuliar wax of B. alboglabra , B. oleracea var. botrytis, B. parachinensis and B. campestris ssp.chinensis var. utilis were measured quantitatively. The result showed that the amount of epicuticuliar wax of B.alboglabra and B. oleracea var. botrytis which were feed less by SFB was 1881.3mg/kg fresh weight and 2446.7mg/kg fresh weight respectively and the amount of epicuticuliar wax of B. parachinensis and B. campestris ssp.chinensis var. utilis, two preferable hosts of SFB was 281.3mg/kg fresh weight and 258.3mg/kg fresh weight respectively.Removal of epicuticular wax from the leaves of B. alboglabra , B. oleracea var. botrytis and B. oleracea var. capitata led to dramatic increase of flea beetle feeding. It was concluded that epicuticuliar wax was an important factor that impeded the feeding of SFB.After the epicuticuliar wax of B. alboglabra , B. oleracea var. botrytis and B. oleracea var. capitata was removed,the feeding areas of SFB on different vegetables were measured.The comparison of the feeding areas and the content of the glucosinolate of different vegetables showed that SFB preferred vegetables with high content of glucosinolate.Based on the research results, the possible mechanism of host selection of SFB was put forward and it was suggested that choosing varieties with high amount of the epicuticuliar wax and increasing the epicuticuliar wax of vegetables through conventional breeding or genetic engineering to enhance the plant resistance to SFB would be effective measures in the integrated management program of SFB.