Effects Of Feeding Amount Virulence And Activity Of Enzymes To Phyllotreta Striolata Under The Host Conversion

In recent years, phenomenons of potency and medicament sensitivity decreasing have been appeared in control of Phyllotreta striolata, and disasters have been come about by phyllotreta striolata in many vegetable fields in the main areas of Southern China. In the ecosystems of vegetable fields, rampant again phenomenons of Phyllotreta striolata occurred more seriously. Long term stress and host conversion of six cruciferous vegetables,virulence and enzymes in vivo of Phyllotreta striolata have been researched in this article.1. Long-term stress of six cruciferous vegetables made trends of virulence changes and conversion rates of Phyllotreta striolata varying from each other.The order of feeding amount of phyllotreta striolata feeding on different cruciferous vegetables were as follows: Brassica juncea L.,B.chinensis L.,B.parachinensis Bailey,Raphanus sativus L.,B.alboglabra Bailey,B.oleracea. Long-term stress of six cruciferous vegetables made virulence capacity of Phyllotreta striolata change in varying degrees. R.sativus L.and B. parachinensis Bailey had a sharp increase, the change of B. juncea L.was not relatively obivious, B.oleracea and B.oleracea had decreasing trends.2. In Long-term stress of six cruciferous vegetables, the order of carboxylesterase activity were as follows: B. juncea L.,R..sativus L.,B. chinensis L.,B.oleracea,B. parachinensis Bailey,B. alboglabra Bailey, the order of acetylcholinesterase activity were as follows: R .sativus L.,B. juncea L.,B. oleracea,B. chinensis L.,B. alboglabra Bailey,B. parachinensis Bailey,the order of glutathione S-transferase activity were as follows: B. juncea L.,R .sativus L.,B. chinensis L.,B.oleracea,B.parachinensis Bailey,B.alboglabra Bailey.Changes of enzymes in vivo of Phyllotreta striolata by host stress were inconsistent. The biggest changes of carboxylesterase of Phyllotreta striolata occurred in B. juncea L.and B. parachinensis Bailey,and the smallest changes of carboxylesterase of Phyllotreta striolata occurred in B.oleracea and B. alboglabra Bailey, Activity of carboxylesterase in vivo of Phyllotreta striolata had decentralization trends after 45 days.Acetylcholinesterase activity in vivo of Phyllotreta striolata feeding on different host plants were consistent after 45 days. Acetylcholinesterase activity of Phyllotreta striolata feeding on B. juncea L.,B. juncea L.,B. alboglabra Bailey decreased, the one feeding on B. chinensis L.increased, great changes occurred in B. alboglabra Bailey,smallest changes occurred in R.sativus L..3. Host conversion based on such determination indicators: feeding amount,carboxylesterase activity,acetylcholinesterase activity,glutathione S-transferase activity, researched variation rules of Phyllotreta striolata after host conversion. The results showed that variation rule of feeding amount of Phyllotreta striolata was not consistent. Changes of feeding amount of Phyllotreta striolata were not obvious after host conversion on B. chinensis L.and B. parachinensis Bailey, changes of feeding amount of Phyllotreta striolata were more obvious after shifting them from B. juncea L.,B. parachinensis Bailey,B. chinensis L.,R.sativus L. to B. alboglabra Bailey and B.oleracea.Variation rules of carboxylesterase,acetylcholinesterase,glutathione S-transferase in vivo of Phyllotreta striolata were different with different host conversion, changing rates of carboxylesterase activity in vivo of Phyllotreta striolata were more slowly than those of acetylcholinesterase and glutathione S-transferase. This may be in relation to nutrients and secondary materials of plants. Acetylcholinesterase appeared actively after host conversion,this may be a important factor of medicament sensitivity decreasing and rampant again of Phyllotreta striolata in vegetable ecosystems.