Oviposition Preference Of Beet Armyworm (Spodoptera Exigua) By Host Plants

The beet armyworm,Spodoptera exigua(Hübner),is one of key agricultural pest in the world.It has wide distribute range,strong ability of migration and dispersal,characteristics of many host plants,almost 170 species of plants.In recent years,damage of plant has become more serious. Studies on the interaction between the beet armyworm and its hosts are helpful to developing new methods to IPM.Based on aspects of behavior, biology,and phytochemistry,Oviposition preference of the beet armyworm by host plants,volatiles of four host plants(Brassica pekinesis,Ipomoea aquatica Forsskal,Allium fistulosum L.,Chinese chive)and the interactions between four host plants beet armyworm were studied in the laboratory.1 The artificial diet and the rearing technique of the beet armywormS.exigua(Hübner)was continuously reared on 3 kinds of artificial diets and one natural diet(chive)for 3 generations under 27℃±1℃and RH 75%-80%conditions.The results indicated that the first and the second artificial diets were best.The two diets supplied necessarily nutrient substance to the larvae development of S.exigua(Hübner),The survival rate of larvae,larvae durations,rate of pupation,pupal durations,pupal weight, number of eggs and eclosion rate were similar to or better than those of the natural diet.It indicated that the first and the second artificial diets were suitable for rearing S.exigua(Hübner).2 Oviposition preference of the beet armyworm on four host plantsLaboratory experiments showed that female moths preferred chinese cabbage in four host plants combination,and preferred Chinese cabbage in three host plants for oviposition,but had a similar preference water spinach and onions.Female moths preferred Chinese cabbage to water spinach,and preferred chive to onions for oviposition.Furthermore,Oviposition test on host plant showed that female moths preferred positive of leaves for oviposition in Chinese cabbage and water spinach,but preferred tip of leaves for oviposition in onions and chive.3 Extraction and identification volatiles of four host plantsVolatiles from healthy host plants(Brassica pekinesis,Ipomoea aquatica Forsskal,Allium fistulosum L.,Chinese chive)were extracted by Headspace (HAS)sampling and analyzed and identified with GC-MS.Volatiles of four plants belong to terpenoid,alcohol,ester,aldehyde,ketone,hydrocarbon etc., and most of them belong to terpenoid.There were 4 volatiles in common:1R-a-Pinene, D-limonene,Nonanal,and Caryophyllene,which could relateal to oviposition preference of the beet armyworm.Oviposition test on standard chemicals combination showed that female moths preferred a-Myrcene to Caryophyllene and D-limenene to n-hexane for oviposition.