Investigation Of Parasitoids Of Liriomyza Sativae In Shandong And Its Controlling On Vegetable Leafminer

In this dissertation, the species of parasitiodsand parasitism of vegetable leafminer at different season and different kinds of vegetable crops were investigated. The main parasitizi behaviors of Chrysocharis penthus (Walker ) and Neochrysocharis formosa(Westwood), which were two dominant parasitoids of vegetable leafminer and the effects of temperature on development were studied, the effects of pesticides on parasitizi were studied.1. There are 9 species of parasitoids parasitizi vegetable leafminer in Taian and most area of Shandong province .Two or three of which ,C. penthus, N. formosa and C.okazakii are dominant at those area in different seasons.At different seasons, different vegetable crops, different height and different location of vegetable in the field, the was difference among the quantity of each parasitoid.The mortality of larvae of vegetable leafminer caused by parasitoids in field is lower at early phases ,then increased at middle periods and arrived the highest at the late phases of vegetable crops. The parasitism of vegetable leafminer is different from the methods of vegetable leafminer , which at the natural growth control is higher than chemical control .The parasitoids mainly parasitize the second and the third instar host larvae,the species and rate of female emerged from different instar larvae are different.2. N. formosa could attack all instar larvae ,but only oviposited on the late second and the third instarlarvae of vegetable ,when all the instars larvae put together ,it usually attack and oviposited on the larger larvae more than smaller ones ,and the coefficient of attack and parasitizi selection to the third instar almost higher than the second instar. Na?ve and experienced N. formosa were attacted by host plant odours of dean to search and probe on infested and uninfested leaves. At close range ,visual stimuli were unnecessary for oviposition and host feeding. Host larval movement appeared to aid host detection at close range . Dead hosts were frequently walked over or missed .At the range of 15~32℃,the developmental periods of N. Formosa3. was decreased with the temperature increasing .The low temperature threshold of development of N. formosa.egg,larvae and pupae were estimated to be 11.99℃,12.44℃ and 10.66℃,The effective accumulated temperature of N. formosa for egg,larvae and pupae were 30.51 day-degree,48.2 day-degree and 119.24 day-degree. 4. The 12 pesticides usually used for vegetable leafminer control were toxicity to the adult,larvae and pupae of N. formosa ,especially to the adult and larvae.5. Parasitoids play a determinant role in the control of natural population of vegetable leafminer ,as the increase of the quantity of parasitoids released and as the periods length ,the mortality caused by parasitoids of vegetable leafminer larvae was obviously increased.