Studies On Biology Of Parasitoid Pnigalio Phragmitis Of Polyphagous Leafminer Liriomyza Sativae

Liriornyza sativae Blanchard is one of the most serious and dangerous polyphagous leafininer in the world. Up to now, as the parasitoid of Liriomyza sativae , Pnigalia phragmitis Erd ) has not been reported in the world and also no biological study has been conducted. In order to meet the requirement of r environment protection and sustainable development, exploitation and utilization of new source of parasitoids, and serving agriculture, this experiment first detailedly and systematically studied its biology. The main results obtained are summarized as follows: 1. Development time of different Life stages have been recorded under growing chamber conditions designed with certain temperature, humidity and illumination combination. The results showed that temperature is the most important factor that affected the development of different life stages, relative humidity and illuminating time have little effect. The development time of every stages have become shorter along with the more higher temperature at the range of 1 50C?00C, they are in negative correlation. The livability of adults and the rate of eclosion of pupae are over 98 percent under the condition which are storing at 50C for 7 days, and they have rapidly descend when storing time get longer. 2. Cages were used to estimate the number of killed host larvae and the number of eggs oviposited by each female and also offspring sex ratio. The results showed that the longevity of females is 17 days. about 6 days longer than male . The sex ratio is 0.9:1. The number of killed and parasited host larvae from 6:00am to I 4:00pm account for 60 percent about the whole day. Adults do&t eat and oviposit from 22:OOpm to 6:00am. The peak of daily oviposition appeared on the fourth day and ninth day after copulateing. The trend of feeding to kill was similar to the trend of oviposition, they are in correlation in a sort of way. 3. The longevity and pregnant eggs of females were recorded by feeding different kind of foods. Rresults showed : the longevity and pregnant eggs can be prolonged evidently when feed with 5% honey and pollen solution. 4. Reproduction of the wasp was studied by controlling the ratio of sex and the time of copulating. The results showed that the ratio of sex have rather big influence on individual female reproductive capacity. Time of copulating only has little effect. The amount of progeny increased when the time of copulating had prolonged at. the same sex ratio, the species of Pnigalio phragmitis Erd is belong to virgin birth. 5. The host selectivity was tested by suppling host larvae with different instar . The results showed that larvae in first, second and third instar could be stung but only later second and third instar could be oviposited. Apparently, third instar larvae is the suitable host for the wasp. 6. Copulating appears shortly after emergence. Female after copulating searched second or third instar host larvae by following the host channel and ovipositing on host. The wasps are generally active in the morning, and inactive from 16:OOpm to 6:00 am. The results of Pnigalio phragmitis Erd development and reproduction biolo~?study set LI a elementary and theoretical foundation of further research or mass production and have the value of theory and practice. ShixinXu Entomology Supervisor: Professor GuoxunLi Vice researcher: HongyinChen...