| The vegetable leafminer, Liriomyza huidobrensis (Blanchard) is one of the most important pests in many counties. And now it has become the destructive insect pest on vegetable and ornamental crops of China since it was firstly found in Kunming in 1995.The biology and ecology of Opius flavus Weng et Chen, the important larval-pupa endoparasitoid of L, huidobrensis (Blanchard), were studied in this paper.The result of research in field showed that the quantity of Opius flavus Weng et Chen changed at different location of vegetable. The parastism rate had two the peaks, one in the mid-last ten-days of Apr. and the other in the mid-last ten-days of Oct., respectively.The parasitic process often was divided into two steps . the search with the longer time between 4-10 mins and the oviposition with the shorter time between 20-40 seconds.With the room temperature, it took Opius flavus Weng et Chen 14.3±2.08 days to complete a generation,and the adult could lay 57.03 eggs with the sex ratio♀ :♂ =1.16:1 on the normal condition, while under the another condition all parthenogenesis were males. The longevity of the adult was 10.7±1.27 days with 20% honey-water solution. In the treatment with different food sources, 20% honey-water solution could significantly prolong the longevity of the adult.Temperature significantly affected the development of Opius flavus Weng et Chen at the range of 15~30℃, the developmental period of Opius flavus Weng et Chen was decreased with the temperature incresaing. According to the law of effective accumulative temperature, the low temperature threshold of development for the egg, larva, pupa and egg-to-adult of Opius flavus Weng et Chen were estimated to be 8.518℃, 9.909℃, 8.656+ and 9.631℃, respectively; the effevtive accumulated temperature for egg, larva, pupa and egg-to-adult were 60.27, 65.75, 87.78 and 203.04 day-degrees, respectively. At 15℃, 18℃, 211℃, 24℃, 27℃ and 30℃, the net reproductive rates of the experimental population(R0), the innate capacity of increase(rm) and finite rates of increase( A ) were different. The most optimum temperature for development and fecundity was estimated to be about 21℃,with Max-R0 (52.15) and Max-rm (1.1935). Both the longevity of adult and generation period decreased with the temperature rising, the relationship between generation period (y1), longevity of adult (y2) and temperature (x) weredescribed as the following formula: y1=-1.7716x+62.9181 (r2=-0.9713), y2=-0.7592x+30.06 (r2=0.9752). The regress equation for the mean total number of eggs laid by per female (y3) against temperature (x) was y3=-l.llx2+47.45x-415.65.The density of host larvae significantly affected the reproduction of Opius flavus Weng et Chen. More host larvae were parasitized, more the waspbecomed, which could be decribed with Rolling II model: Na =(Na:the number of host larvae; Th,:total parasitic time; N0:host larval density), it was concluded that the instant attacking-ability of Opius. flavus Weng et Chen was 0.3886. A female, parastizing one host larva with 0.624 days, could lay 38.46 eggs within one day theoretically.The density of Opius flavus Weng et Chen also affected the parasitism, which can be simulated with the following equationa = 0.0899 p-0.2629 (a .-the attacking ability;P:the density of Opiusflavus Weng et Chen), The attacking ability would decreased with the rising of the number of the wasp, parastizing the same number of host larvae.Chemical insecticide caused different mortality of L huidobrensis and Opius flavus Weng et Chea The insecticide abamectin with stong penetrate showed powerfully toxicity to the larvae of L. huidobrensis; and the insecticide with strong suffocating had powerfully toxicity to the adults of L. huidobrensis and Opius flavus Weng et Chen . From all the results, it could be concluded that each of the insecticides used in the expriment had much more toxicity to the adult of Opius flavus Weng et Chen than the adult of L. huidobrensis, making almost all the adult of Opius flavu...
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