| Tamarixa lyciumi Yang (Hymenoptera:Eulophidae) is a new specie parasitoid of Paratrioza sinica Yang & Li (Homoptera:Psyllidae), which is an important insect of Lycium spp.. The biological characteristics of Tamarixa lyciumi is systematically studied in this paper. Morphology, behavior, davelopmentle, survival and reproduction of the parasitoid were studied under laboratory conditions, the results are briefly summarized as below.1. Morphology: The body of the adult T. lyciumi is black, having a metallic sheen. The female is obviously larger than the male. The egg is long oval, somooth , with an inflated end.2. T. lyciumi multiply 5~6 generations annually in west Inner Mongolia, and the parasitism is highest in the end of July to the early August.3. The egg of T. lyciumi was laid on the prothoracic legs of the host namph, which takes 40-80 seconds for each one. The peak period of eclosion is am6:00~am8:00 and pm6:00~pm8:00, adult male eclosion is 2~3 days earlier than female. Both the male and female can mate more times than once, the mating behavior lasts 30~40s, female will lay eggs after mating. Study of negative phototaxis of adult shows that T. lyciumi has a great negative phototaxis. The adult shows slow-moving and won't copulate in dark.4. Sexual reproduction occurs much more than parthenogenesis, from which the offspring is male only. The sex ratio of T. lyciumi is 1.51:1-2.28:l in nature, with a mean ratio of 1.80:1.5. The 1~3 days old T. lyciumi has a stronger parasitic ability, which prefers the 4th nymphal stage of Paratrioza sinica to the 3rd to 5th nymphal stages. One female, lays one egg and parasitizes one nymph at a time, could identify its host easily. Under the controlled condition, the T. lyciumi would never lay eggs on the nymph of Trioza magnisetosa Log. and Eustigmata tamaricina Log., but Paratrioza sinica.6. At 16℃to 36℃, feeding the non-mating and non-spawning adult with 15% honey water, 15% sucrose water, pepsi coke and nothing as control, shows that the temperature and nutrition affect the lifetime of adult significantly. A higher temperature offers a shorter life, which happens under all the trophic levels, while the nutrition protracts the lifetime at every temperature. The adult fed by 15% honey water has the longest life, while the control has the shortest life.7. Nutrient conditions had significant effect on the fecundity of Tamarixa lyciumi. The adults with 20% honey water supply have the highest fecundity. The adults had the longest longevity of 7.56 days for female and 3.92 days for male. The spawning period of female is 7.16 days, averaging 5.65 eggs per adult per day and totally 40.24 eggs with eclosion number of 35.68 through its life. The adult with 20% sucrose water supply has the secondly highest fecundity, Supplying water, however, could prolong the lifetime but not increase the reproduction.8. The interior experiment shows that temperature significantly affects the development of T. lyciumi at the range of 15-35℃,the developmental period of T. lycium is decreased with the temperature increasing. According to the law of effective accumulative temperature , the low temperature threshold of development for the egg, larval, pupa and egg-pupa of T. lycium are estimated to be 8.06℃, 9.16℃, 7.65℃and 8.22℃respectively; the effective accumulative temperature for the egg, larval, pupa and egg-pupa are 20.53, 69.37, 127.49 and 217.21 day-degrees respectively. Both the longevity of adult and generation period decrease with the temperature rising, the relationship between longevity of adult (y) and temperature(x),are described as the following formula: y= -0.44x + 17.904 (R2 = 0.9571)(female), y=-0.1864x + 7.82(R2 = 0.9136)(male), meanwhile, the average total number of eggs laid by per female (y) and temperature (x) were described as the following formula: y = -0.2523x2 + 12.059x– 105.27(R2 = 0.9773)。9. There is no significant difference in the [0]progeny number of per female at 5℃cold storage in 15 days. The emergence rate decreased obviously after the pupa cold storage keeps longer than 15 days; the life span of the adults which emerged after the pupa cold storage within 30 days has no significant difference with the no cold ones, and the fecundity of the female has no significant difference also.10. the parasitic functional response of Tamarixa lycium adult parasitizes different instar stages host at 25℃, [0]and parasitizes the 4th instar stage Paratrioza sinica at different temperature are also studied in this research. The results showed that all the response of Tamarixa lycium fit Holling TypeⅡequation, and it is affected by the host instar stage, temperature and the densities of host and parasitoid. Supplying the host on the same instar stage at 25℃, the number of parasitized host increase with increasing host density. the number of parasitized comes highest when the host is on 4th instar stages, which on 5th is sencondly, and the 3rd nympha is the lowest. At the same temperature, the number of parasitized host increase with increasing host density also. At 15~25℃, the parasitized number increase with temperature; while at 25~35℃, it is in adverse. There is a strong intraspecific interference in the parasitic functional response of Tamarixa lycium. The relationship between discovered area (a)of T. lycium and its density(P) could be well simulated as a = 0.1222P -0.4641 by Hassell-varley(1969) model a=QP–m, which under the 4th instar stage Paratrioza sinica as the host at 25℃.
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