Study On Screening And Culturing Virulent Species Of Metarhizium For Controlling D.houi Lajorquiere

Dendrolimus spp. is a kind of most serious pest of forest in history; there had a record that the amount of the pest exploded largely caused to calamity at A.D370. Dendrolimus spp. was classified 30 species (included 4 subspecies) almost, and there are 6 species included D.houi Lajorquiere et al in 30 species of Dendrolimus spp. distributed largely, and the harm far more serious than that caused by other species of Dendrolimus spp. D.houi Lajorquiere is one of most important pest harm to Cryptomeria fortunei Hooibreak et al, the harmed area reached to about 33 thousand hm² each year.Metarhizium is entomopatogenic fungi, whose host is very large include almost 200 species pest and acarus from 8 orders. The products of Matarhizium have entered into the field for controlling pest in agriculture and forest in Brazil, Australia and America et al. So far as 1985 in China, Li zengzhi et al test firstly the virulence of Metarhizium to D.houi Lajorquiere in laboratory, founded that Metarhizium have virulence to D.houi Lajorquiere. After that, many a researchers have done a lot of experiments and researches of Metarhizium, founded the effect of controlling pest as good as Beauveria, even better in the aspects of enduring thermal or drying. Our research focus on screening the high virulence species of Metarhizium for controlling D.houi Lajorquiere, and then use the screened species of Metarhizium to do the next experiments about semi-solid culture and liquid-culture, in order to find out a fit of appropriate method for mass produce of Metarhizium and offer the base of theory for controlling D.houi Lajorquiere.The result of our experiments followed as:1).ln this experiment, we test the virulence of 6 species of Metarhizium to 3-4 instars D.houi Lajorquiere in lab. The result of virulence test demonstrated that 6 species of Metarhizium all have virulence to D.houi Lajorquiere, but only M336 and M337 species come out stiff-insect in the process of infection, so far as, M336 and M337 species more infective than other 4 species of Metarhizium apparently. M336 with LT₅₀ values (95% C.I.) at (9.29 to 18.65d) of the spore's concentration (1. OX 10" to 1. OX 10⁷conidia/L) and LC₅₀ values (95% C. I.) at 2.04×10⁸conidia/L; M337 with LT₅₀ values (95% C.I.) at (9.26 to 13.42d) of the spore's concentration (1.0×10¹¹ to 1. 0×10⁷conidia/L) and LC₅₀ values (95% C. I.) at 7. 53×10⁷ conidia/L. Compare LT₅₀ and LCso values of M336 to that of M337, we can easily get a conclusion that M337 is more infective than M336, and is more fit to be used to control D.houi Lajorquiere. Therefore, M337 of Metarhizium. Anisopliae is most promising prospect in using controlling D.houi Lajorquiere.2). Using the high virulence species after screening to do researches of semi-solid culture of Metarhizium, and the result demonstrated that: A). The values of relative between ingredients of nutrient of culture and spore production did not reached to 0. 8(high relative level) (99% C. I.), and the content of 15 ingredients of nutrient in certain range will have linearity relativity or have not any relativity with spore production of So(?)-culture of Metarhizium. B).In the experiment of screening solid-culture, we founded that the spore production of culture 10, culture 24 and culture 25 is 10. 4×10⁹conidia·L^-1, 17. 0×10⁹ conidia ?L^-1 and 15. 0×10⁹ conidia·L^-1, higher than that of other cultures apparently; the reason can...