Culture Production Technology Of Metarhizium Flavoviride And Its Application In Pest Control

Nowadays, fungal pesticides are widely used in biological control, such as Beauveria bassiana, Metarhizium anisopliae, Paecilomyces Aschersonia bacteria, VerticiIlium lecanii. etc. In this paper, a highly virulent strain is screened out according to incubation traits and indoor toxicity tests on two agricultural pests, and on this basis formula of solid state fermentation medium of this strain is optimized in large scale production. And in order to test the actual application effects on pest biological control, field efficacy trials are carried out with the fungus powder. The main results are as follows:1. Incubation traits of test strains and research on indoor toxicity on pests20test strains are selected, including Metarhizium anisopliae, Metarhizjum flavovirde, Beauveria bassiana, Brinell bassiana, to study their growth diameter, initial sporulation time, sporulation quantity, spore germination rate and their indooor vtrulence on the brown planthoppers and whitefly.The test results of incubation traits show that:vegetative growths of strains Mf82, Ma73and Bb552are of the highest speed, with colony diameters on the5th and10th days significantly higher than that of others; sporulation initial time is less than5days, significantly lower than that of others; sporulation quantity on the10th day is significantly higher than that of others; average germination rates of spores in the24th hour are all greater than97%, significantly higher than that of others.Pathogenicity of the selected strains Mf82, the Ma73and Bb552on two agricultural pests brown planthopper and whitefly are evaluated. The results of pathogenicity on brown planthopper show that the virulence effects of different strains on different instars of brown planthopper vary significantly. The same instar of brown planthopper treated with different strains show that the modified death rates on the4th,7th and10th day vary significantly, among which modified death rate of strain Mf82against BPH is as high as82.63%. The different instars of brown planthopper treated with the same strain show that modified death rates on the4th,7th and10th day are in size order as follows:adult> old nymph> young nymph. The results of pathogenicity on whiteflies show that there are significant differences between different strain treatments on whiteflies, among which the toxicity of Mf82on whitefly adults is the highest, the modified death rate on the8th day is80.92%and the infection rate is92.44%, significantly higher than that of others. In addition, indoor biological assay results all show that toxicity of test strains on adults is higher than the larva.Toxicity test results on the two pests indicate that the higher the modified death rates and the infection rates are, the lower LT50will be. The virulence of three tested strains against two pests is significantly different by the comprehensive indicators, among which strain Mf82shows the highest virulence on the two pests. Meanwhile, virulence of Mf82on whitefly is a little higher than its virulence on the brown planthopper, which is also consistent with the theory by Jackson et al.(1985) that virulence of entomogenous fungi on original host is slightly higher than the other hosts. Therefore, further large scale cultivation is considered for field efficacy trials of Mf82against planthopper.2. Formula optimization of solid fermentation medium of M flavovirde82Cheap and easy to get experimental materials are chosen for the medium of solid-state fermentation, on the basis of single factor test, quadratic general rotary unitized design is applied to optimize composition and ratio of each component, and quality index of spore powder is evaluated.Single factor test shows that when wheat flour, bean shell and molitor slough with the ratio of4:1:0.2are chosen as the solid culture medium formula, this strain has the highest spores production; the optimization experiment shows that when proportion of experimental materials wheat flour, bean shell and molitor slough reaches4:1:0.25, this strain has the highest spores production of2.39×1012spores per kilogram of medium; spore powder index tests show that spore powder produced with this medium formula reaches the industry standards of spore powder production. Thus, the formula of solid-state fermentation medium with wheat flour, bean shell and molitor slough at the ratio of4:1:0.25can be used in industrial production to gain more spores powder.3. Field efficacy trials of strain Mf82against brown planthoppers and whitebacked planthopperThe field efficacy trials of M. flavovirde against brown planthoppers are conducted in the experimental field of Plant Protection Station of Lujiang County, Anhui Province. Results show that M. flavovirde powder has certain control effect on brown planthoppers and whitebacked planthopper. With the increase of fungus powder dosage, control effect enhances significantly, it shows great persistence.1d after powder application, relative control effect of each treatment is relatively low, and relative control effect of M. flavovirde powder is lower than that of25%pymetrozine WP, namely fast-acting result of M. flavovirde powder is not better than that of25%pymetrozine WP. However, with time goes by after spraying, control effects of two doses of M. flavovirde powder are markedly increased. Control effects of two doses of M. flavovirde powder both exceed34%on the21st day. Comprehensive comparison of the insecticidal effect of M. flavovirde powder against the two pests, field efficacy of brown planthoppers is better than that of whitebacked planthopper, and field efficacy on adults are better than that of nymphs.