Screening, Identification and Culture Conditions of Metarhizium Anisopliae Against Lepidoptera Pests
|Keywords||Lepidoptera Metarhizium anisopliae Biological control Fermentation conditions Milk powder agent|
Caterpillar, diamondback moth, armyworm moth lepidopteran pests are a major pest hazards vegetables, especially the threat Cruciferae, Leguminosae, Qiegua and the bindweed vegetable growth, yield and quality of goods . A long time, in order to combat these pests, continuous heavy use of chemical pesticides, frequent replacement of the types of pesticides, and even the use of highly toxic, highly toxic pesticides, a direct threat to human health, becoming increasingly resistant pests, prevention and treatment costs getting higher and higher, and cause great harm to the environment and biodiversity, bio-pesticides gradually received wide attention. Metarhizium anisopliae is an important class of fungal biocontrol agents, or broad-spectrum or specific insecticidal activity of the diversity of strains has a variety of pests, no pollution, no residue, is harmless to humans and animals, the pest is not easy produce drug resistance and other advantages, has become increasingly widely used in biological control of vegetable pests as well as a variety of crops and forest pests. The research from the laboratory to collect multiple insecticidal strains of Metarhizium anisopliae, Metarhizium anisopliae strain lepidopteran pests of vegetables screening with virulent high, broad spectrum insecticide, and filter out strains biometric taxonomic status, culture conditions, insecticidal virulence were studied. Conducted a preliminary exploration strain formulations according to the characteristics of vegetable pests. The strains to the grubs have good insecticidal insecticidal efficiency of the grubs of the preparation of the preliminary test. The main results are as follows: and one pair ① from the existing strains screened a variety of lepidopteran pests good insecticidal activity of Metarhizium anisopliae strain CQMa128. According to the morphological characteristics of the strain, the biological characteristics and rDNA sequences compared the results to determine the strain taxonomic status of Metarhizium anisopliae the large spore varieties (Metarihzium, anisopliae that var.majus of). (2) to the strain CQMa128 spore suspension drop method were inoculated with the 4th instar larvae of the cabbage worm, diamondback moth, corn borer, Bombyx mori, corrected mortality of 1.0 x 108 mL-1 concentration of spore suspension of the corn borer caterpillar, diamondback moth, were 100%, 83.3%, 76.7%, while the the silkworm accumulated mortality is only 10%, below this concentration silkworm mortality is very low, and no significant difference from the blank control. The high infection ability and insecticidal activity of the strains on the cabbage worm, corn borer, diamondback moth, silkworms relatively safe. Received bioassay data established CQMa128 strain with the four Lepidoptera time - dose - mortality model (time-dose-Mortality Model TMD) analysis showed that the model fitting heterogeneity through the Hosmer-Lemeshow test by the model to estimate the dose-response and time-dependent strains Lepidoptera. ③ by single factor experiment, test the impact of different pH, carbon, nitrogen and trace elements liquid fermentation growth and sporulation the Metarhizium anisopliae CQMa128 of strains, culture conditions parameters to determine the optimum growth and sporulation single factor optimum growth of the strain PH 7.0 the best sucrose as carbon source, nitrogen source, yeast extract, add 0.01% Mg2 can promote the growth of the strain on the production saturated. On this basis, the orthogonal test by the three levels of the carbon source, a nitrogen source, and trace elements, identified by the strain preferred liquid culture conditions: suitable culture liquid culture medium of pH 7.0, L to 10.0g of sucrose as carbon source, 3g yeast extract as nitrogen source, 1.5 g of peptone and add 0.01% Mg2 nutritional supplements can make CQMa128 Conidiation than basal medium doubling the biomass an increase of 51.9%. Provide the basis for large-scale fungal pesticide production. ④ screened a variety of commonly used surfactants, from which the filters can effectively disperse the spores, surface active agent SP80 extend the spores save time T80 optimum proportion of the additives, the percentage by weight of salad oil and spores were 8 %, 25% -30% 60% -70%, to obtain a good dispersion in water, germination rate Metarhizium milk powder agent. The milk powder agent insecticidal activity is high, long shelf life, product quality is stable, easy to use and transport, pollution-free vegetables, can be used for the prevention and treatment of major lepidopteran pests of vegetables. (5) to the Metarhizium CQMa128 milk powder agent Insecticidal Activity of soil pests chafer grubs larvae, the the soil spore powder concentration to 5 x 107 / g grubs have a good control effect, grubs corrected mortality can reach 85.2% . The results show with strong potential for application of the Metarhizium preparation in the biological control of grubs.