Formulation and characterization of the microencapsulated entomopathogenic fungus Metarhizium anisopliae MA126.
Bioinsecticides are expected to be used for controlling major species of aphids. The present study explored a liquid phase coating technique for the formulation of microencapsulated conidia of the entomopathogenic fungus Metarhizium anisopliae MA126. Various parameters for microencapsulation were investigated. The biopolymers sodium alginate, hydroxypropyl methyl cellulose (HPMC) and chitosan were tested as coating materials. Calcium chloride was used as the cross-linking agent for converting soluble sodium alginate into an insoluble form. To improve the efficiency of microencapsulation, the additives of HPMC, dextrin, chitosan or HPMC/chitosan in various ratios (1 : 1, 1 : 3 and 3 : 1) were used as the coating materials. The particle size of a bare microcapsule was less than 30 microm. Larger size microcapsules were produced using vortex method by comparison with that using homogenization method. The latter method, however, was easy to scale up. The effect of coating materials on the morphology and encapsulation efficiency of the microcapsules was also studied. The best encapsulation efficiency (78%) was using HPMC as the additive of the coating material. The next was dextrin (70%). By measuring the germination rate, the results showed that the activity was approximately 80% of the initial after 6 months of storage at 4 degrees C, while that of the bare conidia was less than 50% stored in identical conditions.
Liu
Ching Piao
CP
Department of Biological Science and Technology, Mei Ho Institute of Technology, Pingtung, Taiwan. cpliu@ntu.edu.tw
Liu
Shan Da
SD
D000464:Alginates / Q000737:chemistry; D000818:Animals; D001042:Aphids / Q000382:microbiology; D001704:Biopolymers / Q000737:chemistry*; D002122:Calcium Chloride / Q000737:chemistry; D048271:Chitosan / Q000737:chemistry; D003432:Cross-Linking Reagents / Q000737:chemistry; D003912:Dextrins / Q000737:chemistry; D004339:Drug Compounding / Q000379:methods*; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D007306:Insecticides / Q000138:chemical synthesis / Q000737:chemistry; D052981:Metarhizium / Q000254:growth & development / Q000472:pathogenicity; D008747:Methylcellulose / Q000031:analogs & derivatives / Q000737:chemistry; D010316:Particle Size; D012995:Solubility; D013172:Spores, Fungal / Q000254:growth & development / Q000472:pathogenicity; D013696:Temperature; D013997:Time Factors
D000464:Alginates; D001704:Biopolymers; D003432:Cross-Linking Reagents; D003912:Dextrins; D006603:Hexuronic Acids; D007306:Insecticides; D020723:Glucuronic Acid; D008747:Methylcellulose; D048271:Chitosan; D002122:Calcium Chloride