ENTRAPMENT OF BIOLOGICAL-CONTROL AGENTS APPLIED TO ENTOMOPATHOGENIC NEMATODES

Hydrogels of alginate, phospho guar gum, carboxymethyl guar gum, k-carrageenan and cellulose sulphate, respectively were tested to find easily redissolvable gels. The entomopathogenic nematode, Heterorhabditis sp., was entrapped in calcium alginate beads, calcium alginate hollow spheres and foils made from different hydrogels. Emigration from calcium alginate beads after 7 days of storage was 100 % at room temperature and was lowered to 6 % at 6-degrees-C, whereas no emigration from calcium alginate hollow spheres was found at either temperature. Highly concentrated polymer foils produced on gauze showed reduced emigration with a survival of 80 % after 24 h compared to foils produced on glass slides. Calcium alginate beads can be used for a controlled release of the nematode into the environment, while hollow spheres and foils are suitable for storage.