Research Product

Experiments were performed in which developing embryos of the grass shrimp, Palaemonetes pugio, were exposed to conidiospores of the insect pathogenic fungus, Metar-hizium anisopliae. Responses were variable with significant (p less than or equal to 0.05) adverse effects observed in 5 out of 6 experiments conducted. Dead embryos and larvae with visible growth of Metarhizium anisopliae were observed in all experiments. Growth of Metarhizium anisopliae was occasionally observed on embryos and larvae prior to death. Delayed hatch was also observed. In one of the initial experiments an increase in N-acetyl-B-D-glucosaminidase. EC3.2.1.30, (NAGase) activity accompanied by an increase in virulence toward shrimp embryos was observed. Additional experiments in which conidiospores were produced on homogenized caterpillars suggested a positive correlation between virulence of M. anisopliae to P. pugio embryos and activity of spore-associated NAGase. M. anisopliae was an invasive pathogen of grass shrimp embryos, and the growth substrates on which their spores develop can 'condition' them for enhanced virulence toward nontargets.