Research Product

Embryos, larvae, and adult grass shrimp, Palaemonetes pugio, were exposed to spores of the insect-control fungus, Beauveria bassiana. Conidiospores attached to embryos held by gravid females and remained with the egg mass for at least 6 d. In the first experiment where individual developing embryos contained in test tubes were exposed to conidiospores of B. bassiana, 2 of the 75 embryos became infected and died and a third was abnormal at hatch. In Experiment 2, a repeat experiment, no adverse effects were observed. In subsequent experiments, attempts were made to increase the probability of infection or abnormal development for embryos exposed to B. bassiana. Strategies for these attempts included lowering the salinity, adding a carbon source for the fungus to the test water, or rendering embryos free of potentially protective symbiotic bacteria with an antibacterial agent. All attempts were unsuccessful in promoting infection or abnormal development. B. bassiana did not cause any adverse effects during shrimp larval development. In adult shrimp, lethal infections only occurred in specimens injected with either conidiospores or blastospores of B. bassiana.