TESTING OF THE INSECT PEST-CONTROL FUNGUS BEAUVERIA-BASSIANA IN GRASSSHRIMP PALAEMONETES-PUGIO

Embryos, larvae and adult grass shrimp Palaemonetes pugio were exposed to spores of the insect-control fungus Beauveria bassiana. Conidiospo res attached to embryos held by gravid females and remained with the e gg mass for at least 6 d. In the first experiment where individual dev eloping embryos contained in test tubes were exposed to conidiospores of B. bassiana, 2 of the 75 embryos became infected and died, and a th ird was abnormal at hatch. In Expt 2, a repeat experiment, no adverse effects were observed. In subsequent experiments, attempts were made t o increase the probability of infection or abnormal development for em bryos exposed to B. bassiana. Strategies for these attempts included l owering the salinity, adding a carbon source for the fungus to the tes t 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 ca use any adverse effects during shrimp larval development. In adult shr imp lethal infections only occurred in specimens injected with either conidiospores or blastospores of B. bassiana.