COMPARISON OF ENTOMOPATHOGENIC NEMATODE DISPERSAL FROM INFECTED HOSTSVERSUS AQUEOUS SUSPENSION

Dispersal of the entomopathogenic nematodes Heterorhabdidtis bacteriop hora Poinar (HP88 strain) and Steinernema carpocapsae (Weiser) (All st rain) was measured when nematodes were applied to sand either in Galle ria mellonella (L.) cadavers or in aqueous suspension. Dispersal abili ty was estimated as the percentage of nematodes that migrated through sand or from sand onto an agar surface. Results of overnight assays in dicated that the dispersal ability of both species was significantly g reater when nematodes were applied in cadavers relative to when they w ere applied in aqueous suspension. Assays that measured migration onto an agar surface after 1 h also indicated. enhanced. dispersal of S. c arpocapsae when exiting cadavers, but results from H. bacteriophora on ly weakly supported the trend. The relatively greater movement of nema todes exiting infected hosts was not the result of differences in nema tode age or persistence in sand. Tile enhanced dispersal may have been caused by physiological or behavioral differences between nematodes e xiting hosts and those kept in aqueous suspension. Because of the disp ersal advantage. application of entomopathogenic nematodes in infected hosts may increase their efficacy in biological control. This study d emonstrated a need to further investigate behavior of entomopathogenic nematodes when they exit a host under natural conditions.