INTERACTIONS OF THE MICROSPORIDIUM VAIRIMORPHA-NECATRIX WITH A BACTERIUM, VIRUS, AND FUNGUS IN HELIOTHIS-ZEA

Interactions between V. necatrix and 3 other pathogens of H. zea were evaluated with dose-mortality studies to find a synergistic combination for field control of H. zea. The effect of the microsporidium combined with the bacterium Bacillus thuringiensis was at least additive, with indications of synergism. Interaction between V. necatrix and Heliothis nuclear-polyhedrosis virus was antagonistic except that the highest microsporidian dose overcame the antagonism with a resultant independent action. Interaction between V. necatrix and the fungus Nomuraea rileyi was additive, though response varied with different proportions of the 2 pathogens. Even though none of these interactions is likely to be valuable in microbial control, V. necatrix has the potential to synergize or antagonize any biological or chemical agent that acts on the midgut epithelium of host insects.