IN-VITRO EFFECTS OF SECONDARY PLANT-COMPOUNDS ON GERMINATION OF BLASTOSPORES OF THE ENTOMOPATHOGENIC FUNGUS PAECILOMYCES-FUMOSOROSEUS (DEUTEROMYCOTINA, HYPHOMYCETES)

Seven secondary plant compounds (catechol, chlorogenic acid, gallic ac id, salicylic acid, saponin, sinigrin, and tannic acid) mixed with Nob le agar at three concentrations (100, 500, and 1000 ppm) were tested f or their effects on germination of blastospores of the fungal entomopa thogen Paecilomyces fumosoroseus. With individual allelochemicals inco rporated at 100 ppm in Noble agar, significant differences in time to 95% germination were found between two allelochemicals (catechol and s alicylic acid) and the control. Blastospores in media containing 100 p pm catechol took twice as long (10 hr) to reach 95% germination as the control. Germination of blastospores in medium containing catechol, s alicylic acid, or tannic acid at 500 was 55, 56, and 46%, respectively , in contrast to less than 10% when the concentration was 1000 ppm. Th ese results indicate that the presence of allelochemicals on a substra te (e.g., insect cuticle or leaf) may be an additional constraint to t he survival of entomopathogenic fungi. (C) 1997 Academic Press.