Abstract
The conidial spores of Aspergillus terreus were treated singly and in combination (alternatively and simultaneously) with latex of Calotropis procera Ait (used as natural insecticide) and the synthetic insecticide Chlorcyrin. The single mutagenic effects of Calotropis procera Ait latex and the insecticide Chlorcyrin were tested by treating conidia of Aspergillus terreus with four different concentrations of Calotropis procera latex; 5%, 10%, 20% and 40%, and with five concentrations of Chlorcyrin; 0.2ml/L, 0.4ml/L, 0.6l/L, 0.8ml/L and lml/L (the field concentration) for different exposure times individually. Whereas, the combined mutagenic effects of the both substances, were tested in three ways of treatments. First, the conidia of Aspergillus terreus were exposed to the optimal dose of Calotropis procera Ait latex (20%) for 45min., followed by exposure to the optimal concentration of Chlorcyrin (0.8ml/L) for 45 minutes. Second, same conidia were exposed to Chlorcyrin followed by Calotropis procera Ait latex with the mentioned concentrations and exposure times. Finally, third treatment included the exposure of the fungus conidia to a mixture of the two substances (same concentrations) for 90 minutes. As a results, it was found in the first single treatment that, an increase of Calotropis procera Ait latex concentration and exposure time led to an increase in auxotrophic mutants percentage, and the optimal dose for inducing mutation was found to be (20%) for 45min. of exposure which induced a percentage of 1.6 auxotrophic mutants Similar trend were obtained in the second single treatment, that an increase of Chlorcyrin concentration and exposure time led to an increase in auxotrophic mutants percentage, and the optimal dose was found to be 0.8ml/L for 45min. of exposure (the concentration of which 3.6% of auxotrophic mutants were obtained). Furthermore, Chlorcyrin shows to be a potent mutagenic substance as compared with Calotropis procera Ait latex which shows a milder mutagenic effect, and more cytotoxic effect. All combined treatments revealed an antagonistic effect.