INTRASPECIFIC VARIABILITY IN CONIDIOBOLUS OBSCURUS

Abstract

The electrophoretic behavior of 34 strains of Conidiobolus obscurus was examined in an attempt to study both the interspecific differences from other entomopathogenic Conidiobolus species and the intraspecific variability existing among C. obscurus strains. Initially, the non-significant variability occurring among strains was estimated by comparing isozymic patterns of mycelial samples of a particular strain grown under variable culture conditions or collected at different growth stages. The species C. coronatus, C. osmodes, C. thromboides, and C. apiculatus look electrophoretically homogeneous: comparisons of electrophoretic profiles between strains of the same species produced coefficients of similarity (CS) greater than 0.67, the baseline value established to measure non-significant differences. Strains of C. obscurus, unlike the other Conidiobolus species, appeared heterogeneous with certain pairs having a calculated CS value less than 0.1. The relationships among the C. obscurus strains appeared to be independent of the insect host from which they were isolated and from the locality of origin. An analysis of a dendrogram constructed for C. obscurus having known in vitro growth characteristics produced 3 major groups of strains. The clustering of these strains appeared to depend on their ability to produce resting spores in vitro. The first group were capable of producing azygospores in both liquid and solid media. Group II strains were able to sporulate on solid media but not in liquid culture, and group III strains were unable to produce resting spores in vitro.