Sensibility of the entomopathogenic fungus Metarhizium anisopliae (Metschnikoff) Sorokin to Pelargonium sidoides extract (EPs 7630®) assessed by conidia germination speed parameter

Abstract

Pelargonium sidoides, known as umckaloabo, is a plant originally from South Africa and its extract is used in popular medicine. The fungus Metarhizium anisopliae, an important entomopathogen used in biological control of pests, is also employed as model for the evaluation of toxicity and compatibility of different products, considering, among other parameters, conidia germination speed. Therefore, this study aimed to evaluate the sensibility of M. anisopliae var. anisopliae in the presence of the extract of P. sidoides, at a concentration of 20.625 and 2.0625 mg/ml. During incubation at 28°C, samples were collected at 0, 6, 8, 10, 12 and 24 h and analyzed by light microscopy, with observation of 300 conidia, in triplicate, for both treatments and negative controls (in a completely randomized design). This study shows that the two concentrations of P. sidoides extract tested are capable of delaying the M. anisopliae conidia germination speed, in comparison to the controls, although the germination frequency has been restored after about 12 h of conidia incubations, with did not lack conidia viability, indicating no toxicity.

Keywords: Model fungus; toxicity; vegetative development; viability.