Biosafety of an entomopathogenic fungus Isaria fumosorosea in an acute dermal test in rabbits

Abstract

Isaria fumosorosea (formerly Paecilomyces fumosoroseus) is an entomopathogenic fungus that has been proposed as a low risk environmental alternative to the use of chemical insecticides to control agricultural pests and disease vectors. Although there are some mycoinsecticides already being marketed in many countries, not all their biosafety protocols have been published. The acute dermal toxicity test in an animal model is one in a series of biosafety protocols that must be developed, in order to provide information on health hazards, while taking into consideration the periods that the workers are in direct contact with the microbial agent when applied for the control of pests. For this test, we used I. fumosorosea monospore culture EH-506/3, isolated in Mexico from the Bemisia tabaci whitefly, applying a dose of 2 g/kg of animal body weight, on the shaved skin of 16 New Zealand rabbits, with an exposure time of 24 h. Clinical observations were conducted to evaluate the presence of erythema, edema and other alterations in the skin, as well as the behavior and health of the animals, for a period of 14 days. None of the rabbits showed clinical signs of any disease and their body weight corresponded to the expected weight for a healthy rabbit. The test showed no inflammatory reactions in the skin, supporting the safety of a single dose of this fungus in dermal exposure. Therefore, these data support the safety of I. fumosorosea EH-506/3 when applied to the skin.