Pathogenicity of the entomopathogenic fungus metarhizium anisopliae to ticks and the protection of Conida from ultra-violet radiation damage

Theses submitted in partial fulfilment of the requirements for the Degree of Master of Science
provided by author
The potential of the entomopathogenic fungus, Metarhizium anisopliae to serve as a bio-control agent of ticks has been studied and promising results reported. In this study, efficacy of M.anisopliae conidia formulated in either oil or water, in inducing mortalities to various developmental stages of ticks was evaluated. A fungal concentration of 108 conidia/ml induced in Rhipicephalus evertsi evertsi mortalities of: 87 percent in eggs, 100 percent in unfed larvae, 72 percent in engorged nymphs, 91percent in unfed adults, and 97 percent in fed adults when formulated in oil, and 77percent in eggs, 95 percent in unfed larvae, 64percent in engorged nymphs, 83 percent in unfed adults, and 90 percent in fed adults when formulated in water. Various stages of Amblyomma hebraeum, Amblyomma variegatum, Rhipicephalus appendiculatus and R. e. evertsi were also found to be highly susceptible to M. anisopliae in water and oil formulation. Furthermore in this study, conidia were protected with 3 percent chemical sunscreens, Everysun and E45, respectively, and exposed to UV radiation for 1, 2, 3, 4, and 5 hours. Survival of conidia after 5 hrs of exposure to UV in oil formulation was: 4 percent in control, 29 percent in conidia protected with Everysun, and 40 percent in conidia protected with E45. In comparison, survival of conidia formulated in water was: 0 percent in control, 13 percent in conidia protected with Everysun, and 24 percent in conidia protected with E45. Furthermore, effects of the 2 sunscreens on viability and on pathogenicity of conidia to in various stages of R. e. evertsi were evaluated. The 2 sunscreens were found to confer protection to conidia against damage by UV radiation without interfering with their pathogenicity to ticks. This study has therefore indicated that M. anisopliae has a potential as a myco pesticide to control different developmental stages and species of tick populations. Results of this study have also shown that oil and chemical sunscreens
Windhoek
Namibia
University of Namibia
Master of Science