Field bioassay of Metarhizium anisopliae strains to control the poultry red mite Dermanyssus gallinae.

The poultry red mite, Dermanyssus gallinae is one of the most economically deleterious ectoparasite of laying hens worldwide. To evaluate the efficacy of three strains (V245, 3247 and 715C) of entomopathogenic fungus Metarhizium anisopliae with potential as acaricides against D. gallinae, this investigation was carried out in a commercial caged laying poultry farm in Naghedeh, West Azarbaijan of Iran. The parasite infestation already existed in the farm. Sunflower oil suspension of all fungal strains, each in two concentrations (1×10(7) and 1×10(9) conidia/ml) were used separately as spray on hens and cages, and in the control group the cages were only sprayed with sunflower oil and sterile distilled water. For estimating the population rate of mites before and after treatment, special cardboard traps were fixed to cages during a 1-month period. The traps were placed on weeks -1, 0, 1, 2 and 3 and always removed after 1 w. The results showed that the population rates post fungal treatment with the lower concentration were not significantly different compared to the control group. However, the reduction in mite numbers induced by all three strains at the concentration of 1×10(9) conidia/ml was significantly higher than the control (P<0.05). The results revealed that under field conditions, higher concentrations of M. anisopliae will be required for controlling D. gallinae.

Metarhizium anisopliae (Ascomycota: Hypocreales): an effective alternative to chemical acaricides against different developmental stages of fowl tick Argas persicus (Acari: Argasidae).

The fowl bloodsucking tick Argas persicus is of great medical and veterinary importance in tropical and subtropical regions because of its role as vector of certain parasitic, bacterial and viral pathogens. A variety of acaricides are used for the control of tick infestation in poultry, resulting in environmental contamination and the development of resistance. In order to develop an alternative control method, the efficacy of three strains (V245, 685 and 715C) of entomopathogenic fungus Metarhizium anisopliae against different life stages of A. persicus including eggs, larvae, unfed and engorged adult females was evaluated under laboratory conditions. Five concentrations of different strains of M. anisopliae ranging from 10(3) to 10(7)conidia/ml were utilized. The effects of fungal strains on egg hatchability and larva and adult female mortality were significant and dose-dependent compared to the control groups (P<0.05). The mortality rates of larvae ranged from 92% to 100% for two different concentrations (10(3) and 10(4)conidia/ml) of M. anisopliae strains. Treated engorged females were more susceptible than the unfed females reaching mortality rate of 100% at the highest concentration (10(7)conidia/ml) at 18 days post-inoculation. Among strains used in this study, V245 was the most virulent strain regarding the LC(50) values for adult females exposed to fungal conidia. The results demonstrate that the application of M. anisopliae as a biocontrol agent is a promising option in reducing the use of chemical acaricides, resulting in benefits to poultry and the environment.

Laboratory evaluation of three strains of the entomopathogenic fungus Metarhizium anisopliae for controlling Dermanyssus gallinae.

The pathogenicity of three strains of the entomopathogenic fungus Metarhizium anisopliae on different life stages of Dermanyssus gallinae was evaluated in the laboratory. All the strains tested were virulent to D. gallinae but pathogenicity varied among the strains. Strain V245 induced a higher mortality rate using different concentrations than other two strains. The estimated median lethal concentration of different strains of M. anisopliae against D. gallinae varied depending on the exposure time of D. gallinae to M. anisopliae. It was concluded that the pathogenicity of the entomopathogenic fungus M. anisopliae on different life stages of D. gallinae was concentration and time dependent.