Efficacy of the entomopathogenic fungi Metarhizium anisopliae in the control of infestation by stable flies Stomoxys calcitrans (L.), under natural infestation conditions.

The objective of this study was to evaluate the efficacy of an isolate of Metarhizium anisopliae applied by aspersion to control of Stomoxys calcitrans flies in dairy cattle naturally infested. Was applied by aspersion an aqueous formulation of M. anisopliae sensu lato (Ma134), at a concentration of 1×10(8)conidia/ml, four times with seven day intervals, on a group of eight Holstein cows; a control group of eight Holstein cows, received a water solution with Tween 80 (0.1%). The average number of flies per animal was estimated one day before each application, and then daily counts were done in both groups. The effectiveness of the formulation was calculated using the Abbott's formula. At the same time, defensive behaviors of stamp/kicks and tail movements were evaluated daily, estimating relative frequency per hour. The Ma134 formulation had an infestation control efficacy of 73%, taking into consideration the four study weeks. The population reduction effect was observed since the first week post-application (p<0.05), and the effect increased with the subsequent applications. Defensive behaviors were reduced beginning from the first application, reaching a reduction of 66% and 70%, respectively, during the four weeks of study. These results demonstrated the effectiveness of the formulation to control infestation by S. calcitrans, as well as reduce defensive behaviors which involves the infestation.

Frequency of infection by Neospora caninum in wild rodents associated with dairy farms in Aguascalientes, Mexico.

The purpose of this study was to detect the presence of Neospora caninum in tissues from wild rodents associated with dairy farms in Aguascalientes, Mexico. Individuals from Mus musculus, Rattus novergicus and Spermophilus variegatus were caught in dairy farms with history of positive status to N. caninum. A total of 33 rodents were caught from which samples were taken of brain, spinal cord, liver and heart and were tested with nested PCR and Immunohistochemistry (IHC). Results obtained with PCR showed that M. musculus had 77% (10/13) positive samples to N. caninum, S. variegatus had 71% (10/14) and R. novergicus had 50% (3/6). The results obtained with IHC showed that 15% (2/13) of M. musculus individuals were positive, while 43% (6/14) of S. variegatus and 33% (2/6) R. novergicus were also positive. This is the first report of the presence of N. caninum in S. variegatus.

Relationships between stable fly infestation with some physical facility characteristics and sanitation practices in several dairy farms in the State of Aguascalientes, Mexico.

The possible relationships between stable fly infestation with dairy farm facilities and sanitation practices were studied using path analysis. Twelve dairies located in four counties of Aguascalientes dairy region were selected. The dairies were monitored from May to November 2003. In each occasion, fly infestation, individual physical facility characteristics, and sanitation practices were recorded. In all, 11 independent variables were involved in the study and related variables were grouped together and analyzed in two blocks by path analysis for each one of five population events (begin of fly season, first peak, fluctuation, second peak and decrease). There were significant regression coefficients only in the second peak for two variables, the distance to the silos and the distance to the dung heap (r(2)=0.96 for the full model). Among the 11 variables examined in the study, none had a statistical significant indirect contribution to fly infestation; direct contribution was observed for distance to the silos and for distance to the dung heap variables. However, only the distance to the silos variable was significantly related to stable fly Infestation.

Seasonal occurrence of Ctenocephalides felis felis and Ctenocephalides canis (Siphonaptera: Pulicidae) infesting dogs and cats in an urban area in Cuernavaca, Mexico.

The seasonal occurrence of Ctenocephalides felis felis (Bouché and Ctenocephalides canis (Curtis) infestation on dogs and cats in Cuernavaca City in Mexico, was determined by examining 1,803 dogs and 517 cats at two veterinary clinics during 1995-1997. The overall flea infestation was 30.3 and 30.1% for dogs and cats, respectively. There were no significant differences (P > 0.05) in percentage of infestation among years for both hosts. The infestation was somewhat higher in spring, summer, and autumn than in winter, but no statistical differences was found among seasons (P > 0.05) for both pets. No relationship existed between percentage of flea infestation and temperature or rainfall among seasons. On dogs, 81.1% were infested with only C. felis felis, 16.8% with C. canis, and 2% had both flea species; whereas 92.3% of the cats were infested with C. felis felis and 7.7% with C. felis felis and C. canis. The cat flea was the most prevalent flea species found other than C. canis; no other species were found on the dogs and cats. It appeared that flea life cycle development continued throughout the year.