Seasonality and relative abundance of Tabanidae (Diptera) captured on horses in the Pantanal, Brazil.

The research article focuses on the one-year study (June 1992 – May 1993) that analyzed seasonality and abundance of various Tabanidae species, commonly known as horse flies, in two habitats (grassland and cerradão) of the Nhecolândia, Pantanal State of Mato Grosso do Sul in Brazil.

Research Methodology

• The researchers conducted the study for a full year in order to track the seasonality and relative abundance of the Tabanidae species.
• Data was collected monthly from June 1992 to May 1993 by manually catching tabanids on horses using hand nets.
• Collection of tabanids was carried out from sunrise to sunset in two different habitats: grassland and cerradão (dense savanna).

Findings

• A total of 3,442 tabanids were collected, representing 21 species, 12 genera, and 3 subfamilies.
• Even though the abundance of species varied with the seasons and habitat, no particular habitat specificity was observed for the most abundant species.
• In the grassland, 1,625 (47.2%) tabanids belonging to 19 species were collected, whereas 1,817 (52.8%) tabanids from 17 species were caught in the cerradão.
• The species variety ranged from 7 during winter (July/August) to 15 in the spring (October).
• Tabanus importunus (56%) was the most abundant species, followed by T. occidentalis (8.2%), and T. claripennis (8.1%).

Implications

• The abundance of tabanids peaked in October, which coincides with the onset of the rainy season.
• Most species, including those with higher vector potential, had their population peak during the start of the rainy season.
• This suggests that the rainy season may be a period with a higher risk of mechanical transmission of pathogens from tabanids to horses in the region.