Juan A. Schnack

Diversity and Seasonal Dynamics of an Assemblage of Sarcophagid Diptera in a Gradient of Urbanization

Abstract Sarcophagid species inhabiting different locations in a rural-urban gradient were surveyed in the east central Argentine district of the Almirante Brown, Buenos Aires province. The main objectives of this research were to identify the most prevalent sarcophagid species and to describe community richness and diversity according to the degree of urbanization and the environmental variables measured in three locations within a rural-urban gradient sampled during two years from May 2005 to April 2007. Spatial and seasonal variations were the main factors involved in structuring the sarcophagid communities. Diversity was lower in urbanized areas than in rural ones. Bait and microhabitat preferences (sunny or shady places) and seasonal fluctuations were described for 17 sarcophagid species.

Species composition and heterogeneity of blowflies assemblages (Diptera: Calliphoridae) in urban–rural gradients at regional scale in Argentinean Patagonia

This work is aimed at describing the spatial distribution of Calliphoridae species along urban–rural gradients in the southern Patagonian steppe, and the influence of geographical factors on species composition and relative abundance. Blowfly assemblages from 12 localities of Santa Cruz and Tierra del Fuego, Argentina between 1997 and 2007 were studied. Samples were assigned to three categories of sites (wild sites, mid-urbanized and urbanized) and four environmental variables were recorded. Three dominant species account for 98% of all specimens, the wild Compsomyiops fulvicrura, and two synanthropic species: Lucilia sericata and Calliphora vicina. Additionally we tested the homogenization of urban calliphorid fauna by comparing the turnover of species among sites, but our findings showed similar heterogeneity of urban and non-urban assemblages.

The Sarcophagidae (Diptera) of the Coastline of Buenos Aires City, Argentina

Abstract The flesh fly community was surveyed on the shoreline of Río de la Plata at an ecological reserve whose western border directly abuts downtown eastern Buenos Aires. Samples were taken at monthly intervals from September 2004 to August 2005. To attract the flies, dog faeces and rotten cow liver were used as bait. Overall number, species composition and sex ratio were referred to each chosen bait. Of the thirteen species captured during the sampling period, Helicobia aurescens (Townsend), Oxysarcodexia culmiforceps Dodge, Oxysarcodexia marina (Hall), Oxysarcodexia thornax (Walker), Sarcophaga (Lipoptilocnema) koehleri (Blanchard), S. (L.) lanei (Townsend) and Tricharaea (Sarcophagula) occidua (Fabricius) were recorded for the first time in Buenos Aires city. Regardless of species composition, higher number of flies were obtained on faeces. Tricharaea (S.) occidua, was highly dominant (78,35%) followed in abundance by Oxysarcodexia varia (7,82%), both species showing a strong preference for dog faeces. Microcerella muehni and Oxysarcodexia paulistanensis did not show any preference on either bait. Sex ratio was male biased for O. varia, while females were dominant for O. paulistanensis and T. (S.) occidua, and no differences were found for M. muehni. Baits preference and sex ratio could not be estimated for the remaining species due to their low abundance.

The population ecology of Muscina stabulans (Fallén) (Diptera: Muscidae), along an Urban-Rural Gradient of Buenos Aires, Argentina

The false stable fly, Muscina stabulans (Fallén), was surveyed along an urban-rural gradient at Almirante Brown, Buenos Aires province, Argentina. Samples were taken at monthly intervals from May 2005 to April 2007. Hourly captures of adult flies (10:00 am-04:00 pm) were taken at each sampling date with a hand net. The baits used were 250 g of rotten cow liver and 250 g of fresh dog faeces exposed in shaded and sunny areas. The entire sample accumulated 358 specimens. The number of specimens captured during the second year was higher than in the fi rst year. Muscina stabulans was more abundant at urban-suburban sites. Females showed significant preferences for cow liver. We caught more specimens in shaded areas. The hourly activity increased toward the afternoon at the three sites. The present work was the first ecological study related to a muscid species in Argentina.

LAGUNA DON BLANCO, ARGENTINA: FIRST RECORD OF HORVATHINIA (HEMIPTERA: BELOSTOMATIDAE) AS A WETLAND DWELLER

ABSTRACT Two adult Horvathinia pelocoroides Montandon 1911 (Hemiptera, Belostomatidae, Horvathininae) are recorded for the first time in a true wetland habitat. This species, probably the only valid ones in the monobasic subfamily Horvathininae Lauck and Menke 1961, was discovered in a permanent shallow pond near the city of Corrientes, Corrientes Province (27° 28′S, 58° 50′W), Argentina, during surveys conducted on December 29, 2004, and September 23, 2005. At both dates, the specimens were taken from a fresh water marsh densely filled with floating hydrophytes dominated by water hyacinth, Eicchornia crassipes, and water lettuce, Pistia stratiotes. This is the first record of any horvathinine specimen collected in any situation other than flying to light.