Egg development and growth of Sigara alternata in southeastern Pennsylvania, USA were evaluated in six fluctuating temperature regimes with daily maxima ranging from 12.0° to 21. 5°C. Developmental rate was positively correlated with increased magnitude of the diel temperature pulse. Developmental acceleration was most apparent for environments pulsing beyond 15.0°C for both stages. Oviposition rates were studied at natural temperatures during the initial days of reproduction. Egg deposition was sporadic but highly correlated with maximum diel temperatures. A critical temperature region of 11.0—12.5°C was observed for initiation and maintenance of egg laying. Metabolic rates were measured using a different respirometer. The thermal response of metabolism varied with animal soze and the range of test temperatures. The energy demand per uniy weight of tissue was inversely related to body size at all temperatures. Adult population metabolism decreased exponentially during the peak reproductive period due to high mortality. Energy budgets were determined for nymphal development in all thermal regimes. Net growth efficiencies and production/respiration ratios for Sigara alternata ranged from 49.7—73.4% and 0.9—2.7 respectively. Assimilation rates increased with rinsing temperatures and varied between 1.05 and 3.52 J.mg—1.day—1 [=0.25 —0.84 cal.mg—1.day—1]. Net growth efficiencies tended to decrease with increased temperatures due to higher maintenance costs. The significance of fluctuating temperatures to the bioenergetics, developmental dynamics, and ecology are discussed .

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.

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.El objetivo de este trabajo fue describir la distribución espacial de las Calliphoridae presentes en gradientes urbano-rurales de la estepa Patagónica austral, y la influencia de factores geográficos sobre su composición y abundancia relativa. Se registró la composición de califóridos en 12 localidades de Santa Cruz y Tierra del Fuego, Argentina entre 1997 y 2007. Las muestras fueron asignadas a tres categorías de sitio (urbano, semi-urbano y no habitados) y se registraron cuatro variables ambientales. Tres especies dominantes acumularon el 98% del total capturado de especimenes, la asinantrópica Compsomyiops fulvicrura, y dos especies sinantrópicas: Lucilia sericata y Calliphora vicina. Adicionalmente se puso a prueba la homogenización de la fauna de callifóridos urbana, mediante la comparación del recambio de especies entre sitios, pero nuestros resultados indicaron una similar heterogeneidad de las comunidades urbanas y no urbanas.

Temporal changes of flesh flies abundance were simultaneously recorded at monthly intervals during a year in a woodland and in a grassland at the "Reserva Ecológica Costanera Sur" (RECS), Buenos Aires city, Argentina. Samples were taken at monthly intervals (February 2004-January 2005). Hourly captures of adult flies (10:00 am-04:00 pm) were taken each sampling date with a hand net. Temperature was recorded at each hourly capture. The baits used were 200 g of rotten cow liver and 200 g of fresh dog faeces. Records of abundance included only species whose abundance was ≥30 individuals accumulated during the whole sampling period. Considering overall abundance, a non-parametric Chi-square test was used to estimate deviations of an expected habitat and bait preference ratios of 1:1. The same criterion was applied to include species in a contingency table to describe their seasonality. The final matrix included four species whose associations to seasons were analyzed by using a Correspondence Analysis. To normalize the data, a log 10 (n+1) transformation was applied prior to the analysis of correlation. Pearson product-moment correlations were used to examine the relationship between flesh-fly abundance with temperature and habitat preference. The entire sample accumulated 1 305 individuals and 18 species. The flies were more abundant in the grassland than in the woodland. Microcerella muehni, Oxysarcodexia paulistanensis, O. varia and Tricharaea (Sarcophagula) occidua exhibited the higher relative abundance, representing the remaining species less than 8 % of the entire sample. Most of the recorded species showed preference for faces as bait. Concerning the dominant species, all of them but M. muehni, a suggestively termophobic species, prevailed in late spring-summer. The observed species arrangement at both sites indicates low species diversity and equitability and high information per individual in the average. The referred community traits would indicate the possible effects of environmental disturbance due to the proximity of study sites to dense urban settlements.