Resumen Calliphora vicina Robineau-Desvoidy es una especie colonizadora primaria en cuerpos en descomposición siendo predominante en las estaciones frías en Provincia de Buenos Aires, Argentina. Se estimó el intervalo post-mortem mínimo (PMImin) usando el crecimiento y longitud larvales como evidencia entomológica precisa del tiempo de muerte transcurrido. Se criaron especímenes a 12, 14, 16 y 18 °C para determinar las tasas de crecimiento larvales y pupales. Se registraron diferencias en los tiempos de desarrollo (43,2 días a 12 °C; 34,3 días a 14 °C; 29,1 días a 16 °C y 24,3 días a 18 °C), observándose tiempos de vida más cortos a mayor temperatura, sin alterarse los rangos de longitud larval (~1,5–18,0 mm). La temperatura también afectó la supervivencia y tamaño de los adultos emergidos; registrándose mayor porcentaje de supervivencia a 14 (29,73%) y 16 °C (38,65%) y mayor mortalidad a temperaturas extremas (19,00% a 12 °C y 12,61% a 18 °C). Los adultos criados a 12 °C fueron los más grandes, las hembras mayores que los machos con una relación inversa entre tamaño y supervivencia. Estos resultados permiten estimar el PMI basado en datos de poblaciones locales en lugar de consultar registros obtenidos en otras regiones.

Abstract Calliphora vicina Robineau-Desvoidy is a primary colonizing species of decomposing bodies, being predominant in the cold seasons in Buenos Aires province, Argentina. The minimum post-mortem interval (PMImin) was estimated using growth and larval length parameters as the accurate entomological evidence of the elapsed time since death. Specimens were reared at 12, 14, 16, and 18 °C, and the larval and pupal growth rates were determined. Differences in the developmental times were registered (43.2 days at 12 °C, 34.3 days at 14 °C, 29.1 days at 16 °C, and 24.3 days at 18 °C), with the lifespan shortened at higher temperatures, without changing the larval length range (~1.5–18.0 mm). Temperature also influenced the survival and size of emerged adults; the highest percentage of survival registered at 14 (29.73%) and 16 °C (38.65%), and more mortality in extreme temperatures (19.00% at 12 °C and 12.61% at 18 °C). Adults reared at 12 °C were the largest of all, females were longer than males, and body size showed an inverse relationship with survival. These results allowed the PMI estimation based on data from local populations instead of consulting papers based on other regions.

Abstract Cyanolicimex (Haematosiphoninae) includes a single species, C. patagonicus, which is found in the largest known colony of its avian host Cyanoliseus patagonus (Psittacidae) located in Patagonia (Argentina). Relationships between Cyanolicimex and other genera of Haematosiphoninae are still unclear because this genus shares some characters with other South American genera and possesses some similarities with Hesperocimex from the Neoarctic region. The aim of the present study was to provide additional data of C. patagonicus so as to better understand its relationships with other South American species. We examined some biological features of C. patagonicus in the field and we performed a cytogenetic analysis. We observed in the field that C. patagonicus does not live inside the hollow nests of Cyanoliseus patagonus. The cytogenetic analysis showed that the male karyotype is 2n= 31= 28A+X1X2Y and revealed an achiasmate male meiosis and of the collochore type. Our results together with available cytogenetic data in other cimicids, allow proposing the possible chromosomal rearrangements involved in the chromosomal evolution of C. patagonicus and also contribute to better understand the evolutionary divergence at the chromosomal level within Haematosiphoninae. Based on the whole evidence, we propose to place in four groups the species of Haematosiphoninae cytogenetically hitherto studied.

Pseudacteon flies, parasitoids of worker ants, are being intensively studied as potentially effective agents in the biological control of the invasive pest fire ant genus Solenopsis (Hymenoptera: Formicidae). This is the first attempt to describe the karyotype of P. curvatus Borgmeier, P. nocens Borgmeier and P. tricuspis Borgmeier. The three species possess 2n = 6; chromosomes I and II were metacentric in the three species, but chromosome pair III was subtelocentric in P. curvatus and P. tricuspis, and telocentric in P. nocens. All three species possess a C positive band in chromosome II, lack C positive heterochromatin on chromosome I, and are mostly differentiated with respect to chromosome III. P. curvatus and P. tricuspis possess a C positive band, but at different locations, whereas this band is absent in P. nocens. Heterochromatic bands are neither AT nor GC rich as revealed by fluorescent banding. In situ hybridization with an 18S rDNA probe revealed a signal on chromosome II in a similar location to the C positive band in the three species. The apparent lack of morphologically distinct sex chromosomes is consistent with proposals of environmental sex determination in the genus. Small differences detected in chromosome length and morphology suggests that chromosomes have been highly conserved during the evolutionary radiation of Pseudacteon. Possible mechanisms of karyotype evolution in the three species are suggested.

ABSTRACT. Pseudacteon Coquillett phorid flies oviposit on Solenopsis Westwood ants and pupate within the ant's head. We have evaluated the relationship between pupae's viability, presence of respiratory horns and the operculum color in four species of Pseudacteon reared on Solenopsis invicta Buren and Solenopsis richteri Forel ants. The presence of respiratory horns was significantly associated with pupae's viability for all species considered (p < 0,001) but operculum color was not (p > 0,09), except (p < 0,01) when Pseudacteon cultellatus Borgmeier had developed on S. invicta nanitic and reserve workers. Pupae with light-colored opercula were more frequent in P. cultellatus, whereas brown opercula were more frequent for the other species that attack bigger ants. Mimetism can be invoked to explain the similarity in opercula color with that of the head of the parasitized ant as a way to avoid recognition by members of the colony. We conclude that the presence of respiratory horns is necessary for pupae survival of most of the pupae and we suggest to use the presence of respiratory horns as an indicator of the efficiency of rearing protocols for this group of parasitoids. We also recommend using forager ants because other casts do not seem to be appropriate hosts.

RESUMEN. Fóridos del género Pseudacteon Coquillett oviponen en forrajeras del género Solenopsis Westwood y empupan en sus cabezas. Se evaluó la relación entre la viabilidad de los parasitoides, la presencia de cuernos respiratorios y el color en los opérculos de los puparios de cuatro especies de Pseudacteon criados sobre Solenopsis invicta Buren y Solenopsis richteri Forel. La presencia de cuernos respiratorios estuvo asociada a la viabilidad de las pupas para las especies consideradas (p < 0,01), pero no el color de los opérculos (p > 0,09); excepto cuando Pseudacteon cultellatus Borgmeier se desarrolló sobre hormigas de la reserva y niñeras de S. invicta (p < 0,01). Los opérculos claros predominaron en P. cultellatus; mientras que en las demás especies, que atacan a hormigas más grandes, predominaron los opérculos castaños. Debido a que los opérculos presentaron un color similar al de la hormiga parasitada, esto representaría un mimetismo por parte del parasitoide para evitar ser detectado por el huésped. Dado que los cuernos respiratorios son necesarios para la supervivencia de la mayoría de las pupas, sugerimos que sean usados como indicadores de eficiencia en los protocolos de cría. Recomendamos usar solo forrajeras dado que las otras castas no parecen ser huéspedes apropiados.