ABSTRACT
El Paso de Portachuelo es un abra utilizado por una gran diversidad de especies de aves, bien sea como residentes o para movimientos estacionales o migratorios, en el cual se han reportado 32 especies de colibríes en la familia Trochilidae. Debido a esto nos planteamos como objetivo evaluar la dinámica del ensamble de colibríes que usa dicho Paso. Se realizaron salidas de campo mensuales desde abril 1990 hasta noviembre 1994, y desde junio 2010 hasta noviembre 2013. Se capturaron 14 685 individuos, pertenecientes a 38 especies. Las especies con poblaciones que presentaron mayores abundancias fueron: Heliodoxa leadbeateri y Sternoclyta cyanopectus. Con base en los resultados obtenidos, la comunidad de colibríes del área de Portachuelo se puede dividir en: seis especies altamente abundantes y que se observan durante todo o la mayor parte del año, siete especies que utilizan el paso durante la mayor parte del año pero con densidades bajas, cuatro especies que utilizan la zona de manera estacional y siete especies raras en las capturas debido al tipo de muestreo, o a que no presentan movimientos de desplazamiento y prefieren otros hábitats.
Portachuelo Pass is an open area used by a great diversity of bird species, either as residents or for seasonal or migratory movements, reporting 32 species of hummingbirds in the Trochilidae family. Due to this, our goal was evaluating the hummingbird assemblage dynamics in Portachuelo Pass, analyzing the abundance of the captures over four years of sampling and comparing these data with samples taken between 1990 and 2013. Monthly field trips were made from April 1990 to November 1994, and from June 2010 to November 2013, between 5 and 8 mist-nets were used to catch the birds. 14 685 individuals were captured, belonging to 25 species. The relative abundance per species was estimated in each of the sampling months, separating the community into four groups: A) Hummingbirds with high abundances, B) Hummingbirds with low abundances, C) Hummingbirds rare and D) Phaethornithinae. The species with the highest abundance populations were: Heliodoxa leadbeateri and Sternoclyta cyanopectus, followed by Aglaiocercus kingi, Chalybura buffoni, Chrysuronia oenone and Coeligena coeligena. For the rest of the species the densities in the mist-net captures were from low to medium. Based on the results obtained, the community of hummingbirds in the area of Portachuelo can be divided into: six highly abundant species that are observed throughout all or most of the year, seven species that use the passage during most of the year but with low densities, four species that use the area in a seasonal manner and seven rare species in the catches due to the type of sampling, or that do not present displacement movements and prefer other habitats. Statistically significant differences were found between the abundance of hummingbirds of sampling years, being the year with the highest abundance 1991, followed by 2013.
ABSTRACT
Nestmate recognition is fundamental for the cohesiveness of the colony in social insects. Acromyrmex landolti is a higher Attini, a leaf-cutter ant with largest nest and morphological castes. We studied the location of the recognition signal of A. landolti on the whole ant body, the isolation effect on the capacity of nestmaterecognition, and the role of the mandibular (MG) and post-pharyngeal glands (PPG) as putative sources for chemical recognition signals in this species. We performed behavioral bioassays and chemical analyses of MG and PPG glands; MG volatiles in different castes were also characterized. In order to determine the occurrence of nestmate recognition signals, behavioral tests were performed for which the whole body, body parts or gland extracts from a nestmate and an alien worker ant, were placed on the central axis of an active field trail. Besides, the isolation effect of the nestmate chemical signal persistence was evaluated by repeating the experiments with whole ant bodies after 12h, 24h and 48h of isolation. The agonistic behavior of the ants on the trail was classified as inspection, threatening and biting. Gland volatiles were obtained by headspace solid phase microextraction, and PPG by solid sample analyses; and chemical analyses were performed using gas chromatography-mass spectrometry. Workers performed agonistic behaviors more frequently towards non-nestmate whole bodies, body parts and gland extracts, primarily those from the post-pharyngeal glands. Nestmate thoraces odorized with alien extracts were also recognized from aliens. Nestmate recognition ability persists for 12h and 24h after isolation, but decreases after 48h, suggesting that the chemical signal changes over time. Inter-colonial chemical analyses showed no differences in the PPG hydrocarbon profiles, while the relative proportions of MG compounds showed significant differences between colonies. These results showed that nestmate recognition was achieved by MG volatiles. Possibly, the PPG secretion works as a matrix that absorbs MG volatiles. We report, for the first time, some mandibular gland compounds for the genus Acromyrmex and for the tribe Attini group.
El reconocimiento de compañeras de nido es fundamental para la cohesión de la colonia en los insectos sociales. Las señales de reconocimiento de compañeras en Acromyrmex landolti fueron estudiadas mediante bioensayos de comportamiento y análisis químicos de los componentes de la glándula mandibular (GM) y postfaríngea (GPF). Los bioensayos de comportamiento fueron realizados usando cuerpos completos de hormigas, partes del cuerpo y extractos glandulares de GM y GPF de una compañera de nido y una intrusa en el centro de una trilla activa. Los comportamientos agonísticos de las obreras se clasificaron en exploración, ataque y mordida. Las obreras se mostraron más agresivas hacia los cuerpos completos, partes del cuerpo y extractos glandulares de las intrusas que hacia los de las compañeras de nido. Los volátiles glandulares se obtuvieron mediante la técnica de espacio en cabeza con microextracción en fase sólida, y los hidrocarburos de la PPG por análisis de muestra sólida. Se encontró que los volátiles de la GM conforman la señal de reconocimiento. No se encontraron diferencias intercoloniales para los volátiles de la GM. Posiblemente los hidrocarburos cuticulares actúan como una matriz que absorbe volátiles de la GM.