Rediscovery and reclassification of the dipteran taxon Nothomicrodon Wheeler, an exclusive endoparasitoid of gyne ant larvae

The myrmecophile larva of the dipteran taxon Nothomicrodon Wheeler is rediscovered, almost a century after its original description and unique report. The systematic position of this dipteran has remained enigmatic due to the absence of reared imagos to confirm indentity. We also failed to rear imagos, but we scrutinized entire nests of the Brazilian arboreal dolichoderine ant Azteca chartifex which, combined with morphological and molecular studies, enabled us to establish beyond doubt that Nothomicrodon belongs to the Phoridae (Insecta: Diptera), not the Syrphidae where it was first placed, and that the species we studied is an endoparasitoid of the larvae of A. chartifex, exclusively attacking sexual female (gyne) larvae. Northomicrodon parasitism can exert high fitness costs to a host colony. Our discovery adds one more case to the growing number of phorid taxa known to parasitize ant larvae and suggests that many others remain to be discovered. Our findings and literature review confirm that the Phoridae is the only taxon known that parasitizes both adults and the immature stages of different castes of ants, thus threatening ants on all fronts.Peer reviewe

Use of the 3D radon transform to examine the properties of oceanic Rossby waves

One of the most successful applications of satellite-borne radar altimeter data over the oceans in recent years has been the extraction of information about long-wavelength baroclinic Rossby (or planetary) waves, which play a significant role in ocean circulation and climate dynamics. These waves cross ocean basins from east to west at speeds of few centimetres per second at mid-latitudes. The cross-basin propagation time may therefore be several months or even years and an accurate estimation of the speed of the waves is important. We review the methods for obtaining information on Rossby wave velocity from altimetry data, particularly the two-dimensional Radon transform. Unfortunately the use of longitude-time plots, although it allows the estimation of the zonal phase speeds, does not give any information on the speed vector when the propagation of the waves is not purely zonal (east-west). We show how the two-dimensional Radon Transform can be generalised to three dimensions, enabling not only the true propagation velocity component to be determined, but also the direction of the waves and thus any deviation from the pure-westward case. As examples of the application of this extended technique, we show maps of direction, speed and energy of Rossby waves in the North Atlantic Ocean

Diversity of the myrmecophilous communities associated with the ectatommine ant genus Ectatomma

International audienc

Impact of natural parasitism by two eucharitid wasps on a potential biocontrol agent ant in southeastern Mexico

International audienc

Co-occurrence in ant primary parasitoids: a Camponotus rectangularis colony as host of two eucharitid wasp genera

International audienceDifferent assemblages of parasitoids may attack a given host species and non-random distribution patterns in parasitoid species assemblages have been reported on various occasions, resulting in co-occurrence at the population, colony, or even individual host levels. This is the case for different closely related species of eucharitid wasps (a family of specialized ant parasitoids) sharing similar niches and co-occurring on the same host at different levels. Here we reviewed all known associations between eucharitid wasps and the ant host genus Camponotus Mayr, 1861 and reported new ant-parasitoid associations. In addition, we report a new case of co-occurrence in eucharitid wasps, at the host colony level, involving a new undescribed species of Pseudochalcura Ashmead, 1904 and an unidentified species of Obeza Heraty, 1985, which attack the common but very poorly known neotropical arboreal ant Camponotus rectangularis Emery, 1890. Most attacks were solitary, but various cocoons were parasitized by two (16%) or three (8%) parasitoids. Globally, parasitism prevalence was very low (3.7%) but showed an important variability among samples. Low parasitism prevalence along with host exposure to parasitoid attack on host plants and overlapping reproductive periods of both parasitoid species may have allowed the evolution of co-occurrence. We also provided some additional data regarding the host ant nesting habits, the colony composition and new symbiotic associations with membracids and pseudococcids. The seemingly polydomous nesting habits of C. rectangularis could play a part in the reduction of parasitism pressure at the population level and, combined with occasionally important local parasitism rates, could also contribute to some parts of the colonies escaping from parasites, polydomy possibly representing an effective parasitism avoidance trait

Recruitment by selective activation: an archaic type of mass recruitment in the ponerine ant (Ectatomma ruidum)

International audienc

Foraging activity and diet in some neotropical ponerine ants. I. Ectatomma ruidum Roger (Hymenoptera, Formicidae)

International audienceAnalysis of the patterns of food-gathering activity in Ectatomma ruidum Roger revealed clear differences between those ofthe dry season and the rainy season, though the diet remainedmainly carnivorous. The rainy season was characterized partly by less total foraging activity (compensated for by a 1.5-fold higher yield), and by a decrease in carbohydrate intake andan increase in protein intake. Also, a wider range of prey was captured during the rainy season, anda substantially greater fraction was energy-rich prey (larval type); at the same time, active predation increased sharply relative to necrophagy, which was three times greater in the dry season. The correlations between these various factors, meterological conditions, and the lifecycle of the especies are discussed.El análisis de las características de la actividad de aprovisionamiento de la hormiga Ectatonuna ruidum Roger indica claras diferencias entre los datos obtenidos en época de secas y en época de lluvias, aun cuando la dieta se mantiene principalmente carnívora. La época de lluvias se caracteriza por una actividad general más baja (compensada por un aumento de un 50% de la tasa de éxitos en la captura), una disminución del aprovisionamiento en carbohidratos y Wl aumento en el de proteínas. Una variedad más amplia de presas se nota también en época de lluvias, además de incluir Wla fracción de presas ricas en energía (de tipo larvas) mucho más importante. Al mismo tiempo, se puede notar que la depredación aumenta de manera notable en comparación con la necrofagia que presenta un valor tres veces más alto en época de secas. Se presenta Wla discusión sobre las correlaciones entre esos factores varios, las condiciones meteorológicas y el ciclo biológico de esta especie neotropical