Seasonal and annual abundance of Ephuta wasp (Hymenoptera: Mutillidae) in Panama

Introduction: Ephuta Say is a widespread New World genus of mutillid wasp whose ecology is poorly understood. Objective: The objective of this study was to determine how Ephuta species abundance varies annually and seasonally driven by weather conditions and hosts. Methods: Ephuta specimens, located in the "old forest" at Barro Colorado Island, were examined from weekly samples (2001-2006) of ten Malaise traps. The monthly abundance of each Ephuta species was compared with monthly average humidity, solar radiation, temperature and rainfall. Results: Nine species and ten morphospecies were identified. Most specimens were collected from March to June. April was the month reported with the greatest abundance. Of the four abiotic variables measured, only average monthly temperature was correlated with Ephuta abundance. Months with the highest number of Ephuta specimens were correlated with suspected host abundance, as indicated by the monthly abundance of Pompilidae (Hymenoptera) captured during the year 2007. Conclusions: We concluded that Ephuta display strong seasonal variation in abundance, with the peaks occurring during the end of the dry season and beginning of the rainy season, which correlate broadly with temperature and the abundance of their pompilid hosts.

Introducción: Ephuta es un género de avispas mutílidas ampliamente distribuido en el Nuevo Mundo y cuya ecología es poco conocida. Objetivo: El objetivo de este trabajo fue determinar cómo varía la abundancia de especies de Ephuta anualmente y estacionalmente debido a las condiciones climáticas y sus hospederos. Métodos: Se examinaron especímenes de Ephuta tomados de muestras semanales (2001-2006) de diez trampas Malaise, ubicadas en el "bosque viejo" de Isla Barro Colorado. La abundancia mensual de cada especie de Ephuta se comparó con el promedio mensual de la humedad, la radiación solar, la temperatura y las precipitaciones. Resultados: Se identificaron nueve especies y diez morfoespecies. La mayoría de los especímenes fueron recolectados de marzo a junio. La mayor abundancia mensual promedio se dio en abril. De las cuatro variables abióticas medidas, solo la temperatura mensual promedio se correlacionó con la abundancia de Ephuta. Los meses con el mayor número de especímenes de Ephuta se correlacionan con la sospechosa abundancia del huésped, como lo indica la abundancia mensual de Pompilidae (Hymenoptera) capturada durante el 2007. Conclusiones: Ephuta muestra una fuerte variación estacional en la abundancia, con picos durante el final de la estación seca y el comienzo de la temporada de lluvias. Esta se correlaciona ampliamente con la temperatura y la abundancia de sus huéspedes pompílidos.

Protocol for collecting Mutillidae (Hymenoptera, Aculeata) in ecological studies: species-area effects on Mutillidae communities

ABSTRACT The species-area relationship is one of the most consistent patterns in ecology, and fragmentation is a major cause of habitat loss. Environmental changes in a site can affect the spatial distribution of organisms. Knowledge of Mutillidae ecology is still scarce due to the lack of standardized sampling. Our aim was to: (1) determine the effect of habitat fragmentation on the Mutillidae community and (2) establish a standard method for sampling Mutillidae in ecological studies. Sampling was conducted in four fragments of Brazilian Savanna in an urbanized matrix. We used quadrats with different areas: 25 m2, 100 m2 and 400 m2 to verify sampling effort. Male and female Mutillidae were collected from each of these three treatments. Males were collected using Malaise traps while females were collected through active search. Ecological index, richness, abundance, and percent similarity between fragments were used to analyze the communities. The Kruskal-Wallis test was performed to verify differences between treatments. Nonparametric multivariate analysis of variance was used to determine community composition. Analysis of direct ordination of community with respect to the sample area size was performed. Three hundred individuals were collected; of which 201 were female, 99 male; belonging to 42 species distributed in 13 genera and two subfamilies. The richness, abundance and composition of the community were different between treatments. It was found that a 100 m2 quadrat was sufficient for comparison and application of ecological concepts and theories for the group.