Environmental Heterogeneity in Parasitoid-Host Interaction for Mutillidae (Hymenoptera: Apocrita)

Trap-nesting biology of an ectoparasitoid spider wasp, Auplopus subaurarius (Hymenoptera: Pompilidae): the importance of wooded environments for niche generalist species

The insect group is one of the most diverse on the planet and due to habitat degradation, many of these species are becoming extinct, leaving a lack of information on the basic biology of each one. In this study, previously unseen information about nesting biology is revealed in Auplopus subaurarius trap nests. This is a solitary ectoparasitoid spider wasp that nests in preexisting cavities. We used a trap-nesting methodology to sample A. subaurarius in two different sampling periods (2017/2018 and 2020/2021) in three types of environment (forest, grassland and Eucalyptus plantation). In our study, the A. subaurarius nest building was more frequent during the hottest months of the year (November to March), with its highest abundance found within natural forest areas and in Eucalyptus plantation than in grassland areas. In addition, the species had two development times: a short one (three months) and a delayed one (up to one year). Moreover, females were larger than males (weight and size) and the species' sex ratio had a tendency toward female production. Auplopus subaurarius presented seven natural enemy species: Ceyxia longispina, Caenochrysis crotonis, Photochryptus sp.1, Photochryptus sp.2, Messatoporus sp., Ephuta icema and Sphaeropthalma sp. We emphasize the importance of wooded environments to maintain the A. subaurarius populations and their associated interactors, both spiders and natural enemies, as these environments can provide better life conditions than grassland areas. Furthermore, other solitary wasps that may have the same lifestyle of A. subaurarius can also be improved by natural forest conservation and by good silviculture plantation planning, which should consider ecological aspects of Atlantic Forest landscapes.

Spatial-temporal dynamics of neotropical velvet ant (Hymenoptera: Mutillidae) communities along a forest-savanna gradient

Understanding how and why biological communities are organized over space and time is a major challenge and can aid biodiversity conservation in times of global changes. Herein, spatial-temporal variation in the structure of velvet ant communities was examined along a forest-savanna gradient in the Brazilian Cerrado to assess the roles of environmental filters and interspecific interactions upon community assembly. Velvet ants were sampled using 25 arrays of Y-shaped pitfall traps with drift fences for one year along an environmental gradient from cerrado sensu stricto (open canopy, warmer, drier) to cerradão (closed canopy, cooler, moister). Dataloggers installed on each trap recorded microclimate parameters throughout the study period. The effects of spatial distances, microclimate parameters and shared ancestry on species abundances and turnover were assessed with canonical correspondence analysis, generalized dissimilarity modelling and variance components analysis. Velvet ant diversity and abundance were higher in the cerrado sensu stricto and early in the wet season. There was pronounced compositional turnover along the environmental gradient, and temporal variation in richness and abundance was stronger than spatial variation. The dry season blooming of woody plant species fosters host abundance and, subsequently, velvet ant captures. Species were taxonomically clustered along the gradient with Sphaeropthalmina (especially Traumatomutilla spp.) and Pseudomethocina more associated, respectively, with cerrado sensu stricto and cerradão. This suggests a predominant role of environmental filters on community assemble, with physiological tolerances and host preferences being shared among members of the same lineages. Induced environmental changes in Cerrado can impact communities of wasps and their hosts with unpredictable consequences upon ecosystem functioning and services.

Evaluation of Malaise and Yellow Pan Trap Performance to Assess Velvet Ant (Hymenoptera: Mutillidae) Diversity in a Neotropical Savanna

Given the global biodiversity crisis, it is crucial to identify methods best suited for conducting inventories. We evaluated the relative merits of Malaise traps (MT) and ground-level yellow pan traps (YPT) to sample male velvet ants (Hymenoptera: Mutillidae) in a Neotropical savanna biodiversity hotspot. We compared richness, number of captures, evenness, composition, and body size of male velvet ants (Hymenoptera: Mutillidae) sampled with both methods in four sites at Parque Nacional da Chapada dos Veadeiros, central Brazil, during 19 d. We expected reduced diversity and smaller body size of velvet ants sampled with YPT, because they target visually oriented insects that are active closer to the ground, whereas MT represent a passive method that intercepts insects flying at different heights. Richness, total number of captures, and evenness of species and genera were significantly higher in MT. The body size of velvet ants captured with MT was significantly larger than those found in YPT. Generalized linear model and nonmetric multidimensional scaling analyses revealed a clear difference in the patterns of abundances and composition of velvet ants sampled with MT and YPT, especially for the genera Darditilla, Traumatomutilla, Lomachaeta, Pseudomethoca, Tallium, and Ephuta. YPT were effective at capturing few species that were rare in MT but, overall, MT were much more effective than YPT. We found similar patterns when using either species or genus for assessing samples obtained with MT or YPT, suggesting that ecological studies on Neotropical velvet ants may not require taxonomic resolution to the species level.