Microsatellites for the Neotropical Ant, Odontomachus chelifer (Hymenoptera: Formicidae).

Odontomachus chelifer (Latreille) (Ponerinae) is a ground-dwelling, predominantly carnivorous ant whose colonies may contain multiple egg-laying queens and are potentially susceptible to border effects in the Brazilian savanna known as Cerrado. The ecology and natural history of O. chelifer is well studied, but very little is known about the genetic diversity of O. chelifer colonies. In this study, we developed microsatellite markers for the study of genetic variation in O. chelifer. We created a microsatellite-enriched library that resulted in the development and characterization of 22 markers, of which 18 were found to be polymorphic in the population studied. The mean expected heterozygosity was 0.59, whereas the mean rarified allelic richness was determined as 4.27 alleles per locus. The polymorphism level detected was similar to genetic diversity estimates found in other poneromorph ant species. The microsatellites developed here are likely to be useful for the investigation of colony structure, functional polygyny, breeding system, and population genetics in O. chelifer. Moreover, the description of O. chelifer's genetic diversity is crucial for its conservation and maintenance of its ecological role in the Cerrado savanna.

Are There Edge Effects on the Genetic Diversity of the Trap-Jaw Ant Odontomachus chelifer (Formicidae: Ponerinae) in a Neotropical Savanna Fragment? A First Assessment.

Habitat fragmentation is considered an important threat to biodiversity, increasing species exposure to edge effects. The Brazilian Cerrado savanna is considered a biodiversity hotspot and has been converted to small, isolated fragments due to human activities. Ant communities and colony survivorship are known to be affected by edge effects in Cerrado, but to date there is no information on the genetic diversity of ant colonies at the edge of fragmented areas. Here, we investigate if colony genetic diversity and structure of Odontomachus chelifer (Latreille) ants (Hymenoptera: Formicidae) are subject to edge effects in a Cerrado reserve in southeast Brazil. Using microsatellites, we evaluated the number of breeders (queens and males) and the genetic diversity in O. chelifer colonies located in the interior versus edge of a Cerrado fragment. All O. chelifer nests had multiple queens, which presented a low mating frequency. The number of breeders and most estimates of genetic diversity did not differ between colonies at the edge versus interior of the fragment. Genetic structure was not influenced by nest location as well. However, we detected a small and positive increase in the observed heterozygosity in colonies located at fragment edges. High heterozygosity is thought to be particularly important in fast-changing environments, such as edges, providing an advantage for genetic diversity. Further investigation is needed to assess in greater detail how habitat loss affects O. chelifer biology. Our study is a first step toward elucidating edge effects on genetic diversity of ant colonies, a topic still poorly explored in tropical environments.

Parasitoids Turn Herbivores into Mutualists in a Nursery System Involving Active Pollination.

Nursery pollination involves pollinators that lay eggs on the flowers they pollinate and have their brood fed on flower parts or developing ovules [1-4]. Active pollination, a ritualistic behavioral sequence shown by nursery pollinators when transferring pollen from anthers to stigmas, is known in only four plant lineages [5-8], including the classical examples of fig trees-fig wasps and yuccas-yucca moths [5, 6]. We report in detail a system in which weevils actively pollinate orchids prior to having their larvae fed on the developing fruits. Sampling over five years revealed that although weevils trigger fruit set, this interaction is negative for the plant as weevil larvae often consume all contents of infested fruits. However, part of weevil-infested fruits is often "rescued" by parasitoid wasps, which kill the weevil larvae before all fruit content is consumed (Figure 1). "Rescued" fruits present high seed viability and biomass similar to that of non-infested fruits, much higher than that of fruits with weevils only. Hence, parasitoids mediate the fitness consequences of the interaction between the plant and its parasitic pollinator. Weevils constitute a megadiverse group of herbivores commonly reported as florivores [9] but are also appreciated as flower-ovipositing pollinators of cycads and palms [4, 10-13] and were previously recorded carrying orchid pollinaria [14-16]. The orchid-weevil system presented here shows that plant-floral visitor interaction outcome can be mediated by a third party (parasitoids) and illustrates a way by which the biological context may allow the emergence and persistence of active nursery pollination behavior in nature.