Genetic diversity of cultivated and wild-type peanuts evaluated with M13-tailed SSR markers and sequencing

Thirty-one genomic SSR markers with a M13 tail attached were used to assess the genetic diversity of the peanut mini core collection. The M13-tailed method was effective in discriminating almost all the cultivated and wild accessions. A total of 477 alleles were detected with an average of 15.4 alleles per locus. The mean polymorphic information content (PIC) score was 0.687. The cultivated peanut (Arachis hypogaea L.) mini core produced a total of 312 alleles with an average of 10.1 alleles per locus. A neighbour-joining tree was constructed to determine the interspecific and intraspecific relationships in this data set. Almost all the peanut accessions in this data set classified into subspecies and botanical varieties such as subsp. hypogaea var. hypogaea, subsp. fastigiata var. fastigiata, and subsp. fastigiata var. vulgaris clustered with other accessions with the same classification, which lends further support to their current taxonomy. Alleles were sequenced from one of the SSR markers used in this study, which demonstrated that the repeat motif is conserved when transferring the marker across species borders. This study allowed the examination of the diversity and phylogenetic relationships in the peanut mini core which has not been previously reported.     

No Evidence of Enemy Release in Pathogen and Microbial Communities of Common Wasps (Vespula vulgaris) in Their Native and Introduced Range

When invasive species move to new environments they typically experience population bottlenecks that limit the probability that pathogens and parasites are also moved. The invasive species may thus be released from biotic interactions that can be a major source of density-dependent mortality, referred to as enemy release. We examined for evidence of enemy release in populations of the common wasp (Vespula vulgaris), which attains high densities and represents a major threat to biodiversity in its invaded range. Mass spectrometry proteomic methods were used to compare the microbial communities in wasp populations in the native (Belgium and England) and invaded range (Argentina and New Zealand). We found no evidence of enemy release, as the number of microbial taxa was similar in both the introduced and native range. However, some evidence of distinctiveness in the microbial communities was observed between countries. The pathogens observed were similar to a variety of taxa observed in honey bees. These taxa included Nosema, Paenibacillus, and Yersina spp. Genomic methods confirmed a diversity of Nosema spp., Actinobacteria, and the Deformed wing and Kashmir bee viruses. We also analysed published records of bacteria, viruses, nematodes and fungi from both V. vulgaris and the related invader V. germanica. Thirty-three different microorganism taxa have been associated with wasps including Kashmir bee virus and entomophagous fungi such as Aspergillus flavus. There was no evidence that the presence or absence of these microorganisms was dependent on region of wasp samples (i.e. their native or invaded range). Given the similarity of the wasp pathogen fauna to that from honey bees, the lack of enemy release in wasp populations is probably related to spill-over or spill-back from bees and other social insects. Social insects appear to form a reservoir of generalist parasites and pathogens, which makes the management of wasp and bee disease difficult.     

Phylogeny and divergence of the pinnipeds (Carnivora: Mammalia) assessed using a multigene dataset

Background  

Phylogenetic comparative methods are often improved by complete phylogenies with meaningful branch lengths (e.g., divergence dates). This study presents a dated molecular supertree for all 34 world pinniped species derived from a weighted matrix representation with parsimony (MRP) supertree analysis of 50 gene trees, each determined under a maximum likelihood (ML) framework. Divergence times were determined by mapping the same sequence data (plus two additional genes) on to the supertree topology and calibrating the ML branch lengths against a range of fossil calibrations. We assessed the sensitivity of our supertree topology in two ways: 1) a second supertree with all mtDNA genes combined into a single source tree, and 2) likelihood-based supermatrix analyses. Divergence dates were also calculated using a Bayesian relaxed molecular clock with rate autocorrelation to test the sensitivity of our supertree results further.     

Linking reproductive and feeding strategies in the parasitoid Ibalia leucospoides: does feeding always imply profit?

Resource acquisition and allocation to different biological functions over the course of life have strong implications for animal reproductive success. Animals can experience different environmental conditions during their lifetime, and this may play an important role in shaping their life-history and resource allocation strategies. In this study we investigate larval and adult resource allocation to reproductive and survival functions in the parasitoid wasp Ibalia leucospoides (family Ibaliidae). The pattern of larval resource allocation was inferred from the relationship between adult body size and ovigeny index (OI; a relative measure of investment in early reproduction determined as the ratio between the initial egg load and the potential lifetime fecundity); and adult resource allocation was explored through the influence of adult feeding on reproduction, maintenance and metabolism, in laboratory experiments. Food acquisition by this parasitoid in the wild was also examined. The relationship between size and OI was constant, suggesting no differential resource allocation to initial egg load and potential lifetime fecundity with size. This finding is in line with that predicted by adaptive models for the proovigenic egg maturation strategy (OI = 1). Despite of this, I. leucospoides showed a high OI of 0.77, which places this species among the weakly synovigenic ones (OI < 1). Adult feeding had no effect on post-emergence egg maturation. However, wasps extended their lifespan through feeding albeit only when food was provided ad libitum. Although the information we obtained on the feeding behaviour of free-foraging wasps is limited, our results suggest that food intake in the wild, while possible, may not be frequent in this parasitoid. We discuss the results relative to the environmental factors, such as reproductive opportunities and food availability, which may have driven the evolution of larval and adult pattern of resource allocation in parasitoids.     

c-Abl is required for oxidative stress-induced phosphorylation of caveolin-1 on tyrosine 14

Caveolin-1 is phosphorylated at tyrosine 14 in response to cellular stress. Tyrosine 14 is a consensus Abl phosphorylation site suggesting that caveolin-1 may be an Abl substrate. We report here that expression of c-Abl is required for oxidative stress-induced caveolin-1 phosphorylation. In contrast, c-Src expression is not required. Phosphocaveolin is one of only two phosphotyrosine signals missing in lysates from the Abl(-/-) cells, indicating that these cells still respond to oxidative stress. Oxidative stress-induced tyrosine phosphorylation of caveolin-1 occurs only at the Abl site, tyrosine 14. Caveolin-1 is also a major phosphotyrosine signal detected in cells over-expressing c-Abl. Our results show that Abl activation leads to phosphorylation of caveolin-1 on tyrosine 14. Both Abl and caveolin have been linked to the actin cytoskeleton, and oxidative stress-induced phosphocaveolin is enriched at focal contacts. This suggests that phosphocaveolin regulates these structures, perhaps through recruiting and activating SH2-domain proteins such as Csk.     

Of volcanoes and insects: the impact of the Puyehue–Cordon Caulle ash fall on populations of invasive social wasps, Vespula spp.

Volcanic eruptions have important effects on terrestrial ecosystems. The biotic effects of volcanic ash on insect populations vary from widespread and catastrophic to subtle and localized. Volcanic eruptions may increase insect mortality through the effects of the ash plume, and these vary by taxon or specific biological features. The Puyehue–Cordon Caulle Volcanic Complex is the most recent eruption in Patagonia. Here we explore and describe the effects of the eruption of this volcanic complex on invasive Vespula spp. populations. These wasps are very abundant social hymenoptera that have recently invaded Patagonia. We placed baited traps following the gradient of deposited ash, and revisited them once a week during February to April. No wasps were caught where ash deposition levels exceeded 3.0 cm. The number of wasps caught in sites with minimal ash deposits was similar to that of previous years. In locations where ash layers are intermediate, a few wasps were observed, but only during the peak of wasp abundance. We show that Vespula spp. populations were severely affected by the ash deposition and plume, caused by this eruption. These results show catastrophic effects of ash deposition over a large area, even at great distances from the eruption epicenter. We conclude that wasp mortality explained by the volcanic eruption may reach distant areas, and cause local extinction. In areas where active volcanoes are common, invasive insects may encounter an additional obstacle in their invasion success.     

Delayed emergence and the success of parasitoids in biological control

Delayed emergence, a life history feature of many insects living in unpredictable environments, can have major consequences for the dynamics of host–parasitoid interactions, which vary according to their physiological interactions. We studied, through simple modeling, the significance of prolonged diapause on the suppression levels achieved by parasitoids and illustrate our case with a system involving a major forest pest, the woodwasp Sirex noctilio and two of its parasitoid species that have been introduced into different geographical regions through classical biological control programmes. Our findings suggest that the physiological relationship between parasitoid and host delayed emergence patterns may help understand observed variable success in several bio-control programs. We conclude that for given environments, host delayed emergence and the way in which parasitoids deal with it, should be included in the list of selection criteria of natural enemies of many pests, especially those affecting forests.