Track analysis of the Mexican species of Buprestidae (Coleoptera): testing the complex nature of the Mexican Transition Zone

Aim  We analysed the geographical distributions of species of Buprestidae (Coleoptera) in Mexico by means of a panbiogeographical analysis, in order to identify their main distributional patterns and test the complex nature of the Mexican Transition Zone, located between the Nearctic and Neotropical regions.
Location  Mexico.
Methods  The geographical distributions of 228 species belonging to 33 genera of Buprestidae were analysed. Localities of the buprestid species were represented on maps and their individual tracks were drawn. Based on a comparison of the individual tracks, generalized tracks were detected and mapped. Nodes were identified as the areas where generalized tracks converged.
Results  Thirteen generalized tracks were obtained: one was restricted to the Mexican Transition Zone and five to the Neotropical region (Antillean and Mesoamerican dominions), a further two occurred in both the Nearctic region (Continental Nearctic dominion) and the Mexican Transition Zone, and a further five in both the Neotropical region (Mesoamerican dominion) and the Mexican Transition Zone. Seven nodes were identified at the intersections of the generalized tracks – in the Mesoamerican dominion (Mexican Pacific Coast, Mexican Gulf and Chiapas biogeographical provinces) and the Mexican Transition Zone (Trans-Mexican Volcanic Belt, Balsas Basin and Sierra Madre Oriental biogeographical provinces).
Main conclusions  We conclude that the geographical distribution of Buprestidae is mainly Neotropical, corresponding to the Mesoamerican dominion and the Antillean dominion of the Neotropical region, and the Mexican Transition Zone. Most of the generalized tracks and nodes correspond to the Mexican Transition Zone, thus confirming its complex nature. We suggest that the nodes we have identified could be particularly important areas to choose for conservation prioritization.     

Trade-offs in plant responses to herbivory influence trophic routes of production in a freshwater wetland

Responses of aquatic macrophytes to leaf herbivory may differ from those documented for terrestrial plants, in part, because the potential to maximize growth following herbivory may be limited by the stress of being rooted in flooded, anaerobic sediments. Herbivory on aquatic macrophytes may have ecosystem consequences by altering the allocation of nutrients and production of biomass within individual plants and changing the quality and quantity of aboveground biomass available to consumers or decomposers. To test the effects of leaf herbivory on plant growth and production, herbivory of a dominant macrophyte, Nymphaea odorata, by chrysomelid beetles and crambid moths was controlled during a 2-year field experiment. Plants exposed to herbivory maintained, or tended to increase, biomass and aboveground net primary production relative to controls, which resulted in 1.5 times more aboveground primary production entering the detrital pathway of the wetland. In a complementary greenhouse experiment, the effects of simulated leaf herbivory on total plant responses, including biomass and nutrient allocation, were investigated. Plants in the greenhouse responded to moderate herbivory by maintaining aboveground biomass relative to controls, but this response occurred at the expense of belowground growth. Results of these studies suggest that N. odorata may tolerate moderate levels of herbivory by reallocating biomass and resources aboveground, which in turn influences the quantity, quality and fate of organic matter available to herbivores and decomposers.     

Diet affects female mating behaviour in a seed‐feeding beetle

In species where males provide nuptial gifts, females can improve their nutritional status and thus increase their fecundity by mating when in need of resources. However, mating can be costly, so females should only mate to acquire resources when the need for resources is large, such as when females are nutritionally‐deprived. Two populations of the seed‐feeding beetle Callosobruchus maculatus, a species that produces relatively large nuptial gifts, are used to test whether female nutritional status affects mating behaviour. Female access to water, sugar and yeast are manipulated and the fitness consequences of these manipulations are examined together with the effects of diet on the propensity of nonvirgin females to mate. Access to water has a small but significant effect on mass loss over time, lifespan and fecundity of females, relative to unfed controls. Access to sugar (dissolved in water) improves female fecundity and lifespan above that of hydrated females but access to yeast has no positive effects on female survival or reproduction. Diet has a large effect on both receptivity of nonvirgin females to a male and how quickly they accept that male. Unfed females are both more likely to mate, and accept a mate more quickly, than females provided access to water, which are more likely to mate and accept a mate more quickly than females provided with sugar. This rank order of behaviours matches the order predicted if females increase their mating rate when nutritionally deprived (i.e. it matches the effect of diet on female fitness). The results obtained also suggest that mate choice may be condition‐dependent: females from one population (Burkina Faso) show a preference for large males when well‐fed but not when unfed, although this result is not found in a second population (South India). It is concluded that nutritionally‐deprived females are more receptive to mates than are well‐fed females, consistent with the hypothesis that females ‘forage’ for nuptial gifts, or at least more willingly accept sperm in exchange for nuptial gifts, when they are nutritionally deprived.     

Field trials against Hoplia philanthus (Coleoptera: Scarabaeidae) with a combination of an entomopathogenic nematode and the fungus Metarhizium anisopliae CLO 53

The white grub, Hoplia philanthus Füessly (Coleoptera: Scarabaeidae), is a major pest of turf and ornamental plants in Belgium. Previously, the combination of lethal concentration of the entomopathogenic nematodes Heterorhabditis megidis or Steinernema glaseri with the entomopathogenic fungus Metarhizium anisopliae (strain CLO 53) caused additive or synergistic mortality to third-instar H. philanthus in the laboratory and greenhouse. In this present study, we examined this interaction under field conditions and compared a combination of a commercial formulation of Heterorhabditis bacteriophora (Nema-green^®) and M. anisopliae. Controls were M. anisopliae, chlorpyrifos (Dursban 5 Granules) and H. bacteriophora. Field applications (surface or subsurface) were made against a mixed population of second/third-instar H. philanthus at a sport field and lawn infested in the province of West-Flanders. In both trials, the combination of M. anisopliae with H. bacteriophora at 5 × 10¹² conidia/ha +2.5 × 10⁹ infective juveniles/ha resulted in additive or synergistic effects, causing more than 95% grub mortality when the nematodes was applied 4 weeks after the application of fungus. However, application of nematode, chlorpyrifos or fungus alone provided 39–66%, 42–60% (surface) and 33–76%, 82–100% or 37–65%, (subsurface) control of H. philanthus. We concluded that the pathogen combinations we tested are compatible elements of integrated pest management and are likely to improve control of H. philanthus larvae and perhaps other insect pests beyond what is expected from single application of the pathogen.     

Estimation of effective population size and detection of a recent population decline coinciding with habitat fragmentation in a ground beetle

We assess the impact of habitat fragmentation on the effective size (N(e)) of local populations of the flightless ground beetle Carabus violaceus in a small (<25 ha) and a large (>80 ha) forest fragment separated by a highway. N(e) was estimated based on the temporal variation of allele frequencies at 13 microsatellite loci using two different methods. In the smaller fragment, N(e) estimates ranged between 59 and a few hundred, whereas values between 190 and positive infinity were estimated for the larger fragment. In both samples, we detected a signal of population decline, which was stronger in the small fragment. The estimated time of onset of this N(e) reduction was consistent with the hypothesis that recent road constructions have divided a continuous population into several isolated subpopulations. In the small fragment, N(e) of the local population may be so small that its long-term persistence is endangered.     

Fire Frequency and Mosaic Burning Effects on a Tallgrass Prairie Ground Beetle Assemblage

Fire frequency has significant effects on the biota of tallgrass prairie, including mammals, vascular plants and birds. Recent concern has been expressed that widespread annual burning, sometimes in combination with heavy livestock grazing, negatively impacts the biota of remaining prairie remnants. A common management recommendation, intended to address this problem, is to create a landscape with a mosaic of different burn regimes. Pitfall trapping was used to investigate the impacts of fire pattern on the diversity and species composition of ground beetles (Coleoptera: Carabidae) at Konza Prairie Biological Station in eastern Kansas, USA. Trapping was conducted over three seasons in landscape units burned on average every 1, 4, or 20 years, and in a fourth season across the available range of vegetative structure to assess the variability of the community within the study system. In the fifth season communities were also followed immediately after two fire events to detect within-season effects of fire and to study short-term patterns of post-disturbance community assembly. Fire frequency had comparatively minimal effects on ground beetle diversity measures, and most numerically common species were observed widely across habitat and management types. Fire frequency effects were manifested primarily in changes in abundance of common species. Colonization of burned areas apparently did not occur from juxtaposed non-burned areas, but from underground or from long distances. While these results suggest that widespread annual burning of tallgrass prairie remnants may not have dramatic effects on prairie ground beetles, we urge caution regarding the application of these results to other taxa within tallgrass prairie.     

Phylogeny of the Saprininae reveals interesting ecological shifts in the history of the subfamily (Coleoptera: Histeridae)

A morphological data set for the histerid beetle subfamily Saprininae comprising 95 adult morphological characters scored (multistate coding) from 72 terminal taxa and four outgroups was developed in order to analyse and determine the relationships amongst the genera and subgenera of the Saprininae subfamily. Cladograms were rooted with exemplars of Dendrophilinae (genus Dendrophilus), Bacaniini (genus Bacanius), Abraeinae (genus Chaetabraeus), and Anapleini (genus Anapleus). Parsimony‐based phylogenetic analyses were performed based on the type species of each genus and subgenus of the Saprininae occurring around the world, with the exception of three taxa: Paramyrmetes foveipennis (type species of the genus Paramyrmetes), Satrapister nitens (type species of the genus Satrapister) and Xerosaprinus (Auchmosaprinus) laciniatus (type species of the subgenus Auchmosaprinus) that were not available. In addition, in order to test the monophyly of several questionable genera, multiple exemplars were added in a few cases. The analysis also included an exemplar of an apparently undescribed genus. The results of the analysis confirm the monophyly of the subfamily supported by two unique synapomorphies: (1) presence of sensory structures of the antenna; and (2) presence of the antennal cavity, as well as several other weaker synapomorphies. However, the phylogeny inferred here shows mostly low support for the deeper branches and consequently no major changes in the Saprininae classification are proposed. The presented cladogram is discussed together with its implications for the evolution of the subfamily. The most informative characters and their respective states are outlined. Multiple shifts in lifestyles have evolved during the evolutionary history of the group. Taxa found near the root of the cladogram are mostly nidicolous or myrmecophilous, and inquiliny is presumed to be the plesiomorphic lifestyle of the subfamily. The nidicolous lifestyle has undergone several transformations to other lifestyles and myrmecophily has evolved three times independently during the evolution of the subfamily. Termitoxeny has evolved two times independently in the group whereas ecological adaptation for life in caves has likewise evolved two times independently. The analyses yielded a large clade of predominantly psammophilous taxa; psammophily is thought to have evolved once and has been subsequently lost several times. © 2014 The Linnean Society of London     

Global warming promotes biological invasion of a honey bee pest

Climate change and biological invasions are two major global environmental challenges. Both may interact, e.g. via altered impact and distribution of invasive alien species. Even though invasive species play a key role for compromising the health of honey bees, the impact of climate change on the severity of such species is still unknown. The small hive beetle (SHB, Aethina tumida, Murray) is a parasite of honey bee colonies. It is endemic to sub‐Saharan Africa and has established populations on all continents except Antarctica. Since SHBs pupate in soil, pupation performance is governed foremost by two abiotic factors, soil temperature and moisture, which will be affected by climate change. Here, we investigated SHB invasion risk globally under current and future climate scenarios. We modelled survival and development time during pupation (=pupal performance) in response to soil temperature and soil moisture using published and novel experimental data. Presence data on SHB distribution were used for model validation. We then linked the model with global soil data in order to classify areas (resolution: 10 arcmin; i.e. 18.6 km at the equator) as unsuitable, marginal and suitable for SHB pupation performance. Under the current climate, the results show that many areas globally yet uninvaded are actually suitable, suggesting considerable SHB invasion risk. Future scenarios of global warming project a vehement increase in climatic suitability for SHB and corresponding potential for invasion, especially in the temperate regions of the Northern hemisphere, thereby creating demand for enhanced and adapted mitigation and management. Our analysis shows, for the first time, effects of global warming on a honey bee pest and will help areas at risk to prepare adequately. In conclusion, this is a clear case for global warming promoting biological invasion of a pest species with severe potential to harm important pollinator species globally.     

Experimental evidence for the role of sexual selection in the evolution of cuticular hydrocarbons in the dung beetle,Onthophagus taurus

A role for sexual selection in the evolution of insect cuticular hydrocarbons (CHCs) is suggested by observations of selection acting on male CHCs during female mate choice. However, evidence that CHCs evolve in response to sexual selection is generally lacking, and there is a need to extend our understanding beyond well‐studied taxa. Experimental evolution offers a powerful approach to investigate the effect of sexual selection on the evolution of insect CHCs. We conducted such an experiment using the dung beetle, Onthophagus taurus. After six, 12 and 21 generations of experimental evolution, we measured the CHCs of beetles from three populations subject to sexual selection and three populations within which sexual selection had been removed via enforced monogamy. We found that the male CHC profile responded to the experimental removal of sexual selection. Conversely, the CHC profile of females responded to the presence of sexual selection but not to its removal. These results show that sexual selection can be an important mechanism affecting the evolution of insect CHCs and that male and female CHCs can evolve independently.