Vector preference for hosts differing in infection status: sharpshooter movement and Xylella fastidiosa transmission

1. Epidemiological theory predicts that vector preference for hosts differing in infection status (i.e. healthy or infected) affects disease dynamics. 2. Numerous studies have documented strong vector preference for or discrimination against infected hosts. However, the significance of these behaviours for pathogen transmission and spread has been poorly described. 3. We conducted a series of choice assays to evaluate orientation preference, feeding preference, and movement rates of an important group of vectors, the sharpshooter leafhoppers, based on host infection status for the generalist plant pathogen, Xylella fastidiosa Wells et al. 4. Sharpshooters did not discriminate between healthy versus infected‐but‐asymptomatic grapevines, but they oriented preferentially to healthy grapevines more frequently than either symptomatic vines or those artificially coloured to mimic disease symptoms. 5. In a field trial three sharpshooter species showed different movement rates and preferences for feeding site, but all species exhibited similar and significant preference for healthy hosts. 6. Although there was no significant difference in acquisition efficiency among vector species, those individuals that spent more time on healthy hosts tended to be less likely to acquire the pathogen. 7. These results suggest that sharpshooters discriminate against infected grapevines, which are likely to be of poorer quality, with visual cues playing a role in host selection. Preference by these vectors may affect pathogen acquisition, which could affect disease spread in the field.     

Thresholds and Time Lags in Effects of Energy Development on Greater Sage-Grouse Populations

ABSTRACT Rapid expansion of energy development in some portions of the Intermountain West, USA, has prompted concern regarding impacts to declining greater sage-grouse (Centrocercus urophasianus) populations. We used retrospective analyses of public data to explicitly investigate potential thresholds in the relationship between lek attendance by male greater sage-grouse, the presence of oil or gas wells near leks (surface occupancy), and landscape-level density of well pads. We used generalized linear models and generalized estimating equations to analyze data on peak male attendance at 704 leks over 12 years in Wyoming, USA. Within this framework we also tested for time-lag effects between development activity and changes in lek attendance. Surface occupancy of oil or gas wells adjacent to leks was negatively associated with male lek attendance in 5 of 7 study areas. For example, leks that had ≥ 1 oil or gas well within a 0.4-km (0.25-mile) radius encircling the lek had 35–91% fewer attending males than leks with no well within this radius. In 2 of these 5 study areas, negative effects of well surface occupancy were present out to 4.8 km, the largest radius we investigated. Declining lek attendance was also associated with a higher landscape-level density of well pads; lek attendance at well-pad densities of 1.54 well pads/km² (4 well pads/mile²) ranged from 13% to 74% lower than attendance at unimpacted leks (leks with zero well pads within 8.5 km). Lek attendance at a well-pad density of 3.09 well pads/km² (8 well pads/mile²) ranged from 77% to 79% lower than attendance at leks with no well pad within 8.5 km. Further, our analysis of time-lag effects suggested that there is a delay of 2–10 years between activity associated with energy development and its measurable effects on lek attendance. These results offer new information for consideration by land managers on spatial and temporal associations between human activity and lek attendance in sage-grouse, and suggest that regional variation is an important consideration in refining existing management strategies.     

The timing of resource availability does not affect reproductive allotment or the rate of oocyte development in the flesh fly,Sarcophaga crassipalpis

1. The flesh fly, Sarcophaga crassipalpis, is anautogenous and largely relies on adult‐acquired income resources for reproduction, but allocates some larvally derived capital into the first clutch. Therefore, the timing of adult resource acquisition may be important for both reproductive timing and magnitude of capital vs. income resources allocated to reproduction. Specifically, we predict that flesh flies that wait longer to acquire adult income resources will allocate greater quantities of larvally derived capital to the first clutch. 2. To test how reproductive allocation in flesh flies responds to the timing of adult protein availability, we provided pulses of protein only on day 3, 6, 9, or 12 after eclosion, a series of times equivalent to the onset of oogensis and early, middle and late oogenic development in individuals fed ad libitum. Protein pulses contained isotopically distinct carbon (¹³C), allowing us to distinguish between larval capital and adult‐income resources allocated towards reproduction. 3. Neither the timing of oocyte development nor reproductive allotment (egg number by egg size) was altered by the timing of protein availability. 4. There was no effect of adult protein acquisition timing on the quantity of larvally derived somatic capital vs. adult‐acquired income carbon allocated to reproduction. While flesh flies have remarkable pre‐feeding plasticity in reproductive timing, they appear to have little post‐feeding plasticity in allocation of stored reserves towards reproduction.     

7‐methylheptacosane is a major component of the contact sex pheromone of the cerambycid beetle Neoclytus acuminatus acuminatus

Abstract Male Neoclytus acuminatus acuminatus (F.) (Coleoptera: Cerambycidae) attempt to mate with females only after touching them with their antennae, suggesting that mate recognition is mediated by contact pheromones in the cuticular wax layer of females. Consistent with that hypothesis, males exhibit similar responses to dead females in laboratory bioassays, but not to solvent‐washed dead females with their cuticular hydrocarbons removed. The mating response of males is restored when solvent extracts are reapplied to carcasses of solvent‐washed females, indicating that the contact pheromone is present in solvent extracts. Solvent extracts of the female cuticle contain six methylalkanes that are not present in extracts of males, three of which (7Me‐C₂₅, 7Me‐C₂₇ and 9Me‐C₂₇) constitute almost 40% of the total hydrocarbons. The bioactivity of these three compounds is tested by applying synthetic standards to solvent‐washed carcasses of females and presenting them to males. Standards are tested singly, pairwise and as the complete blend; freeze‐killed females serve as controls. Males attempt to couple with solvent‐washed female carcasses treated with 7Me‐C₂₇ alone and in combination with 9Me‐C₂₇ but only the complete blend elicits the same number of mounting and coupling attempts as does the control. These findings suggest that 7Me‐C₂₇ (7‐methylheptacosane) is the major component of the contact sex pheromone of N. a. acuminatus and that 7Me‐C₂₅ and 9Me‐C₂₇ act as synergists.     

Mixed-conifer understory response to climate change, nitrogen, and fire

California's Sierra Nevada mountains are predicted to experience greater variation in annual precipitation according to climate change models, while nitrogen deposition from pollution continues to increase. These changes may significantly affect understory communities and fuels in forests where managers are attempting to restore historic conditions after a century of altered fire regimes. The objective of this research was to experimentally test the effects of increasing and decreasing snowpack depth, increasing nitrogen, and applying prescribed fire to mixed-conifer forest understories at two sites in the central and southern Sierra Nevada. Understory response to treatments significantly differed between sites with herb biomass increasing in shrub-dominated communities when snowpack was reduced. Fire was a more important factor in post-treatment species richness and cover than either snowpack addition or reduction. Nitrogen additions unexpectedly increased herbaceous species richness. These varied findings indicate that modeling future climatic influences on biodiversity may be more difficult than additive prediction based on increasing the ecosystem's two limiting growth resources. Increasing snowpack and nitrogen resulted in increased shrub biomass production at both sites and increased herb production at the southern site. This additional understory biomass has the potential to increase fuel connectivity in patchy Sierran mixed-conifer forests, increasing fire severity and size.     

PARENTAL LOVE PILLS: SOME ETHICAL CONSIDERATIONS

It may soon be possible to develop pills that allow parents to induce in themselves more loving behaviour, attitudes and emotions towards their children. In this paper, I consider whether pharmacologically induced parental love can satisfy reasonable conditions of authenticity; why anyone would be interested in taking such parental love pills at all, and whether inducing parental love pharmacologically promotes narcissism or results in self‐instrumentalization. I also examine how the availability of such pills may affect the duty to love a child.     

Interspecific Interactions between Primates,Birds, Bats,and Squirrels May Affect Community Composition on Borneo

For several decades, primatologists have been interested in understanding how sympatric primate species are able to coexist. Most of our understanding of primate community ecology derives from the assumption that these animals interact predominantly with other primates. In this study, we investigate to what extent multiple community assembly hypotheses consistent with this assumption are supported when tested with communities of primates in isolation versus with communities of primates, birds, bats, and squirrels together. We focus on vertebrate communities on the island of Borneo, where we examine the determinants of presence or absence of species, and how these communities are structured. We test for checkerboard distributions, guild proportionality, and Fox's assembly rule for favored states, and predict that statistical signals reflecting interactions between ecologically similar species will be stronger when nonprimate taxa are included in analyses. We found strong support for checkerboard distributions in several communities, particularly when taxonomic groups were combined, and after controlling for habitat effects. We found evidence of guild proportionality in some communities, but did not find significant support for Fox's assembly rule in any of the communities examined. These results demonstrate the presence of vertebrate community structure that is ecologically determined rather than randomly generated, which is a finding consistent with the interpretation that interactions within and between these taxonomic groups may have shaped species composition in these communities. This research highlights the importance of considering the broader vertebrate communities with which primates co‐occur, and so we urge primatologists to explicitly consider nonprimate taxa in the study of primate ecology. Am. J. Primatol. 75:170‐185, 2013. © 2012 Wiley Periodicals, Inc.     

Agricultural Seed Biomass for Migrating and Wintering Waterfowl in the Southeastern United States

ABSTRACT Waterfowl frequently acquire high-energy agricultural seeds in harvested and unharvested croplands during migration and winter. Estimates of agricultural seed biomass in harvested and unharvested corn, soybean, and grain sorghum fields do not exist or are outdated for the southeastern United States. Therefore, we estimated seed biomass in 105 harvested and 59 unharvested corn, soybean, and grain sorghum fields across 4 climate regions in Tennessee, USA, from September through January 2006 and 2007. We also used estimates of seed biomass to calculate duck-energy days (DEDs) in December and January when migratory waterfowl abundance peaks in the southeastern United States. Mean biomass of corn, soybean, and grain sorghum seed in harvested fields declined 239 kg/ha to 39 kg/ha, 118 kg/ha to 26 kg/ha, and 392 kg/ha to 19 kg/ha, respectively, from postharvest to January. Continuous monthly rates of decline were 64% for corn, 84% for soybean, and 74% for grain sorghum. Agricultural seed biomass in harvested corn and grain sorghum fields dropped below the waterfowl giving-up density (i.e., 50 kg/ha) in 3 months; soybean dropped below this threshold 1 month postharvest. Mean DEDs/ha in harvested corn, soybean, and grain sorghum fields were low (274, 90, and 27, respectively) in January, and DEDs were zero in >85% of fields. In unharvested corn, soybean, and grain sorghum fields, mean DEDs/ha in January were high (69,000, 18,000, and 26,000, respectively), and continuous rates of decline (3%, 7%, and 18%, respectively) were much lower than for harvested crops. Waterfowl biologists in the Southeast should use our estimates of agricultural seed biomass in DED calculations. We also recommend that biologists provide unharvested grain fields and natural wetlands for migrating and wintering waterfowl because seed resources are low in harvested agricultural fields.     

Assessing conservation value of stream communities: a comparison of approaches based on centres of density and species richness

1. We used a recently developed Index of Centres of Density (ICD) to assess conservation value of thirty-nine sites in the upper Clinch River drainage of Virginia and Tennessee, U.S.A. The ICD incorporates information on the population density of each species at a site relative to sites throughout the region.
2. Value assessments based on the ICD were compared to those based on species richness. Species richness at sites was not related to ICD scores, but collective species lists from high-ranking sites were similar for both approaches. All sites with rare species had either a high ICD score or high species richness.
3. Four community types (defined by physiography and stream size) were better represented in sites with high-ranking ICDs than in sites with high-ranking species richness. Sites with high ICD scores were distributed uniformly throughout the region.
4. The ICD is a more powerful tool than species richness for assessing conservation value because the ICD identifies areas with regionally rare species, especially viable populations, or distinctive communities, all of which are key components of a region's biodiversity.