Effects of Large-Scale Predator Reduction on Nest Success of Upland Nesting Ducks

ABSTRACT Population growth for mallards (Anas platyrhynchos), and presumably other upland nesting ducks, in the Prairie Pothole Region of the United States and Canada is most sensitive to nest success, and nest success is most strongly influenced by predation. We evaluated the efficacy of reducing predator populations to improve nest success of upland nesting ducks on township-sized (93.2 km²) management units in eastern North Dakota, USA, during 2005–2007. We monitored 7,489 nests on 7 trapped and 5 nontrapped sites. Trappers annually removed an average of 245 predators per trapped site, and we found nest success to be 1.4–1.9 times greater on trapped sites than nontrapped sites, depending on year. Nest success was greater on both trapped and nontrapped sites when compared with a study conducted in the same areas in the mid-1990s, likely because of changes in red fox (Vulpes vulpes) and coyote (Canis latrans) population dynamics. Nests initiated midseason had higher daily survival rates (DSR) than those initiated earlier or later in the season. Daily survival rates for nests in the middle of the nesting cycle were higher than for nests that were early in laying or late in incubation. Nests near the periphery of trapped sites had slightly higher DSRs than nests in the center of trapped sites. Predator reduction at the township scale provides managers with an effective tool to improve nest success at large spatial scales.     

A line transect density index for wolf spiders (Pardosa spp.), and a note on the applicability of catch per unit effort methods to entomological studies

Abstract. 1. A line transect density index for small wolf spiders is described and shown by means of regression analysis to provide adequate accuracy and excellent reproducibility.
2. A review of the literature discloses numerous regression and replication studies of other catch per unit effort methods possessing equal precision and reliability.
3. Such methods, when used judiciously, can provide accuracy and reproducibility as good as those obtainable using the statistical methods now in wider use, and deserve serious consideration in many kinds of sampling situations.     

One and the same: integrative taxonomic evidence that Bactrocera invadens (Diptera: Tephritidae) is the same species as the Oriental fruit fly Bactrocera dorsalis

The invasive fruit fly Bactrocera invadens Drew, Tsuruta & White, and the Oriental fruit fly Bactrocera dorsalis (Hendel) are highly destructive horticultural pests of global significance. Bactrocera invadens originates from the Indian subcontinent and has recently invaded all of sub‐Saharan Africa, while B. dorsalis principally occurs from the Indian subcontinent towards southern China and South‐east Asia. High morphological and genetic similarity has cast doubt over whether B. invadens is a distinct species from B. dorsalis. Addressing this issue within an integrative taxonomic framework, we sampled from across the geographic distribution of both taxa and: (i) analysed morphological variation, including those characters considered diagnostic (scutum colour, length of aedeagus, width of postsutural lateral vittae, wing size, and wing shape); (ii) sequenced four loci (ITS1, ITS2, cox1 and nad4) for phylogenetic inference; and (iii) generated a cox1 haplotype network to examine population structure. Molecular analyses included the closely related species, Bactrocera kandiensis Drew & Hancock. Scutum colour varies from red‐brown to fully black for individuals from Africa and the Indian subcontinent. All individuals east of the Indian subcontinent are black except for a few red‐brown individuals from China. The postsutural lateral vittae width of B. invadens is narrower than B. dorsalis from eastern Asia, but the variation is clinal, with subcontinent B. dorsalis populations intermediate in size. Aedeagus length, wing shape and wing size cannot discriminate between the two taxa. Phylogenetic analyses failed to resolve B. invadens from B. dorsalis, but did resolve B. kandiensis. Bactrocera dorsalis and B. invadens shared cox1 haplotypes, yet the haplotype network pattern does not reflect current taxonomy or patterns in thoracic colour. Some individuals of B. dorsalis/B. invadens possessed haplotypes more closely related to B. kandiensis than to conspecifics, suggestive of mitochondrial introgression between these species. The combined evidence fails to support the delimitation of B. dorsalis and B. invadens as separate biological species. Consequently, existing biological data for B. dorsalis may be applied to the invasive population in Africa. Our recommendation, in line with other recent publications, is that B. invadens be synonymized with B. dorsalis.     

Ecological and economic analysis of lake eutrophication by nonpoint pollution

Abstract The hypothesis that economic damage due to nonpoint pollution exceeds costs of mitigation can be tested by ecologists, economists, and resource managers working at the spatial scale of watersheds for periods of years to decades. We present a framework for combining ecological and economic information to compare management scenarios for nonpoint pollution. Eutrophication of lakes caused by nonpoint phosphorus pollution, a common environmental problem, is the focus of our approach. Economic advantages of mitigating nonpoint pollution increase as the uncertainty of ecological predictions decreases. Uncertainty is measured by the prediction variance of nonpoint pollution models. A major source of variance in nonpoint pollution predictions is the effect of land use change on phosphorus transport. This variance is often large because calibration data sets do not have sufficiently wide ranges of land use variables. Ecological predictions and the resulting economic assessments could be improved by comparative studies of watersheds with contrasting land uses, and by viewing nonpoint pollution management as a large-scale experiment.     

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.