Modeling Climatic Influences on Three Parasitoids of Low-Density Spruce Budworm Populations. Part 2: Meteorus trachynotus (Hymenoptera: Braconidae)

This is the second article of a series of three where we develop temperature-driven models to describe the seasonal interactions between parasitoids and their hosts which we use to explore the impact of climate on their spatiotemporal biology. Here, we model the biology of Meteorus trachynotus (Hymenoptera: Braconidae) with an individual-based model of its daily interactions with two host species. This model predicts the performance of the parasitoid in response to temperature affecting its seasonal development and that of the two hosts. We compare model output with an extensive set of field observations from natural host populations. The predicted activity of the first adult parasitoid generation closely matches the seasonal pattern of attack on the spruce budworm, Choristoneura fumiferana (Lepidoptera: Tortricidae) within the limitations of available data. The model predicts 1–4 full generations of M. trachynotus per year in eastern North America, with generations well synchronized with larvae of a known overwintering host, the obliquebanded leafroller Choristoneura rosaceana. The model predicts the observed density dependence of parasitism on spruce budworm. Predicted performance exhibits spatial variation caused by complex life-history interactions, especially synchrony with the overwintering host. This leads to a better performance in warm but not hot environments at middle latitudes and elevations. The model’s predicted spatial patterns correspond closely to our field observations on the frequency of parasitism on spruce budworm. Under climate change, the model predicts that the performance of M. trachynotus populations will improve in the northern portion of its range.

Missing pieces in the full annual cycle of fish ecology: a systematic review of the phenology of freshwater fish research

In recent decades, fish ecologists have become increasingly aware of the need for spatially comprehensive sampling. However, a corresponding reflection on the temporal aspects of research has been lacking. We quantified the seasonal timing and extent of freshwater fish research. Since reviewing all prior work was not feasible, we considered two different subsets. First, we compiled the last 30 years of ecological research on juvenile Pacific salmon and trout (Oncorhynchus spp.) (n = 371 studies). In addition to the aggregate, we compared groups classified by subject matter. Next, to evaluate whether riverscape ecology has embraced space at the expense of time, we compiled research across taxa in which fish were enumerated in a spatially continuous fashion (n = 46). We found that ecological Oncorhynchus spp. research was biased towards summer (40% occurred during June-August) and the month of June in particular, at the expense of winter work (only 13% occurred during December-February). Riverscape studies were also biased toward summer (47% of studies) and against winter (11%). It was less common for studies to encompass multiple seasons (43% of ecological Oncorhynchus spp. studies and 54% of riverscape studies) and most were shorter than 4 months (73% of ecological Oncorhynchus spp. studies and 81% of riverscape studies). These temporal biases may cause researchers to overemphasize ecological phenomena observed during summer and limit our ability to recognize seasonal interactions such as carry-over effects or compensatory responses. Full year and winter studies likely hold valuable insights for conservation and management.

Vertebrate species richness at littoral beaver lodges in a temperate artificial pond

The North American beaver Castor canadensis is widely recognized for its ability to modify freshwater habitats and facilitate changes in community composition. However, the seasonal composition of terrestrial wildlife at littoral beaver lodges remains poorly described, even though these structures are distinctive semi-permanent features of the terrestrial-aquatic interface and thus important resources for wildlife. Over 17 months, we used camera trapping, weather data, and satellite vegetation data to determine how vertebrate species richness and seasonal changes in community composition are associated with beaver activity and beaver lodges in a temperate artificial pond. Our results indicate clear changes in the composition of lodge visitors across seasons. Moreover, species richness was not strongly associated with beaver activity, vegetative condition, or weather condition. Littoral beaver lodges are likely important foraging sites for a wide range of taxa throughout the year. Our findings highlight the importance of beaver lodges in facilitating seasonal interactions and variation in species composition. We hope our work can be used as a baseline to investigate the importance of beaver structures in promoting diversity at the terrestrial-aquatic interface.

The NASA ORACLES airborne flight projects – lessons learned for future multi-platform missions to study aerosol-cloud-climate interactions

<p>Three deployments involving the NASA P-3 and ER-2 aircraft in the ORACLES (ObseRvations of Aerosols above CLouds and their intEractionS) project in September 2016, August 2017 and October 2018 were designed to study the seasonal interactions of biomass burning (BB) aerosols emanating from Southern Africa with the semi-permanent subtropical stratocumulus (Sc) cloud deck over the South-East (SE) Atlantic. We provide a science overview of all deployments, describing novel approaches for coordinating the NASA aircraft with each other, with the Bae-146 aircraft during flights near Ascension Island in 2017, and with satellite overpasses. Based on various examples, we describe the requirements for spatiotemporal coordination and the scientific benefits gleaned from successful synergy of datasets thus obtained. We provide the current status of integrative work that addresses the overarching science questions regarding aerosol-radiation-climate interactions in the region. We conclude by linking the suborbital observations with overarching observational efforts, in particular NASA’s ACCP (Aerosols, Clouds, Convection, and Precipitation) Designated Observable study, which aims to define combinations of orbital and suborbital observing system concepts for addressing integrated aerosol-cloud-climate objectives as defined in the 2017 US Decadal Survey.</p>

212 Ovarian ultrasound of sows by parity and season to determine effects of induced ovulation and single PCAI on farrowing rate and litter size

Increasing the distribution of semen from genetically superior sires accelerates the rate of improvement of economically important traits. Using a single fixed time post-cervical AI (SFTI) with ovulation control, the number of inseminations per ejaculate can be doubled. The objective of the study was to determine whether ovarian ultrasound could help identify parity (P1, 2, 3-6, ≥ 7) and seasonal (May-Jun, Jul-Aug, Sep-Oct) effects on fertility following induced ovulation and SFTI. Sows received OvuGel® (n = 914) on Days 3-5 after weaning and a SFTI 24 h later. Control sows (n = 881) that expressed estrus on Days 3-6 received a post-cervical AI on each day standing. Ovaries of a sub-population of sows (n = 436) were scanned by ultrasound to assess follicle size and insemination to ovulation interval. Interval from insemination to ovulation > 24 h tended (P = 0.09) to reduce farrowing rate (FR, 74.1 ± 2.8%) compared to inseminations £ 24 h (83.4 ± 2.8%), regardless of treatment. In addition, sows that ovulated by Day 6 after weaning had greater (P = 0.03) total born (TB, 12.9 ± 0.5) than those ovulating ≥ 7 d (11.5 ± 0.5). Follicle number (16.3 ± 0.7) and size (7.0 ± 0.5 mm) on Day 4 did not differ between treatments. OvuGel increased (P = 0.002) the proportion of sows ovulating (88.9%) versus Controls (78.6%), but for both treatments, fewer P1 sows ovulated (75.0%) when compared to P3-6 (90.4%). Treatments did not differ in FR (78.5%), but seasonal interactions were observed (P = 0.05), most notably in Sep-Oct. Parity affected FR (P = 0.02), and was lower in P1 (66.1%) compared to 3 P2 (82.2%). Also, OvuGel and Control did not differ in TB (13.0) but parity ≥ 7 had the lowest TB (11.8) compared to younger parity females. In summary, OvuGel increased the proportion of sows ovulating by 10.3%, resulting in similar FR and TB compared to Control sows inseminated multiple times based on estrus.

Relationship between soil apparent electrical conductivity and forage yield in temperate pastures according to nitrogen availability and growing season

Mapping of the apparent soil electrical conductivity (ECa) can be used to estimate the variability of forage yield within a plot. However, forage production can vary according to the growing season and to soil properties that do not affect the ECa (e.g. nitrogen (N) content). The aim of this study was to assess the relationship between ECa and forage yield of tall fescue (Lolium arundinaceum (Schreb.) Darbysh.) during different regrowth periods and contrasting levels of N availability and then use this information to determine potential management zones. The ECa was measured and geo-referenced in a 5.75-ha paddock that sustained a permanent pasture dominated by tall fescue. In addition, a 30 m by 30 m grid cell size was chosen and 43 sampling areas, each 4 m2 in size, were geo-referenced and divided into two experimental units of 1 m by 2 m, one of which was fertilised with 250 kg N ha–1 (N250) at the beginning of four regrowth periods (spring 2015, spring 2016, autumn 2016 and autumn 2017) and the other was not fertilised with N (N0). At the end of each regrowth period, we estimated the accumulated biomass. During the spring growing season, accumulated biomass was positively associated with ECa in both N0 and N250 treatments (R2 = 47% and 54%, respectively). By contrast, in autumn, accumulated biomass and ECa were poorly associated (R2 = 10% and 27% for N0 and N250). This may be due to seasonal interactions that alter soil–yield relationships. To assess whether ECa can be used to determine management zones, the differences in accumulated biomass were compared through analysis of variance. Results showed that ECa is associated with the spatial distribution of tall fescue forage yield variability in spring at different N availabilities. Thus, ECa can be reliably used for defining management zones in marginal soils under permanent pastures.

TREND–CYCLE–SEASONAL INTERACTIONS: IDENTIFICATION AND ESTIMATION

Economists typically use seasonally adjusted data in which the assumption is imposed that seasonality is uncorrelated with trend and cycle. The importance of this assumption has been highlighted by the Great Recession. The paper examines an unobserved components model that permits nonzero correlations between seasonal and nonseasonal shocks. Identification conditions for estimation of the parameters are discussed from the perspectives of both analytical and simulation results. Applications to UK household consumption expenditures and US employment reject the zero correlation restrictions and also show that the correlation assumptions imposed have important implications about the evolution of the trend and cycle in the post-Great Recession period.