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In establishing Integrated Pest Management (IPM) plans for understudied pests, it is crucial to understand the nature of their herbivory and resulting damage. European earwig (Forficula auricularia L.; Dermaptera: Forficulidae) densities are increasing in citrus orchards in Central California. Field observations suggest that earwigs feed on young, developing citrus fruit, but this hypothesis had not been examined with formal experimentation. Forktailed bush katydid nymphs (Scudderia furcata Brunner von Wattenwyl; Orthoptera: Tettigoniidae) are well-known citrus herbivores that feed on young citrus fruit, and it is possible that earwig damage may be misdiagnosed as katydid damage. Here we report findings from two field experiments in navel oranges (Citrus sinensis (L.) Osbeck; Sapindales: Rutaceae) that together tested: (1) whether earwigs damage young citrus fruit; (2) whether the amount of damage earwigs generate differs across developmental stage or sex of adult earwigs; (3) the window of time during which fruit are most sensitive to earwig damage; (4) whether damaged fruit are retained to harvest; and (5) the resulting damage morphology caused by earwigs relative to katydids. Earwigs, particularly nymphs, chewed deep holes in young citrus fruit from 0 to 3 wk after petal fall. Fruit damaged by earwigs were retained and exhibited scars at harvest. The morphology and distribution of scars on mature fruit only subtly differed between earwigs and katydids. This study establishes that earwigs can be direct pests in mature navel orange trees by generating scars on fruit and likely contribute to fruit quality downgrades.

Individuals with potential exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) do not necessarily develop PCR or antibody positivity, suggesting that some individuals may clear subclinical infection before seroconversion. T cells can contribute to the rapid clearance of SARS-CoV-2 and other coronavirus infections1–3. Here we hypothesize that pre-existing memory T cell responses, with cross-protective potential against SARS-CoV-2 (refs. 4–11), would expand in vivo to support rapid viral control, aborting infection. We measured SARS-CoV-2-reactive T cells, including those against the early transcribed replication–transcription complex (RTC)12,13, in intensively monitored healthcare workers (HCWs) who tested repeatedly negative according to PCR, antibody binding and neutralization assays (seronegative HCWs (SN-HCWs)). SN-HCWs had stronger, more multispecific memory T cells compared with a cohort of unexposed individuals from before the pandemic (prepandemic cohort), and these cells were more frequently directed against the RTC than the structural-protein-dominated responses observed after detectable infection (matched concurrent cohort). SN-HCWs with the strongest RTC-specific T cells had an increase in IFI27, a robust early innate signature of SARS-CoV-2 (ref. 14), suggesting abortive infection. RNA polymerase within RTC was the largest region of high sequence conservation across human seasonal coronaviruses (HCoV) and SARS-CoV-2 clades. RNA polymerase was preferentially targeted (among the regions tested) by T cells from prepandemic cohorts and SN-HCWs. RTC-epitope-specific T cells that cross-recognized HCoV variants were identified in SN-HCWs. Enriched pre-existing RNA-polymerase-specific T cells expanded in vivo to preferentially accumulate in the memory response after putative abortive compared to overt SARS-CoV-2 infection. Our data highlight RTC-specific T cells as targets for vaccines against endemic and emerging Coronaviridae.

Due to the difficulty of tracking microbial dispersal, it is rarely possible to disentangle the relative importance of dispersal and species sorting for microbial community assembly. Here, we leverage a detailed multilevel network to examine drivers of bacterial community assembly within flowers. We observed flower visitors to 20 focal plant species in a coflowering community in the Sierra Nevada, revealing 289 species of arthropods. We also analyzed bacterial communities on flowers of each species. We found that plant species with similar visitor communities tend to have similar bacterial communities, and visitor identity to be more important than plant relatedness in structuring floral bacterial communities. However, plant species that were hubs of arthropod visitation were not necessarily hubs of floral bacteria, suggesting an important role for species sorting. Across plant species, the composition of flower‐visiting Diptera (flies), bees and non‐bee Hymenoptera best predicted bacterial species composition on flowers. Taken together, our analyses suggest dispersal is important in determining similarity in microbial communities across plant species, but not as important in determining the overall macrostructure (nestedness, modularity) and microstructure (connectedness based on shared interactors) of the floral bacterial network. A multilevel network approach thus allows us to address features of community assembly that cannot be considered when viewing networks as separate entities.

Sweet oranges (Citrus sinensis (L.) Osbeck Sapindales: Rutaceae) dominated commercial citrus production in California until recently when there has been a shift to mandarins, mostly Citrus reticulata (Blanco) mandarins and Citrus clementina (hort. ex Tanaka) clementines. Past analyses of commercial field scouting and harvest data indicated that fork-tailed bush katydids (Scudderia furcata Brunner von Wattenwyl), a major pest in oranges, are present in clementine groves, but that fruit scarring attributed to katydids is rare. Conversely, jagged or web-like scarring attributed to caterpillars was more prevalent than expected. We used two field experiments in four representative cultivars of clementines to test four explanatory hypotheses for this observation: 1) katydids do not feed on clementine fruit, 2) damaged clementine fruit recover, 3) damaged clementine fruit preferentially abscise, and 4) katydid scars on clementine fruit have a different, undocumented morphology, not recognized as katydid damage. We find support for the latter two hypotheses. Katydids fed readily on the clementine fruit of all cultivars tested, chewing irregular holes that developed into jagged or web-like scars of a range of shapes and often led to splitting and abscission of maturing fruit. The katydid scars often more closely resembled chewing caterpillar damage than the round katydid scars in oranges, suggesting that katydid damage is being misclassified in clementines. The resistance documented in some other mandarins was not observed. Katydids are clearly a frugivorous pest causing previously unrecognized scarring in clementines.

Individuals with likely exposure to the highly infectious SARS-CoV-2 do not necessarily develop PCR or antibody positivity, suggesting some may clear sub-clinical infection before seroconversion. T cells can contribute to the rapid clearance of SARS-CoV-2 and other coronavirus infections1–5. We hypothesised that pre-existing memory T cell responses, with cross-protective potential against SARS-CoV-26–12, would expand in vivo to mediate rapid viral control, potentially aborting infection. We studied T cells against the replication transcription complex (RTC) of SARS-CoV-2 since this is transcribed first in the viral life cycle13–15and should be highly conserved. We measured SARS-CoV-2-reactive T cells in a cohort of intensively monitored healthcare workers (HCW) who remained repeatedly negative by PCR, antibody binding, and neutralisation for SARS-CoV-2 (exposed seronegative, ES). 16-weeks post-recruitment, ES had memory T cells that were stronger and more multispecific than an unexposed pre-pandemic cohort, and more frequently directed against the RTC than the structural protein-dominated responses seen post-detectable infection (matched concurrent cohort). The postulate that HCW with the strongest RTC-specific T cells had an abortive infection was supported by a low-level increase in IFI27 transcript, a robust early innate signature of SARS-CoV-2 infection16. We showed that the RNA-polymerase within RTC was the largest region of high sequence conservation across human seasonal coronaviruses (HCoV) and was preferentially targeted by T cells from UK and Singapore pre-pandemic cohorts and from ES. RTC epitope-specific T cells capable of cross-recognising HCoV variants were identified in ES. Longitudinal samples from ES and an additional validation cohort, showed pre-existing RNA-polymerase-specific T cells expanded in vivo following SARS-CoV-2 exposure, becoming enriched in the memory response of those with abortive compared to overt infection. In summary, we provide evidence of abortive seronegative SARS-CoV-2 infection with expansion of cross-reactive RTC-specific T cells, highlighting these highly conserved proteins as targets for future vaccines against endemic and emerging Coronaviridae.

Although surveys of pest populations documenting evolved insecticide resistance often suggest abundant potential for insecticide control failures, studies documenting the actual occurrence of such failures in commercial agriculture are rare. If farmers currently practice adaptive management, abandoning the use of insecticides once resistance emerges, actual control failures could be rare. Here I use data gathered by independent pest management consultants to describe a case study of the realized efficacy of commercial field applications of insecticides, examining the control of Lygus hesperus Knight on cotton. On average, insecticides reduced target pest populations to 19% of their preapplication densities. Short-term efficacy of insecticides was variable, but only one severe control failure was observed (1 of 50, 2%). The rarity of severe control failures observed in this study is in agreement with the few other studies conducted in commercial settings, but additional research is needed to assess the generality of this result. Although pesticides can cause longer-term problems, including target pest resurgences and secondary pest outbreaks, risk-averse attitudes among farmers coupled with relatively consistent short-term insecticide efficacy may be potent forces propelling farmers toward the use of insecticides.

Integrated pest management (IPM) guidelines for horticulture are typically established from years of experimental research and experience for a crop species. Ecoinformatics methods can help to quickly adapt these guidelines following major changes in growing practices. Citrus production in California is facing several major challenges, one of which is a shift away from sweet oranges [Citrus sinensis (L.) Osbeck Sapindales: Rutaceae] toward mandarins (including mostly cultivars of C. reticulata Blanco and C. clementina hort. ex Tanaka). In the absence of IPM guidelines for mandarins, growers are relying on pest information developed from oranges. We mined a database of management records from commercial growers and consultants to determine densities for four arthropod pests: cottony cushion scale (Icerya purchasi Maskell Hemiptera: Monophlebidae), citricola scale (Coccus pseudomagnoliarum Kuwana Hemiptera: Coccidae), European earwig (Forficula auricularia Linnaeus Dermaptera: Forficulidae), citrus red mite (Panonychus citri McGregor Acari: Tetranychidae), and a natural enemy, predatory mites in the genus Euseius (Congdon Acarina: Phytoseiidae). Densities of cottony cushion scale were approximately 10–40 times higher in the two most commonly grown mandarin species than in sweet oranges, suggesting this pest is reaching outbreak levels more often on mandarins. Densities of the other pests and predatory mites did not differ significantly across citrus species. This is a first step toward establishing IPM guidelines for mandarins for these pests; more research is needed to determine how arthropod densities relate to crop performance in mandarins.

The Deepwater Horizon (DWH) blowout resulted in the deposition to the seafloor of up to 4.9% of 200 million gallons of oil released into the Gulf of Mexico. The petroleum hydrocarbon concentrations near the wellhead were high immediately after the spill, but returned to background levels a few years after the spill. Microbial communities in the seafloor are thought to be responsible for the degradation of hydrocarbons, however, our knowledge is primarily based upon gene diversity surveys and hydrocarbon concentration in field sediment samples. Here, we investigated the oil degradation potential and changes in bacterial community by amending seafloor sediment collected near the DWH site with crude oil and both oil and Corexit dispersant. Polycyclic aromatic hydrocarbons were rapidly degraded during the first 30 days of incubation, while alkanes were degraded more slowly. With the degradation of hydrocarbons, the relative abundances of Colwelliaceae, Alteromonadaceae, Methylococales, Alcanivorax, Bacteriovorax, and Phaeobacter increased remarkably. However, the abundances of oil-degrading bacteria changed with oil chemistry. Colwelliaceae decreased with increasing oil degradation, whereas Alcanivorax and Methylococcales increased considerably. We assembled seven genomes from the metagenome, including ones belonging to Colwellia, Alteromonadaceae, Rhodobacteraceae, the newly reported genus Woeseia, and candidate phylum NC10, all of which possess a repertoire of genes for hydrocarbon degradation. Moreover, genes related to hydrocarbon degradation were highly enriched in the oiled treatment, suggesting that the hydrocarbons were biodegraded, and that the indigenous microflora have a remarkable potential for the natural attenuation of spilled oil in the deep-sea surface sediment.

Modern observations of planktic foraminifera from sediment trap studies help to constrain the regional ecology of paleoceanographically valuable species. Results from a weekly-resolved sediment trap time series (2008–2014) in the northern Gulf of Mexico demonstrate that 92% of Globorotalia truncatulinoides flux occurs in winter (January, February, and March), and that encrusted and non-encrusted individuals represent calcification in distinct depth habitats. We use individual foraminiferal analysis (IFA) of G. truncatulinoides tests to investigate differences in the elemental (Mg/Ca) and isotopic composition (δ18O and δ13C) of the encrusted and non-encrusted ontogenetic forms of G. truncatulinoides, and to estimate their calcification depth in the northern Gulf of Mexico. We estimate that non-encrusted and encrusted G. truncatulinoides have mean calcification depths of 66 ± 9 m and 379 ± 76 m, respectively. We validate the Mg/Ca-calcification temperature relationship for G. truncatulinoides and demonstrate that the δ18O and Mg/Ca of the non-encrusted form is a suitable proxy for winter surface mixed layer conditions in the Gulf of Mexico. Care should be taken not to combine encrusted and non-encrusted individuals of G. truncatulinoides for down core paleoceanographic studies.

Although the Sr/Ca ratio in the skeletons of sclerosponges appears to be robustly correlated with water temperature, the measurement of Sr/Ca ratios from several specimens by different workers yields unexpectedly large (up to 5 °C) increases in temperature over the past 150 years. This is considerably greater than spatially and temporally averaged observational temperature increases. One possible culprit for the larger than anticipated temperature changes in these samples arises from the calibration between temperature and Sr/Ca ratios of the skeleton that was derived from specimens grown in a relatively narrow range of high temperatures (26 to 30 °C). In order to improve the calibration, we acquired a number of samples of sclerosponges collected at lower average water temperatures (different localities and deeper water depths), and combined measurements of the Sr/Ca ratios from bulk samples representing the last ~15 years of growth with the previous calibration dataset. Analyses of these samples have produced a revised relationship between temperature and Sr/Ca ratios in the skeletons of sclerosponges. Application of this new calibration equation to published sclerosponge data reduces the magnitude of the increase in temperature reconstructed from Sr/Ca ratios to values in better agreement with spatially and temporally gridded observational ocean temperature data sets. However, the acceleration of warming indicated by nearly all Caribbean sclerosponge records over the last several decades remains unchanged by this revised calibration.

Experimental approaches to studying the consequences of pesticide use, including impacts on beneficial insects, are vital; however, they can be limited in scale and realism. We show that an ecoinformatics approach that leverages existing data on pesticides, pests, and beneficials across multiple fields can provide complementary insights. We do this using a multi-year dataset (2002-2013) on pesticide applications and density estimates of two pests, citrus thrips (Scirtothrips citri (Moulton [Thysanoptera: Thripidae])) and citrus red mites (Panonychus citri McGregor [Acari: Tetranychidae]), and a natural enemy (Euseius spp. predatory mites) collected from citrus groves in the San Joaquin Valley of California. Using correlative analyses, we investigated the long-term consequences of pesticide use on S. citri and P. citri population densities to evaluate the hypothesis that the pest status of these species is largely due to the disruption of natural biological control-i.e., these are induced pests. We also evaluated short-term pesticide efficacy (suppression of citrus thrips and citrus red mite populations immediately post-application) and asked if it was correlated with the suppression of Euseius predator populations. Although the short-term efficacy of different pesticides varied significantly, our dataset does not suggest that the use of citrus pesticides suppressed Euseius densities or worsened pest problems. We also find that there is no general trade-off between pesticide efficacy and pesticide risk to Eusieus, such that highly effective and minimally disruptive compounds were available to citrus growers during the studied time period.

Sediments up to about 50 ka old can be dated by radiocarbon (14C), and typically biogenic carbonate minerals formed by organisms like foraminifera or mollusks are the primary choice for dating. However, carbonate-poor environments, typical for polar seas, limit the possibilities for 14C dating to bulk organic matter (OM), which is typically biased by the old carbon. In this study, ramped pyrolysis-oxidation (RPO) 14C dating of bulk OM was applied to two Arctic Ocean sediment cores with independent age constraints from prior studies in order to assess its applicability in this environment. Application of RPO to Arctic sediment samples yielded a series of progressively older ages with increasing pyrolysis temperatures and with sediment depth, similar to previous applications in Antarctica. The difference between the independently dated carbonate ages and the RPO-derived ages was proportional to the gradient of 14C ages of the released carbon vs. the pyrolysis temperature. Using this empirical relationship, we propose a new method to estimate sediment age based on RPO 14C data. Ages derived by this method in our data set show offsets from the independent age controls mostly under ~700 years. These results are much closer to the actual ages than the bulk OM data. This simple method may have a broad application to sediments with biogenic carbonate deficiency whereby dating is reliant on bulk OM.

Despite decades of research on management tactics for the navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae), on almonds, we still do not have an established means of using in-season pest-density estimates to predict damage to nuts at harvest. As a result, hull-split pesticide applications, although timed carefully to coincide with navel orangeworm oviposition and with crop vulnerability, are not tied to pest densities-thus falling short of our goals under modern pest management. Here we use an ecoinformatics approach, analyzing a pre-existing data set collected in commercial almond production in California, to ask: 1) are navel orangeworm density estimates obtained using different sampling methods in strong agreement with one another? and 2) can we use either single density estimates or combinations of density estimates to explain variation in nutmeat damage at harvest? We find that correlations between density estimates of navel orangeworm made over a single growing season are often weak, and suggest that density estimates taken closer to the time of harvest (catches of adult females between hull split and harvest; infestation of early-split nuts) may be most useful for predicting damage at harvest. Single-density estimates explained ≤39.1% of variation in harvest damage, whereas a combination of predictors explained 51.5% of the total variance in nutmeat damage at harvest. Our results suggest that density estimates taken just prior to harvest may, with refinement, be usable within a predictive framework to guide late-season control decisions.

Plants use a variety of mechanisms to defend against herbivore damage, each with different consequences for agricultural production. Crops relying on tolerance strategies may need different pest management approaches versus those relying on resistance strategies. Previous work suggested that densities of fork-tailed bush katydids (Scudderia furcata Brunner von Wattenwyl [Orthoptera: Tettigoniidae]) that generated substantial scarring on cultivars of sweet oranges (Citrus sinensis, (L.) Osbeck [Sapindales: Rutaceae]) produced only low levels of scarring on cultivars of Citrus reticulata Blanco mandarins. We used field experiments in representative cultivars of these species to test non-mutually exclusive hypotheses regarding the mechanisms underlying this observation: 1) katydids are averse to feeding on mandarin fruits, 2) damaged mandarin fruits preferentially abscise, 3) damaged mandarin fruit tissue recovers during development, and 4) katydid scars on mandarins have a different morphology that may result in misclassification. We found strong support for the first hypothesis, demonstrating that katydids reject opportunities to feed on C. reticulata fruit. Instead of chewing deep holes in the fruit, as was commonly observed for C. sinensis, the katydids only scratched the surface of the C. reticulata fruits. The hypotheses of preferential abscission of damaged fruits and of recovery of damaged tissue were not supported. The low incidence of damage to the mandarins prevented a comprehensive assessment of the scar morphology; however, at harvest, the superficial cuts in C. reticulata were not easily distinguishable from background damage. This indicates that in contrast to C. sinensis, C. reticulata has substantial natural resistance to fork-tailed bush katydids making them a non-pest in this crop.

Several domesticated Citrus species are grown as major commercial crops in California. Despite this, farmers currently use a single set of management practices, originally created for sweet oranges (Citrus sinensis (L.) Osbeck [Sapindales: Rutaceae]), for both sweet oranges and all mandarin species. Mandarins, primarily Citrus reticulata Blanco, Citrus clementina hort. ex Tanaka, and Citrus unshiu Marcovitch, comprise almost 25% of California citrus acreage, and little work has been done to assess host–pest interactions for these species. Citrus thrips (Scirtothripscitri Moulton [Thysanoptera: Thripidae]) are one of the main pests in California citrus and are major targets for early spring, “petal fall” insecticide applications. We used mixed species citrus blocks to test the influence of Citrus species, including C. sinensis, C. reticulata, C. clementina, and C. unshiu, on 1) citrus thrips densities following petal fall; 2) citrus thrips-induced scarring on both the calyx and stylar ends of fruit; and 3) fruit deformation. Citrus sinensis and C. unshiu had relatively high citrus thrips densities and scarring levels, whereas C. reticulata had lower densities of citrus thrips and scarring levels. The age structure of citrus thrips populations also varied across Citrus species. Fruit deformity associated with citrus thrips scarring was found on all Citrus species examined. Scarring on the stylar-end of fruit, a previously largely ignored location of citrus thrips scarring, was found to be common in C. reticulata. It is clear from our work that species-specific management guidelines for citrus thrips are needed in sweet oranges and mandarins.

One of the major challenges facing citrus integrated pest management (IPM) in California is the recent, sharp increase in the acreage of mandarins being planted. The current citrus IPM guidelines have been established from years of experiments and experience in oranges, with no specific guidelines for mandarins. In the absence of research into key arthropod pest effects in mandarins, the assumption that the pest management practices for oranges appropriately transfer for optimal production in mandarins has not been tested. We used a data mining or ‘ecoinformatics’ approach in which we compiled and analyzed production records collected by growers and pest control advisors to gain an overview of direct pest densities and their relationships with fruit damage for 202 commercial groves, each surveyed for 1–10 yr in the main production region of California. Pest densities were different among four commonly grown species of citrus marketed as mandarins (Citrus reticulata, C. clementina, C. unshiu, and C. tangelo) compared with the standard Citrus sinensis sweet oranges, for fork-tailed bush katydids (Scudderia furcata Brunner von Wattenwyl [Orthoptera: Tettigoniidae]), and citrus thrips (Scirtothrips citri Moulton [Thysanoptera: Thripidae]). Citrus reticulata had notably low levels of fruit damage, suggesting they have natural resistance to direct pests, especially fork-tailed bush katydids. These results suggest that mandarin-specific research and recommendations would improve citrus IPM. More broadly, this is an example of how an ecoinformatics approach can serve as a complement to traditional experimental methods to raise new and unexpected hypotheses that expand our understanding of agricultural systems.

What shapes the relative investment in reproduction versus survival of organisms is among the key questions in life history. Proovigenic insects mature all their eggs prior to emergence and are short lived, providing a unique opportunity to quantify their lifetime investments in the different functions. We investigated the initial eggloads and longevity of 2 proovigenic parasitoid wasps: Anagrus erythroneurae and Anagrus daanei, (Hymenoptera: Mymaridae) that develop within leafhopper eggs in both agricultural vineyards and natural riparian habitats in Northern California. We collected Vitis spp. leaves containing developing parasitoids from 3 natural sites (Knight Landing, American River and Putah Creek) and 3 agricultural vineyards (Solano Farm, Davis Campus and Village Homes). We recorded eggloads at parasitoid emergence and female parasitoid longevity with or without honey-feeding. Theory predicts that parasitoids from vineyards (where hosts are abundant) would have higher initial eggloads and lower longevity compared with parasitoids from riparian habitats (where hosts are scarce). Although host density and parasitoid eggloads were, indeed, higher in vineyards than in riparian habitats, parasitoid longevity did not follow the predicted pattern. Longevity without feeding differed among field sites, but it was not affected by habitat type (natural vs agricultural), whereas longevity with feeding was not significantly affected by any of the examined factors. Moreover, longevity was positively, rather than negatively, correlated with eggloads at the individual level, even after correcting for parasitoid body size. The combined results suggest a more complex allocation mechanism than initially predicted, and the possibility of variation in host quality that is independent of size.

BACKGROUND Landscape crop composition surrounding agricultural fields is known to affect the density of crop pests, but quantifying these effects, as well as measuring how they translate to changes in yield, is difficult. Using a large dataset consisting of 1498 records of commercial cotton production in California between 1997 and 2008, we explored the relationship between landscape composition and cotton yield, the density of Lygus hesperus (a key cotton pest) at field-level and within-field spatial scales and pesticide use. RESULTS We found that the crop composition immediately adjacent to a cotton field was associated with substantial differences in cotton yield, L. hesperus density and pesticide use. Furthermore, crops that tended to be associated with increased L. hesperus density also tended to be associated with increased pesticide use and decreased cotton yield. CONCLUSION Our results suggest a possible mechanism by which landscape composition can affect cotton yield: by increasing the density of pests which in turn damage cotton plants. Our quantification of how surrounding crops affect pest densities, and in turn yield, in cotton fields has significant impacts for cotton farmers, who can use this information to help optimize crop selection and ranch layout. © 2016 Society of Chemical Industry

The carbonate clumped isotope thermometer is a promising tool for determining past ocean temperatures. It is based on the temperature dependence of rare isotopes 'clumping' into the same carbonate ion group in the carbonate mineral lattice. The extent of this clumping effect is independent of the isotope composition of the water from which carbonate precipitates, providing unique advantages over many other paleotemperature proxies. Existing calibrations of this thermometer in cold-water and warm-water corals suggest clumped isotope 'vital effects' are negligible in cold-water corals but may be significant in warm-water corals. Here, we test the calibration of the carbonate clumped isotope thermometer in cold-water corals with a recently collected and well characterised sample set spanning a range of coral genera (Balanophyllia, Caryophyllia, Dasmosmilia, Desmophyllum, Enallopsammia and Javania). The clumped isotope compositions (δ47) of these corals exhibit systematic dependences on their growth temperatures, confirming the basis of the carbonate clumped isotope thermometer. However, some cold-water coral genera show δ47 values that are higher than the expected equilibrium values by up to 0.05‰ (equivalent to underestimating temperature by ~9 °C) similar to previous findings for some warm-water corals. This finding suggests that the vital effects affecting corals δ47 are common to both warm- and cold-water corals. By comparison with models of the coral calcification process we suggest that the clumped isotope offsets in these genera are related to the kinetic isotope effects associated with CO2 hydration/hydroxylation reactions in the corals' calcifying fluid. Our findings complicate the use of the carbonate clumped isotope thermometer in corals, but suggest that species- or genus-specific calibrations could be useful for the future application of this paleotemperature proxy.

Author(s): Zemenick, AT; Rosenheim, JA; Vannette, RL | Abstract: Metacommunity structure is strongly influenced by dispersal between habitat patches. Dispersal mode (e.g., active or passively via vector, wind, or water) is recognized to influence metacommunity dynamics, but it is not well understood how within-mode heterogeneity impacts dispersal and community assembly, particularly for microbial communities. Microbes often rely on flower visitors for dispersal among short-lived floral nectar habitats, but it is unclear whether flower visitor guilds (e.g., legitimate visitors vs. larcenists) differentially influence nectar microbial diversity and community structure. We surveyed the community of legitimate nectar foragers and nectar robbers, which damage flowers to obtain floral rewards, of Aquilegia formosa. Then, we evaluated how manipulating access by legitimate nectar foragers, primary nectar robbers, and/or secondary nectar robbers influenced the diversity, species composition, and beta diversity of nectar bacteria within individual flowers. A taxonomically diverse insect community visited A.nformosa, and visitors differentially influenced nectar bacterial community structure at within-flower (local) and among-flower (regional) scales. When legitimate nectar foragers were allowed to access A.nformosa, we observed an increase in bacterial diversity and changes in bacterial species composition such that common nectar bacteria had higher relative abundances. In contrast, effects of natural and simulated robbing had little effect on bacterial alpha diversity, but simulated robbing decreased the relative abundance of common nectar bacteria, and natural nectar robbing events reduced beta diversity of nectar bacteria. This work highlights the importance of visitor identity on microbial diversity and species composition in flowers, and, more broadly, suggests that vectors can differentially influence metacommunity structure.

Recent thinning and loss of Antarctic ice shelves has been followed by near synchronous acceleration of ice flow that may eventually lead to sustained deflation and significant contraction in the extent of grounded and floating ice. Here, we present radiocarbon dates from foraminifera that constrain the time elapsed between a previously described paleo-ice-shelf collapse and the subsequent major grounding-line retreat in the Whales Deep Basin (WDB) of eastern Ross Sea. The dates indicate that West Antarctic Ice Sheet (WAIS) grounding-line retreat from the continental shelf edge was underway prior to 14.7 ± 0.4 cal kyr BP. A paleo-ice-shelf collapse occurred at 12.3 ± 0.2 cal kyr BP. The grounding position was maintained on the outer-continental shelf until at least 11.5 ± 0.3 cal kyr BP before experiencing a 200-km retreat. Given the age uncertainties, the major grounding-line retreat lagged ice-shelf collapse by at least two centuries and by as much as fourteen centuries. In the WDB, the centuries-long delay in the retreat of grounded ice was partly due to rapid aggradational stacking of an unusually large volume of grounding-zone-wedge sediment as ice-stream discharge accelerated following ice-shelf collapse. This new deglacial reconstruction shows that ongoing changes to ice shelves may trigger complex dynamics whose consequences are realized only after a significant lag.

Among blue carbon ecosystems, mangroves are very efficient in storing carbon in their sediments over decadal to millennial time scales. However, this ability varies with numerous parameters, including climate and sea-level variations. In New Caledonia, mangrove ecosystems develop in semi-arid conditions with a typical zonation: Rhizophora spp. colonize the seaward side of the intertidal area, while wAvicennia marina develops at higher elevations, just below the salt-flat. Within this context, we determined both the quantity (organic carbon content and carbon stocks) and the characteristics (carbon over nitrogen ratios (C/N), stable carbon and nitrogen isotopes, radiocarbon age) of the organic matter stored beneath each mangrove stands. Carbon stocks were determined down to different limits with depth: approximate extension of the root systems, one-meter depth, and the hard substrate. Within the extension of the root systems, the sediment carbon stock was lower than 100 MgC ha(-1) regardless of the mangrove species. This low value resulted directly from the dry climate that limits mangrove productivity. At depth beneath every zone, a buried layer enriched in mangrove-derived organic matter, with C/N values around 40 and delta C-13 values around -26 parts per thousand was observed. This layer likely resulted from a sea-level high stand during the late Holocene that allowed a long period of stability of the mangrove, slowly accumulating organic matter within the sediment. In this buried layer, the carbon stock was higher than in the upper sediment and reached up to 665, 255 and 300 MgC ha(-1) in the salt-flat zone, the A. marina stand and the R. spp. stand, respectively. The highest stock, determined beneath the salt-flat, was suggested to be related to a period of sea-level stability that lasted similar to 3000 years, whereas beneath the other zones, which are at lower elevations, mangrove colonization was more recent and the sea-level was continuously decreasing till recently. Sea level variations, and, specifically current sea-level rise, may strongly influence mangrove development due to their migration along the tidal elevation gradient to maintain the biotic conditions needed for their development.

We present coral- and sclerosponge-based reconstructions of the 14C content in North Atlantic dissolved inorganic carbon (DIC) during the last ~100 years from the subtropical cells (STCs). These waters are sensitive to the dynamics of the shallow overturning meridional circulation that transports heat and water masses from the subtropics to the tropics. We use these records to investigate the circulation patterns of the off-equatorial upwelling regions of the STCs, which are not well understood. Coral and sclerosponge skeletons provide long time series of ocean DIC 14C content, a tracer of oceanic circulation, effectively extending the observational record back in time. Sclerosponge data from the Bahamas were used to extend the existing subtropical 14C time series to the 21st century. Coral 14C data from the Cape Verde Islands (1890–2002) captured the 14C signature of water brought to the surface in the off-equatorial regions of the STC present near the West African coast. We observe a unique postbomb trend at Cape Verde that is similar to the upwelling regions in the Pacific, and we interpret this trend as the result of the slow penetration of bomb 14C into the interior ocean as part of the STC circulation. Using a multibox mixing model we constrain the time history of bomb 14C in the eastern tropical Atlantic, and we estimate a 20 year time scale for ventilation of the thermocline in this area of the ocean. The similarity between the Atlantic and Pacific 14C-based records of upwelling suggests that both are caused by bomb 14C penetration rather than more complex explanations that invoke changes in thermocline depth (e.g., related to El Nino–Southern Oscillation variability) or changes in the strength of the subtropical cells. Our results offer constraints for models of tropical ocean circulation and anthropogenic CO2 uptake that attempt to reproduce the characteristics of the shallow wind-driven circulation in the Atlantic.

We report on predation on adult females of the parasitoids Aphytis aonidiae and A. vandenboschi (Hymenoptera: Aphelinidae) foraging in the field. During 89.6 h of observation, we witnessed 18 encounters with predators, 6 of which resulted in parasitoid capture. Three classes of generalist predators attacked Aphytis: spiders (unidentified Salticidae and Thomisidae), workers of the Argentine ant, Linepithema humile, and nymphs of the assassin bug Zelus renardii (Hemiptera: Reduviidae). Although observations were conducted during most months of the year, encounters with predators occurred only during September, October and November. During these months, encounters with predators occurred on average every 3.2 h of observation, with one in three encounters resulting in parasitoid capture. Peaks in predation coincided with population peaks of A. aonidiae, but were unrelated to population dynamics of any of the predators. We compare these results with previously published laboratory studies on longevity of Aphytis parasitoids, and conclude that predation pressure has the potential to severely limit parasitoid fitness in the field.

Capturing the complementary strengths of observational and experimental research methods usually requires the researcher to gather separate experimental and observational data sets. In some cases, however, commercial agricultural practices produce the spatial and temporal mixing of 'treatments' independently of other possibly covarying factors that is normally achieved only with formal experimentation. The resulting 'pseudoexperiments' can provide strong evidence for causal relationships. Here, we analyze a large observational data set that creates a series of such pseudoexperiments to assess the effect of different commercial varieties of almond, Prunus dulcis (Mill.) on the impact of two key lepidopteran pests, the navel orangeworm Amyelois transitella (Walker) (Lepidoptera: Pyralidae), and the peach twig borer Anarsia lineatella Zeller (Lepidoptera: Gelechiidae). Almonds are universally planted as polycultures of different varieties to obtain efficient cross-pollination. We find substantial differences across almond varieties in the rates of infestation of almond hulls and nutmeats by the two pests. We find no support for the hypothesis that earlier-maturing varieties sustain higher attack; for A. transitella, later-maturing varieties instead had more frequent infestation. On many almond varieties, A. lineatella reaches high infestation levels by feeding almost exclusively on the hulls, rather than nutmeats. Given the importance of these pests in directly destroying almond nuts and in promoting aflatoxin-producing Aspergillus sp. fungal infections of almonds, further work exploring the impact of these pests is warranted. Because many crops requiring cross-pollination are planted as mixtures of different varieties, commercial agricultural production data hold great potential for studying within-crop variation in susceptibility to insect attack.

Insect reproduction is typically spread out in time and space, making estimates of lifetime reproductive success quite difÞcult under natural Þeld conditions. Such estimates are, however, critical to providing rigorous tests of theory for reproductive behavior. One approach to circumventing this problem is to study insects whose lifetime reproduction is compressed in space and time, and whose ovarian dynamics (oogenesis, oosorption, and oviposition) are simpliÞed. We investigated the gall midge Rhopalomyia californica Felt (Diptera: Cecidomyiidae) as a possible candidate for an herbivore with such a simpliÞed pattern of lifetime reproduction. We demonstrate here that R. californica matures all of its eggs before adult eclosion (it is strictly proovigenic), and it does not resorb eggs, even when deprived of oviposition sites. Observational and experimental studies in the Þeld demonstrate that this midge typically completes its entire lifetime reproduction in a single day: females usually emerge at dawn, mate, and after a posteclosion period of resting, they initiate a sustained period of active oviposition during which most eggs are laid over a 4 Ð5-h period. Mean longevity of adult females is very short, consistently 1 d and only 5Ð 6 h on clear and warm days. Two key aspects of senescence are experimentally demonstrated: an increase in mortality rates and a decrease in oviposition rates with age. The life history traits associated with the ephemeral adult stage of R. californica are consistent with a syndrome that has been characterized recently for many proovigenic herbivorous and parasitic insects. Proovigenic species, including R. californica, may be particularly valuable as model systems for studies of lifetime reproductive success in nature.

1. Individual fitness is often assumed to be positively correlated with body size, but this has rarely been explored under realistic field conditions. This assumption was tested in a minute parasitoid foraging for planthopper eggs in saltmarsh habitats. 2. We used a novel sampling technique that captures females as they naturally die and fall off the vegetation, and estimated their oviposition success according to the number of eggs remaining in their bodies. 3. Our results support a positive relationship between oviposition success and body size of female parasitoids. 4. Only a single female had exhausted her eggs before she died suggesting that the larger body size advantage is not realised primarily via increased fecundity, but instead via increased longevity or foraging-efficiency.

highlights Feeding on honey enhanced the longevity of Anagrus parasitoids in the laboratory. Feeding rates and survival of Anagrus parasitoids in the field were low, suggesting many die of starvation. Feeding rates differed among field sites and decreased as the season progressed. Feeding rates had a weak positive effect on the reproductive success of Anagrus females in the field. graphical a bstract abstract Our ability to improve biological control of insect pests depends on our understanding of factors that limit the reproductive success of their natural enemies in the field. Pest control by parasitoids in agricultural fields can be compromised by the availability of sugar resources. We studied sugar availability for Anagrus parasitoids that parasitize the eggs of leafhopper pests (genus Erythroneura) in vineyards in northern Cal- ifornia. Laboratory assays indicated that parasitoids survive less than a day on average without feeding, and 3 days when supplied with honey. We captured foraging parasitoids in five unsprayed vineyards in north- ern California and applied a simple chemical test to assay the presence of sugar in their abdomen. Parasitoid abundance decreased throughout the day (08:00-16:00 h), suggesting that many parasitoids survive less than a day in the field. The proportion of feeding (sugar-positive) individuals was generally low (10% on average); it varied among field sites and decreased as the season progressed (from July to October). Par- asitoids captured in the afternoon were more often found with sugar in their guts compared to those cap- tured in the morning hours. This may be explained by a direct positive effect of sugar on parasitoid survival, but may also result from longer-lived parasitoids simply having more time to locate scarce sugar resources. The egg loads of female parasitoids were negatively related to sugar availability, suggesting that sugar increases oviposition success, although we could not rule out a causal role for other site-date specific fac- tors. Overall, our results suggest that Anagrus parasitoids in vineyards may be limited by sugar availability, and that adding sugar resources such as flowering cover crops, especially towards the end of the season, could potentially improve their efficacy as biological control agents. However, this is only likely to be suc- cessful in combination with the elimination of other factors that compromise parasitoid success.

Debates on the relative importance of different factors in limiting the realized fitness of insect parasitoids and herbivores have continued for decades. One major reason for the duration of these debates is the paucity of empirical evidence regarding the reproductive success of minute insects under field conditions. We used a novel technique to estimate lifetime reproductive success in two Anagrus spp. parasitoids, whose hosts are eggs of leafhoppers that feed on grape leaves. Females were collected soon after they died naturally, and the number of eggs in their ovaries was counted. We used these data to estimate the lifetime oviposition success of individual females. We found that more than 10% of females from the field exhausted their entire supply of eggs before they died. The lifetime reproductive success of females was positively related to their body size and was higher at field sites with more abundant hosts, although we could not rule out a causal role for other site-specific factors. In addition, we found that females from habitats rich with hosts emerged with more eggs, suggesting that they might be adapted to local conditions. The results are consistent with theoretical predictions from models considering the risk of egg limitation.

Landscape composition plays an important, but poorly understood, role in the population dynamics of agricultural pest species with broad host ranges including both crops and weeds. One such pest, the generalist plant bug Lygus hesperus Knight (Hemiptera: Miridae), is a key cotton pest that feeds on various hosts differing in quality in California's San Joaquin Valley (USA). We investigated the effects of 15 common crops and uncultivated agricultural land on L. hesperus populations, by correlating the densities of L. hesperus in focal cotton fields with the areas of the 16 crops in surrounding rings. Insect counts were provided by private pest-control advisors, and spatial data were obtained from Kern County records. We first calculated Spearman's partial correlation coefficients on an annual basis for each crop separately, and then performed a meta-analysis of these correlations across years to describe the overall effect of a particular crop on L. hesperus after the effects of the 15 other crops are removed. Consistent with studies conducted in other areas, L. hesperus density was positively correlated with safflower, and negatively with cotton. Lygus hesperus density was also correlated with several other crops that are often not considered in pest management, including grape, oat, and onion (positive correlations), and almond, pistachio, and potato (negative correlations). Lygus hesperus density was also found to be negatively correlated with alfalfa and positively correlated with uncultivated habitats, a relationship that receives mixed support in the literature. Several other crops tested were not significantly correlated with L. hesperus densities in focal cotton fields, suggesting a neutral role for them in L. hesperus dynamics. The improved understanding of the effects of a greater variety of crops on L. hesperus population dynamics will be useful in the design of agricultural landscapes for enhanced management of this important polyphagous pest.

Summary Theory predicts that organisms should invest more heavily in overcoming factors that more frequently emerge as the primary constraints to fitness, and especially, those factors that constrain the fitness of the most highly reproductive members of the population. We tested the hypothesis that the fecundity of a pro-ovigenic parasitoid (where females emerge with their full egg load) should be positively correlated with the mean expectation for oviposition opportunities in the environment. More specifically, we tested whether females from agricultural systems, where hosts are often relatively abundant, emerge with more eggs than those from natural habitats. We studied the pro-ovigenic parasitoid wasp Anagrus daanei, which parasitizes eggs of leafhoppers of the genus Erythroneura. Erythroneura spp. leafhoppers feed on Vitis spp. (grapes) and are major pests of commercial vineyards as well as common herbivores of wild Vitis californica, which grows in riparian habitats. We sampled leafhoppers and parasitoids from eight vineyards and eight riparian habitats in central California. We found that leafhopper density was higher at vineyards than in riparian habitats, whereas leafhopper egg volume and parasitoid body size did not differ among these habitat types. Parasitoids from vineyards had higher egg loads than parasitoids from wild grapes, and fecundity was positively related to host density across field sites. Parasitoid egg volume was larger in natural sites; however, this variation was not significantly correlated with host density across field sites. Within a single population of parasitoids collected from a vineyard, parasitoid egg load was negatively correlated with longevity, suggesting a trade-off between reproduction and life span. The results may be explained by a rapid evolution of reproductive traits in response to oviposition opportunities; or alternatively, by the occurrence of maternal effects on the fecundity of daughters based on the foraging experience of their mothers. The ability of parasitoid fecundity to track mean host availability is likely to modulate the likelihood that parasitoid fitness will be constrained by a shortage of eggs and strengthen the ability of parasitoids to suppress the population densities of their hosts.

Because the farmer is typically excluded from the experimental research setting, experimental research may face challenges in evaluating pest management tactics whose costs and benefits hinge on farmer decision-making. In these cases an ecoinformatics approach, in which observational data collected from the commercial farming setting are “mined” to quantify both biological variables and farmer behavior, can complement experimentation as a useful research tool. Here I analyze such an observational data set to characterize associations between early- (June) and mid-season (July) Lygus hesperus Knight populations and farmer decisions to apply plant growth regulators and defoliants. Previous experimental work suggested the hypothesis that Lygus herbivory, by inducing abscission of young flower buds, might generate increased use of plant growth regulators and defoliants. Cotton's ability to compensate for loss of flower buds may, however, increase as plants grow. On upland cotton, June Lygus populations were associated with increased use of plant growth regulators, as expected, but this relationship was not observed for July Lygus populations. June Lygus populations were not associated with the use of defoliants, whereas, surprisingly, July Lygus populations were associated with decreases in defoliant use. In contrast to these positive and negative associations observed on upland cotton, on Pima cotton Lygus populations exhibited no associations with use of either plant growth regulators or defoliants. These results suggest that cotton responses to Lygus herbivory, as demonstrated in previously published experimental studies, can translate into economically meaningful changes in farmer decisions to apply agricultural chemicals.

In predator–prey interactions, a widely held view is that prey species have higher dispersal rates relative to their predators and are thereby able to escape from predation by colonizing habitats before their predators. Despite major implications for predator–prey interactions, community assembly, and biological control, this view has rarely been tested, and measuring relative dispersal abilities is often complicated by colonizing predators and prey originating from different locations. In California’s San Joaquin Valley, the periodic harvest of alfalfa presents an opportunity to measure dispersal of a key generalist pest, Lygus spp., relative to a suite of its generalist predators. We performed a large-scale mark-capture study by marking a mature alfalfa field containing Lygus and its predators with an aerial application of a protein marker. The alfalfa was then harvested by the grower, prompting a dispersal event. At several times following harvest, surrounding cotton fields were sampled at known distances from the marked field to quantify movement by Lygus and its predators. Contrary to the general view, our data do not suggest that Lygus routinely out-disperses its suite of predators. Instead, the mean dispersal distance for Lygus fell near the average dispersal distances of its predators. Implications for biological control are discussed in light of these results, and the importance of predators’ trophic strategy is stressed.

Understanding the population dynamics of herbivorous insects is critical to developing and implementing effective pest control protocols. In the context of inverse problems, we explore the dynamic effects of pesticide treatments on Lygus hesperus, a common pest of cotton in the western United States. Fitting models to field data, we explore the topic of model selection for an appropriate mathematical model and corresponding statistical models, and use techniques including ANOVA-based model comparison tests and residual plot analysis to make the best selections. In addition we explore the topic of data information content: in this example, we are testing the question of whether data, as it is currently collected, can support time-dependent parameter estimation. Furthermore, we investigate the statistical assumptions often haphazardly made in the process of parameter estimation and consider the implications of unfounded assumptions.

Secondary pest outbreaks occur when the use of a pesticide to reduce densities of an unwanted target pest species triggers subsequent outbreaks of other pest species. Although secondary pest outbreaks are thought to be familiar in agriculture, their rigorous documentation is made difficult by the challenges of performing randomized experiments at suitable scales. Here, we quantify the frequency and monetary cost of secondary pest outbreaks elicited by early-season applications of broad-spectrum insecticides to control the plant bug Lygus spp. (primarily L. hesperus) in cotton grown in the San Joaquin Valley, California, USA. We do so by analyzing pest-control management practices for 969 cotton fields spanning nine years and 11 private ranches. Our analysis uses statistical methods to draw formal causal inferences from nonexperimental data that have become popular in public health and economics, but that are not yet widely known in ecology or agriculture. We find that, in fields that received an early-season broad-spectrum insecticide treatment for Lygus, 20.2% +/- 4.4% (mean +/- SE) of late-season pesticide costs were attributable to secondary pest outbreaks elicited by the early-season insecticide application for Lygus. In 2010 U.S. dollars, this equates to an additional $6.00 +/- $1.30 (mean +/- SE) per acre in management costs. To the extent that secondary pest outbreaks may be driven by eliminating pests' natural enemies, these figures place a lower bound on the monetary value of ecosystem services provided by native communities of arthropod predators and parasitoids in this agricultural system.

Interactions between plants and their herbivores are often multidimensional, complicating interpretation of herbivore-impact studies. A previous study, directed toward understanding variation in incidences of flower bud abscission among cotton plants attacked by Lygus plant bugs, revealed an unanticipated correlation between levels of phosphorus nutrition and the propensity of plants to abscise developing flower buds. Here, we further investigate the relationship between phosphorus nutrition and cotton [Gossypium hirsutum Tod. (Malvaceae)] plant responses to herbivory by tarnished plant bugs, Lygus hesperus Knight (Hemiptera: Miridae). Complementary experimental approaches and survey data both suggest that levels of phosphorus nutrition falling within the normal range of variation can influence the manner by which plants respond to herbivory. In particular, higher levels of phosphorus nutrition resulted in elevated bud abscission rates when buds were damaged. Interestingly, increased levels of abscission under high-phosphorus regimes did not translate into a decrease in overall cotton lint yield, suggesting that the ‘phosphorus effect' may ultimately reflect how environmentally contingent differences in the allocation of vegetative vs. reproductive investments can provide parallel pathways to equal yields.

A greater diversity of natural enemies can in some cases disrupt prey suppression, particularly when natural enemies engage in intraguild predation, where natural enemies compete with and prey upon each other. However, empirical studies have often demonstrated enhanced prey suppression despite intraguild predation. A recent theoretical study proposed the hypothesis that, when the intermediate predator is cannibalistic, intraguild predation can reduce cannibalism within the intermediate predator population, leading to little change in intermediate predator mortality and thus enhanced prey suppression. The goal of this study was to examine this hypothesis empirically. Two summer-long field enclosure experiments were conducted in cotton fields. We investigated the effects of adding an intraguild predator, Zelus renardii, on (1) the abundance of a cannibalistic intermediate predator, Geocoris pallens, (2) the abundance of a herbivore, Lygus hesperus, and (3) cotton plant performance. G. pallens adult abundance did not increase, even when food availability was high and natural enemies were absent, suggesting that density-dependent cannibalism imposes an upper limit on its densities. Furthermore, although Z. renardii is an intraguild predator of G. pallens, G. pallens long-term densities were unaffected by Z. renardii. In the presence of the intermediate predator, the addition of the intraguild predator Z. renardii enhanced suppression of L. hesperus, and there were suggestions that Z. renardii and G. pallens partitioned the L. hesperus population. Effects of herbivore suppression cascaded to the plant level, improving plant performance. In conclusion, we provide empirical support for the hypothesis that the addition of an intraguild predator may enhance prey suppression if the intermediate predator expresses density-dependent cannibalism. Intraguild predation and cannibalism co-occur in many communities; thus their joint effects may be broadly important in shaping predator effects on herbivores and plant performance.

Polyembryony has evolved independently in four families of parasitoid wasps. We review three main hypotheses for the selective forces favouring this developmental mode in parasitoids: polyembryony (i) reduces the costs of egg limitation; (ii) reduces the genetic conflict among offspring; and (iii) allows offspring to adjust their numbers to the quality of the host. Using comparative data and verbal and mathematical arguments, we evaluate the relative importance of the different selective forces through different evolutionary stages and in the different groups of polyembryonic wasps. We conclude that reducing the cost of egg limitation is especially important when large broods are favoured. Reducing genetic conflict may be most important when broods are small, thus might have been important during, or immediately following, the initial transition from monoembryony to polyembryony. Empirical data provide little support for the brood-size adjustment hypothesis, although it is likely to interact with other selective forces favouring polyembryony.

A revised calibration is presented relating the oxygen isotope composition of the aragonite-secreting sclerosponge Ceratoporella nicholsoni, oxygen isotope composition of seawater, and ambient water temperature. This new relationship has been obtained using high-resolution d 18 O data measured in sclerosponges from the Bahamas and Jamaica compared to ambient temperature measurements and d 18 O values of seawater from the two locations, both measured and published. New data improve an existing calibration which was determined using measurements of salinity rather than directly measured d 18 O values of the seawater and was composed of measurements from different species of sclerosponge and other aragonite-secreting organisms. The updated calibration (n = 12, r 2 = 0.95) is

OBJECTIVE To determine the extent of carnivore-transmitted parasitic zoonoses in a community in eastern Kazakhstan, a region where cystic echinococcosis (CE) re-emerged in recent years. METHODS Cross sectional ultrasound study of 3126 human subjects to determine the extent of human cystic and alveolar echinococcosis (AE). Blood samples were taken from each subject and analysed for antibodies against Echinococcus, Toxocara and Toxoplasma spp. Each subject was questioned about possible risk factors that might be associated with zoonotic transmission. Analysis employed a mixed modelling approach based on the results of the ultrasound study, the serological results and the results of the questionnaire. Bayesian techniques were employed to estimate diagnostic performance. A helminthological study of the local dog population was also undertaken. RESULTS A total of 23 subjects tested positive for CE on ultrasound and a further three individuals had strong serological evidence of infection. Another 24 reported treatment for CE. Ultrasound lesions or treatment for CE were associated with poverty. No ultrasound evidence of AE was found, but one individual had strong serological evidence of exposure to Echinococcus multilocularis. Toxoplasma seropositivity (16%; 504 individuals) increased with age. Household level Toxoplasma-seropositivity was associated with unsafe drinking water. Toxocara seropositivity (11%; 349 individuals) was more frequent in children and in individuals who disposed of dog faeces on the vegetable garden. A purgation study of dogs indicated that 13% of dogs in the community were infected with Echinococcus granulosus, 5% with E. multilocularis and 2% with Toxocara canis respectively. CONCLUSIONS There is significant transmission of E. granulosus to humans in this community. Transmission may be associated with poverty. There is little evidence of E. multilocularis transmission to humans, despite the presence in the parasite in the domestic dog population. Toxoplasma is actively transmitted and there is evidence for transmission by the water supply. Children are at highest risk of exposure to Toxocara.

Previously unpublished AMS radiocarbon measurements of a sclerosponge from tongue of the ocean (TOTO), Bahamas, as well as preliminary data from an investigation of the radiocarbon records of sclerosponges living at different depths in the adjacent Bahamas basin, Exuma Sound, are interpreted in terms of U-series age models. The data are compared to an existing Caribbean sclerosponge radiocarbon bomb curve measured using standard gas proportional beta counting and used to interpret a 210 Pb age model. The D 14 C records from the sclerosponges illustrate a potential for use of radiocarbon both as a tracer of subsurface water masses or as an additional age constraint on recently sampled sclerosponges. By using an independent age model, this study lays the framework for utilizing sclerosponges from different locations in the tropics and subtropics and different depths within their wide depth range (0–250 m) to constrain changes in production of subtropical underwater in the Atlantic Ocean. This framework is significant because the proxy approach is necessary to supplement the short and coarse time series being used to constrain variability in the formation of Caribbean subtropical underwater, the return flow of a shallow circulation cell responsible for nearly 10% of the heat transported poleward in the N. Atlantic. 2007 Elsevier B.V. All rights reserved.

Pesticides targeted at pest species have often been demonstrated to have strong adverse effects on the survival of biological control agents in short-term laboratory bioassays; however, studies examining the influence of pesticides on the actual reproductive success of biological control agents in the field are rare. Because natural enemy reproduction is often directly tied to biological control success, effects of pesticides on reproduction are of central importance. Here we use a new technique to examine the influence of sulfur, a fungicide widely used in grape production, on the reproductive success of Anagrus erythroneurae (Hymenoptera: Mymaridae) and Anagrus daanei (Hymenoptera: Mymaridae), egg parasitoids of the grape leafhopper, Erythroneura elegantula (Homoptera: Cicadellidae). Sulfur has previously been shown to be highly toxic to Anagrus spp. in short-term laboratory and field bioassays, creating the expectation that sulfur should also reduce Anagrus reproductive success in the field. Surprisingly, in two studies, the first comparing the oviposition success of Anagrus collected live in paired sulfur-treated versus untreated vineyards and the second comparing the lifetime reproductive success of Anagrus collected at the end of their lives in unpaired sulfur-treated versus untreated vineyards, we found no effect of sulfur on parasitoid reproductive success. In this system, traditional short-term assays of laboratory toxicity do not appear to predict effects on parasitoid reproductive success, suggesting that demographic approaches to assessing the disruptive effects of pesticides may have an important role in designing IPM programs.

We examined the toxicity of a fungicide, sulfur, to the egg parasitoid Anagrus erythroneurae (Hymenoptera: Mymaridae) Trjapitsyn and Chiapini and the vineyard leafhopper pest Erythroneura elegantula Osborn (Homoptera: Cicadellidae) and tested whether or not the use of sulfur in the field affects biological control of E. elegantula. Using field cage bioassays, we demonstrated that sulfur is toxic to adult A. erythroneurae parasitoids, but not toxic to adult E. elegantula leafhoppers. We nonetheless found in a field experiment that sulfur produced no changes in rates of parasitism or E. elegantula egg density, and generated only a very small increase in the density of E. elegantula nymphs. These results suggest that sulfur, although toxic to A. erythroneurae, is not highly disruptive of E. elegantula biological control in vineyards. Our results suggest that simple bioassays of acute toxicity may not accurately predict the impact of agricultural chemicals on biological control.

International audience; We continue our efforts on modeling of the population dynamics of herbivorous insects in order to develop and implement effective pest control protocols. In the context of inverse problems, we explore the dynamic effects of pesticide treatments on Lygus hesperus, a common pest of cotton in the western United States. Fitting models to field data, we consider model selection for an appropriate mathematical model and corresponding statistical models, and use techniques to compare models. We address the question of whether data, as it is currently collected, can support time-dependent (as opposed to constant) parameter estimates.

The combined impact of multiple plant parasites on plant performance can either be additive (the total damage equals the sum of the individual effects) or nonadditive (synergistic or antagonistic damage). Two statistical models are available for testing the independent (=additive) effects of two factors. Here we suggest that the natural history of the plant-parasite system should motivate the choice of a statistical model to test for additivity. Using in-field, manipulative experiments, we examined the interactions between the herbivorous mite Calacarus flagelliseta Fletchmann, De Moraes and Barbosa (Acari: Eriophyidae), the fungal pathogen Oidium caricae F. Noack (a powdery mildew), and their host plant Carica papaya L. in Hawaii. First, we found that herbivorous mites had a moderate negative effect on powdery mildew: when mites were absent, powdery mildew colonies were larger and more numerous. Second, we showed that each plant parasite, when evaluated alone, significantly reduced several measures of plant performance. Third, we found that the combined impact of mites and mildew on plant performance is mostly additive and, for a few variables, less than additive. Finally, we explored compensatory responses and found no evidence for nonlinearities in the relationship between plant performance and cumulative parasite impact. Plants are almost universally subject to attack by multiple herbivores and pathogens; thus a deeper understanding of how multiple plant parasites shape each other's population dynamics and plant performance is essential to understanding plant-parasite interactions.

Unexplained variation in the relationship between herbivore densities and the short- term appearance of crop damage is sometimes observed in pest management. Here we used a Þeld survey of commercial cotton Þelds and a linked questionnaire for cooperating pest control advisors to document the existence of such unexplained variation in the impact of the western tarnished plant bug, Lygus hesperus, on upland cotton, Gossypium hirsutum. L. hesperus feeds preferentially on sower buds ("squares"), and the plant may respond to this damage with abscission of the square. We explored four classes of factors that might contribute to unexplained variation in square abscission. First, misperceptions by the human observer (i.e., sampling problems) may play a role, because commercial Þeld scouts signiÞcantly underestimate densities of L. hesperus nymphs. Second, we found no support for the hypothesis that variable behavior expressed byL.hesperus contributes to unexplained variation in square abscission. L. hesperus seems to generate relatively predictable levels of square feeding damage; the variation that was observed was unrelated to grower categorization of Þelds as exhibiting normal versus unexpectedly high or low levels of square abscission. Third, variable plant responses to damage may instead be the key source of unexplained square abscission. Younger plants and plants with higher petiole phosphate concentrations expressed increased sensitivity to L. hesperus feeding; these correlations must, however, be tested experimentally before deÞnitive conclusions are drawn. Fourth, another arthropod might be generating damage that was erroneously being attributed to L. hesperus. The omnivoreGeocoris pallens was a candidate agent of cryptic damage to squares; however, an experiment showed thatG.pallens generated only trivial square damage and no detectable increase in square abscission. Thus, this study has focused our attention away from the arthropod side of the interaction and toward the host plant as the primary source of greater than expected square abscission generated by L. hesperus.

Ecologists may wish to evaluate the potential for predators to suppress prey populations through the costs of induced defensive behaviors as well as through consumption. In this paper, we measure the ratio of non-consumptive, defense-inducing encounters relative to consumptive encounters (henceforth the ‘disturbed : consumed ratio’) for two species of aphids and propose that these disturbed : consumed ratios can help evaluate the potential for behaviorally mediated prey suppression. For the pea aphid, Acyrthosiphon pisum (Harris) (Homoptera: Aphididae), the ratio of induced disturbances to consumption events was high, 30 : 1. For the cotton aphid, Aphis gossypii (Glover) (Homoptera: Aphididae), the ratio of induced disturbances to consumption events was low, approximately 1 : 14. These results indicate that the potential for predators to suppress pea aphid populations through induction of defensive behaviors is high, whereas the potential for predators to suppress cotton aphid populations through induced behaviors is low. In measuring the disturbed : consumed ratios of two prey species, this paper makes two novel points: it highlights the variability of the disturbed : consumed ratio, and it offers a simple statistic to help ecologists draw connections between predator‐prey behaviors and predator‐prey population dynamics.

Unexplained variability in the relationship between the number of herbivores in a field and the amount of crop damage can arise if there is a large amount of variation among herbivore individuals in the amount of feeding damage each generates. In California, populations of the western tarnished plant bug, Lygus hesperus Knight (Heteroptera: Miridae), produce highly variable levels of damage to cotton plants ( Gossypium hirsutum L.) (Malvaceae), even when found at low densities. Because L. hesperus populations are also highly variable in their overall stage structure, we hypothesize that differences in crop damage might result from varying impact by each L. hesperus stage on cotton flower buds (termed squares). Laboratory measurements of L. hesperus mouth-parts and distance to anther sacs, a preferred feeding site, revealed that 1st − 3rd instar L. hesperus nymphs will not be able to feed on anther sacs of larger squares (over 8 mm in length) but will be able to feed on squares that are most sensitive to L. hesperus damage (< 7 mm). Because even the 1st instars can feed on the most sensitive ‘pinhead’ squares, size constraints do not rule out damaging effects from the youngest L. hesperus . Laboratory observations revealed that later developmental stages, and adults, spend more time feeding on cotton squares relative to 2nd and 3rd instars. In addition, a field experiment revealed no effect of 2nd instars on square retention (relative to control cages) but did reveal a significant decrease in square retention generated by adult L. hesperus (4th instar L. hesperus resulted in an intermediate level of square retention). In a final study we sampled L. hesperus stage structure and density across 38 cotton fields. Multiple regression revealed that the densities of 1st − 3rd instars of L. hesperus are not correlated with anther sac damage or square retention. However, in 2 years 4th and 5th instars were positively correlated with anther sac damage and negatively correlated with square retention. In the a third year, adult L. hesperus showed correlations in the same direction, across fields and across sites within fields. Overall, these results suggest that the adults and the largest nymphs of L. hesperus (4th and 5th instars) are particularly damaging to cotton squares, with the 1st − 3rd instars of L. hesperus causing little damage to plants.

The trace and minor element composition have been investigated in the accretionary skeletons of two specimens of the Caribbean sclerosponge species, Ceratoporella nicholsoni ; one from Tongue of the Ocean, Bahamas (TOTO), and the other from Pear Tree Bottom, Jamaica (PTB). Both sclerosponges were analyzed at high resolution using laser ablation ICP-MS (LA-ICP-MS) and verified using wet chemical methods (ICP-OES). The shallow PTB sclerosponge (25 m) was analyzed for a short, temperature-calibrated record of trace and minor elements while the TOTO sclerosponge (146 m) was analyzed for a century long record from subsurface waters. The resulting Ba/Ca, Mg/Ca, Pb/Ca, and U/Ca ratios were compared with Sr/Ca ratios, which have been shown to reliably record seasonal-scale temperature change in sclerosponges, close to equilibrium precipitation of inorganic aragonite. Sclerosponge aragonite incorporates minor and trace elements according to general mineralogic constraints with less “vital” effects than other calcium carbonate secreting organisms. This is perhaps most obvious in the behavior of Mg/Ca ratios which show an inverse correlation to temperature unlike any other calcite or aragonite organism, despite having Mg concentrations (∼ 1 mmol/mol) within published estimates of equilibrium aragonite. Ratios of Mg/Ca and Ba/Ca show a strong positive correlation despite large differences in ionic radii and U/Ca values (∼ 3.15 μmol/mol) are 2.5× higher in sclerosponge aragonite than in aragonite from corals, supporting earlier work. Ratios of U/Ca show an insignificant correlation with temperature-dependent Sr/Ca ratios ( r 2 = 0.05), supporting existing theories that temperature signals recorded by U/Ca ratios can be convolved with pH, [CO 3 − 2 ], and phosphate signals. Differences between sclerosponge aragonite and other calcium carbonate arising from siliceous spicule contamination are unlikely because of the small mole percent of silicon in the aragonite. Small differences between the two sclerosponges were noticed in Pb/Ca and Sr/Ca because of the average ages of the sampled material and average temperatures of the ambient environment, respectively. Anomalies between LA-ICP-MS and ICP-OES were noticed in measurements of Ba/Ca and Pb/Ca due to standardization differences for LA-ICP-MS (Ba/Ca) and measurements close to the instrument detection limits of Pb (ICP-OES).

It is paradoxical when a community of several natural enemies fails to control a pest population when it can be shown experimentally that single members of the natural enemy community are effective control agents when tested individually. This is the case for spider mites, Tetranychus spp., in California cotton. Spider mites exhibit irruptive population dynamics despite that fact that experiments have shown that there are at least four predators ( Galendromus occidentalis , Frankliniella occidentalis , Orius tristicolor , and Geocoris spp.) that, when tested singly, can suppress mite populations. One possible explanation for the paradox is intraguild predation, wherein one predator consumes another. Here, I evaluate the hypothesis that intraguild predation is a strong interaction among spider mite predators. I report manipulative field experiments, focal observations of freely foraging predators in the field, and population survey data that suggest that the minute pirate bug O. tristicolor , is subject to strong predation by other members of the predator community, and in particular by Geocoris spp. These results, combined with the results of prior work, suggest that pervasive intraguild predation among spider mite predators may explain the pest status of Tetranychus spp. in cotton.