The effect of warmer winters on the demography of an outbreak insect is hidden by intraspecific competition

Warmer climates are predicted to increase bark beetle outbreak frequency, severity, and range. Even in favorable climates, however, outbreaks can decelerate due to resource limitation, which necessitates the inclusion of competition for limited resources in analyses of climatic effects on populations. We evaluated several hypotheses of how climate impacts mountain pine beetle reproduction using an extensive 9‐year dataset, in which nearly 10,000 trees were sampled across a region of approximately 90,000 km², that was recently invaded by the mountain pine beetle in Alberta, Canada. Our analysis supports the hypothesis of a positive effect of warmer winter temperatures on mountain pine beetle overwinter survival and provides evidence that the increasing trend in minimum winter temperatures over time in North America is an important driver of increased mountain pine beetle reproduction across the region. Although we demonstrate a consistent effect of warmer minimum winter temperatures on mountain pine beetle reproductive rates that is evident at the landscape and regional scales, this effect is overwhelmed by the effect of competition for resources within trees at the site level. Our results suggest that detection of the effects of a warming climate on bark beetle populations at small spatial scales may be difficult without accounting for negative density dependence due to competition for resources.     

Anthrax outbreak among Grevy's zebra (Equus grevyi) in Samburu, Kenya

An anthrax outbreak occurred in the Wamba area of southern Samburu, Kenya, between December 2005 and March 2006. The outbreak affected equids including the endangered Grevy's zebras (Equus grevyi), plain zebras (Equis Burchelli) and donkeys (Equus asinus). Most of the deaths were localized in Nkaroni area just west of Wamba town. The diagnosis of anthrax was rapidly confirmed by bacteriological methods. The relevant government departments, including the Kenya Wildlife Service and Veterinary Department, and other stakeholders were promptly informed. Fifty‐three Grevy's zebra and 26 plains zebras died from anthrax. An equal number (eighteen) of adult male and female Grevy's zebras succumbed to the disease. The outbreak affected immature and mature individuals equally. The dead plain zebras included fifteen adult females, two adult males and nine immature individuals. The Veterinary Department responded by vaccinating livestock while Kenya Wildlife Service vaccinated 620 Grevy's zebras within southern Samburu. Examination of sites at which carcasses of animals which succumbed to the disease were burnt, revealed that unsupervised burning did not eliminate anthrax spores in 42% of the cases (n = 14). There is an urgent need to incorporate strategic wildlife disease monitoring in the struggle to save Grevy's zebras and other endangered species.     

Preventing desert locust plagues: optimizing management interventions

Solitarious desert locusts, Schistocerca gregaria (Forskål) (Orthoptera: Acrididae), inhabit the central, arid, and semi‐arid parts of the species’ invasion area in Africa, the Middle East, and South‐West Asia. Their annual migration circuit takes them downwind to breed sequentially where winter, spring, and summer rains fall. In many years, sparse and erratic seasonal rains support phase change and local outbreaks at only a few sites. Less frequently, seasonal rains are widespread, frequent, heavy, and long lasting, and many contemporaneous outbreaks occur. When such seasonal rains fall sequentially, populations develop into an upsurge and eventually into a plague unless checked by drought, migration to hostile habitats, or effective control. Increases in the proportion of gregarious populations as the plague develops alter the effectiveness of control. As an upsurge starts, only a minority of locusts is aggregated into treatable targets and spraying them leaves sufficient unsprayed individuals to continue the upsurge. Spraying all individuals scattered within an entire infested zone is arguably both financially and environmentally unacceptable. More of the population gregarizes and forms sprayable targets after each successive season of good rains and successful breeding. Eventually, unless the rains fail, the entire upsurge population becomes aggregated at high densities so that the infested area diminishes and a plague begins. These populations must continue to increase numerically and spread geographically to achieve peak plague levels, a stage last reached in the 1950s. Effective control, aided by poor rains, accompanied each subsequent late upsurge and early plague stage and all declined rapidly. The control strategy aims to reduce populations to prevent plagues and damage to crops and grazing. Differing opinions on the optimum stage to interrupt pre‐plague breeding sequences are reviewed.     

The impact of global warming and land-use change on the pest status of rice and fruit bugs (Heteroptera) in Japan

Infestation by rice and fruit bugs (Heteroptera) became a nationwide problem in Japan in the early 1970s. Nine rice bug species and three fruit bug species have been designated as economically important. Cropping restrictions for rice produced fallow paddy fields where various rice bugs reproduced and became abundant. Plautia crossota stali, Halyomorpha halys and Glaucias subpunctatus are dominant species of fruit bug that cause damage to a range of fruit crops. However, they require cones in order to complete their life cycle. Coniferous trees planted in the 1950s bore cones after 20 years. A dry and hot summer contributes to good masting the following year and good cone production, in turn, contributes to the abundance of fruit bugs in the third year. Thus, there is strong circumstantial evidence that land‐use changes were responsible for the abundance of both rice and fruit bugs during the last 30 years. Poleward range expansion was observed in Nezara viridula, Leptocorisa chinensis, G. subpunctatus and Paradasynus spinosus. A survey conducted to assess winter mortality revealed that every 1 °C rise in mean winter temperature resulted in a reduction of about 15% in winter mortality of N. viridula and H. halys in localities where the mean winter temperature ranges from 2 to 6 °C. In general, species with low developmental zero (T₀) and small thermal constant (K) show the greatest increase in annual number of generations. Species with a high T₀ for preoviposition period show the greatest increase in reproductive activity, while overwintering insects with a lower T₀ tend to appear earlier in response to the elevation of temperature. Numbers of warnings issued by the prefectures on the occurrence of rice bugs and fruit bugs were correlated. Recent global warming operates in various ways, (e.g. by increasing annual number of generations, reproductive activity and food, to produce such correlation). There are no substantial bug problems in Korea where no significant land‐use changes have occurred. Rice bug outbreaks in Japan are predicted to become less frequent in the future, because there is no further scope for cropping restriction. Planting of coniferous trees has been continuously decreasing since 1970, but the area of coniferous forest is still almost the same. This suggests that the fruit bug problem will continue for the foreseeable future.     

Insect outbreaks alter nutrient dynamics in a southern African savanna: patchy defoliation of Colophospermum mopane savanna by Imbrasia belina larvae

Invertebrate herbivore outbreaks have important impacts on system biogeochemical cycling, but these effects have been poorly documented in African savanna ecosystems. In semi‐arid African savannas, outbreaks of the lepidopteran Imbrasia belina (mopane worm) affect discrete patches of the dominant Colophospermum mopane trees; larvae may completely defoliate trees for up to six weeks during each of the early and late growing seasons. We studied the impact of mopane worm outbreaks on the availability of nitrogen (N), phosphorus (P), and potassium (K) within mopane savanna by quantifying major nutrient pools in defoliated and non‐defoliated savanna patches, including leaves, leaf litter, worm frass, and the soil beneath trees. Within an outbreak area, approximately 44 percent of trees were infested, supporting ~29,000 worms/ha, leading to ~640 kg/ha dry weight frass deposition at 1.4 g of frass/day‐individual (fourth or fifth instar), compared with an average 1645 kg/ha dry weight of leaf on trees most of which should be deposited by litterfall at the end of the growing season. Frass had twofold higher P, 10 percent higher K, but equivalent N content than litter. Taking frass and litter deposition together, the N, P, and K contents added due to the outbreak event at our study site were 0.88, 5.8, and 2.8 times those measured in non‐outbreak patches, a pattern which was reflected in the nutrient contents of soil surfaces beneath defoliated trees. Invertebrate herbivory appears to be an important driver for mopane savanna but has been largely neglected.     

A spatial scan statistic for survival data

Spatial scan statistics with Bernoulli and Poisson models are commonly used for geographical disease surveillance and cluster detection. These models, suitable for count data, were not designed for data with continuous outcomes. We propose a spatial scan statistic based on an exponential model to handle either uncensored or censored continuous survival data. The power and sensitivity of the developed model are investigated through intensive simulations. The method performs well for different survival distribution functions including the exponential, gamma, and log-normal distributions. We also present a method to adjust the analysis for covariates. The cluster detection method is illustrated using survival data for men diagnosed with prostate cancer in Connecticut from 1984 to 1995.     

非计划再次手术关键环节管理与效果分析

目的 探索有效降低非计划再次手术发生率的管理方法。方法 对2012年1月—2016年12月住院并进行手术的患者进行主动监测,加强管理,发现非计划再次手术病例,统计发生率及引发原因。结果 225 944例手术共发生非计划再次手术914例,平均发生率为0.40%且五年呈显著下降趋势。引发原因以手术部位感染、切口裂开、切口疝或愈合不良,术后出血,出现漏或瘘为主,共占73.9%。结论 完善主动监测与报告系统、加强院科两级管理、注重原因分析与改进可有效降低非计划再次手术的发生率。     

Evaluation of rapid post-mortem test kits for bovine spongiform encephalopathy (BSE) screening in Japan: Their analytical sensitivity to atypical BSE prions

A classical type of bovine spongiform encephalopathy (C-BSE), recognized in 1987, had a large impact on public health due to its zoonotic link to variant Creutzfeldt-Jakob disease by the human consumption of dietary products contaminated with the C-BSE prion. Thus, a number of countries implemented BSE surveillance using rapid post-mortem test kits that were approved for detection of the C-BSE prion in the cattle brain. However, as atypical BSE (L- and H-BSE) cases emerged in subsequent years, the efficacy of the kits for the detection of atypical BSE prions became a matter of concern. In response to this, laboratories in the European Union and Canada evaluated the kits used in their countries. Here, we carried out an evaluation study of NippiBL®, a kit currently used for BSE screening in Japan. By applying the kit to cattle brains of field cases of C-BSE and L-BSE, and an experimental case of H-BSE, we showed its comparable sensitivities to C, L-, and H-BSE prions, and satisfactory performance required by the European Food Safety Authority. In addition to NippiBL®, two kits (TeSeE® and FRELISA®) formerly used in Japan were effective for detection of the L-BSE prion, although the two kits were unable to be tested for the H-BSE prion due to the discontinuation of domestic sales during this study. These results indicate that BSE screening in Japan is as effective as those in other countries, and it is unlikely that cases of atypical BSE have been overlooked.