Effects of temperature on the establishment potential in the U.K. of the non-native glasshouse biocontrol agent Macrolophus caliginosus

Abstract This study investigated the effect of temperature on the development and winter survival of the predatory mirid Macrolophus caliginosus Wagner, recently introduced into the U.K. as a biocontrol agent for glasshouse whitefly Trialeurodes vaporariorum . The developmental threshold for M. caliginosus calculated by three methods was between 7.3 and 8.4 °C, with a day-degree requirement per generation varying between 472 and 524 day-degrees. It was estimated that under outdoor conditions M. caliginosus could complete two generations per year in the U.K. All life stages of M. caliginosus had supercooling points around −20 °C, with some pre-freeze mortality evident in both acute and chronic low temperature exposures. Acclimation increased survival of nymphal M. caliginosus from approximately 24–52 days when exposed to a constant 0 °C. Provision of prey extended survival of nymphs in the laboratory at a constant 5 °C from 39 to 64 days and in the field by c . 150 days. The results are discussed in the context of the occurrence and establishment of M. caliginosus in the U.K. and the need to develop a reliable risk assessment system for non-native species used in glasshouse biocontrol.     

Metabolism and cold tolerance of Chinese white pine beetle Dendroctonus armandi (Coleoptera: Curculionidae: Scolytinae) during the overwintering period

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Winter warming effects on overwinter survival,energy use,and spring emergence of Cerotoma trifurcata (Coleoptera: Chrysomelidae)

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Diapause and overwintering of two spruce bark beetle species

Diapause, a strategy to endure unfavourable conditions (e.g. cold winters) is commonly found in ectothermic organisms and is characterized by an arrest of development and reproduction, a reduction of metabolic rate, and an increased resistance to adversity. Diapause, in addition to adaptations for surviving low winter temperatures, significantly influences phenology, voltinism and ultimately population growth. We review the literature on diapause and overwintering behaviour of two bark beetle species that affect spruce‐dominated forests in the northern hemisphere, and describe and compare how these strategies can influence population dynamics. The European spruce bark beetle Ips typographus (L.) (Coleoptera, Curculionidae) is the most important forest pest of Norway spruce in Europe. It enters an adult reproductive diapause that might be either facultative or obligate. Obligate diapausing beetles are considered strictly univoltine, entering this dormancy type regardless of environmental cues. Facultative diapausing individuals enter diapause induced by photoperiod, modified by temperature, thus being potentially multivoltine. The spruce beetle Dendroctonus rufipennis (Kirby) (Coleoptera: Curculionidae) infests all spruce species in its natural range in North America. A facultative prepupal diapause is averted by relatively warm temperatures, resulting in a univoltine life cycle, whereas cool temperatures induce prepupal diapause leading to a semivoltine cycle. An adult obligate diapause in D. rufipennis could limit bi‐ or multivoltinism. We discuss and compare the influence of diapause and overwinter survival on voltinism and population dynamics of these two species in a changing climate and provide an outlook on future research.     

气候变暖对中国褐飞虱越冬北界的影响

基于GIS技术,利用1951—2010年中国南方地区289个气象站点观测资料和褐飞虱历史越冬考察资料,通过采用典型年褐飞虱越冬实况调查资料进行检验,对前人研究的褐飞虱越冬北界指标进行优选,最终选择1月10℃等温线作为中国褐飞虱越冬北界位置确定的指标,分析了最近60年来气候变暖背景下中国褐飞虱越冬北界年代际变化以及前后30年的变化。结果表明:在气候变暖背景下,由于暖冬年份频次的增加,使得每隔10年、30年褐飞虱越冬北界平均界限均不同程度北移,与冷冬年相比,暖冬年褐飞虱越冬北界位置可向北推移2～3个纬度;年代际变化以20世纪80年代最为明显,80年代之后的30年较之前的30年北移显著;空间北移较明显的地区为云南中部和福建南部,其中云南境内最大位移处60年约向北移动了近90km。     

Adaptive winter survival strategies: defended energy levels in juvenile Atlantic salmon along a latitudinal gradient

Current knowledge suggests that patterns of energy storage and depletion in animals are governed by behavioural trade-offs between risks associated with feeding and future energy demands. However, the length of adverse periods varies over geographical or climatic gradients. To explore the potential for genotypic sources of variation in behavioural trade-offs, we compared the winter energy-depletion patterns among 13 wild populations of juvenile Atlantic salmon (Salmo salar L.) along a latitudinal gradient (58–70°N) and performed common-environment experiments of energy-state-dependent feeding. In the wild, winter lipid-depletion rates were lower for northern than for southern populations. The variation in spring lipid levels among the population was lower than autumn variation, with storage lipid levels clustered close to critical limits for survival. In semi-natural stream channels with natural food supply, hatchery-reared fish originating from northern populations showed a positive scaling of feeding activity with decreasing energy levels, whereas southern populations did not. In conclusion, juvenile Atlantic salmon from northern populations defend their energy levels more strongly than fish from southern populations. Adaptive variation in feeding activity appears important for this difference. Thus, the present study shows a link between geographical patterns in storage energy trajectories and adaptive differences in state-dependent feeding motivation.     

中国东南部越冬区白尾鹞种群动态

主要从湖北沙湖湿地自然保护区白尾鹞(Circus cyaneus)的生境偏爱和影响因子两方面分析中国东南部越冬区白尾鹞的种群动态。方差分析表明:年度间白尾鹞丰富度差异不显著。T检验表明:4a季节间白尾鹞丰富度差异极显著,秋季高于冬季。方差分析表明:4种生境中白尾鹞的丰富度存在极显著差异,草甸芦苇农田水域。4种生境中白尾鹞丰富度变异系数为:草甸水域芦苇农田。草甸生境是白尾鹞相对较好的越冬生境。多独立样本非参数检验(Kruskal-Wallis H法)表明:4种生境中雀形目鸟类和环颈雉的丰富度均存在极显著差异。多元线性回归模型(Enter进入法)显示:白尾鹞丰富度与其捕食对象丰富度在芦苇和草甸生境中呈强正相关,在农田和水域生境中相关性不显著。虚拟线性回归模型(Enter进入法)表明:草甸中的影响因子极显著的影响草甸中白尾鹞的丰富度。方差分析表明:草甸中白尾鹞的丰富度随草甸面积的下降而显著性下降。T检验表明:围网对白尾鹞在水域生境出现频次无显著影响。     

U.K. winter egg survival in the field and laboratory diapause of Typhlodromips montdorensis

Abstract. Typhlodromips montdorensis has potential for release as a glasshouse biological control agent in the U.K. against thrips and spider mites. This study investigates the field survival in the U.K. of T. montdorensis when released as eggs, and the diapause response when reared in a regime related to its location of origin. All acclimated and nonacclimated eggs of T. montdorensis die in the field within 7 days of exposure. It is not possible to induce diapause in T. montdorensis reared at 21 °C under a LD 11 : 13 h photoperiod. The results presented here support the view that T. montdorensis is unlikely to survive a U.K. winter outside of the glasshouse environment, and contribute to the understanding of the biology of this little known species.     

Moulting reduces freeze susceptibility in the Antarctic mite Alaskozetes antarcticus (Michael)

Abstract.  The effect of moulting on the cold hardiness of the oribatid mite Alaskozetes antarcticus (Michael) is investigated. Non moulting animals show clear seasonal patterns of cold hardiness with high supercooling points (SCPs) at the peak of summer and an increasing proportion of low SCPs with declining environmental temperatures. By contrast, both field-fresh and laboratory acclimated (5 °C) mites in the moult state are consistently found to have low SCPs regardless of environmental temperature.     

Ongoing changes in migration phenology and winter residency at Bracken Bat Cave

Bats play an important role in agroecology and are effective bioindicators of environmental conditions, but little is known about their fundamental migration ecology, much less how these systems are responding to global change. Some of the world's largest bat populations occur during the summer in the south‐central United States, when millions of pregnant females migrate from lower latitudes to give birth in communal maternity colonies. Despite a relatively large volume of research into these colonies, many fundamental questions regarding their abundance—including their intra‐ and interseasonal variability—remain unanswered, and even estimating the size of individual populations has been a long‐running challenge. Overall, monitoring these bat populations at high temporal resolution (e.g., nightly) and across long time spans (e.g., decades) has been impossible. Here, we show 22 continuous years of nightly population counts at Bracken Cave, a large bat colony in south‐central Texas, enabling the first climate‐scale phenological analysis. Using quantitative radar monitoring, we found that spring migration and the summer reproductive cycle have advanced by approximately 2 weeks over the study period. Furthermore, we quantify the ongoing growth of a newly—established overwintering population that indicates a system‐wide response to changing environmental conditions. Our observations reveal behavioral plasticity in bats’ ability to adapt to changing resource availability, and provide the first long‐term quantification of their response to a changing climate. As aerial insectivores, these changes in bat phenology and propensity for overwintering indicate probable shifts in prey availability, with clear implications for pest management across wider regional agrisystems.