Intraguild predation involving Harmonia axyridis: a review of current knowledge and future perspectives

As an effective generalist predator of aphids and other hemipteran pests H. axyridis has been a successful biological control agent. However, the very functional traits that have contributed to its success in this regard also implicate it as an intraguild predator that poses a significant risk not only to the diversity of other natural enemies of Hemiptera (and their associated ecosystem services), but to biodiversity more widely. In this paper we will specifically review the existing data on intraguild predation involving H. axyridis, and consider the strength and symmetry of such interactions both within its native guild and within exotic guilds where it has established as an invasive alien. We will use these studies to interpret the observed population declines in predator diversity in the field, predict species at risk in regions not yet invaded and consider implications for resulting ecosystem services. We will also indicate gaps in our knowledge that require further study in order to identify opportunities for mitigation.     

南蝠回声定位叫声的分析

蝙蝠科是翼手目中种类最繁多、分布最广泛、进化最成功的科之一 ,全球共有 42属 35 5种(Ｎｏｗａｋ ,1991)。该类群的大多数物种都以超声波回声定位来进行捕食 ,其回声定位行为的多样性以及捕食策略的多样性 ,一直都是动物生态学中的研究热点。南蝠 (Ｉａｉｏ)属蝙蝠科南蝠属 ,为单型种 ,主要分布于我国 (罗蓉等 ,1993)。它是蝙蝠科中体形最大者 ,以前对其生态学方面的研究非常少 ,而对其回声定位的研究则未见报道。南蝠捕食时的叫声与飞行及悬挂状态下的叫声的基本特征一致 (声谱图及谐波等 ) ,仅在叫声次数上有一定差异。因此本文将录制南…     

Differences in functional trait responses to elevation among feeding guilds of Aculeata community

The response of communities to environmental change is expected to vary among feeding guilds. To evaluate the response of guilds to environmental factors without considering the taxonomic specificities, it is useful to examine Aculeata bees and wasps, which consist of closely related taxa including different guilds, pollinators, predators, and parasitoids. In this study, we evaluated changes in species diversity (SD) and functional traits of each feeding guild along an elevational gradient in a boreal forest in northern Japan. We used yellow pan traps to collect Aculeata bees and wasps at 200–1600 m above sea level. We investigated six functional traits (trophic level, seasonal duration, body size, elevational range, nesting position, and soil dependency) and the horizontal distribution of the species. The SD of all Aculeata, predators, and parasitoids decreased with an increase in elevation; however, the SD of pollinators did not show any specific trend. Although the functional trait composition of all Aculeata species did not show any trend, that of each feeding guild responded to elevation in different ways. Pollinators increased in body size and showed a decrease in seasonal duration with increasing elevation, suggesting that tolerance and seasonal escape from physical stress at high elevations are important for shaping pollinator communities. Predators increased their elevational range and the proportion of above‐ground nesting species increased with increasing elevation, suggesting that the ability to live in a wider range of environments and avoid unsuitable soil environments at high elevations might be important. Parasitoids changed their hosts and displayed variable traits with increasing elevation, suggesting that brood parasitoids have difficulty in surviving at high elevation. The traits for each guild responded in different ways, even if they were dominated by the same environmental factors. Our findings imply that differences in the responses of functional traits would produce different community assembly patterns in different guilds during further climate change.     

Fungal genome size and composition reflect ecological strategies along soil fertility gradients

Genomic traits reflect the evolutionary processes that have led to ecological variation among extant organisms, including variation in how they acquire and use resources. Soil fungi have diverse nutritional strategies and exhibit extensive variation in fitness along resource gradients. We tested for trade-offs in genomic traits with mycelial nutritional traits and hypothesize that such trade-offs differ among fungal guilds as they reflect contrasting resource exploitation and habitat preferences. We found species with large genomes exhibited nutrient-poor mycelium and low GC content. These patterns were observed across fungal guilds but with varying explanatory power. We then matched trait data to fungal species observed in 463 Australian grassland, woodland and forest soil samples. Fungi with large genomes and lower GC content dominated in nutrient-poor soils, associated with shifts in guild composition and with species turnover within guilds. These findings highlight fundamental mechanisms that underpin successful ecological strategies for soil fungi.     

Mechanisms determining the spatial distribution of microtine predators on the Arctic tundra

1. We studied the spatial distribution of avian microtine predators using data from 19 study areas on the tundra of northern Siberia.
2. Numbers of snowy owls, and long-tailed skuas and pomarine skuas depended strongly on lemming density. However, a significant relationship between lemming density and number of rough-legged buzzards appeared first after removal of the effect of snowy owl abundance on the distribution of rough-legged buzzards.
3. We applied a recently developed method (Manly 1995) to examine co-occurrences of species and found that rough-legged buzzards and snowy owls did not co-occur while snowy owls, long-tailed skuas and pomarine skuas did.
4. There are large differences in nest construction and chick behaviour between rough-legged buzzards and the three other species. Moreover, the snow owl is a polyphagous predator preying also on large birds including raptor chicks. Therefore, we propose that reduced risk of nest predation favours rough-legged buzzards nesting away from snowy owls.
5. Variations in abundance of the two lemming species did not seem to influence the distributions of snowy owls and rough-legged buzzards. Neither was it likely that latitudinally related factors such as breeding season length affected the distribution of rough-legged buzzards.     

A review of predation as a limiting factor for bird populations in mesopredator‐rich landscapes: a case study of the UK

The impact of increasing vertebrate predator numbers on bird populations is widely debated among the general public, game managers and conservationists across Europe. However, there are few systematic reviews of whether predation limits the population sizes of European bird species. Views on the impacts of predation are particularly polarised in the UK, probably because the UK has a globally exceptional culture of intensive, high‐yield gamebird management where predator removal is the norm. In addition, most apex predators have been exterminated or much depleted in numbers, contributing to a widely held perception that the UK has high numbers of mesopredators. This has resulted in many high‐quality studies of mesopredator impacts over several decades. Here we present results from a systematic review of predator trends and abundance, and assess whether predation limits the population sizes of 90 bird species in the UK. Our results confirm that the generalist predators Red Fox (Vulpes vulpes) and Crows (Corvus corone and C. cornix) occur at high densities in the UK compared with other European countries. In addition, some avian and mammalian predators have increased numerically in the UK during recent decades. Despite these high and increasing densities of predators, we found little evidence that predation limits populations of pigeons, woodpeckers and passerines, whereas evidence suggests that ground‐nesting seabirds, waders and gamebirds can be limited by predation. Using life‐history characteristics of prey species, we found that mainly long‐lived species with high adult survival and late onset of breeding were limited by predation. Single‐brooded species were also more likely to be limited by predation than multi‐brooded species. Predators that depredate prey species during all life stages (i.e. from nest to adult stages) limited prey numbers more than predators that depredated only specific life stages (e.g. solely during the nest phase). The Red Fox and non‐native mammals (e.g. the American Mink Neovison vison) were frequently identified as numerically limiting their prey species. Our review has identified predator–prey interactions that are particularly likely to result in population declines of prey species. In the short term, traditional predator‐management techniques (e.g. lethal control or fencing to reduce predation by a small number of predator species) could be used to protect these vulnerable species. However, as these techniques are costly and time‐consuming, we advocate that future research should identify land‐use practices and landscape configurations that would reduce predator numbers and predation rates.     

天津滨海滩涂湿地鸟类丰富度与环境因子的关系研究

由于湿地生态系统的重要性、脆弱性和复杂性,湿地生态系统的保护与修复是当今世界的热点与难点问题之一。本研究选取天津滨海新区的3处湿地生态系统作为参考场地,1处湿地生态系统作为验证场地,通过量化4处场地不同类型栖息地的7个环境因素,综合鸟类对各类型栖息地的使用情况,并采用逐步回归分析,结果表明植被覆盖率、植物水平斑块丰富度及人为干扰程度与鸟类物种丰富度呈显著相关,并建立模型1;植物香农－威纳指数、植物水平斑块丰富度及人为干扰程度与鸟类共位群丰富度呈显著相关关系,并建立模型2。最后,利用验证场地的数据进行模型验证,得出所建立的模型能够较为准确地对栖息地内的鸟类丰富度进行预测。该研究构架了1种利用栖息地类型预测场地鸟类丰富度的方法,以期供相关研究或实际规划设计工作参考。     

Fruiting phenology of animal-dispersed plants in response to winter migration of frugivores in a warm temperate forest on Yakushima Island, Japan

The fruiting phenology of animal-dispersed plants was observed in a warm temperate, evergreen forest on Yakushima Island. The number of ripe fruits was counted for 22 trees, four lianas and one parasitic epiphyte species with sapfruit. These fruits were consumed by birds and Japanese macaques (Macaca fuscata yakui). Birds with small gapes (e.g. Japanese white-eye [Zosterops japonica]) consumed only small fruit less than 6 mm in diameter, while birds with large gapes (e.g. red-capped green pigeon [Sphenurus formosae]) and Japanese macaques consumed a wide range of fruits from 4 to 16 mm in diameter. The larger animals did not ignore the smaller fruits. Brown-eared bulbul (Hypsipetes amaurotis) and Japanese white-eye were the main consumers of sapfruit in terms of frequency in winter. Some of the observed consumers were year-round residents, but most of the consumers migrated to Yakushima Island from the main islands of Japan to overwinter (from November to March), and their abundance in winter was four times as high as during the rest of the year (from May to October). In 23 of the 27 plant species investigated, sapfruit production coincided with their immigration season, whereas tree species bear capsules and nuts during autumn from September to November. We suggest that sapfruit species set their ripe period to the season when frugivorous birds are most abundant.     

A pilot analysis of gut contents in termites from the Mbalmayo Forest Reserve,Cameroon

Abstract.

• 1 Gut content analysis was carried out on eight species of higher termites representing the four included subfamilies and notional soil-feeding and wood-feeding forms. A lower termite species feeding on wood was also examined.
• 2 Pooled homogenates equivalent in volume to twenty hindguts of Thoracotermes macrothorax were diluted, stained and scored present/absent in 500 haemacytometer fields for ten content item categories: macerated organic material, lignified tissue, plant tissue fragments, fungal mycelium, arthropod parts, plant roots, safranin +ve, gentian violet +ve, humus and silica. For interspecific comparisons, the occurrence of each category was expressed as a proportion of the total haemacytometer cells examined.
• 3 A hierarchical classification of the species, based on gut contents, was prepared using a two-way indicator species analysis, and suggested the following rank order of species along a hypothetical humification gradient (soil to sound wood): Thoracotermes macrothorax, Astalotermes quietus (both soil-feeders), Termes hospes, Amalotermes phaecocephalus, Pseudacanthotermes militaris, Microtermes congoensis, Nasutitermes lujae, Microcerotermes parvus, Schedorhinotermes putorius (all notional wood-feeders). Arthropod parts, silica and humus were identified as indicator factors.
• 4 It is proposed that wood-feeding forms can be subdivided into a group consuming some silica and humus (five species: humified wood-feeders) and a second group of sound wood-feeders (two species).
• 5 Pianka's equations for diet breadth and diet overlap were also applied to the data. These identified Microtermes congoensis, Schedorhinotermes putorius and Pseudacanthotermes militaris as the most specialized feeders, i.e. that they can extract their nutrients from the least heterogenous substrates.