Tree diversity drives abundance and spatiotemporal β‐diversity of true bugs (Heteroptera)

1. Spatiotemporal patterns of canopy true bug diversity in forests of different tree species diversity have not yet been disentangled, although plant diversity has been shown to strongly impact the diversity and distribution of many insect communities. 2. Here we compare species richness of canopy true bugs across a tree diversity gradient ranging from simple beech to mixed forest stands. We analyse changes in community composition by additive partitioning of species diversity, for communities on various tree species, as well as for communities dwelling on beech alone. 3. Total species richness (γ‐diversity) and α‐diversity, and abundance of true bugs increased across the tree diversity gradient, while diversity changes were mediated by increased true bug abundance in the highly diverse forest stands. The same pattern was found for γ‐diversity in most functional guilds (e.g. forest specialists, herbivores, predators). Temporal and even more, spatial turnover (β‐diversity) among trees was closely related to tree diversity and accounted for ～90% of total γ‐diversity. 4. Results for beech alone were similar, but species turnover could not be related to the tree diversity gradient, and monthly turnover was higher compared to turnover among trees. 5. Our findings support the hypothesis that with increasing tree diversity and thereby increasing habitat heterogeneity, enhanced resource availability supports a greater number of individuals and species of true bugs. Tree species identity and the dissimilarity of true bug communities from tree to tree determine community patterns. 6. In conclusion, understanding diversity and distribution of insect communities in deciduous forests needs a perspective on patterns of spatiotemporal turnover. Heterogeneity among sites, tree species, as well as tree individuals contributed greatly to overall bug diversity.     

Spectral composition and visual foraging in the three‐spined stickleback (Gasterosteidae: Gasterosteus aculeatus L.): elucidating the role of ultraviolet wavelengths

Visual signalling can be affected by both the intensity and spectral distribution of environmental light. In shallow aquatic habitats, the spectral range available for visually mediated behaviour, such as foraging, can reach from ultraviolet (UV) to long wavelengths in the human visible range. However, the relative importance of different wavebands in foraging behaviour is generally unknown. Here, we test how the spectral composition of ambient light influences the behaviour of three‐spined sticklebacks (Gasterosteus aculeatus) when foraging for live cladoceran Daphnia magna. Although paying particular attention to the UV waveband, we measured the foraging preferences of sticklebacks for prey presented under four different spectral conditions. These conditions selectively removed UV (UV–), short‐wave (SW–), mid‐wave (MW–) or long‐wave (LW–) light from the entire spectrum. The absence of UV and long wavelengths strongly reduced prey attractiveness for G. aculeatus compared with conditions without short‐wave and mid‐wave light. To control for potential light habitat preferences in the main experiment, we conducted a further choice experiment without prey stimuli. Fish in these trials did not discriminate significantly between the different spectral conditions. When comparing both experiments, it was observed that, although filter preferences for MW– and LW– conditions were virtually consistent, they differed at shorter wavelengths, with a reduced preference for UV– conditions and, at the same time, an increased preference for SW– conditions in the presence of prey. Thus, prey choice seems to be strongly affected by visual information at the short‐wave end of the spectrum. The foraging preferences were also mirrored by the chromatic contrast values between prey and the experimental background, as calculated for each lighting condition using a series of physiological models on stickleback perception. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, 105 , 359–368.     

Foraging trip duration of bumblebees in relation to landscape-wide resource availability

Abstract.  1. The study tested the hypotheses that bumblebees have shorter foraging trips in environments that provide abundant resources than in environments that provide sparse resources, and that shorter foraging trips translate into greater colony growth.
2. Six even-aged Bombus terrestris colonies were established in contrasting resource environments. Three colonies had access to abundant resources ( Phacelia tanacetifolia fields with high flower densities), and three colonies were placed in an environment with sparse resources (scattered semi-natural habitats with food plants at lower densities).
3. A total of 870 foraging trips of 220 marked B. terrestris foragers were observed using automated camcorder recordings.
4. The duration of foraging trips was shorter in environments with abundant resources (66 ± 4.6 min) than in environments with sparse resources (82 ± 3.7 min). Within 34 days colonies that had access to abundant resources gained significantly more weight (129 ± 40 g) than colonies foraging on sparse resources (19 ± 7 g).
5. Thus, the spatial distribution and quality of resources at landscape level affected the duration of foraging trips and the colony growth. It was concluded that future conservation schemes need to improve the spatial and temporal availability of resources in agricultural landscapes to counteract the ongoing decline of bumblebees.     

Genetic diversity of European cattle breeds highlights the conservation value of traditional unselected breeds with high effective population size

In times of rapid global and unforeseeable environmental changes, there is an urgent need for a sustainable cattle breeding policy, based on a global view. Most of the indigenous breeds are specialized in a particular habitat or production system but are rapidly disappearing. Thus, they represent an important resource to meet present and future breeding objectives. Based on 105 microsatellites, we obtained thorough information on genetic diversity and population structure of 16 cattle breeds that cover a geographical area from the domestication centre near Anatolia, through the Balkan and alpine regions, to the North-West of Europe. Breeds under strict artificial selection and indigenous breeds under traditional breeding schemes were included. The overall results showed that the genetic diversity is widespread in Buša breeds in the Anatolian and Balkan areas, when compared with the alpine and north-western European breeds. Our results reflect long-term evolutionary and short-term breeding events very well. The regular pattern of allele frequency distribution in the entire cattle population studied clearly suggests conservation of rare alleles by conservation of preferably unselected traditional breeds with large effective population sizes. From a global and long-term conservation genetics point of view, the native and highly variable breeds closer to the domestication centre could serve as valuable sources of genes for future needs, not only for cattle but also for other farm animals.     

RELEASE OF ARTIFICIAL CHERRY FLAVOR FROM ICE CREAMS VARYING IN FAT AND FAT REPLACERS

The effect of fat and fat replacers (FR) on the flavor release from cherry ice cream was investigated. Protein based FR, Simplesse ("S") and carbohydrate based FR, Litesse ("L") either partially or completely substituted milk fat in ice cream. Overall and temporal flavor profiles of ice cream during eating were obtained using chemical and sensory analyses. The performance of FR depended on the level of fat it was substituting and the amount of fat present in the ice cream. In the reduced fat ice cream group, both FRs failed to mimic the characteristics of 6% fat ice cream, mainly because of the low retention of cherry flavor. In the full fat ice cream group, the sensory properties of ice cream containing "L" were closer to the full-fat (12%) ice cream than those with "S". The critical flavor volatile compounds that strongly impact the sensory flavor attributes were identified.     

Elevation and experimental snowmelt manipulation affect emergence phenology and abundance of soil‐hibernating arthropods

1. Effects of climate change, such as higher average temperatures and earlier snowmelt, are already apparent, especially in alpine regions. However, community responses of functionally important arthropod taxa to changing climatic conditions are mostly unknown. 2. In this study, an earlier snowmelt was simulated at 15 plots along an elevational gradient in the German Alps. At each study site, soil emergence traps were established for sampling soil‐hibernating arthropods on earlier and control snowmelt treatments during the growing season. The abundance and emergence phenology of the five most common arthropod orders (Araneae, Coleoptera, Diptera, Hemiptera, Hymenoptera) were analysed, as well as the species richness of Coleoptera. 3. There was increasing abundance and species richness of Coleoptera along the elevational gradient, indicating that at higher altitudes more individuals and species hibernate in the soil. Abundances of Diptera also increased with elevation. By contrast, abundances of Hemiptera declined with increasing elevation, while abundances of Araneae and Hymenoptera did not show significant elevational patterns. Arthropods at higher elevations emerged, on average, 5 weeks later than arthropods at lower elevations, because of a longer‐lasting snow cover. The earlier snowmelt treatment resulted in higher abundances of Araneae and Hymenoptera compared with the control plots, indicating that the time of snowmelt influenced the abundance of predators, such as spiders or parasitic wasps, more than that of herbivores. 4. An earlier emergence of certain arthropod guilds and a change in relative abundance of guilds might desynchronise species interactions, leading to a possible loss of biodiversity.