Apidologie最新文献

Tetragonisca angustula and T. fiebrigi are morphologically similar and differentiated mainly by the mesepisternum color, black in the former and ferruginous in the latter. Mixed mesepisternum color on some bees has raised discussions about the taxonomic status of these species if some degree of hybridization can occur between them and they should be regarded as subspecies. Our goal was to investigate if T. angustula and T. fiebrigi are two valid species and contribute to their taxonomic identification. We sampled several colonies from distant Brazilian regions (range of 3,000 km) to analyze the mesepisternum color variation of males and workers, genitalia morphology of males and females (queens and workers), and aggressiveness of the workers in both species. Despite some color variations in some colonies, there are always individuals with typical mesepisternum color inside each colony, i.e., black in T. angustula and ferruginous in T. fiebrigi. The fact that both T. angustula and T. fiebrigi males have black mesepisternum could be causing species misclassifications. The genitalia morphology of males (shape and length of gonostylus and penis valve) and females (gonostylus shape) was consistently different between both species. None of the analyzed male aggregations exhibited mixed males of T. angustula and T. fiebrigi, which indicates that the queen attracts only co-specific males. Tetragonisca angustula workers displayed an aggressive behavior, whereas T. fiebrigi workers were unaggressive. The observed morphological and behavioral differences may be indicators of reproductive isolation between the two species. Therefore, we conclude that T. angustula and T. fiebrigi are two valid species.

Xylocopa nigrocincta Smith, 1854, and Xylocopa suspecta Moure & Camargo, 1988, are two nominal species within the subgenus Neoxylocopa and have a sympatric geographic distribution in South America. While X. nigrocincta is recognized by the presence of reddish metasomatic bands, X. suspecta is entirely black. Although morphologically distinct in terms of metasomal band colour, other morphological characters suggest that both species could be the same evolutionary entity and therefore synonymous. The aim of this research was to review both nigrocincta and suspecta morphotypes using an integrative approach (morphological and molecular) to evaluate if they are truly two different evolutionary lineages. Females of both species were obtained from field collections and museums, representing a large part of their morphotype distribution. Additional diagnostic characters of the external morphology were investigated, such as metasomal band colour, metasomal punctuation, wing colours, and apical regions of the basitibial plate. Mitochondrial gene sequences (COI and CytB) were used for phylogenetic reconstructions. Our results showed that both nigrocincta and suspecta morphotypes are undistinguished based on morphology, although the metasomal band colour, together with the geographic distribution, revealed the presence of three distinct morphogroups, including an intermediate one with a variable number of reddish bands. Nonetheless, the three morphogroups are not supported by molecular data and therefore represent intra-specific variations. In conclusion, our results do not support the hypothesis that the two nominal species are distinct evolutionary lineages, and we propose a synonym between X. nigrocincta and X. suspecta.

Abstract

Most terrestrial ecosystems are shaped by the pollination service provided by insects, foremost bees. As bees are also important pollinators of crop plants, they are key for both the pollination of wild plants and for agricultural production. Meadows and semi-natural habitats (SNHs) are important habitats for bees. However, there is limited knowledge on how land-use intensity of meadows affects wild bees and managed Western honey bees. Further, it is unknown whether SNHs adjacent to meadows affect bees in meadows. Here, we examined in a landscape dominated by grasslands, the effects of land-use intensity (nitrogen input, grazing intensity, mowing frequency), flower availability and adjacent SNHs on bee communities in meadows. We recorded more than 5000 individuals of 87 species of bees and found no effect of land-use intensity on wild and honey bees. Flowering plant species richness had a positive effect on bee species richness in one study year. Though we recorded more bee species in SNHs than meadows, overall and specifically in ecologically specialized bee species (e.g. parasitic bees, oligoleges), the availability of adjacent SNHs did not affect bee abundance and richness in meadows. We discuss why land-use intensity and SNHs adjacent to meadows did not affect bees in meadows and conclude that SNHs are important in sustaining functionally diverse bee communities in landscapes dominated by grasslands.

The evaluation of beekeeping management practices (BMPs) is important for beekeepers worldwide because their choice affects health and survival of managed honeybee (A. mellifera L.) colonies and touches ethical and economic questions. This study focusses on queen excluders, a common hive addition in contemporary beekeeping. Its impacts are controversially discussed but have not been studied scientifically yet. Within a 4-year participatory on-farm experiment, we assessed the effects on colony dynamics in 64 hives in 8 apiaries during one season in Germany using the Liebefeld estimation method. We found no significant deviation for parameters of colony dynamics between hives managed with and without queen excluders. A qualitative decision-making tool (Pugh decision matrix) facilitated concept selection only for specific beekeepers.

Fatty acids (FAs) are important in metabolism and in the maintenance of Apis mellifera colonies. Our objective was to identify the variation in FA composition of the bodies of A. mellifera worker bees after immunological challenges with sterile injections and Paenibacillus larvae vegetative cells. The expression of the hymenoptaecin and abaecin genes was studied and the FAs were identified and quantified. After a challenge with P. larvae, the immune system was activated and abaecin and hymenoptaecin peptide genes were overexpressed. Also, the content of short-chain FAs such as caprylic, capric, and tridecylic acids increased significantly; on the contrary, oleic acid decreased. To the best of our knowledge, this is the first analysis of changes in the FA profile of honey bee workers after immune stimulation with P. larvae. Health status may be a key factor that alters FA composition. More research about the interaction with other stressors affecting the survival of honey bee colonies is needed.

Abstract

Healthy honey bee colonies follow predictable patterns of weight change through the season, gaining weight when resources are abundant and losing weight during periods of scarcity. Divergence from this pattern can indicate trouble in the colony, necessitating beekeeper intervention. While colony weight monitoring has long been used to evaluate colony progress and diagnose potential problems, research has been limited by the labor associated with manual weight measurements. The introduction of next generation colony weight monitoring permits the collection of hive weight data continuously and remotely, enhancing the range of questions that can be answered with these data. However, there is currently no central guide for researchers aiming to use hive scales in their research. Here, we review the literature and describe current methods used to process and analyze within-day, or diel, and seasonal colony weight changes. Diel weight dynamics are based around the circadian rhythm of the colony, resulting from the departure and arrival of foragers and the intake, consumption, and dehydration of food stores. Seasonal weight dynamics can be used to assess colony survival and productivity, often in relation to large-scale patterns of climate, landscape, and floral resource phenology. In addition to describing methods, we highlight future applications of hive weight monitoring, including monitoring weight across ecological gradients and physiological time, coupling of weight monitoring with other colony monitoring techniques, and the practical use of weight monitoring in commercial beekeeping operations. This paper serves as a tool for those wishing to conduct research using colony weight monitoring, and guides the future of remote weight monitoring in honey bee research.