Apidologie最新文献

Changes in landscape structure have increased the edge amount between different environments, and its implications for biodiversity may vary depending on the level of analysis, ecological groups, and species life history. We investigated the effect of distance from the forest edge on species of solitary wasps and bees and their associated natural enemies, on a gradient from 200 m into the anthropogenic matrix to 200 m into the forest, in Atlantic Forest biome in Brazil. In general, species were positively affected by forest edge proximity, while those forest specialists were more negatively influenced. The natural enemy species were more dependent on the distribution of their hosts than on the edge effect directly. Caterpillar and spider hunters seem to be positively affected by the edge, while pollen collectors progressively decrease their richness and abundance from the matrix towards the interior of forest area, and cockroach hunters present an opposite response. We demonstrate the importance of forest conservation and reforestation programs, not only by some cavity-nesting wasps and bees being entirely dependent on forests to persist, but also because most species sampled here depend on being close to a forest edge (less than 100 m) to carry out their ecological holes. Therefore, understanding how different species respond to environmental and landscape changes and may depend on staying close to forests is essential for effective management and planning strategies for biodiversity conservation.

The study of the performance of animal pollinators has expanded in recent decades mainly due to the concern on crop productivity. Among insects, bees are the main pollinators of most Angiosperm species. The aim of this paper was to study the effect of bee body size on the pollination of Cucurbita maxima Duch. (Cucurbitaceae) var. zapallito crops. We quantified stigmatic pollen deposition by single visits of bee species with different body sizes. Bee species were classified into four categories accordingly to their intertegular distance: Very small (≤ 1.7 mm), Small (1.71 mm < 2.7 mm), Medium (2.71 mm < 3.7 mm) and Large (> 3.71 mm). Fifteen bee species belonging to the Apidae and Halictidae families were observed depositing pollen on the stigmas of C. maxima. The number of pollen grains deposited and the probability of pollen deposition per visit increased significantly with body size. Large bees Xylocopa augusti and Bombus pauloensis were the most efficient species at depositing pollen on stigmas followed by medium-sized bees Eucera fervens and Apis mellifera. The results show that several wild bee species play an important role in the pollination of C. maxima crops. This research provides baseline data for the design of pollination studies to develop strategies to optimize pollination of this crop.

The Mayan bee Melipona beecheii is one of the most important and widely cultivated stingless bees in Mexico. In order to document pollen and nectar resources for M. beecheii during the dry season, 25 pot-pollen and 25 pot-honey samples were collected from February to May 2021 at eight villages in Yucatan, Mexico. All samples were acetolysed, and 500 pollen grains were counted randomly for each sample. A total of 21 taxa belonging to eight botanical families were observed in the pot-pollen samples; in contrast, 32 pollen types from 16 botanical families were recorded in the pot-honey samples. According to PCA analyses, the pollen types that explained the maximum variance among the pot-pollen samples were Senna racemosa var. racemosa, Lonchocarpus punctatum, Cochlospermum vitifolium, Bursera schlechtendalii and B. simaruba, while S. racemosa var. racemosa, C. vitifolium, Alternanthera ramosissima, Psidium guajava, B. schlechtendalii, B. simaruba, L. punctatum, Mimosa bahamensis and Solanum americanum explained the greatest variance among the pot-honey samples. Our results confirm that M. beecheii displays polylectic foraging and targets for the secondary vegetation of tropical deciduous and tropical semideciduous forests. Diversity in the pot-pollen was found to be lower than that of the pot-honey samples. Since some pot-honey samples were overrepresented by the pollen grains of S. racemosa var. racemosa, PCA and cluster analysis grouped those pot-pollen and pot-honey samples together.

The antagonistic interaction between wasps and bees has long driven the attention of beekeepers and evolutionary entomologists. In the most classic reported interaction, Vespa velutina may invade the nest of honeybees and kill many of workers. Although this interaction has been registered to Asian honeybees, which was shown how to defend the nests, little or no attention has been given to similar interactions in the Neotropical region. Here, we report for the first time an antagonistic interaction between the wasp Polybia ignobilis and the stingless bees, Tetragonisca angustula. The wasp of this species was recorded killing and chewing guard bees near at the nest entrance of the stingless bee. Although our report is limited to answer evolutionary aspects of this interaction, it raises questions which may help to understand in the future the reasons this behavior evolved.

Abstract

Decreasing the dependence on external inputs to crop yield maximization is one of the main objectives of agricultural breeding programs. For this reason, new crop varieties once highly dependent on pollinators have been developed to be self-fertile and are now cultivated as pollinator-independent. However, the contribution of pollinators to these varieties remains unknown. In this study, we evaluated pollinators’ contribution to two self-fertile almond varieties (Marta and Marinada) and the density of pollinators needed to ensure adequate pollination. We measured the effects of pollinators on fruit set, seed yield, and pollination limitation at the tree level. Managed honeybees and wild bumblebees were the main floral visitors in both varieties. Both fruit set and seed yield were ~ 50% higher in pollinated trees than in excluded ones in the two varieties. We found no evidence of pollination limitation, suggesting that pollinators’ abundance was sufficient for adequate pollination. We recommend that almond growers actively manage pollinators to maximize seed yield and profits in these self-fertile varieties.

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.