LD50 values may be misleading predictors of neonicotinoid toxicity across different bee species

The importance of not only honey bees (Apis mellifera) but also other non-managed bee species and their pollination services has come to light with their recently reported declines. One contributing factor in these declines is thought to be sub-lethal exposure to neonicotinoid insecticides such as thiacloprid. However, current government regulatory agencies do not require the assessment of insecticide toxicity on bee species other than the honey bee, even though previous studies have demonstrated that sensitivity to insecticides is not likely to be generalizable from honey bees to non-managed bee species. Replicating standardized protocols and testing five different doses of thiacloprid on individual caged bees, we assessed the acute contact toxicity by calculating mortality and the lethal dose (LD50) value for three bee species with different life history traits: Apis mellifera, Bombus terrestris, and Osmia bicornis. We found that Apis mellifera and Osmia bicornis had significantly higher mortality in comparison to Bombus terrestris, but there was no dose-dependent response for any of the three bee species. Bee size and sex were also not useful predictors of thiacloprid toxicity. These results suggest that solely relying on LD50 values, especially when they do not produce a dose-dependent response, may be misleading when assessing insecticide toxicity risk for honey bees and other non-managed bee species

Survival rate and changes in foraging performances of solitary bees exposed to a novel insecticide

Abstract Solitary bees are among the most important pollinators worldwide however population declines especially in croplands has been noticed. The novel pesticide sulfoxaflor is a competitive modulator of nicotinic acetylcholine receptors (nAChR) in insects. While there is evidence of a negative impact of neonicotinoids on bees of several social organization levels, our overall knowledge on the impact of sulfoxaflor on bees is poor. Here we present for the first time a study showing effects of field realistic doses of sulfoxaflor on solitary bees. Bees submitted to long term exposure of field realistic doses of sulfoxaflor (5 µg dm-3, 10 µg dm-3, 50 µg dm-3) and control were observed regarding their survival rate. Moreover, we recorded metrics related to flower visitation and flight performance. We discover that the highest field realistic dose is lethal to Osmia bicornis along five days of exposure. The effect of sulfoxaflor reduces the outcome of foraging, important features for fruit and seed production of cross-pollinated plant species. Bees exposed to pesticide visited flowers mostly walking rather than flying. Flight performance was also impaired by the pesticide

A botanic garden as a tool to combine public perception of nature and life-science investigations on native/exotic plants interactions with local pollinators

Life-sciences are pointing towards an alarming worldwide pollinator decline. This decline proceeds along with overall biodiversity losses, even in the context of urban landscapes and human welfare. At the same time, social-sciences are arguing an increased distance from nature, experienced by citizens. The strong connection between the public good and pollinator sustainability, even in urban areas, is well-documented. However, usually basic and applied life-sciences tend to underestimate public perception of nature, which is better tackled by the fields of social-sciences. Therefore, more efforts are needed to link scientific questions and public 'perception' of nature. We designed a transversal project where research questions directly confront public concerns: i.e., even while addressing scientific knowledge gaps, our questions directly arise from public concerns. Social studies highlighted that appreciation of (exotic) plants is related to the impact they may have on the surrounding natural environment: therefore, we investigated links of native and exotic flowers to local pollinators. Other studies highlighted that scientific results need to link to everyday individual experience: therefore, we investigated pollination modes of the renown Salvia, native and exotic, largely used in cuisine and gardening. The botanic garden was the promoter of scientific questions addressed by the public, and also collated the results in a travelling exhibition. The exhibition, together with a dedicated catalogue, were especially designed to enlighten the wide public on the relationships that plants, native and exotic alike, establish with the surrounding world.info:eu-repo/semantics/publishedVersio

High visitation rate of oil bees may increase pollination efficiency of Couepia uiti in Pantanal wetland

International audienceAbstractPollen transfer to the stigma is the primary mechanism of sexual reproduction in plants. Among bee species that act as pollen vectors and pollinators, attributes such as floral visitation rate, synchrony with the receptive phase of the flower, compatibility between flower shape and foraging behavior, and morphological traits are often used to infer pollination efficiency. Herein, we evaluate visitation frequency and behavior of bee species on Couepia uiti (Chrysobalanaceae) flowers in the southern Pantanal, Brazil. Additionally, after experimental manipulation of flower visitation and by accompanying pollen tube growth in the pistil after one single visit to the flowers, we were able to pinpoint the roles of Centris spilopoda and Apis mellifera on the pollination of C. uiti. Centris spilopoda was the most important pollinator of C. uiti in the study area. In fact, we found that this oil bee might enhance plant reproductive success by almost 40% after a single visit. In addition to its high abundance, the efficiency of C. spilopoda as pollinator may be explained by its tight synchrony with pollen liberation and stigmatic receptivity of flowers of C. uiti

Neonikotinoidlerin zehir etkilerini belirlemede ld50 değerleri farklı arı türleri için yanıltıcı bir öngösterge olabilir

The importance of not only honey bees (Apis mellifera) but also other non-managed bee species and their pollination Services has come to light with their recently reported declines. One contributing factor in these declines is thought to be sub-lethal exposure to neonicotinoid insecticides such as thiacloprid. Hovvever, current government regulatory agencies do not require the assessment of insecticide toxicity on bee species other than the honey bee, even though previous studies have demonstrated that sensitivity to insecticides is not likely to be generalizable from honey bees to non- managed bee species. Replicating standardized protocols and testing five different doses of thiacloprid on individual caged bees, we assessed the acute contact toxicity by calculating mortality and the lethal dose (LDso) value for three bee species with different life history traits: Apis mellifera, Bombus terrestris, and Osmia bicornis. \Ne found that Apis mellifera and Osmla bicornis had significantly higher mortality in comparison to Bombus terrestris, but there was no dose-dependent response for any of the three bee species. Bee size and sex were also not useful predictors of thiacloprid toxicity. These results suggest that solely relying on LDso values, especially when they do not produce a dose-dependent response, may be misleading when assessing insecticide toxicity risk for honey bees and other non-managed bee species.Son yapılan kayıp raporları ile sadece bal arıları değil diğer yabani arılar ve onların yaptığı tozlaşma hizmeti gündeme gelmiş oldu. Bu kayıpların oluşmasında önemli faktörlerden biri örneğin thiacloprid gibi neonikotinoid böcek öldürücülerin ölümcül etkinin altındaki dozları düşünülmektedir. Daha önce yapılan çalışmalar göstermiştirki böcek öldürücülere karşı duyarlılığı bal arıları üzerinde yapılan çalışmaları kullanarak yabani arılar için genelleştirmek doğru olmaz. Gerçi güncel devlet düzenleme kurumlan bal arısı dışında diğer arılar üzerinde böcek öldürücüler ile ilgili değerlendirmeyi gerekli görmez. Kafese konulmuş her bir arı üzerinde thiacloprid’in beş farklı dozunu test ve standart protokolü tekrar ederek farklı yaşam karakterlerine sahip üç farklı arı türü için ani temas ile zehirlenmeyi ölüm oranlarını hesaplayarak ve ölümcül doz (LDso) değerlerini kullanarak belirledik. Bu çalışma ile Apis mellifera ve Osmia bicornis türlerinde Bombus terrestris’e göre ciddi derecede yüksek arı ölümleri tespit ettik. Fakat üç farklı arı türü için doza bağlı bir reaksiyon görülmemiştir. Arı büyüklüğü ve cinsiyet thiacloprid zehirlenmesi için yararlı bir öngösterge değildir. Bu sonuçlara göre doza bağlı bir reaksiyon üretilmeden tamamen LDso değerlerine güvenmek, bal arılarında ve yabani arı türlerinde böcek öldrücülerin zehir seviyesini belirlemede yanıltıcı olabilir

Dynamics of nest occupation and homing of solitary bees in painted trap nests

1. The oil‐collecting bee Centris analis (Fabricius, 1804) is an important pollinator for the Neotropical region. The species can be attracted to nest in human‐made cavities. Such trap nests or insect hotels offer the opportunity to study the behaviour of populations in semifield conditions. 2. We studied a newly established trap nest aggregation of C. analis in Mato Grosso do Sul, Brazil and tested the effect that differentially painted nesting options have on the rate of nest foundation, and on the ability of relocating the nest when returning from a foraging trip (homing behaviour). Moreover, we tested if the duration of foraging trips decreased with time. 3. We found that females preferred to nest in painted nests compared to unpainted nests, with blue nests being the most occupied ones, followed by purple, yellow, white, and green. Furthermore, bees improved their homing behaviour with time, however, nest colour did not seem to have an effect on this process. Moreover, we found that bees reduce the duration of their foraging trips with time. This could be an indicator of improved foraging efficiency through learning. 4. These findings could inform a new and fruitful line of research on the behaviour and ecology of trap nesting solitary bees

Cavities in bromeliad stolons used as nest sites by Euglossa cordata (Hymenoptera, Euglossini)

Herein, we describe nests of the orchid bee Euglossa cordata that were constructed in cavities of Aechmea distichantha (Bromeliaceae) stolons. We present data about nest and cell size, number of adults and brood, and analyses of larval provisions. The presence of E. cordata carcasses embedded in the resin of nest partitions indicates that these nests were used by multiple generations. Based on larval provisioning, E. cordata is polylectic and relies heavily on a few plant species

Disentangling the path of pollinator attraction in temporarily colored flowers

Plants may use different strategies to attract pollinators in long distance (e.g. floral display) and in short distance (e.g. ratio between differentially colored flowers) scales. The Verbenaceae Lantana canescens Kunth is a wide spread species in open sites of the Brazilian Pantanal wetland. Individuals of this generalist species can produce a variable number of open inflorescences with yellow and white flowers that are organized in whorls. In this study we tested the hypothesis that increased floral display (long distance attraction) and the ratio between yellow and white flowers (short distance attraction) enhances the number of pollinator species and individuals. We observed flower visitors and calculated floral parameters in 38 plots of 1 m2 each, that contained a varying number of flowering L. canescens individuals. Non-metric multidimensional scaling and Bray-Curtis distances were used to account for flower visitor composition and the relative visitation rate, respectively. We used a structural equation model to test the power of each predictor variable on the visitation rate and a covariance analysis to disentangle the effect of each independent variable on the frequency of plant-pollinator interactions. We found that the number of flower visitors and the visitation rate increased with increasing number of inflorescences. Disentangling long and short distance attraction indicated that the number of inflorescences (per plot) and the number of yellow flowers (yellowing effect) contributed most to flower visitation at long and short distance, respectively

Insetos visitantes de gomas exsudadas por Terminalia argentea Mart & Zucc (Combretaceae)

Uma das fontes efêmeras de alimento que os insetos podem utilizar são as gomas exsudadas por plantas. No mês de maio de 2005, em uma área de cerrado no município de Campo Grande, Mato Grosso do Sul, foram observados insetos visitando as estruturas de exsudação em um indivíduo de Terminalia agentea Mart & Zucc (Combretaceae). Foram registradas 19 espécies, principalmente Trigona branneri (Cockerell) e Mesembrinella bicolor (Fabricius). Todos os visitantes foram observados coletando ou ingerindo a goma exsudada. Observações sobre o horário de visitação e comportamento das espécies mais abundantes são relatadas. As amostras de exsudatos apresentaram baixa concentração de proteínas e açucares redutores e alta concentração de carboidratos complexos, permitindo inferir que os visitantes de T. argentea buscam na goma um recurso alimentar de alta massa molecular que contribui para o armazenamento de reservas energéticas

Bioecological and behavioral interaction between pollinating bees and the pioneer shrub Ludwigia nervosa in degraded area suggests an exotic bee as its major pollinator

The flowers of plants of the genus Ludwigia are an important source of food for several species of bees. In the current study, we conducted an experiment with the aim to describe the reproductive biology and phenology of L. nervosa; to identify the species of visiting bees; analyze the foraging behavior of bees; and to investigate whether the reproductive success of the species is related to the foraging activity of bees. We found that the flowers received visits from several native bee species (n = 7), in addition of the exotic honey bees which came to be the dominant species. During visits the majority of the bees foraged in both resources, pollen and nectar. The significantly higher production of fruits in open pollinated pollination experiment compared to artificial cross pollination, suggests honey bees as effective pollinator of this plant species in the study site. Pollen deposition occurs efficiently, given the absence of pollen limitation. Despite massive visitation of honey bees, Ludwigianervosa is attractive to native bees, and therefore it may help to sustain population of both native and exotic pollinators in fragmented humid areas