Bee Activity Research Articles

Rangeland Sharing by Cattle and Bees: Moderate Grazing Does Not Impair Bee Communities and Resource Availability

Rangelands are a dominant anthropogenic land use and a main driver of natural habitat loss worldwide. Land sharing, the integration of agricultural production and biodiversity conservation, may provide a platform for managing rangelands to fulfill multiple ecosystem services. However, livestock grazing can greatly affect biodiversity and little is known about its effects on providers of focal ecosystem services, such as pollinators. We investigated the effect of cattle grazing on bee communities and their foraging and nesting resources in Mediterranean rangelands. Specifically, we explored the effect of moderate cattle grazing on flowering plant abundance, species richness and composition, the diversity of nesting substrates, and consequently, the possible effects on wild bee and honey bee foraging activity, species diversity, and community composition. We conducted field research in the Mediterranean rangelands of Israel during the main bee activity season, in the spring of 2012 and 2013, comparing paired cattle-grazed and ungrazed areas. The availability of floral and nesting resources for bees was unaffected or positively affected by grazing. Similarly, wild bee abundance, species richness, and composition were not affected by grazing, but were instead shaped by spatiotemporal factors. Nor was honey bee activity level impaired by grazing. The foraging preferences of bees, as well as flower species composition and peak bloom differed between grazed and ungrazed areas. Therefore, in our studied rangelands, grazing had its main effect on the foraging choices of honey bees and wild bees, rather than on their abundance and diversity. Moreover, our results indicate the potentially important role of ungrazed patches in increasing nectar and pollen diversity and availability in rangelands for both honey bees and wild bees in the spring. Hence, maintaining a mosaic of moderately grazed and ungrazed patches is expected to provide the greatest benefits for wild bee conservation and honey bee activity in Mediterranean rangelands. Our findings support the notion of rangeland sharing by cattle and bees in Mediterranean ecosystems under moderate grazing intensities, mimicking the coexistence of honey bees, wild bees, and cattle in Mediterranean ecosystems on an evolutionary timescale.

Effects of Chinese Privet on Bees and Their Vertical Distribution in Riparian Forests

AbstractChinese privet (Ligustrum sinense Lour.), is known to negatively affect biodiversity near the ground in invaded forests by forming thick layers of non-native vegetation in the midstory. Whether these effects extend above the shrub layer into the canopy remains unclear. We sought to test this question by using flight-intercept traps (clear plastic panels attached to a white bucket) to sample bees at three heights (0.5, 5, and 15 m) in plots in which L. sinense had or had not been experimentally eliminated. Privet removal (i.e., restoration) resulted in significantly higher bee abundance, richness, and diversity than in invaded sites, but this effect was only observed at 0.5 m. In restored plots, bee diversity was generally higher at 5 and 15 m than near the forest floor, but there were no differences between traps at 5 and 15 m. Our findings show that bees will benefit from the removal of invasive shrubs near the forest floor but not in the canopy. Why bee diversity is higher in the canopy than near the ground in temperate deciduous forests remains unknown.Study ImplicationsChinese privet is recognized as one of the most problematic plants invading southeastern US forests where it has strong negative effects on native plant and insect diversity near the forest floor. This study tested the impacts of privet removal on the diversity of bees at three heights to determine whether the effects of removing privet extend into the canopies of temperate deciduous forests. The findings indicate that management activities aimed at eliminating Chinese privet will greatly increase bee activity near the forest floor but will not immediately impact bee numbers in the canopy.

Characterization of wild bee communities in apple and blueberry orchards

AbstractWild bees provide invaluable ecosystem services in agricultural landscapes such as pollination. However, in recent decades, pollinator biodiversity, especially in wild bees, is declining on a global scale, with potentially far‐reaching consequences for crop production. Thus, there is an urgent need to determine whether wild bees are present in agricultural systems, such as fruit orchards. In the present study, we examined the wild bee fauna at species and community levels during the period of bee activity (May to August) in apple and high‐bush blueberry orchards in New England. Bee communities are crop‐specific and dominated by very few species, which fluctuate according to crop and season. The blueberry associated bee fauna was more diverse. In apple, communities were phylogenetically clustered at the genus level and dominated by solitary ground nesting bees within the genus Andrena. Species fluctuated widely in presence and abundance throughout the season, leading to differences in community composition and functional trait structure. The results obtained in the present study show that apple and blueberry harbour a distinct and diverse bee fauna that performs vital pollination services in orchards. Our results provide essential baseline data for wild bees in blueberry and apple orchards and this can be used to improve management and conservation strategies for wild bee preservation in these crops.

Rangeland sharing by cattle and bees: moderate grazing does not impair bee communities and resource availability.

Rangelands are a dominant anthropogenic land use and a main driver of natural habitat loss worldwide. Land sharing, the integration of agricultural production and biodiversity conservation, may provide a platform for managing rangelands to fulfill multiple ecosystem services. However, livestock grazing can greatly affect biodiversity and little is known about its effects on providers of focal ecosystem services, such as pollinators. We investigated the effect of cattle grazing on bee communities and their foraging and nesting resources in Mediterranean rangelands. Specifically, we explored the effect of moderate cattle grazing on flowering plant abundance, species richness and composition, the diversity of nesting substrates, and consequently, the possible effects on wild bee and honey bee foraging activity, species diversity, and community composition. We conducted field research in the Mediterranean rangelands of Israel during the main bee activity season, in the spring of 2012 and 2013, comparing paired cattle-grazed and ungrazed areas. The availability of floral and nesting resources for bees was unaffected or positively affected by grazing. Similarly, wild bee abundance, species richness, and composition were not affected by grazing, but were instead shaped by spatiotemporal factors. Nor was honey bee activity level impaired by grazing. The foraging preferences of bees, as well as flower species composition and peak bloom differed between grazed and ungrazed areas. Therefore, in our studied rangelands, grazing had its main effect on the foraging choices of honey bees and wild bees, rather than on their abundance and diversity. Moreover, our results indicate the potentially important role of ungrazed patches in increasing nectar and pollen diversity and availability in rangelands for both honey bees and wild bees in the spring. Hence, maintaining a mosaic of moderately grazed and ungrazed patches is expected to provide the greatest benefits for wild bee conservation and honey bee activity in Mediterranean rangelands. Our findings support the notion of rangeland sharing by cattle and bees in Mediterranean ecosystems under moderate grazing intensities, mimicking the coexistence of honey bees, wild bees, and cattle in Mediterranean ecosystems on an evolutionary timescale.

Relative foraging intensity of various honey bee species on Brassica juncea (L.) czern & coss

Foraging preference of various species of honey bees on Brassica juncea (var. RLC-1) blooms was recorded consecutively for two years at University Seed Farm, Ladhowal (Ludhiana, Punjab, India) during the blooming period i.e. January and February months. The mean foraging intensity of Apis cerana (2.7 bees/m2/min) was only marginally higher than the foraging intensity of Apis mellifera (2.6 bees/m2/min). Among the wild honey bees, Apis florea was not recorded on the crop, while the foraging intensity of Apis dorsata was comparatively lower (1.4 bees/m2/min). The maximum foraging intensity was recorded during the fourth week of initiation of flowering when the crop was in full bloom. Improvement in sunshine hours and the mean maximum temperature during this period also favoured the foraging intensity. Cool weather conditions affected the timings of initiation and cessation of foraging activity; the peak activity of all the recorded honey bees was registered at 1200 h, though the bee activity on the crop was recorded during 1000-1600h. Owing to the maximum honey bees’ intensity during noon, the chemical control of insect pests should not be executed during noon hours towards pollinators’ conservation and consequent yield enhancement.

Influence of coniferous-wormwood extract on the viability of bee colonies in Eastern Siberia

The article is devoted to the problems of maintaining viability and increasing the productivity of honey bees in Eastern Siberia. The benefits of coniferous wormwood extract for autumn-spring feeding of bee colonies are described. The researches have shown that bees more actively took food with coniferous wormwood extract than regular sugar syrup. Feeding bees with syrup with extract positively influenced the course of wintering of bees: in the experimental group there was 100% safety. A positive effect of the extract on the development of bee colonies, flight activity of bees was noted: it was seen that the individuals were strong and active. As a result of the researches, it was noticed that after a six-fold feeding of bees with coniferous wormwood extract, the strength of the bee colonies, the average honey and wax productivity, the number of brood and received nucleus increased. The daily increase of population made it possible to maintain an optimal microclimate in the brood nest. It was found that stimulative feeding with the extract increased resistance to such common diseases as varroatosis (there was an 82.8% reduction in the mite strike of bee colonies), nosematosis and ascospherosis. These observations indicate that bee colonies had a huge army of working bees, the microclimate inside the nest was healthy, and it made the maximum use of forces for further increase of individuals and making products.

Temperature Conditions for Determination of Beekeeping Regions in the Light of Climate Change. Case study: Fars Province

Abstract The importance of the honey bee lays in its huge role in pollination and, as a result, maintaining the flora of the environment and also increasing agricultural production. Temperature is the most important element of the atmosphere affecting beekeeping. Results of stationary conclusions are generalized to the area of Fars province by using geographical information system (GIS) according to direct relationship between elevation changes and temperature variations. A beekeeping capability map was then drawn for the Fars province by months of the year. The results showed that heat conditions in four months of the year, from December to March, are not suitable in most of the northern and eastern parts of the province. The southern regions with an altitude of less than 1100 meters above sea level are considered as a suitable place for deployment, wintering and beginning of bee colony activities. The most optimal months of the year for honey bee activities are May and October. For fixed beekeeping, the central strip of the province with an average height of 1500 meters above sea level is the most suitable places.

Bee Swarm Activity Acoustic Classification for an IoT-Based Farm Service.

Beekeeping is one of the widespread and traditional fields in agriculture, where Internet of Things (IoT)-based solutions and machine learning approaches can ease and improve beehive management significantly. A particularly important activity is bee swarming. A beehive monitoring system can be applied for digital farming to alert the user via a service about the beginning of swarming, which requires a response. An IoT-based bee activity acoustic classification system is proposed in this paper. The audio data needed for acoustic training was collected from the Open Source Beehives Project. The input audio signal was converted into feature vectors, using the Mel-Frequency Cepstral Coefficients (with cepstral mean normalization) and Linear Predictive Coding. The influence of the acoustic background noise and denoising procedure was evaluated in an additional step. Different Hidden Markov Models’ and Gaussian Mixture Models’ topologies were developed for acoustic modeling, with the objective being to determine the most suitable one for the proposed IoT-based solution. The evaluation was carried out with a separate test set, in order to successfully classify sound between the normal and swarming conditions in a beehive. The evaluation results showed that good acoustic classification performance can be achieved with the proposed system.

Fungicide suppression of flight performance in the honeybee (Apis mellifera) and its amelioration by quercetin.

As a managed agricultural pollinator, the western honeybee Apis mellifera frequently encounters agrochemicals as contaminants of nectar and pollen. One such contaminant, the fungicide boscalid, is applied at bloom in orchards for fungal floral pathogen control. As an inhibitor of complex II in the mitochondrial electron transport chain of fungi, boscalid can potentially interfere with high energy-demanding activities of bees, including flight. We designed an indoor flight treadmill to evaluate impacts of ingesting boscalid and/or quercetin, a ubiquitous phytochemical in bee food that also affects mitochondrial respiration. Boscalid reduced the wingbeat frequencies of foragers during flight but did not alter the duration of flight. At the colony level, boscalid ingestion may thereby affect overall health by reducing forager efficiency. The consumption of quercetin, by contrast, led to higher adenosine triphosphate levels in flight muscles and a higher wingbeat frequency. Consuming the two compounds together increased wingbeat frequency, demonstrating a hitherto unrecognized mechanism by which dietary phytochemicals may act to ameliorate toxic effects of pesticides to promote honeybee health. In carrying out this work, we also introduce two methodological improvements for use in testing for pesticide effects on flight capacity-a 'force-feeding' to standardize flight fuel supply and a novel indoor flight treadmill.

Pollen Characterization of English Honey from Worcestershire, West Midlands (UK)

Beekeeping in England, United Kingdom, is very popular since much of the country has favourable habitats for honey production. Worcestershire county, in the West Midlands region, has habitats typical of much of the lowland regions of England, comprising a patchwork of pasture with small woodlands, orchards, gardens, meadows, hedgerows, riverbanks and arable crops including oilseed rape and field bean, amongst others. While most beekeepers keep bees as a hobby, commercial honey companies do derive some of their honey from this region, from both smaller and large-scale producers. Pollen surveys of honey are useful for several reasons: to help determine honeybee forage activities for honey producers; to provide information for honey analysts and to compare with earlier surveys to see if habitat and climate change are altering foraging habits, which may also help with bee conservation. In the United Kingdom, peer-reviewed surveys of bee forage and honeys have been quite limited (Balfour, Fensome, Samuelson, & Ratnieks, 2015) but there are good sources of information available to the beekeeper about the likely sources of pollen, such as Kirk and Howes (2012) or Hodges (1984). Although observing bee activity can indicate which plants the bees are using for their various requirements, it may not always be clear which plants are contributing directly to the honey. Furthermore, an empirical, peer-reviewed study of the pollen content of honey in England has not been conducted since 1952 when Deans (1957) analysed 854 honey samples from across the British Isles, including 14 samples from Worcester (110 from the Midlands). Two recent DNA studies have also provided data on the floral composition of eight Welsh honeys and one from the Isle of Wight (Hawkins et al., 2015) and one for the National Botanic Garden of Wales (de Vere et al., 2017). The aim of this research was to characterize the typical pollen content of honey from Worcestershire in the West Midlands region of England.

Seasonal variation of a plant-pollinator network in the Brazilian Cerrado: Implications for community structure and robustness.

Seasonal variation in the availability of floral hosts or pollinators is a key factor influencing diversity in plant-pollinator communities. In seasonally dry Neotropical habitats, where month-long periods of extreme drought are followed by a long rainy season, flowering is often synchronized with the beginning of precipitation, when environmental conditions are most beneficial for plant reproduction. In the Brazilian Cerrado, a seasonally dry ecosystem considered one of the world’s biodiversity hotspots for angiosperms, plants with shallow root systems flower predominantly during the rainy season. Foraging activity in social bees however, the major pollinators in this biome, is not restricted to any particular season because a constant supply of resources is necessary to sustain their perennial colonies. Despite the Cerrado’s importance as a center of plant diversity, the influence of its extreme cycles of drought and precipitation on the dynamics and stability of plant-pollinator communities is not well understood. We sampled plant-pollinator interactions of a Cerrado community weekly for one year and used network analyses to characterize intra-annual seasonal variation in community structure. We also compared seasonal differences in community robustness to species loss by simulating extinctions of plants and pollinators. We find that the community shrinks significantly in size during the dry season, becoming more vulnerable to disturbance due to the smaller pool of floral hosts available to pollinators during this period. Major changes in plant species composition but not in pollinators has led to high levels of turnover in plant-pollinator associations across seasons, indicated by in interaction dissimilarity (<3% of shared interactions). Aseasonal pollinators, which mainly include social bees and some solitary specialized bees, functioned as keystone species, maintaining robustness during periods of drastic changes in climatic conditions.

Effect of Different Beehives Size and Daily Activity of Stingless Bee Tetragonula Laeviceps on Bee-Pollen Production

Bee activities and colony may affect the production of bee products. Bee-pollen is one of the important products of honeybees, besides of honey. Tetragonula laeviceps is a group member of stingless bees found in tropical region. In Indonesia, Tetragonula laeviceps mostly create a nest in bamboos that make unfortunately difficult for harvesting of its products. The aim of this study was to investigate the effect of different beehives size and the daily activity (morning vs. afternoon) of stingless bee Tetragonula laeviceps on bee-pollen production. This study was conducted in Ngrandu, Katongan Village, Sub-district of Nglipar, Gunungkidul, Yogyakarta. Forty colonies of Tetragonula laeviceps were obtained from bamboos (similar in diameter and length) were transferred into four different group of beehives size (BS) made from dried wood, respectively: 35x17.5x13.5 (BS1); 35x20x17.5 (BS2); 37.5x20x20 (BS3) and 40x20x20 cm (BS4). Each group of beehives size had ten colonies/beehives as replicates. The colonies consisted of a queen bee, eggs, worker bees, and drones were transferred into wood beehives, and they were kept for two months for the study. The bee-pollen was harvested from beehives, separated from the propolis then weighed. The production of bee-pollen in the four different beehives size (BS1: 2.34±2.48 g/colony; BS2: 4.56±3.94 g/colony; BS3: 1.30±1.22 g/colony, BS4: 1.02±0.63 g/colony) was not different (ns) among the groups. The daily activity of bee bring the pollen to the nest in the morning (07.00 to 11.00) was significantly different (P&lt;0.05) among the groups, but not significant (ns) different in the afternoon (14.00 to 17.00). The frequency of bringing in pollen into the hives at the morning is higher than at the afternoon (21.75 vs. 12.43 times/5 minutes). It could be concluded that the colony in beehive size of BS2 (35x20x17.5 cm) has higher daily activities and thus higher bee-pollen production, compared to the other beehives groups.

Floral biology of wild marigold (Tagetes minuta L.) and its relation to essential oil composition

Wild marigold (Tagetes minuta L.) is being commercially cultivated due to high demand of its essential oil in flavor and perfumery industry. Present study investigates pollination behavior, mechanism of pollination and floral developmental of wild marigold in to 11 stages each having distinct characteristic feature as observed by visual and light microscopy. Pollen production starts from stage-2, shape of pollen is spherical tricolpate and size varies from 0.025 - 0.031 mm. However, highest pollen availability and viability is observed at stage-6. Bilobed stigma protrude from the flowers at stage-7 indicating protandry. High bee activity is evident under open field conditions suggesting entomophilous mechanism of pollination. Based on viable seed formation and per cent germination, open field conditions are most suitable for good seed set as these conditions favor cross pollination. Despite poor seed set in self-pollinated condition germination percentage was not affected significantly. Floral biology of wild marigold suggests often cross pollinated breeding behaviour. Gas Chromatography - Mass spectrometry results showed significant variation in essential oil composition at foliage and inflorescence. The (Z)-β-ocimene (52.01 %) content was highest in inflorescence while dihydrotagetone (84.85 %) content was highest in foliage. Knowledge of pollination behavior of wild marigold is critical to decide the breeding strategies required for its improvement.

Impacts of dietary supplementation with p-coumaric acid and indole-3-acetic acid on survival and biochemical response of honey bees treated with tau-fluvalinate.

Pollinator populations are in decline worldwide. Multiple factors have been cited as potential causes to these declines. In honey bees, a combination of stressors is known to cause colony losses. Adequate nutrition is a key factor for honey bee growth and colony development. Several studies show that the nutritional quality of the diet is directly proportional to the ability of the bee to face challenges or stressors. We explored the effect of p-coumaric (600 μM) and indole-3-acetic acid (2, 20 or 200 μM) supplementation on the survival and activity of key detoxification enzymes of honey bees exposed to tau-fluvalinate. The dietary supplementation with p-coumaric and indole-3-acetic acids (20 μM) enhanced the survival of bees exposed to tau-fluvalinate (approximately 20%). We also showed that dietary p-coumaric acid increased the levels of cytochrome P450 and glutathione reductase activity in bees treated with tau-fluvalinate, as well as in the untreated controls, while glutathione-S-transferase activity was lower in treated bees than in untreated. In bees fed with indole-3-acetic acid, cytochrome P450 showed increased levels, however, glutathione-S-transferase showed the lowest activity. Moreover, the results showed that supplementation with p-coumaric and indole-3-acetic acids did not alter acetyl cholinesterase activity, nor did treatment with tau-fluvalinate. Altogether, the enzymatic changes related to the detoxification mechanisms observed in bees that were fed with p-coumaric and indole-3-acetic acids could be responsible for the increased survival of bees treated with tau-fluvalinate compared to those that received a control diet. The results presented in this study, together with previous studies, provide evidence of the importance of dietary phytochemicals in the response of honey bees to pesticide exposure. Moreover, these results are the first report of the beneficial effect of the phytohormone indole-3-acetic acid on the survival of honey bees treated with tau-fluvalinate.

Factors influencing the foraging behavior of trigona spinipes (apidae, meliponinae)

ABSTRACT The Trigona spinipes is a species of bee found throughout the Brazilian territory. This study aimed to evaluate the forage behavior of the species T. Spinipes to abiotic and biotic factors. The experiment was accomplished in the field of BeeLab belonging to the Federal University of Paraíba. Four feeders prepared with different levels of sucrose (0%, 25%, 50% and 75%), were arranged on sawhorses and placed next to hives of T. Spinipes. The sawhorses were distanced from the hive each 10 meters until 100 meters away. Each distance the number of visitors was counted hourly. Climatic variables of temperature, relative humidity, dew point, radiation and rainfall were noted in order to observe the behavior of the species in different conditions. It was observed that the foraging activity of bee T. Spinipes was higher in function, primarily, of temperature and radiation the opposite occurred with relative humidity and dew point. The T. Spinipes exhibited a behavior of preference for solutions with higher sucrose levels. No decrease was observed in the number of visitors of the species until the maximum distance observed. T. Spinipes has your forage behavior modulated by climatic variables and can be considered a dominant species on food source.

Acute oral and contact toxicity of new ethyl-carbamates on the mortality and acetylcholinesterase activity of honey bee (Apis mellifera).

The effects produced by the ethyl-carbamates: ethyl-4-bromophenyl carbamate (LQM 919) and ethyl-4-chlorophenyl carbamate (LQM 996) on the mortality and behavior of Apis mellifera were evaluated by the acute oral toxicity test and the acute contact toxicity test. The oral lethal dose, 50% of the ethyl-carbamates was >145.24 μg per bee, and the oral lethal dose, 50% of propoxur was 0.072 μg per bee. Therefore, according to the OECD criteria, the ethyl-carbamates were classified as relatively nontoxic orally; meanwhile, propoxur was classified as highly toxic orally. In the contact test, lethal concentrations 50% of the ethyl-carbamates were 4.83 and 2.23 μg/cm2 for LQM 919 and LQM 996, respectively; therefore, they were at least 10-fold less lethal (p < 0.05) than propoxur (0.22 μg/cm2). The ethyl-carbamates reduced the activity of A.mellifera acetylcholinesterase by up to 30%. The ki and kd values of both ethyl-carbamates were lower (p < 0.05) than those of propoxur and indicated that they are weak inhibitors and with low affinity to A.mellifera acetylcholinesterase, which along with the absence of behavioral alterations suggests that the mortality caused by ethyl carbamates is not related to damage to the nervous system. According to these results, the evaluated ethyl-carbamates can be considered a low ecotoxic risk for A.mellifera.

Foraging behavior of stingless bee (Geniotrigona thoracica and Heterotrigona itama) on star fruit trees (Averrhoa carambola L.)

Star fruit produce flowers and fruits nearly the whole year round and it require cross- pollination for good fruit set and yields. An inadequate pollination rate is one of the factor that contributes to low yield. One of the effective way of increasing the pollination rate is by having insect pollinators such stingless bees in the star fruit farm. Malaysia is rich with native pollinator such as stingless bee, but there still lack of study related on their foraging behaviour. Therefore, the objectives were to study the foraging behaviour of Geniotrigona thoracica and Heterotrigona itama on star fruit trees. The colonies of G. thoracica and H.itama were selected for observation of activity foraging of stingless bee. Foraging bees was enumerated by using a manual tally counter to determine the number of individuals that flew out and into their hive within a 10 minute period each hour for each colonies. Then 10 of foragers’ G. thoracica and H.itama were selected randomly and marked using insect colouring on their thorax The period for each flower that visited by G. thoracica and H.itama was recorded by using stopwatch. The number offlower visited by G. thoracica and H.itama also recorded in 3 minutes. Result showed the peak time foraging activity of both stingless bees were in between 8.00am until 10.00am The foraging activity for each hours showed there was not significant differences, p > 0.05. Then the highest number flower visited by G.thoracica in 3 minute is 31 flowers while the lowest number flower visited in 3 minute is 7 flowers. However, for H.itama the highest number visited flowers are 27 and lowest number visited flowers are 8, for the longest average visited period for each flower is 14.76 seconds and the shortest period is 3.57 seconds. Meanwhile for G.thoracica longest average visited period for each flower is 12.88 seconds and the shortest average visited period for each flower is 2.72 seconds. In conclusion, this experiment showed that stingless bees have the characteristic for effective pollinator and have the potential to be used as a pollinator for star fruit trees. However, temperature, humidity and weather gave big influence on the foraging activity of stingless bees on star fruit plant.

Chronic oral exposure to field-realistic pesticide combinations via pollen and nectar: effects on feeding and thermal performance in a solitary bee

Pesticide use is one of the main causes of pollinator declines in agricultural ecosystems. Traditionally, most laboratory studies on bee ecotoxicology test acute exposure to single compounds. However, under field conditions, bees are often chronically exposed to a variety of chemicals, with potential synergistic effects. We studied the effects of field-realistic concentrations of three pesticides measured in pollen and nectar of commercial melon fields on the solitary bee Osmia bicornis L. We orally exposed females of this species throughout their life span to 8 treatments combining two neonicotinoid insecticides (acetamiprid, imidacloprid) and a triazole fungicide (myclobutanil) via pollen and sugar syrup. We measured pollen and syrup consumption, longevity, ovary maturation and thermogenesis. Although bees consumed larger amounts of syrup than pollen, pesticide intake via syrup and pollen were similar. At the tested concentrations, no synergistic effects emerged, and we found no effects on longevity and ovary maturation. However, all treatments containing imidacloprid resulted in suppressed syrup consumption and drastic decreases in thoracic temperature and bee activity. Our results have important implications for pesticide regulation. If we had measured only lethal effects we would have wrongly concluded that the pesticide combinations containing imidacloprid were safe to O. bicornis. The incorporation of tests specifically intended to detect sublethal effects in bee risk assessment schemes should be an urgent priority. In this way, the effects of pesticide exposure on the dynamics of bee populations in agroecosystems will be better assessed.

Improvement of almond production usingBombus terrestris(Hymenoptera: Apidae) in Mediterranean conditions

AbstractAlmond trees are one of the most important crops in the Balearic Islands. The pollination of almonds is limited to the activity of insects, and cross‐pollination is necessary for fruit development. Currently, honey bees and wild bee populations are declining considerably due to multiple causes, such as the use of pesticides, diseases and habitat loss. An alternative to increase the almond production is the use of commercial pollinators. In this long‐term (3 years) study, the effect of the introduction ofBombus terrestriscolonies on almond production was evaluated in two orchards. Two experimental designs were carried out to study the best management of this pollinator. For 2 years, all bumble bee colonies were placed in the middle of the plot and during the last year, the bumble bee colonies were distributed homogenously in the plot. Fruit set and the foraging behaviour of bumble bees during the blossoming period was determined, and the effect of different environmental variables on the visitation rate of bumble bees was assessed by means of a generalized linear mixed model (GLMM). Moreover, for the first time, the spatial distribution of fruit set was evaluated. Our results show that fruit set was significantly higher in the fields whereB. terrestrishad been introduced than in the control plots. This increased production resulted in a positive economic balance for the farmer. Moreover, bumble bees showed to prefer trees in a southwest orientation that were close to their colony. The activity of bumble bees showed to be significantly influenced by wind speed (the higher the speed the more flowers are visited byB. terrestris) and time after flowering (visitation rate decreased with days after flowering). In order to improve its management and obtain the highest possible almond production, it is important to understand the activity and behaviour of this pollinator.

Visitation activity of native bees (Hymenoptera: Apoidea) on Loasa tricolor Ker-Gawl.(Loasaceae) in relation with environmental temperature and floral resources

Las abejas son conocidas por ser esenciales en la mantención de ecosistemas, debido a su rol en la reproducción de especies de plantas. Sin embargo, aún es desconocido qué características de la flor y condiciones ambientales son esenciales para la presencia de abejas nativas en ciertos ecosistemas. Esta situación representa un problema en constante investigación ya que estas variables actúan en diversas combinaciones que cambian según escalas espaciales y temporales. En el siguiente trabajo, realizamos un análisis en la actividad de visita de abejas nativas a flores de Loasa tricolor en relación a la posible influencia de la temperatura ambiental y variables florales comparando dos temporadas de floración en años consecutivos, y en dos localidades de la Región de Valparaíso, Chile. Para esto se utilizó la riqueza y el número de abejas nativas visitantes de las flores, además de obtener información sobre la temperatura ambiental, la concentración de néctar y la temperatura floral durante la temporada de floración en ambas localidades. Los resultados muestran una asociación negativa entre temperatura y riqueza de abejas, y el número de visitas. En relación con las características florales, los resultados muestran una asociación negativa entre temperatura y concentración de néctar, mientras que la temperatura floral no muestra asociaciones significativascon la visita de abejas.