Determination of fipronil LD50 for the brazilian bee Melipona scutellaris

To better understand the sensitivity of the models represented by Apis mellifera L., 1758 in toxicology studies of insecticides to bees, the aim of this study was to determine the LD50 of fipronil by topical application on the stingless bees Melipona scutellaris Latreille, 1811. Foraging bees were collected at the nest entrance and in laboratory anesthetized with CO2 for applying 1.0 μL of fipronil solution on the pronotum. Each group of treatments was made with thirteen bees divided in three cages, while in the control treatments the bees received only acetone. During the assay, the behavior and the number of dead bees were registered. The results showed that the insecticide fipronil applied topically was harmful to M. scutellaris and for A. mellifera, where the LD50 for 48 hours was 0.41 ng a.i./bee or 4.1 ng a.i./ g of bee. Comparing the LD50 values here obtained with the stingless bee M. scutellaris and those of A. mellifera in literature, we can conclude that the native bees are more sensitive to fipronil than the allochtonous bee, suggesting that further studies should be accomplished to determine the real hazard of pesticides to natives bees. Keywords: stingless bees, pesticides, phenylpyrazole, toxicity, LD5

Losses of Brazilian bees: an overview of factors that may affect these pollinators

The Neotropical region to which Brazil belongs, has a great and rich diversity of natives bees, up to a total of 3.000 species including the allochtone genus Apis that by natural crossing among European and African races produced a hybrid called Africanized honeybee. In this way, beekeeping enjoys a spectacular moment with good production mainly of honey and propolis from Apis mellifera, causing Brazil to be recognized around the world as a country with great potential. Brazilian bee losses nevertheless remain a question, compared with countries of the northern hemisphere where several reports show that the vanishing of honeybees is associated with diseases caused by Varroa, Nosema, virus or pesticides. We can suggest different issues in the Brazilian situation that are directly influencing the honeybee population. Given the extension of the territory and rich flora, all possible food resources and nest sites for the good development of bees may be considered present. However, we verified that annual bee losses in the Southeast can reach 20-30%, mainly due the genetic mechanisms of swarming (nest abandon). Many times the major factor leading to nest abandon is lack of food, often taken mistakenly by the untrained beekeeper as death of the hive caused by diseases or pesticides. Although in Brazil diseases do not represent an important problem for Africanized honeybees, some cases of presence of Nosema ceranae and Varroa destructor led the specialists to precaution and monitoring the colonies. In spite of this, the Brazilian beekeeping is managed without use of any acaricide or antibiotic, producing contaminant-free products. As to pesticides, Brazil has a particular climatic and soil condition that might differently affect the risk of exposure of bees to xenobiotics. For example, comparing the dynamics of carbamate pesticides in soil between Brazil and Europe, it was found that in our condition ten-fold more time is needed to obtain the metabolites sulfone and sulfoxide, both more soluble and toxic than it precursor. Comparing the pesticides consumption, currently Brazil has become the world leader followed by USA, with a total spending of 44.9% herbicide, 28.5% insecticide and 22.1% fungicide. Even with this consumption Brazil still belongs to the group that uses a relatively small amount of active ingredient per hectare, less than Japan and France. However cultures like tomato, potato, citrus, cotton and coffee that are often visited by bees during bloom, are also those where the use of pesticides is needed for the pest control. Thus, little is known yet about pesticide losses of the Brazilian bees! What are real effects of pesticides, toxic plants, diseases, genetic improvement, beekeeping management, starvation or interactions among these? Therefore, our local group on ecotoxicological assessment is trying to increase the knowledge on the pesticides hazard to bees (Apis and non-Apis) in order to protect these. Keywords: Brazilian bees, overview, pesticide, diseases, environment, protection

Fipronil effect on the frequency of anomalous brood in honeybee reared in vitro

Larvae of honeybee workers were exposed to the insecticide fipronil during the feeding phase. To evaluate the effect of fipronil in the post-embryonic development of africanized Apis mellifera, bioassays of toxicity were done. The bioassays were performed by acute exposure applying 1μL of distilled water for control (I) and for experiments: 0.5 ng a.i./μL of fipronil; 5 ng a.i./μL of fipronil and 20 ng a.i./ μL of fipronil. Triplicates were performed for all treatments. The results showed that the rate of anomalous pupae in exposed honeybees was statistically significant in relationship to the control (p <0:03). The most frequent abnormalities were: high pigmentation on the proximal and distal larval body and body malformation, such as absence of head and limbs. Pink eye pupa and white eyed pupae presented malformations in their larval bodies, but with the eye developed. It is assumed that the fat body is related to the high rate of anomalies, since this tissue has proteins linked to the process of metamorphosis. Furthermore, the fat body may be participating in the regulation of juvenile hormone during the process of metamorphosis, and consequently in the release of ecdysteroid hormones that are involved in the change from larva to adult. The high rate of abnormalities in the pupal stage of individuals exposed to fipronil raises concerns about the impacts caused in the colonies of bees and population decline of pollinators. Keywords: bees, larvae, pupae, metamorphosis, anomalies, fiproni

Aspects determining the risk of pesticides to wild bees: risk profiles for focal crops on three continents

In order to conduct a proper risk assessment of pesticides to bees, information is needed in three areas: the toxicity of the pesticide;the probability of bee exposure to that pesticide; andthe population dynamics of the bee species in question.Information was collected on such factors affecting pesticide risk to (primarily wild) bees in several crops in Brazil, Kenya and The Netherlands. These data were used to construct ‘risk profiles’ of pesticide use for bees in the studied cropping systems. Data gaps were identified and potential risks of pesticides to bees were compared between the crops. Initially, risk profiling aims to better identify gaps in our present knowledge. In the longer term, the established risk profiles may provide structured inputs into risk assessment models for wild and managed bees, and lead to recommendations for specific risk mitigation measures. Keywords: pesticide, exposure, risk, wild bees, risk profil