Acute thiamethoxam toxicity in honeybees is not enhanced by common fungicide and herbicide and lacks stress-induced changes in mRNA splicing

Securing food supply for a growing population is a major challenge and heavily relies on the use of agrochemicals to maximize crop yield. It is increasingly recognized, that some neonicotinoid insecticides have a negative impact on non-target organisms, including important pollinators such as the European honeybee Apis mellifera. Toxicity of neonicotinoids may be enhanced through simultaneous exposure with additional pesticides, which could help explain, in part, the global decline of honeybee colonies. Here we examined whether exposure effects of the neonicotinoid thiamethoxam on bee viability are enhanced by the commonly used fungicide carbendazim and the herbicide glyphosate. We also analysed alternative splicing changes upon pesticide exposure in the honeybee. In particular, we examined transcripts of three genes: (i) the stress sensor gene X box binding protein-1 (Xbp1), (ii) the Down Syndrome Cell Adhesion Molecule (Dscam) gene and iii) the embryonic lethal/abnormal visual system (elav) gene, which are important for neuronal function. Our results showed that acute thiamethoxam exposure is not enhanced by carbendazim, nor glyphosate. Toxicity of the compounds did not trigger stress-induced, alternative splicing in the analysed mRNAs, thereby leaving dormant a cellular response pathway to these man-made environmental perturbations

4.1 Progress of working group Non-Apis testing

See summary of progress of the Non-Apis group on page 8 Thomas Steeger: Working Groups of the ICP-PR Bee Protection Group – Developments and ProgressSee summary of progress of the Non-Apis group on page 8 Thomas Steeger: Working Groups of the ICP-PR Bee Protection Group – Developments and Progres

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

Thiamethoxam exposure deregulates short ORF gene expression in the honey bee and compromises immune response to bacteria

© 2021, The Author(s). Maximizing crop yields relies on the use of agrochemicals to control insect pests. One of the most widely used classes of insecticides are neonicotinoids that interfere with signalling of the neurotransmitter acetylcholine, but these can also disrupt crop-pollination services provided by bees. Here, we analysed whether chronic low dose long-term exposure to the neonicotinoid thiamethoxam alters gene expression and alternative splicing in brains of Africanized honey bees, Apis mellifera, as adaptation to altered neuronal signalling. We find differentially regulated genes that show concentration-dependent responses to thiamethoxam, but no changes in alternative splicing. Most differentially expressed genes have no annotated function but encode short Open Reading Frames, a characteristic feature of anti-microbial peptides. As this suggested that immune responses may be compromised by thiamethoxam exposure, we tested the impact of thiamethoxam on bee immunity by injecting bacteria. We show that intrinsically sub-lethal thiamethoxam exposure makes bees more vulnerable to normally non-pathogenic bacteria. Our findings imply a synergistic mechanism for the observed bee population declines that concern agriculturists, conservation ecologists and the public

Diferenciação do cérebro de Apis mellifera (Hymenoptera, Apidae) durante a metamorfose: estudo comparativo entre castas e sexos

Apis mellifera é um organismo de grande interesse para estudos neurobiológicos, pois além de apresentar um cérebro estruturalmente simples, se comparado ao dos vertebrados, apresenta características próprias relacionadas ao comportamento social, com capacidade de memória e aprendizagem. As colônias destas abelhas são constituídas por machos e fêmeas, as fêmeas dividindo-se em duas castas, operárias e rainhas. Sabendo-se que as castas e os machos de A. mellifera apresentam morfologia, fisiologia e padrões comportamentais bastante distintos que, por sua vez, estão, em boa parte representados no polimorfismo cerebral, o presente trabalho visou desvendar como essas diferenças se estabelecem a partir do cérebro larval, basicamente igual para todos. Sendo A. mellifera uma espécie holometábola a transformação das estruturas larvais para as dos adultos ocorre durante a metamorfose, ou seja, durante a pupação. Para melhor compreensão, o estudo iniciou-se com a caracterização das diferenças morfológicas entre os cérebros de operárias, rainhas e machos recém emergidos. A partir da verificação de quais eram as estruturas que mais se diferenciavam entre as classes de indivíduos que compõem a colônia, foram escolhidas para ter sua diferenciação acompanhada os corpos pedunculados, os lobos ópticos e a pars intercerebralis no protocérebero e os lobos antenais no deutocérebro. Dessas estruturas foi feito um estudo comparativo entre operárias, rainhas e zangões usando preparações para microscopia de luz, mensurações da área ocupada por alguns de seus componentes, estudos estruturais de outros, bem como uma estimativa das taxas de multiplicação, e mortes celulares com técnicas citoquímicas e imunocitoquímicas. Esses estudos foram iniciados com larvas no último estágio larval...Apis mellifera is an interesting model to neurobiological studies due to the simplicity of its brain commanding the complex behaviors demanded by the eusocial relationships and its capacity of learning and memorizing. The colonies of this bee consist of males and females. The females are differentiated in two castes: workers and queens. The castes and males from A. mellifera have distinct morphology, physiology and behavior correlated with their functions in the society and represented by some brain polymorphism. In this context the aim of the present study was clear up how the adult brain differences are established parting from the larval brain basicalIy equal to alI kinds of individuaIs. A. melliftra is a holometabolous insect and therefore, the change of the larval structures to the adult ones occurs during pupation or metamorphosis. In order to have a better vision of the differences found among the adult brains. was done a comparative morphological study of the brain from newly emerged workers, queens and males. The results showed that the brain structures more distinct among the individual classes were the mushroom bodies, optic lobes and pars intercerebralis from the protocerebrum and the antennal lobes from the deutocerebrum. Those were choose for have their differentiation accompanied during metamorphosis. Comparative studies of the structures among workers, queens and males were done using light and electronic microscopy, measuring the areas occupied from some of their components and estimative of the rates of mitosis and cell death using cytochemical and immuno-histochemical techniques. These studies started in the last larval instar and continued in pre-pupae, white, pink, brown, and black eyed pupae until black body pupae. Besides a search for differential protein expression among the individual classes whole brain was done... (Complete abstract click electronic access below)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Differentiation of the honey bee (Apis mellifera L.) antennal lobes during metamorphosis: a comparative study among castes and sexes

In insects the antennal lobes (AL) constitute the brain deutocerebrum. In bees they consist of two neuropil regions, each associated with one antenna, delimited by a layer of glial cells and somata of neurons. The neuropil is organized in distinct globular structures of dense synaptic axons coming from the olfactory organs of the antennae, known as glomeruli. In Apis mellifera, as in other eusocial species of bees, queens, workers, and drones perform different functions in the colony and consequently the organs associated with these functions undergo a differential development. In this paper we analyzed the structure and size of the differentiating AL of queens, workers, and drones during metamorphosis using light microscopy. During metamorphosis the neuropil enlarge and differentiates into concentric structures known as glomeruli. The results showed size, structural and temporal differences in the glomeruli development among the classes of individuals of the colony. The neuropil differentiation starts early and is faster in drones and newly emerged worker is the colony individual class with greater neuropil area in AL. These results are discussed taking in account the functions of the individuals in the colony. (C) Koninklijke Brill NV, Leiden, 2011