The effects of four crop protection products on the morphology and ultrastructure of the hypopharyngeal gland of the European honeybee,

This study describes the impact of sublethal doses of 4 pesticides on size and morphology of the honeybee worker’s hypopharyngeal glands. This gland plays an essential role in brood care by young workers, and thus colony growth. Contaminating 7 day old caged bees, we sampled after 1 day and 1 week for Captan-, Imidacloprid- and Indoxacarb-treated bees and after 1, 2, 3, 4, 5 and 7 days for Fenoxycarb-treated bees. The glands’ acini 1 week post-treatment were all significantly smaller in treated bees. However, light- and electron microscopy showed hardly any difference between controls and gland cells, treated with Captan, Imidacloprid or Indoxacarb. Yet upon Fenoxycarb-treatment, acini showed a decrease in size, a granular texture and unorganized cytoplasm more quickly than normal. Indeed, after only 7 days, Fenoxycarb-treated glands displayed features typical of the onset of foraging in older bees

The effects of four crop protection products on the morphology and ultrastructure of the hypopharyngeal gland of the European honeybee, Apis mellifera

This study describes the impact of sublethal doses of 4 pesticides on size and morphology of the honeybee worker's hypopharyngeal glands. This gland plays an essential role in brood care by young workers, and thus colony growth. Contaminating 7 day old caged bees, we sampled after 1 day and 1 week for Captan-, Imidacloprid- and Indoxacarb-treated bees and after 1, 2, 3, 4, 5 and 7 days for Fenoxycarb-treated bees. The glands' acini 1 week post-treatment were all significantly smaller in treated bees. However, lightand electron microscopy showed hardly any difference between controls and gland cells, treated with Captan, Imidacloprid or Indoxacarb. Yet upon Fenoxycarb-treatment, acini showed a decrease in size, a granular texture and unorganized cytoplasm more quickly than normal. Indeed, after only 7 days, Fenoxycarb-treated glands displayed features typical of the onset of foraging in older bees. © INRA/DIB-AGIB/EDP Sciences, 2010.status: publishe

Amfor expression in the honeybee brain: A trigger mechanism for nurse-forager transition

The honeybee's colony fitness relies on an optimized age-dependent division of labor. Transition from nursing activities to foraging activities is associated with an increase in the expression of the Amfor gene. Ben-Shahar et al. [Ben-Shahar, Y., Robichon, A., Sokolowski, M.B., Robinson, G.E., 2002. Influence of gene action across different time scales on behavior. Science 296, 741–744] showed that the Amfor transcripts and their gene products are involved in regulating the transition from one task to the next. In this study, we investigated the trajectory of the expression of this gene in the brain over time. The expression pattern could contribute to our understanding of the involvement of Amfor in the transition process. Is there a gradual increase in transcript or a peak in expression triggering a downstream path of multiple differential gene expression? Hereto, bees were sampled from colonies containing marked 1-day-old bees every 2 or 3 days around the expected time of transition from nurse to forager, from day 13 to 25. To quantify Amfor transcript in the brain, we developed a real-time RT-PCR assay, based on Taqman® technology, using fluorescent probes. Results revealed a trigger mechanism rather than a continued elevation of Amfor expression. The appearance of an Amfor expression peak suggests that under normal physiological conditions foraging behavior is, at least in part, due to a trigger-effect of Amfor.status: publishe

Cloning and expression of PKG, a candidate foraging regulating gene in Vespula vulgaris

In honey bees enhancement of cGMP dependent protein kinase expression accompanies the behavioural transition from in hive working nursing bees towards outdoors foraging worker bees. Accordingly this gene was named amfor or Apis mellifera foraging gene. In the red harvester ant Pogonomyrmex barbatus a gene homologue affected food seeking behaviour as well but in this species the PKG expression decreased from the onset of foraging behaviour. Since the wasp Vespula vulgaris is phylogenetically positioned between both species in this paper we tried to elucidate whether the involvement of PKG in foraging behaviour can be extended to this species and if so, whether its expression is enhanced or decreased at the moment of transition. To enable this candidate gene approach, we first had to clone the PKG homologue from the common wasp. QPCR indicated a relevantly higher expression of Vvfor in nursing versus foraging wasps although interpretation of the results was hampered by a remarkable degree of variation as could be predicted from in the wild captured wasps as a source for mRNA extraction and quantification.status: publishe

Recovery from retinal lesions: molecular plasticity mechanisms in visual cortex far beyond the deprived zone

In cats with central retinal lesions, deprivation of the lesion projection zone (LPZ) in primary visual cortex (area 17) induces remapping of the cortical topography. Recovery of visually driven cortical activity in the LPZ involves distinct changes in protein expression. Recent observations, about molecular activity changes throughout area 17, challenge the view that its remote nondeprived parts would not be involved in this recovery process. We here investigated the dynamics of the protein expression pattern of remote nondeprived area 17 triggered by central retinal lesions to explore to what extent far peripheral area 17 would contribute to the topographic map reorganization inside the visual cortex. Using functional proteomics, we identified 40 proteins specifically differentially expressed between far peripheral area 17 of control and experimental animals 14 days to 8 months postlesion. Our results demonstrate that far peripheral area 17 is implicated in the functional adaptation to the visual deprivation, involving a meshwork of interacting proteins, operating in diverse pathways. In particular, endocytosis/exocytosis processes appeared to be essential via their intimate correlation with long-term potentiation and neurite outgrowth mechanisms.status: publishe

Effects of sublethal doses of crop protection agents on honey bee (Apis mellifera) global colony vitality and its potential link with aberrant foraging activity

Honey bees (Apis mellifera) are the most economically valuable pollinators of fruit crops worldwide. Taking into account bees' contributions to other flowering agricultural crops, about one-third of our total diet comes directly or indirectly from bee-pollinated plants. However, in recent years there increasingly have been worrisome alarm sounds on serious bee mortalities and mysterious disappearance of bees from beehives. Among several environmental factors (e.g. climate and bee pathogens), stress factors arising from agricultural practices can potentially play a role in bee losses. Detailed knowledge on the effects of plant protection products is essential to improve usage with minimal risks. In order to identify potential medium- and long-term effects, we followed up various sublethal contaminated hives during the prolongation of the fruit-growing season. More specifically, a large-scale experiment was conducted in which at four distinct locations (in the Limburg region of Belgium) four different bee colonies (representing three different contaminations -imidacloprid, fenoxycarb, indoxacarb- and a non-contaminated control hive) were thoroughly monitored every 2-7 days. Our observations point towards decays of overall colony vitality for several hives a couple of weeks after treatment, as indicated by a set of carefully assessed parameters including the total amount of active and dead bees, total surface of capped brood and overall colony weight. These outcomes could be linked to subtle differences in foraging activity between distinct hives. The implications of these results are discussed in terms of potential short-term and long-term consequences of disturbed foraging ability triggered by exaggerated exposure to sublethal doses of crop protection chemicals, and its potential impact on colony health.status: publishe