1,721,003 research outputs found
Honey Bee Antiviral Immune Barriers as Affected by Multiple Stress Factors: A Novel Paradigm to Interpret Colony Health Decline and Collapse
Full text linkAny attempt to outline a logical framework in which to interpret the honey bee health decline and its contribution to elevated colony losses should recognize the importance of the multifactorial nature of the responsible syndrome and provide a functional model as a basis for defining and testing working hypotheses. We propose that covert infections by deformed wing virus (DWV) represent a sword of Damocles permanently threatening the survival of honey bee colonies and suggest that any factor affecting the honey bee’s antiviral defenses can turn this pathogen into a killer. Here we discuss the available experimental evidence in the framework of a model based on honey bee immune competence as affected by multiple stress factors that is proposed as a conceptual tool for analyzing bee mortality and its underlying mechanisms
Composti volatili rilasciati da piante di fagiolo infestate da Liriomyza trifolii e loro effetto sul parassitoide Diglyphus isaea
No full textThe reduced brood nursing by mite-infested honey bees depends on their accelerated behavioral maturation
No full textExtensive annual losses of honey bee colonies (Apis mellifera L.) reported in the northern hemisphere
represent a global problem for agriculture and biodiversity. The parasitic mite Varroa destructor, in association
with deformed wing virus (DWV), plays a key role in this phenomenon, but the underlying
mechanisms are still unclear. To elucidate these mechanisms, we analyzed the gene expression profile of
uninfested and mite infested bees, under laboratory and field conditions, highlighting the effects of
parasitization on the bee's transcriptome under a variety of conditions and scenarios. Parasitization was
significantly correlated with higher viral loads. Honey bees exposed to mite infestation exhibited an
altered expression of genes related to stress response, immunity, nervous system function, metabolism
and behavioural maturation. Additionally, mite infested young bees showed a gene expression profile
resembling that of forager bees. To identify potential molecular markers of colony decline, the expression
of genes that were commonly regulated across the experiments were subsequently assessed in colonies
experiencing increasing mite infestation levels. These studies suggest that PGRP-2, hymenoptaecin, a
glucan recognition protein, UNC93 and a p450 cytocrome maybe suitable general biomarkers of Varroainduced
colony decline. Furthermore, the reliability of vitellogenin, a yolk protein previously identified as
a good marker of colony survival, was confirmed here
Behavioural Evidence and Chemical Identification of a Female Sex Pheromone in Anagrus atomus (Hymenoptera: Mymaridae)
Full text linkAnagrus atomus (L.) is an egg parasitoid involved in the biological control of Empoasca vitis (Göthe) in vineyards. Sex pheromones play a crucial role in mate finding for several parasitoid species and could be used for monitoring under field conditions. We carried out laboratory and field studies aimed at assessing the existence and identity of a possible A. atomus sex pheromone. We found that males were significantly attracted by virgin females independent of age. Males were not attracted to individuals of the same sex, but they were attracted by a crude extract from an unmated female and its polar fraction. Eugenol (4-allyl-2-methoxyphenol) was identified as the attractive substance and proved to be attractive not only in the olfactometer but also in another laboratory bioassay and under field conditions. Attraction of males, but not females, confirms that this is not an aggregation pheromone. This is the first sex-pheromone component identified in Mymaridae, however more compounds could be involved in the mating behaviour of A. atomus. The utility of a sex pheromone in A. atomus is discussed in the context of fitness returns
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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