Publications by authors named "Helge Schlüns"

8 Publications

  • Page 1 of 1

The glass is not yet half empty: agitation but not Varroa treatment causes cognitive bias in honey bees.

Anim Cogn 2017 Mar 3;20(2):233-241. Epub 2016 Oct 3.

Department of Behavioral Biology, University of Osnabrueck, Barbarastr. 11, 49076, Osnabrück, Germany.

Honey bees (Apis mellifera) are prone to judge an ambiguous stimulus negatively if they had been agitated through shaking which simulates a predator attack. Such a cognitive bias has been suggested to reflect an internal emotional state analogous to humans who judge more pessimistically when they do not feel well. In order to test cognitive bias experimentally, an animal is conditioned to respond to two different stimuli, where one is punished while the other is rewarded. Subsequently a third, ambiguous stimulus is presented and it is measured whether the subject responds as if it expects a reward or a punishment. Generally, it is assumed that negative experiences lower future expectations, rendering the animals more pessimistic. Here we tested whether a most likely negatively experienced formic acid treatment against the parasitic mite Varroa destructor also affects future expectations of honey bees. We applied an olfactory learning paradigm (i.e., conditioned proboscis extension response) using two odorants and blends of these odorants as the ambiguous stimuli. Unlike agitating honey bees, exposure to formic acid did not significantly change the response to the ambiguous stimuli in comparison with untreated bees. Overall evidence suggests that the commonest treatment against one of the most harmful bee pests has no detrimental effects on cognitive bias in honey bees.
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http://dx.doi.org/10.1007/s10071-016-1042-xDOI Listing
March 2017

Climate rather than geography separates two European honeybee subspecies.

Mol Ecol 2014 May 21;23(9):2353-61. Epub 2014 Apr 21.

Department of Apiculture and Sericulture, University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca, Calea Mănăştur 3-5, 400372, Cluj-Napoca, Romania.

Both climatic and geographical factors play an important role for the biogeographical distribution of species. The Carpathian mountain ridge has been suggested as a natural geographical divide between the two honeybee subspecies Apis mellifera carnica and A. m. macedonica. We sampled one worker from one colony each at 138 traditional apiaries located across the Carpathians spanning from the Hungarian plains to the Danube delta. All samples were sequenced at the mitochondrial tRNA(Leu)-cox2 intergenic region and genotyped at twelve microsatellite loci. The Carpathians had only limited impact on the biogeography because both subspecies were abundant on either side of the mountain ridge. In contrast, subspecies differentiation strongly correlated with the various temperature zones in Romania. A. m. carnica is more abundant in regions with the mean average temperature below 9 °C, whereas A. m. macedonica honeybees are more frequent in regions with mean temperatures above 9 °C. This range selection may have impact on the future biogeography in the light of anticipated global climatic changes.
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http://dx.doi.org/10.1111/mec.12731DOI Listing
May 2014

Interactions among flavonoids of propolis affect antibacterial activity against the honeybee pathogen Paenibacillus larvae.

J Invertebr Pathol 2012 May 22;110(1):68-72. Epub 2012 Feb 22.

Department of Apiculture and Sericulture, University of Agricultural Sciences and Veterinary Medicine, 400372 Cluj-Napoca, Romania.

Propolis is derived from plant resins, collected by honeybees (Apis mellifera) and renown for its antibacterial properties. Here we test the antibacterial effects of ethanolic extracts of propolis from different origins on Paenibacillus larvae, the bacterial pathogen that causes American Foulbrood, a larval disease that can kill the honeybee colony. All tested propolis samples inhibited significantly the growth of P. larvae tested in vitro. The extracts showed major differences in the content of total flavonoids (ranging from 2.4% to 16.4%) and the total polyphenols (ranging between 23.3% and 63.2%). We found that it is not only the content of compounds in propolis, which influences the strength of antimicrobial effects but there is also a significant interaction effect among flavonoids of the propolis extracts. We propose that interaction effects among the various chemical compounds in propolis should be taken into account when considering the antibacterial effects against honeybee pathogens.
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http://dx.doi.org/10.1016/j.jip.2012.02.009DOI Listing
May 2012

Characterization of polymorphic microsatellites in the giant bulldog ant, Myrmecia brevinoda and the jumper ant, M. pilosula.

J Insect Sci 2011 ;11:71

School of Marine and Tropical Biology, and Comparative Genomics Centre, James Cook University, Townsville, QLD 481 I, Australia.

The ant genus Myrmecia Fabricius (Hymenoptera: Formicidae) is endemic to Australia and New Caledonia, and has retained many biological traits that are considered to be basal in the family Formicidae. Here, a set of 16 dinucleotide microsatellite loci were studied that are polymorphic in at least one of the two species of the genus: the giant bulldog ant, M. brevinoda Forel, and the jumper ant, M. pilosula Smith; 13 are novel loci and 3 are loci previously published for the genus Nothomyrmecia Clark (Hymenoptera: Formicidae). In M. brevinoda, the total of 12 polymorphic microsatellites yielded a total of 125 alleles, ranging from 3 to 18 with an average of 10.42 per locus; the observed and expected heterozygosities ranged from 0.4000 to 0.9000 and from 0.5413 to 0.9200, respectively. In M. pilosula, the 9 polymorphic loci yielded a total of 67 alleles, ranging from 3 to 12 with an average of 7.44 per locus; the observed and expected heterozygosities ranged from 0.5625 to 0.9375 and from 0.4863 to 0.8711, respectively. Five loci were polymorphic in both target species. In addition, 15 out of the 16 loci were successfully amplified in M. pyriformis. These informative microsatellite loci provide a powerful tool for investigating the population and colony genetic structure of M. brevinoda and M. pilosula, and may also be applicable to a range of congeners considering the relatively distant phylogenetic relatedness between M. pilosula and the other two species within the genus Myrmecia.
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http://dx.doi.org/10.1673/031.011.7101DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3281428PMC
November 2011

Intraspecific support for the polygyny-vs.-polyandry hypothesis in the bulldog ant Myrmecia brevinoda.

Mol Ecol 2011 Sep 25;20(17):3681-91. Epub 2011 Jul 25.

School of Marine and Tropical Biology, James Cook University, Townsville, QLD 4811, Australia.

The number of queens per colony and the number of matings per queen are the most important determinants of the genetic structure of ant colonies, and understanding their interrelationship is essential to the study of social evolution. The polygyny-vs.-polyandry hypothesis argues that polygyny and polyandry should be negatively associated because both can result in increased intracolonial genetic variability and have costs. However, evidence for this long-debated hypothesis has been lacking at the intraspecific level. Here, we investigated the colony genetic structure in the Australian bulldog ant Myrmecia brevinoda. The numbers of queens per colony varied from 1 to 6. Nestmate queens within polygynous colonies were on average related (r(qq) = 0.171 ± 0.019), but the overall relatedness between queens and their mates was indistinguishable from zero (r(qm) = 0.037 ± 0.030). Queens were inferred to mate with 1-10 males. A lack of genetic isolation by distance among nests indicated the prevalence of independent colony foundation. In accordance with the polygyny-vs.-polyandry hypothesis, the number of queens per colony was significantly negatively associated with the estimated number of matings (Spearman rank correlation R = -0.490, P = 0.028). This study thus provides the rare intraspecific evidence for the polygyny-vs.-polyandry hypothesis. We suggest that the high costs of multiple matings and the strong effect of multiple mating on intracolonial genetic diversity may be essential to the negative association between polygyny and polyandry and that any attempt to empirically test this hypothesis should place emphasis upon these two key underlying aspects.
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http://dx.doi.org/10.1111/j.1365-294X.2011.05195.xDOI Listing
September 2011

Infection with the trypanosome Crithidia bombi and expression of immune-related genes in the bumblebee Bombus terrestris.

Dev Comp Immunol 2010 Jul 16;34(7):705-9. Epub 2010 Feb 16.

School of Marine and Tropical Biology, Centre for Comparative Genomics, James Cook University, Townsville, Queensland 4811, Australia.

Social bees and other insects are frequently parasitized by a large range of different microorganisms. Among these is Crithidia bombi (Kinetoplastida: Trypanosomatidae), a common gut parasite of bumblebees, Bombus spp. (Insecta: Apidae). Bumblebees are important pollinators in commercial and natural environments. There are clear detrimental effects of C. bombi infections on the fitness of bumblebees. However, little has been known about how the bee's immune system responds to infections with trypanosome parasites. Here, we study the immune response of Bombus terrestris on infection by C. bombi. We measured the expression of four immune-related genes (Hemomucin, MyD88, Relish, and TEP7) using RT-qPCR in adult B. terrestris workers that were either healthy or infected with the trypanosome parasite C. bombi. The potential recognition gene Hemomucin was significantly upregulated in the infected bees. Further, there was substantial and significant variation in all four genes among different bumblebee colonies irrespective of infection status.
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http://dx.doi.org/10.1016/j.dci.2010.02.002DOI Listing
July 2010

Functional and evolutionary insights from the genomes of three parasitoid Nasonia species.

Science 2010 Jan;327(5963):343-8

We report here genome sequences and comparative analyses of three closely related parasitoid wasps: Nasonia vitripennis, N. giraulti, and N. longicornis. Parasitoids are important regulators of arthropod populations, including major agricultural pests and disease vectors, and Nasonia is an emerging genetic model, particularly for evolutionary and developmental genetics. Key findings include the identification of a functional DNA methylation tool kit; hymenopteran-specific genes including diverse venoms; lateral gene transfers among Pox viruses, Wolbachia, and Nasonia; and the rapid evolution of genes involved in nuclear-mitochondrial interactions that are implicated in speciation. Newly developed genome resources advance Nasonia for genetic research, accelerate mapping and cloning of quantitative trait loci, and will ultimately provide tools and knowledge for further increasing the utility of parasitoids as pest insect-control agents.
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http://dx.doi.org/10.1126/science.1178028DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2849982PMC
January 2010

Genetic caste determination in termites: out of the shade but not from Mars.

Bioessays 2008 Apr;30(4):299-302

School of Marine and Tropical Biology, James Cook University, Townsville, Queensland, Australia.

Several ant species are known with genetic effects on caste determination but, for termites, the role of environment has been assumed to be omnipotent. Now Hayashi et al. report that commitment to the nymph and worker pathways in Reticulitermes speratus follows a simple model involving two alleles at a sex-linked locus. The spread of this system of genetic caste determination seems best explained by selection at the colony level. This remarkable system may be widely applicable throughout termites, although it cannot be universal, and may provide a window into causal aspects of the molecular biology of caste determination.
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http://dx.doi.org/10.1002/bies.20732DOI Listing
April 2008
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