Dalial Freitak

Dalial Freitak
Karl-Franzens-Universität Graz | KFU Graz · Department of Biosciences

Prof. Dr.

About

55
Publications
6,805
Reads
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1,512
Citations
Additional affiliations
May 2018 - present
Karl-Franzens-Universität Graz
Position
  • Professor (Associate)
September 2015 - April 2018
University of Helsinki
Position
  • Researcher
October 2013 - September 2015
University of Jyväskylä
Position
  • Researcher
Education
January 2005 - April 2009

Publications

Publications (55)
Article
In laboratory conditions, ants can combat a pathogen infection by means of the medicinal use of reactive oxygen species (ROS). However, it is still unknown where they obtain medicinal compounds in the wild and how they use them. Due to an upregulation of ROS in response to herbivory, aphid-infested plants have been suggested to be a potential sourc...
Article
Full-text available
• Insect diversity and biomass have been declining around the world. This might have severe consequences on the environment since insects provide many crucial ecosystem services. One major driver behind the decline is continuous pesticide use which also affects nontarget organisms. Even at low doses, chronic exposure to pesticides may have negative...
Article
Full-text available
Malnutrition and pesticide exposure are severe factors contributing to the current losses of honeybee colonies. As these stressors often occur combined, we studied the synergistic effects of different diets and pesticide exposure on food choice and mobility of Apis mellifera . We fed beehives with different food sources and exposed the bees to subl...
Article
Social immunity is a suite of behavioral and physiological traits that allow colony members to protect one another from pathogens and includes the oral transfer of immunological compounds between nestmates. In honey bees, royal jelly is a glandular secretion produced by a subset of workers that is fed to the queen and young larvae, and which contai...
Article
Full-text available
Pathogens are identified as one of the major drivers behind the honeybee colony losses, as well as one of the reasons for the reported declines in terrestrial insect abundances in recent decades. To fight infections, animals rely on their immune system. The immune system of many invertebrates can be primed by exposure to a pathogen, so that upon fu...
Article
Full-text available
Eusocial insects, such as ants, have access to complex disease defenses both at the individual, and at the colony level. However, different species may be exposed to different diseases, and/or deploy different methods of coping with disease. Here, we studied and compared survival after fungal exposure in 12 species of ants, all of which inhabit sim...
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Full-text available
Seasonal polyphenism constitutes a specific type of phenotypic plasticity in which short‐lived organisms produce different phenotypes in different times of the year. Seasonal generations of such species frequently differ in their overall lifespan and in the values of traits closely related to fitness. Seasonal polyphenisms provide thus excellent, a...
Article
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Organisms are simultaneously exposed to multiple stresses, which requires regulation of the resistance to each stress. Starvation is one of the most severe stresses organisms encounter, yet nutritional state is also one of the most crucial conditions on which other stress resistances depend. Concomitantly, organisms often deploy lower immune defens...
Article
Female insects that survive a pathogen attack can produce more pathogen-resistant offspring in a process called trans-generational immune priming. In the honey bee (Apis mellifera), the egg-yolk precursor protein Vitellogenin transports fragments of pathogen cells into the egg, thereby setting the stage for a recruitment of immunological defenses p...
Article
The evolution of cooperation and social behaviour is often studied in isolation from the ecology of organisms. Yet, the selective environment under which individuals evolve is much more complex in nature, consisting of ecological and abiotic interactions in addition to social ones. Here, we measured the life-history costs of cooperative chemical de...
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Recent studies of honeybees and bumblebees have examined combinatory effects of different stressors, as insect pollinators are naturally exposed to multiple stressors. At the same time the potential influences of simultaneously occurring agricultural agents on insect pollinator health remain largely unknown. Due to different farming methods, and th...
Data
Effect of exposure to different E. faecalis strains and the insecticide thiacloprid on honeybee survival. Cumulative survival of adult honeybees after (A) oral exposure with two different concentrations (OD 1 and OD 0.5) of the E. faecalis strains MMH and FLY (Kaplan-Meier log Rank: df = 4, X2 = 1.603, p = 0.808), and (B) oral exposure of the LD50...
Data
Lysozyme-like activity in the haemolymph of honeybees after being exposed to different E. faecalis strains and concentrations. General antibacterial activity measured as the diameter of the lytic zone on agar plates, transformed to lysozyme equivalents (μg/ml) (ANOVA: F(4,35) = 1.200, p = 0.328). Only the exposure to MMH results in a lysozyme-like...
Article
Social insect societies are long-standing models for understanding social behaviour and evolution. Unlike other advanced biological societies (such as the multicellular body), the component parts of social insect societies can be easily deconstructed and manipulated. Recent methodological and theoretical innovations have exploited this trait to add...
Article
Full-text available
Short term variation in environmental conditions requires individuals to adapt via changes in behavior and/or physiology. In particular variation in temperature and humidity are common, and the physiological adaptation to changes in temperature and humidity often involves alterations in gene expression, in particular that of heat-shock proteins. Ho...
Data
S3_GeneExpressionData.txt. Normalized Ct values of all candidate genes. (TXT)
Data
S1_SupplementaryMaterial.pdf. (PDF)
Data
S2_SurvivalData.txt. Survival data for the bioassay (formatted as individual survival for analysis with the survival package in R). (TXT)
Article
Among-population differences in immunological traits allow to assess both evolutionary and plastic changes in organisms' resistance to pathogens. Such knowledge also provides information necessary to predict responses of such traits to environmental changes. Studies on latitudinal trends in insect immunity have so far yielded contradictory results,...
Article
The insect immune system has versatile ways of coping with microbial insults. Currently, innate immune priming has been described in several invertebrates, and the first insights into its mechanistic basis have been described. Here we studied infections with two different strains of Serratia marcescens bacteria in two different Lepidopteran hosts....
Article
Full-text available
Hundreds of insect species are nowadays reared under laboratory conditions. Rearing of insects always implicates the risk of diseases, among which microbial infections are the most frequent and difficult problems. Although there are effective prophylactic treatments, the side effects of applied antibiotics are not well understood. We examined the e...
Data
Table S2: Transformations used for normalizing dCt values per gene. In order to avoid heteroscedasticity, transformation of the dCt values were done in nine out of ten genes.
Data
Table S1: Primer sequences used in qPCR Primer efficiencies calculated according to Biorad Real-Time PCR applications guide. Primers are considered efficient if their efficiency lies between 90% and 105%.
Data
Figure S1: Survival of starved and control ants Food deprived ants die significantly faster than control ants.
Article
Full-text available
Starvation is one of the most common and severe stressors in nature. Not only does it lead to death if not alleviated, it also forces the starved individual to allocate resources only to the most essential processes. This creates energetic tradeoffs which can lead to many secondary challenges for the individual. These energetic trade-offs could be...
Article
Full-text available
Protection against inflammation and oxidative stress is key in slowing down aging processes. The honey bee (Apis mellifera) shows flexible aging patterns linked to the social role of individual bees. One molecular factor associated with honey bee aging regulation is vitellogenin, a lipoglycophosphoprotein with anti-inflammatory and antioxidant prop...
Article
Full-text available
Parasites are ubiquitous, and the ability to defend against these is of paramount importance. One way to fight diseases is self-medication, which occurs when an organism consumes biologically active compounds to clear, inhibit or alleviate disease symptoms. Here, we show for the first time that ants selectively consume harmful substances (Reactive...
Article
Full-text available
Insect immune systems can recognize specific pathogens and prime offspring immunity. High specificity of immune priming can be achieved when insect females transfer immune elicitors into developing oocytes. The molecular mechanism behind this transfer has been a mystery. Here, we establish that the egg-yolk protein vitellogenin is the carrier of im...
Article
Inbred individuals and populations are predicted to suffer from inbreeding depression, especially in times of stress. Under natural conditions, organisms are exposed to more than one stressor at any one time, highlighting the importance of stress resistance traits. We studied how inbreeding- and immunity-related traits are correlated under differen...
Article
Full-text available
Previous exposure to a pathogen can help organisms cope with recurring infection. This is widely recognised in vertebrates, but increasing occasions are also being reported in invertebrates where this phenomenon is referred to as immune priming. However, the mechanisms that allow acquired pathogen resistance in insects remain largely unknown. We st...
Article
Full-text available
Parents invest in their offspring by preparing them for defense against pathogens and parasites that only the parents have encountered, a phenomenon known as trans-generational immune priming. We investigated the underlying mechanism using the established lepidopteran model host Galleria mellonella. When larvae were fed with non-pathogenic bacteria...
Article
Full-text available
The gut of most insects harbours nonpathogenic microorganisms. Recent work suggests that gut microbiota not only provide nutrients, but also involve in the development and maintenance of the host immune system. However, the complexity, dynamics and types of interactions between the insect hosts and their gut microbiota are far from being well under...
Data
Bacterial partial 16S rRNA gene sequences cloned from S. littoralis larvae and the BLAST results. (DOC)
Data
Bacteria detected in H. armigera larval gut and frass based on cloning and sequencing. (DOC)
Data
FISH probes used to detect bacteria in S. littoralis gut. (DOC)
Article
Full-text available
MicroRNAs (miRNAs) are small non-coding RNAs mediating post-transcriptional regulation of gene expression in eukaryotes. Addressing their role in regulation of physiological adaptations to environmental stress in insects, we selected the red flour beetle Tribolium castaneum as a model. Beetles were fed with the bacterial entomopathogen Pseudomonas...
Article
Full-text available
The mechanisms that shape the host plant range of herbivorous insect are to date not well understood but knowledge of these mechanisms and the selective forces that influence them can expand our understanding of the larger ecological interaction. Nevertheless, it is well established that chemical defenses of plants influence the host range of herbi...
Data
Full-text available
qRT-PCR Primers. List of primers used in the quantitative real-time PCR analysis.
Data
Supplemental Tables. Supplemental Tables S1 - S3.
Article
Full-text available
Oxylipins play important roles in stress signaling in plants. The compound 12-oxophytodienoic acid (cis-OPDA) is an early biosynthetic precursor of jasmonic acid (JA), the key phytohormone orchestrating the plant anti-herbivore defense. When consumed by feeding Lepidopteran larvae, plant-derived cis-OPDA suffers rapid isomerization to iso-OPDA in t...
Article
Full-text available
Poly- and oligophagous insects are able to feed on various host plants with a wide range of defense strategies. However, diverse food plants are also inhabited by microbiota differing in quality and quantity, posing a potential challenge for immune system mediated homeostasis in the herbivore. Recent studies highlight the complex interactions betwe...
Article
Full-text available
Trans-generational effects on immunity are well known in vertebrates and are considered in many evolutionary and ecological theories of species interaction. Maternal effects have been identified to be of special importance, and are now recognized as a mechanism for adaptive phenotypic response to environmental heterogeneity. We have previously show...
Article
Full-text available
The cell surfaces of microorganisms display distinct molecular patterns formed from lipopolysaccharides, peptidoglycans, or beta1,3-glucans. Binding of these surfaces by pattern recognition proteins such as beta1,3-glucan recognition proteins (betaGRPs) activates the immune response in arthropods. We identified a 40-kDa beta1,3-glucan-binding prote...
Data
cDNAs from GeneFishing for Trichoplusia ni, combined with consecutive banding pattern on the agarose gel. Expression data, based on agarose gel banding pattern is shown for different life stages (2B – 2 day old larvae on bacterial diet, 2N – 2 day old larvae on bacteria-free diet, 2P – 2 day old larvae on cabbage plants; 7B – 7 day old larvae on ba...
Article
The antibacterial immune response of the wax moth, Galleria mellonella, was analysed by use of an inhibition zone plate assay. We demonstrated significant stage-specific differences as the immune response was most effective in the pupal, next the larval and then the adult stage. In addition, we demonstrated that an immune challenge at the onset of,...
Article
Full-text available
Insects helped pioneer, and persist as model organisms for, the study of specific aspects of immunity. Although they lack an adaptive immune system, insects possess an innate immune system that recognizes and destroys intruding microorganisms. Its operation under natural conditions has not been well studied, as most studies have introduced microbes...
Article
According to life-history theory, trade-offs emerge because organisms possess a limited amount of resources that they have to allocate between different bodily functions. Here, we tested whether there is a trade-off between melanin-based immune response and dark melanized wing patterning in the large white butterfly, Pieris brassicae L. (Lepidopter...
Article
In immunoecological studies, experimental effects usually explain a relatively small proportion of total variation observed in immune parameters, while the large amount of variation remains unexplained. It is crucial to be aware of such natural variation of immune parameters, which may overshadow the effects of the experiment. We examined factors r...
Article
Full-text available
Parasite-driven coevolution has led hosts to develop a complicated and potentially costly defence machinery, consisting mainly of the immune system. Despite the evidence for the trade-offs between immune function and life-history traits, it is still obscure how the costs of using and maintaining the immune function are paid. We tested whether immun...
Article
Full-text available
Die meisten Organismen auf der Erde werden von Pathogenen bedroht. Um sich gegen Pathogene zu schützen, haben Organismen ein oftmals komplexes Immunsystem entwickelt. Das Immunsystem hat viele unterschiedene Zellulare und Humorale Komponenten. Verschiedene Komponenten des Immunrepertoires sind aktiv gegen unterschiedliche Pathogene und haben daher...

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