Survival and gene expression under different temperature and humidity regimes in ants

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. However, not only traits involved in the resistance to environmental stresses, but also other traits, such as immune defenses, may be influenced indirectly by changes in temperature and humidity. Here we investigated the response of the ant F. exsecta to two temperature regimes (20 degrees C & 25 degrees C), and two humidity regimes (50% & 75%), for two populations. We measured the survival and the expression of six metabolism- and immunity-related genes, and furthermore compared the expression levels in each condition with the pre-experiment expression levels. Both populations survived equally well at the two humidities, but one population showed higher mortality at 25 degrees C than 20 degrees, at 50% humidity. Similarly, the two populations showed striking differences in their gene expression before the experiment, and in their responses to the environmental conditions. Surprisingly, instead of converging to similar expression levels in the same environmental conditions, gene expression diverged further apart. This indicates different reaction norms to both temperature and humidity for the two populations. Furthermore, our results suggest that also immune defenses are indirectly affected by environmental conditions.Peer reviewe

Factors affecting consumer behaviour on the example of domestic and imported strawberries

Bakalaureusetöö Maamajandusliku ettevõtluse ja finantsjuhtimise õppekavalMaasikad on tarbijate seas väga populaarsed. Erinevates müügikohtades leiab nii kodumaist, kui ka välismaist maasikat. Eeldatakse, et inimestel on välja kujunenud kindlad hoiakud ja suhtumised kodumaiste või välismaiste maasikate osas, nad on teadlikumad ja kogenumad, kuid nende ostuotsuseid võivad mõjutada mitmed faktorid. Seetõttu peab autor oluliseks täiendada teadmisi tänase tarbija ostukäitumisest maasikate ostul. Bakalaureusetöö eesmärk on analüüsida Eesti tarbijate ostukäitumist mõjutavad tegureid erineva päritoluga maasikate ostul. Uurimistöö koostamisel on kasutatud nii teiseseid, kui ka esmaseid andmeid. Esmaste andmete kogumise käigus viidi läbi ankeetküsitlus, mille tulemusi analüüsiti tabeltöötlusprogrammi MS Excel tarkvara abil. Edasi analüüsitakse andmeid kvantitatiivsel meetodil (üldjaotused, rühmitamine oluliste tunnuste järgi jne). Teisesed andmed on kogutud teemakohastest kirjandusallikatest, erialasest kirjandusest, andmebaasidest ja internetist. Uurimistöö esimeses osas antakse teoreetiliste allikate järgi ülevaade tarbijate ostukäitumise olemusest ja seda mõjutavatest teguritest. Töö empiirilises osas keskendutakse ankeetküsitluses saadud tulemuste analüüsile ja tehakse järeldusi. Ankeetküsitluse tulemuste analüüsimisel jõuti järeldusele, et vastajate selge eelistus on osta kodumaiseid maasikaid. Selle peamise põhjusena on välja toodud maasika maitseomadused. Tarbijad ostavad maasikaid eelkõige värskelt tarbimise eesmärgil. Tarbijate ostuotsust mõjutavad kompleksselt: maasikate maitseomadused (maasikate küpsusaste, värvus ja lõhn), maasikate kvaliteet (maasikate värskus ja puhtus), sõbra või tuttava soovitus, teiste klientide tagasiside, kauba väljapanek, degusteerimise võimalus ja hind. Uuringu tulemustest saadi olulisi teadmisi, mille arvestamine aitab jõuda nii kodumaiste ja välismaiste maasikate müüjail saavutada paremaid müügitulemusi.Strawberries are very popular among consumers. At different points of sale you can find both domestic and foreign strawberries. People have developed certain attitude towards domestic and foreign strawberries. Consumers have become more knowledgeable and aware, this affects their buying decisions. That is why author considers it to be vital to improve the knowledge of consumer buying behaviour. The aim of the Bachelor’s thesis is to analyze the factors that affect the consumer behaviour on the example of domestic and foreign strawberries. In this research both secondary and primary data have been used. Questionnaire was conducted during the collection of primary data. Results were analyzed in programm MS Excel software using quantitative method. Secondary data has been collected from literature sources, professional literature, databases and from the internet. In the first part of this research author gives an overview based on theoretical sources of consumer behaviour and the factors affecting consumer behaviour. In the empirical part of the research focuses on analysing the results of the questionnaire. During the analyzation the questionnaire results, it became clear that the respondents clearly preferred domestic strawberries. The main reason for this is the flavor of the strawberries. Consumers buy strawberries primarily for fresh consumption. Consumers buying decisions are mainly affected by these factors: strawberry taste characteristics (ripeness, color and smell), quality of strawberries (freshness and the purity of the berries), recommendation from friend, feedback from other customers, display, opportunity to taste strawberries and the price. The results of the study provided important knowledge which helps merchants achieve better sales results

Trans-generational immune priming against American Foulbrood does not affect the performance of honeybee colonies

Honeybees are major pollinators for our food crops, but at the same time they face many stressors all over the world. One of the major threats to honeybee health are bacterial diseases, the most severe of which is the American Foulbrood (AFB). Recently a trans-generational vaccination approach against AFB has been proposed, showing strong potential in protecting the colonies from AFB outbreaks. Yet, what remains unstudied is whether the priming of the colony has any undesired side-effects. It is widely accepted that immune function is often a trade-off against other life-history traits, hence immune priming could have an effect on the colony performance. In this experiment we set up 48 hives, half of them with primed queens and half of them as controls. The hives were placed in six apiaries, located as pair of apiaries in three regions. Through a 2-year study we monitored the hives and measured their health and performance. We measured hive weight and frame contents such as brood amount, worker numbers, and honey yield. We studied the prevalence of the most common honeybee pathogens in the hives and expression of relevant immune genes in the offspring at larval stage. No effect of trans-generational immune priming on any of the hive parameters was found. Instead, we did find other factors contributing on various hive performance parameters. Interestingly not only time but also the region, although only 10 km apart from each other, had an effect on the performance and health of the colonies, suggesting that the local environment plays an important role in hive performance. Our results suggest that exploiting the trans-generational priming could serve as a safe tool in fighting the AFB in apiaries.Peer reviewe

Long-Term Prophylactic Antibiotic Treatment : Effects on Survival, Immunocompetence and Reproduction Success of Parasemia plantaginis (Lepidoptera: Erebidae)

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 effect of prophylactic antibiotic treatment on the overwintering success of wood tiger moth (Parasemia plantaginis) larvae, and the postdiapause effect on their life-history traits. Four weeks before hibernation larvae were treated with a widely used antibiotic (fumagillin). We monitored moths' survival and life-history traits during the following 10 mo, and compared them to those of untreated control larvae. Prophylactic antibiotic treatment had no effect on survival but we show effects on some life-history traits by decreasing the developmental time of treated larvae. However, we also revealed relevant negative effects, as antibiotic treated individuals show a decreased number of laid eggs and also furthermore a suppressed immunocompetence. These results implicate, that a prophylactic medication can also lead to negative effects on life-history traits and reproductive success, which should be seriously taken in consideration when applying a prophylactic treatment to laboratory reared insect populations.Peer reviewe

Bacterial feeding induces changes in immune-related gene expression and has trans-generational impacts in the cabbage looper (Trichoplusia ni)

<p>Abstract</p> <p>Background</p> <p>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 between environmentally encountered microorganisms and herbivorous insects, pointing to a potential adaptational alteration of the insects' physiology. We performed a differential gene expression analysis in whole larvae and eggs laid by parents grown on different diets to identify potential novel genes related to elevated microbial content in the caterpillars' food.</p> <p>Results</p> <p>We used GeneFishing, a novel differential display method, to study the effects of dietary bacteria on the general gene expression in different life stages and tissues of the cabbage looper (<it>Trichoplusia ni</it>). We were able to visualize several hundred transcripts on agarose gels, one fifth of which were differentially expressed between treatments. The largest number of differentially expressed genes was found in defense-related processes (13) and in recognition and metabolism (16). 21 genes were picked out and further tested for differential gene expression by an independent method (qRT-PCR) in various tissues of larvae grown on bacterial and bacteria-free diet, and also in adults. We detected a number of genes indicative of an altered physiological status of the insect, depending on the diet, developmental stage and tissue.</p> <p>Conclusion</p> <p>Changes in immune status are accompanied by specific changes in the transcript levels of genes connected to metabolism and homeostasis of the organism. Our findings show that larval feeding on bacteria-rich diet leads to substantial gene expression changes, potentially resulting in a reorganization of the insects' metabolism to maintain organismal homeostasis, not only in the larval but also in the adult stage. Furthermore, differences in gene expression levels can also be seen in the next generation, strongly influenced by parental diet.</p

Immunity and physiology of Lepidoptera is influenced by midgut mediated environmental signals

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 unterschiedliche Kosten für den Organismus. Das führt zu einen komplexen Muster von trade-offs und anderen life-history Eigenschaften wie zum Beispiel Auswirkungen auf Lebenslänge und Reproduktion. Die Verteilung von Rohstoffen zwischen Immunität und anderen lebenswichtigen Funktionen hat einen substantiellen Einfluss auf die generelle Fitness des Organismus. Eine Investition in Immunität ist nur dann positiv für die Fitness, wenn ein reales Risiko für einen Pathogenbefall besteht. Die Frage besteht also, ob es möglich ist, die Pathogenität der Umwelt wahrzunehmen und den eigenen Immunstatus entsprechend zu ändern. Eine der primären Interaktionsflächen zwischen der Umwelt und der Lepidopteren-Raupe ist das Verdauungssystem. Viele bakterielle Infektionen, wie zum Beispiel Bacillus thuringiensis, fangen im Larvendarm bei der Verdauung an. Das heisst, dass der Darm die Grenzfläche für potentielle Immunsignale und somit den Informationsaustausch über mögliche Infektionen und die Vorbereitung des Immunsystems darstellt. Das Wissen über Immunsignalwege und Moleküle, die in der Immunantwort eine Rolle spielen, ist in den letzten Jahren erheblich gewachsen. Gleichzeitig ist nicht sehr viel über die Umweltfaktoren, die die Entwicklung des Immunsystems beeinflussen können, bekannt. Bis zum heutigen Tag gibt es keine einzige Studie über die Wirkung von nicht-pathogenen Bakterien, die von Insekten mit dem Futter aufgenommen werden, auf das Immunsystem

Stress responses upon starvation and exposure to bacteria in the ant Formica exsecta

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 defenses when deprived of resources. This indicates that the investment into starvation resistance and immune defenses is likely to be subject to trade-offs. Here, we investigated the impact of starvation and oral exposure to bacteria on survival and gene expression in the ant Formica exsecta. Of the three bacteria used in this study, only Serratia marcescens increased the mortality of the ants, whereas exposure to Escherichia coli and Pseudomonas entomophila alleviated the effects of starvation. Both exposure to bacteria and starvation induced changes in gene expression, but in different directions depending on the species of bacteria used, as well as on the nutritional state of the ants.Peer reviewe

Lack of self-medication by fungus infected Lasius platythorax (Formicidae, Formicinae) ants in a multitrophic experiment

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 source of ROS for ants in the wild. We investigated whether infection would cause Lasius platythorax ants to change their foraging on extrafloral nectar on aphid-infested plants. We found no clear evidence for the ants significantly changing their foraging behaviour in response to the pathogen, nor for the extrafloral nectar to contain ROS. The aphids in our experiment had a relatively high concentration of ROS and future research should determine whether predation on aphids could be a potential source of both protein and ROS needed to combat a disease.Peer reviewe

Induced immune responses in Formica fusca (Hymenoptera: Formicidae)

Parental immune experience can enhance offspring defence mechanisms towards prevalent pathogens in the surrounding environment. This process of inherited resistance from one generation to another is known as trans-generational immune priming (TGIP) in invertebrates. In sedentary and dense insect societies, such as ant colonies, TGIP can influence colony survival and fitness upon pathogen outbreaks. However, TGIP appears to depend on species and environmental stressors and therefore can vary in intensity, as well as in the molecular mechanisms leading to resistance. Here, we stimulated the immune system of queens of the ant Formica fusca (LINNAEUS, 1758) by wounding or injecting dead conidia of the entomopathogenic fungus Beauveria bassiana (BALS.-CRIV.) VUILL. (1912). The offspring were subsequently infected with B. bassiana, and the effect of this priming on survival was evaluated. Furthermore, we investigated whether immune challenge of the mother queen induces changes in the expression of immunity-related genes in queens themselves and their brood. We combined this information with measurements of offspring size and number. Larvae produced by untreated queens had a significantly higher mortality after infection with B. bassiana, whereas those produced by immune-primed queens survived no worse than unexposed ones. Adult worker offspring from sham-control mothers showed a protective effect of queen treatment, consistent with transgenerational immune priming. Thus, the effects of queen priming appear to manifest themselves slightly differently in larval and adult offspring. No differences were detected in offspring number or size, but immune gene expression levels showed changes, both in queens and their offspring.Peer reviewe