The Intra- and trans-generational effects of larval nutritional conditions on life-history traits of the greater wax moth, Galleria mellonella

Phenotypic plasticity allows the same genotype to produce distinctly different morphological, physiological or behavioural characteristics depending on the environmental conditions the individual, and even its parents or more remote ancestors, have experienced. However, phenotypic change is limited by physiological, genetic and environmental constraints, which can lead to trade-offs between life-history traits. In this thesis, I investigated the intra- and transgenerational effects of larval nutrition on life-history traits of a ubiquitous pest of apiculture: the greater wax moth Galleria mellonella (Lepidoptera: Pyralidae). I found that a low-nutrition larval diet and periods of fasting negatively affected the moths’ development rate, body size and adult longevity. However, compared with the moths that were reared on a standard diet, the mothsthat were subjected to fasting or a low-nutrition larval diet exhibited lower mortality from infection by an entomopathogenic fungus Beauveria bassiana and stronger encapsulation responses to synthetic immune challenge at the larval and adult stages. Furthermore, the activation of encapsulation response at the pupal stage reduced the strength of adult encapsulation response in males reared on a standard diet but not in males reared on a low-nutrition diet. In contrast to the general pattern, a subgroup of females subjected to a relatively short fast had distinctly high growth rates after the fast, but perhaps as a cost of this compensatory response they exhibited particularly weak encapsulation responses and short adult lifespans. Maternal, but not paternal, lownutrition diet increased the survival time of offspring infected with B. bassiana. In addition, a low-nutrition parental diet had sex-specific effects on development time and body mass of the offspring. My research demonstrates that larval nutrition has diverse and long-lasting effects on immune function and other life-history traits – as well as on associations between the different life-history traits – in G. mellonella. The studies also add to the growing body of evidence indicating that environmental conditions experienced by the parents can contribute to variation in offspring phenotype.Ravinto-olosuhteiden sukupolven sisäiset ja sukupolven yli ulottuvat vaikutukset isovahakoisan (Galleria mellonella) elinkiertopiirteisiin Ilmiasun joustavuus mahdollistaa sen, että sama genotyyppi voi tuottaa hyvin erilaisia morfologiaan, fysiologiaan tai käyttäytymiseen liittyviä piirteitä riippuen yksilön tai jopa sen vanhempien kokemista, ympäristöolosuhteista. Ilmiasun muutoksia rajoittavat kuitenkin fysiologiset, geneettiset ja ympäristöön liittyvät tekijät, mikä voi johtaa vaihtokauppatilanteisiin elinkiertopiirteiden välillä. Yksi tärkeä yksilön ilmiasua muovaava tekijä on kehitysaikainen ravinto, jonka sukupolven sisäisiä ja sukupolven yli ulottuvia vaikutuksia tutkin tässä väitöskirjassa merkittävällä mehiläispesien tuholaisella: isovahakoisa Galleria mellonella (Lepidoptera: Pyralidae). Havaitsin, että eripituisilla paastojaksoilla ja heikkolaatuisella ravinnolla oli pääsääntöisesti negatiivinen vaikutus isovahakoisien kehitysnopeuteen, kokoon ja aikuiseliniän pituuteen. Paastolle tai heikolle toukkaravinnolle altistetuilla yksilöillä kuolleisuus Beauveria bassiana -sieni-infektiosta oli kuitenkin pienempi ja enkapsulaatiovaste keinotekoista immuunihaastetta kohtaan voimakkaampi toukka- ja aikuisvaiheessa verrattuna standardiravinnolla kasvaneisiin yksilöihin. Lisäksi enkapsulaatiovasteen aktivointi kotelovaiheessa heikensi standardiravinnolla, mutta ei heikolla ravinnolla, kehittyneiden koiraiden aikuisvaiheen enkapsulaatiovastetta. Pieni osa lyhytaikaiselle paastolle altistetuista naaraista kasvoi poikkeavan nopeasti paaston seurauksena, mutta mahdollisesti tämän ns. kompensoivan kasvun seurauksena niillä havaittiin huomattavan heikko immuunivaste ja lyhyt aikuiselinikä. Äidin, mutta ei isän, heikko ravinto pidensi B. bassiana -infektion saaneiden jälkeläisten selviytymisaikaa vaikuttamatta kuitenkaan niiden kokonaiskuolleisuuteen. Vanhempien ravinnon laadulla oli lisäksi jälkeläisen sukupuolesta ja sen ravinto-olosuhteista riippuvia vaikutuksia kehitysaikaan ja kokoon. Tutkimukseni osoittavat, että toukka-aikana koetuilla heikoilla ravinto-olosuhteilla on moninaisia vaikutuksia isovahakoisan immuniteettikykyyn ja muihin elinkiertopiirteisiin, sekä eri elinkiertopiirteiden välisiin assosiaatioihin. Tutkimukseni tuovat myös lisänäyttöä siitä, että kehitysaikaisella ravitsemuksella voi olla jopa sukupolven yli ulottuvia vaikutuksia hyönteisten ilmiasuun

Modélisation bayésienne et robotique

This document describes my research around Bayesian modeling and robotics. My work started with the modeling of biological processes before evolving towards robotics. In both cases, I was interested in both perception and action. I first proposed a model of human perception of planar surfaces with optic flow which fuses in a single framework two concurrent hypotheses of the literature. I also proposed and compared several models of eye movement selection in a Multiple Object Tracking task. I was able to show that the model with explicit uncertainty was the closest to the subjects eye movements.In robotics, I worked on the state estimation of several robots with classical filtering techniques but also including fusion of multiple sources of information of various nature and characteristics. I also discuss the Iterative Closest Point algorithm for which we proposed a more rigorous method for evaluating the different variants. The last piece of work I present deals with online three-dimensional path planning and execution of a tracked robot with significant climbing capabilities.I conclude this document with perspectives on what I call situated robotics, that is robots not taken in isolation but embedded in a sensorized environment shared with humans.Ce document décrit mes travaux de recherche autour de la modélisation bayésienne et de la robotique. Mon travail a commencé par la modélisation de processus biologiques avant, dans un deuxième temps, d'évoluer vers la robotique. Dans les deux cas, je me suis intéressé à la fois à la perception et à l'action. J'ai donc proposé un modèle de la perception humaine de plans par le flux optique qui réunit deux hypothèses de la littérature dans un cadre unique. J'ai aussi proposé et comparé différents modèle de la sélection de mouvement oculaire dans une tâche de suivi multi-cibles, et montré que le modèle prenant en compte explicitement l'incertitude proposait des mouvements plus proches de ceux des sujets.Du côté robotique, j'ai travaillé sur l'estimation d'état de plusieurs robots avec des techniques classiques de filtrage mais en incluant la fusion de plusieurs sources d'informations de nature et caractéristiques différentes. Je discute aussi de l'algorithme d'Iterative Closest Point pour proposer une méthode plus rigoureuse d'évaluation des différentes variantes. Le dernier travail que je présente concerne la planification en ligne et l'exécution de chemin pour un robot à chenille avec des capacités de franchissement importantes.Je conclus ce document par des perspectives de travail sur ce que j'appelle la robotique située, c'est-à-dire des robots non plus isolés mais plongés dans un environnement équipé de capteurs et partagé avec des humains

Transgenerational Effects of Heavy Metal Pollution on Immune Defense of the Blow Fly Protophormia terraenovae

Recently environmental conditions during early parental development have been found to have transgenerational effects on immunity and other condition-dependent traits. However, potential transgenerational effects of heavy metal pollution have not previously been studied. Here we show that direct exposure to heavy metal (copper) upregulates the immune system of the blow fly, Protophormia terraenovae, reared in copper contaminated food. In the second experiment, to test transgenerational effects of heavy metal, the parental generation of the P. terraenovae was reared in food supplemented with copper, and the immunocompetence of their offspring, reared on uncontaminated food, was measured. Copper concentration used in this study was, in the preliminary test, found to have no effect on mortality of the flies. Immunity was tested on the imago stage by measuring encapsulation response against an artificial antigen, nylon monofilament. We found that exposure to copper during the parental development stages through the larval diet resulted in immune responses that were still apparent in the next generation that was not exposed to the heavy metal. We found that individuals reared on copper-contaminated food developed more slowly compared with those reared on uncontaminated food. The treatment groups did not differ in their dry body mass. However, parental exposure to copper did not have an effect on the development time or body mass of their offspring. Our study suggests that heavy metal pollution has positive feedback effect on encapsulation response through generations which multiplies the harmful effects of heavy metal pollution in following generations

Transgenerational Effects of Parental Larval Diet on Offspring Development Time, Adult Body Size and Pathogen Resistance in Drosophila melanogaster

Environmental conditions experienced by parents are increasingly recognized to affect offspring performance. We set out to investigate the effect of parental larval diet on offspring development time, adult body size and adult resistance to the bacterium Serratia marcescens in Drosophila melanogaster. Flies for the parental generation were raised on either poor or standard diet and then mated in the four possible sex-by-parental diet crosses. Females that were raised on poor food produced larger offspring than females that were raised on standard food. Furthermore, male progeny sired by fathers that were raised on poor food were larger than male progeny sired by males raised on standard food. Development times were shortest for offspring whose one parent (mother or the father) was raised on standard and the other parent on poor food and longest for offspring whose parents both were raised on poor food. No evidence for transgenerational effects of parental diet on offspring disease resistance was found. Although paternal effects have been previously demonstrated in D. melanogaster, no earlier studies have investigated male-mediated transgenerational effects of diet in this species. The results highlight the importance of not only considering the relative contribution each parental sex has on progeny performance but also the combined effects that the two sexes may have on offspring performance

Effects of Interaction between Temperature Conditions and Copper Exposure on Immune Defense and Other Life-History Traits of the Blow Fly <i>Protophormia terraenovae</i>

Environmental pollution is considered one of the major threats to organisms. Direct effects of heavy metal pollution on various life-history traits are well recognized, while the effects of potential interactions between two distinct environmental conditions on different traits are poorly understood. Here, we have tested the effects of interactions between temperature conditions and heavy metal exposure on innate immunity and other life-history traits. Maggots of the blow fly <i>Protophormia terraenovae</i> were reared on either copper-contaminated or uncontaminated food, under three different temperature environments. Encapsulation response, body mass, and development time were measured for adult flies that were not directly exposed to copper. We found that the effects of copper exposure on immunity and other traits are temperature-dependent, suggesting that the ability to regulate toxic compounds in body tissues might depend on temperature conditions. Furthermore, we found that temperature has an effect on sex differences in immune defense. Males had an encapsulation response at higher temperatures stronger than that of females. Our results indicate that the effects of environmental conditions on different traits are much more intricate than what can be predicted. This is something that should be considered when conducting immunological experiments or comparing results of previous studies

The mean encapsulation rate (artificial unit) of the parental generation reared in copper contaminated and uncontaminated environments (uncontaminated: N=189, mean =64.53, SD =14.54; contaminated: N=184, mean =68.82, SD =14.24).

<p>The encapsulation rate was measured as average gray value of reflected light, which is considered as relative darkness (for more details see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038832#s4" target="_blank">Materials and methods</a>).</p

The mean encapsulation response of the offspring whose parents were reared in copper contaminated and uncontaminated environments (uncontaminated: N=90, mean =53.52, SD =11.97; contaminated: N=92, mean =61.78, SD =19.29).

<p>The mean encapsulation response of the offspring whose parents were reared in copper contaminated and uncontaminated environments (uncontaminated: N=90, mean =53.52, SD =11.97; contaminated: N=92, mean =61.78, SD =19.29).</p

Summary of analysis of variance on offspring body size (thorax length) separately for males and females. Significant effects are shown in bold.

<p>Summary of analysis of variance on offspring body size (thorax length) separately for males and females. Significant effects are shown in bold.</p

Development time was analyzed using Cox regression survival analysis.

<p>A significant interaction between the maternal and the paternal diets indicates that a parent's dietary effect on offspring development time was dependent upon the dietary effect of the other parent.</p