| establishment of the new genus paranosema based on the ultrastructure and molecular phylogeny of the type species paranosema grylli gen. nov., comb. nov. (sokolova, selezniov, dolgikh, issi 1994), from the cricket gryllus bimaculatus deg. | the ultrastructure of the microsporidian parasite nosema grylli, which parasitizes primarily fat body cells and haemocytes of the cricket gryllus bimaculatus (orthoptera, gryllidae) is described. all observed stages (meront, meront/sporont transitional stage ("second meront"), sporont, sporoblast, and spore) are found in direct contact with the host cell cytoplasm. nuclei are diplokaryotic during almost all stages of the life cycle, but a brief stage with one nucleus containing an abundance of e ... | 2003 | 14726239 |
| complex adaptive responses during antagonistic coevolution between tribolium castaneum and its natural parasite nosema whitei revealed by multiple fitness components. | host-parasite coevolution can lead to local adaptation of either parasite or host if there is specificity (gxg interactions) and asymmetric evolutionary potential between host and parasite. this has been demonstrated both experimentally and in field studies, but a substantial proportion of studies fail to detect such clear-cut patterns. one explanation for this is that adaptation can be masked by counter-adaptation by the antagonist. additionally, genetic architecture underlying the interaction ... | 2012 | 22280468 |
| [microsporidiosis and coccidiosis, protozoan diseases of flour beetles (coleoptera, tenebrionidae)]. | tribolium destructor and t. confusum diseases caused by the fat body of the parasites nosema whitei and adelina tribolii were investigated. life span and weight dynamics were examined at different temperatures and infection conditions. infected females of t. confusum lay a less number of eggs. the gas produced by stink glands of t. destructor may inactivate the spores of n. whitei but does not affect those of a. tribolii. | 2009 | 958720 |
| [effect of parasitic protozoa on the physiological state of the body of the confused flour beetle (coleoptera, tenebrionidae)]. | studies were conducted of diseases of tribolium destructor and t. confusum caused by parasites of the fat body, microsporidians of nosema whitei and coccidians of adelina tribolii. the infection of larvae of tenebrionid beetles with microsporidians and coccidians results in substantial changes in the metabolism of insects-hosts (respiratory metabolism is disturbed and activity of tissue catalase is reduced). physiological characteristics of uninfected larvae of t. confusum and t. destructor diff ... | 2007 | 113760 |
| determinants of virulence for the parasite nosema whitei in its host tribolium castaneum. | for many parasites, especially those that obligately kill the host for transmission, host age is crucially important to determine success. here, we have experimentally investigated this relationship with the microsporidian parasite, nosema whitei, in its host, the red flour beetle, tribolium castaneum. we find that infection is only possible in young larvae and that spore load at the time of transmission (i.e., host death) correlates with host body size. the data suggested that an infection by n ... | 2005 | 15963529 |
| selection by parasites may increase host recombination frequency. | meiotic recombination destroys successful genotypes and it is therefore thought to evolve only under a very limited set of conditions. here, we experimentally show that recombination rates across two linkage groups of the host, the red flour beetle tribolium castaneum, increase with exposure to the microsporidian parasite, nosema whitei, particularly when parasites were allowed to coevolve with their hosts. selection by randomly varied parasites resulted in smaller effects, while directional sel ... | 2005 | 17148164 |
| nonadditive genetic components in resistance of the red flour beetle tribolium castanaeum against parasite infection. | genetically coupled antagonistic coevolution between host and parasites can select for the maintenance of recombination in the host. mechanistically, maintenance of recombination relies on epistatic interactions between resistance genes creating linkage disequilibria (ld). the role of epistasis in host resistance traits is however only partly understood. therefore, we applied the joint scaling principle to assess epistasis and other nonadditive genetic components of two resistance traits, surviv ... | 2008 | 18564375 |
| host genetic architecture in single and multiple infections. | hosts are often target to multiple simultaneous infections by genetically diverse parasite strains. the interaction among these strains and the interaction of each strain with the host was shown to have profound effects on the evolution of parasite traits. host factors like genetic architecture of resistance have so far been largely neglected. to see whether genetic architecture differs between different kinds of infections we used joint scaling analysis to compare the genetic components of resi ... | 2009 | 19196387 |
| evolution of host resistance and trade-offs between virulence and transmission potential in an obligately killing parasite. | standard epidemiological theory predicts that parasites, which continuously release propagules during infection, face a trade-off between virulence and transmission. however, little is known how host resistance and parasite virulence change during coevolution with obligate killers. to address this question we have set up a coevolution experiment evolving nosema whitei on eight distinct lines of tribolium castaneum. after 11 generations we conducted a time-shift experiment infecting both the coev ... | 2009 | 19732263 |
| influence of co-evolution with a parasite, nosema whitei, and population size on recombination rates and fitness in the red flour beetle, tribolium castaneum. | the high prevalence of meiotic recombination-an important element of sexual reproduction-represents one of the greatest puzzles in biology. the influence of either selection by a co-evolving parasite alone or in combination with genetic drift on recombination rates was tested in the host-parasite system tribolium castaneum and nosema whitei. after eight generations, populations with smaller genetic drift had a lower recombination rate than those with high drift whereas parasites had no effect. i ... | 2010 | 20383780 |
| antagonistic coevolution with parasites maintains host genetic diversity: an experimental test. | genetic variation in natural populations is a prime prerequisite allowing populations to respond to selection, but is under constant threat from forces that tend to reduce it, such as genetic drift and many types of selection. haldane emphasized the potential importance of parasites as a driving force of genetic diversity. his theory has been taken for granted ever since, but despite numerous studies showing correlations between genetic diversity and parasitism, haldane's hypothesis has rarely b ... | 2011 | 20685701 |
| experimental coevolution leads to a decrease in parasite-induced host mortality. | host-parasite coevolution can lead to a variety of outcomes, but whereas experimental studies on clonal populations have taken prominence over the last years, experimental studies on obligately out-crossing organisms are virtually absent so far. therefore, we set up a coevolution experiment using four genetically distinct lines of tribolium castaneum and its natural obligately killing microsporidian parasite, nosema whitei. after 13 generations of experimental coevolution, we employed a time-shi ... | 2011 | 21599776 |
| antagonistic experimental coevolution with a parasite increases host recombination frequency. | one of the big remaining challenges in evolutionary biology is to understand the evolution and maintenance of meiotic recombination. as recombination breaks down successful genotypes, it should be selected for only under very limited conditions. yet, recombination is very common and phylogenetically widespread. the red queen hypothesis is one of the most prominent hypotheses for the adaptive value of recombination and sexual reproduction. the red queen hypothesis predicts an advantage of recombi ... | 2012 | 22330615 |
| antagonistic coevolution accelerates the evolution of reproductive isolation in tribolium castaneum. | the evolution of reproductive isolation among populations is often the result of selective forces. among those, parasites exert strong selection on host populations and can thus also potentially drive reproductive isolation. this hypothesis has yet to be explicitly tested, and here we set up a multigenerational coevolution experiment to explore this possibility. five lines of tribolium castaneum were allowed to coevolve with their natural parasite, nosema whitei; five paired lines of identical o ... | 2012 | 22976014 |
| coevolving parasites and population size shape the evolution of mating behaviour. | coevolution with parasites and population size are both expected to influence the evolution of mating rates. to gain insights into the interaction between these dual selective factors, we used populations from a coevolution experiment with the red flour beetle, tribolium castaneum, and its microsporidian parasite, nosema whitei. we maintained each experimental population at two different population sizes. we assayed the mating behaviour of both males and females from coevolved and paired non-coe ... | 2013 | 23379749 |
| are there genetic trade-offs between immune and reproductive investments in tribolium castaneum? | parasites impose strong selection on hosts to defend themselves, which is expected to result in trade-offs with other fitness traits such as reproduction. here we test for genetic trade-offs between reproductive traits and immunity using tribolium castaneum lines that were subject to experimental evolution. the lines have been exposed to contrasting sexual selection intensities via different sex ratios (female-biased, equal and male-biased). after 56 generations, the lines have significantly div ... | 2013 | 23770144 |
| insect host-parasite coevolution in the light of experimental evolution. | the many ways parasites can impact their host species have been the focus of intense study using a range of approaches. a particularly promising but under-used method in this context is experimental evolution, because it allows targeted manipulation of known populations exposed to contrasting conditions. the strong potential of applying this method to the study of insect hosts and their associated parasites is demonstrated by the few available long-term experiments where insects have been expose ... | 2014 | 24130157 |
| ultrastructural analysis supports transferring nosema whitei weiser 1953 to the genus paranosema and creation a new combination, paranosema whitei. | the current ultrastructural description of nosema whitei is in agreement with the genus definition of paranosema [sokolova, y.y., dolgikh, v.v., morzhina, e.v., nassonova, e.s., issi, i.v., terry, r.s., ironside, j.e., smith, j.e., vossbrinck, c.r., 2003. establishment of the new genus paranosema based on the ultrastructure and molecular phylogeny of the type species paranosema grylli gen. nov., comb. nov (sokolova, selezniov, dolgikh, issi 1994), from the cricket gryllus bimaculatus deg. journa ... | 2005 | 16083902 |