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Fungal Parasite (fungal + parasite)
Selected AbstractsVIRULENCE AND COMPETITIVENESS: TESTING THE RELATIONSHIP DURING INTER- AND INTRASPECIFIC MIXED INFECTIONSEVOLUTION, Issue 9 2010Peter A. Staves Understanding the reasons why different parasites cause different degrees of harm to their hosts is an important objective in evolutionary biology. One group of models predicts that if hosts are infected with more than one strain or species of parasite, then competition between the parasites will select for higher virulence. While this idea makes intuitive sense, empirical data to support it are rare and equivocal. We investigated the relationship between fitness and virulence during both inter- and intraspecific competition for a fungal parasite of insects, Metarhizium anisopliae. Contrary to theoretical expectations, competition favored parasite strains with either a lower or a higher virulence depending on the competitor: when in interspecific competition with an entomopathogenic nematode, Steinernema feltiae, less virulent strains of the fungus were more successful, but when competing against conspecific fungi, more virulent strains were better competitors. We suggest that the nature of competition (direct via toxin production when competing against the nematode, indirect via exploitation of the host when competing against conspecific fungal strains) determines the relationship between virulence and competitive ability. [source] Evaluating Pochonia chlamydosporia in a double-cropping system of lettuce and tomato in plastic houses infested with Meloidogyne javanicaPLANT PATHOLOGY, Issue 4 2003S. Verdejo-Lucas The effect of Pochonia chlamydosporia, a facultative fungal parasite of nematode eggs, alone or in combination with oxamyl was evaluated in a double-cropping system of lettuce and tomato in unheated plastic houses infested with Meloidogyne javanica at two sites for two consecutive growing seasons. An additional treatment of methyl bromide fumigation was included to compare crop yield in nematode-free vs. nematode-infested soil. Final population densities, reproductive rate, root gall rating, and egg production were determined after each crop. Pochonia chlamydosporia was isolated from nematode eggs up to nine months after application to soil. The fungus survived in the rhizosphere for the entire growing season at one site, but only at low densities. Final population densities of M. javanica decreased after cultivation of lettuce and increased after tomato, and this pattern of population fluctuation was unaffected by treatment, experiment or site. The reproductive rate on lettuce was equal to or below 1, and it was similar among treatments in both experiments at both sites. Eggs were not found on lettuce roots. On tomato, the reproductive rate in the fungus + oxamyl treatment was significantly lower (P < 0·05) than other treatments in experiment 1 at both sites. Fungus + oxamyl consistently reduced root gall ratings on tomato in all cases, but numbers of eggs per g root varied depending on treatment. Methyl bromide-treated plots remained free of M. javanica at the end of the 2-year study. [source] Reductive detoxification of the acetophenone skeleton of the carnation phytoanticipin by Fusarium oxysporum f.sp. dianthiPLANT PATHOLOGY, Issue 6 2000P. Curir The skeleton of the carnation phytoanticipin, acetophenone, was detoxified by Fusarium oxysporum f.sp. dianthi, the main fungal parasite of carnation. This process consisted of the reduction to ethanol of the acetyl group, leading to the formation of phenylethanol, which has lower fungitoxic activity than the parent molecule. The conversion took place through the activity of an adaptive fungal oxidoreductase, which was NADH-dependent and was released by the fungus as two enzymatic forms within the culture substrate in the presence of acetophenone. Reduction was stereospecific and gave rise to only one of the two possible enantiomeric forms. [source] 132 Parasites and Phytoplankton, with a Special Emphasis on Dinoflagellate InfectionsJOURNAL OF PHYCOLOGY, Issue 2003M. G. Park Eukaryotic parasites are believed to play important roles in phytoplankton ecology and particularly in bloom dynamics of red-tide dinoflagellates. Apart from the prokaryotic parasites such as viruses and bacteria, certain flagellates and fungi have received some degree of attention as eukaryotic parasites of phytoplankton. Our understanding of fungal parasites is largely based on studies for freshwater diatoms and dinoflagellates, although fungal infections are known for some marine phytoplankton, including diatoms. By comparison, the dinoflagellate genus Amoebophrya and the newly described Perkinsozoa Pavilucifera infectans are widely distributed in coastal waters of the world and are well known as eukaryotic parasites of dinoflagellates. Recent work indicates that these parasites have significant impacts on the ecophysiology and behavior of dinoflagellate hosts. Thus, the ecological roles of Amoebophrya spp. and Pavilucifera infectans should be carefully considered in developing concepts about plankton dynamics and material flows in marine food webs. [source] | ||||||||||