نتایج جستجو برای: nematodes
تعداد نتایج: 14919 فیلتر نتایج به سال:
The importance of growing sugarcane varieties that minimise losses from nematodes is linked to the effect that the nematodes have on the cane. Revised estimates of crop loss from nematodes in South Africa indicate a reduction in yield equivalent to more than 1.6 million tons cane per annum. The most pathogenic species on sugarcane, Meloidogyne javanica, is restricted to very sandy soils. The ot...
Many organisms live in confined fluidic environments such as the thin liquid layers on the skin of host organisms or in partially-saturated soil. We investigate the collective behaviour of nematodes in a thin liquid layer, which was first described by Gray and Lissmann [J. Exp. Biol., 1964, 41, 135]. We show experimentally that nematodes confined by a thin liquid film come into contact spontane...
Haemonchus contortus and Trichostrongylus colubriformis are among the most important parasitic nematodes of small ruminants. Caenorhabditis elegans, a free-living nematode, is used as a model for evaluating anthelmintic activity of a variety of test substances. Extracts of several medicinal plants are useful in vitro and in vivo against nematode development. Extracts of Curtisia dentata, a Sout...
Living Xiphinema americanum (Xa) and X. rivesi (Xr) extracted from soil samples and stored for 1-5 days at 4 or 20 C contained aseptate fungal hyphae. The fungi directly penetrated the nematode's cuticle from spores encysted near the head. Penetration through the stoma, vulva, or anus was rare. Catenaria anguillulae (Cat), Lagenidium caudatura (Lag), Aphanomyces sp. (Aph), and Leptolegnia sp. (...
The pecan weevil, Curculio caryae (Horn), is a key pest of pecans in the Southeast. Entomopathogenic nematodes have been shown to be pathogenic toward the larval stage of this pest. Before this research, only three species of nematodes had been tested against pecan weevil larvae. In this study, the virulence of the following nine species and 15 strains of nematodes toward fourth-instar pecan we...
The antibiotic 2,4-diacetylphloroglucinol (DAPG) is produced by some isolates of the beneficial bacterium Pseudomonas fluorescens. DAPG is toxic to many organisms, and crop yield increases have been reported after application of DAPG-producing P. fluorescens. This study was conducted to determine whether DAPG is toxic to selected nematodes. The plant-parasitic nematodes Heterodera glycines, Mel...
Sedentary plant-parasitic cyst nematodes are biotrophs that cause significant losses in agriculture. Parasitism is based on modifications of host root cells that lead to the formation of a hypermetabolic feeding site (a syncytium) from which nematodes withdraw nutrients. The host cell cycle is activated in an initial cell selected by the nematode for feeding, followed by activation of neighbori...
FREE-LIVING SOIL NEMATODE POPULATION DIVERSITY DYNAMICS AT AN ASIMINA TILOBA SITE IN VIRGINIA. Sarah R. Marzec & Theresa M. Grana, Department of Biological Sciences, Univ. of Mary Washington, Fredericksburg VA, 22401. Nematodes are microscopic roundworms that are highly successful in many environments. The model organism Caenorhabditis elegans is specifically a free-living nematode which can be...
Cartesian Diver (1) and manometric (2) techniques have frequently been used to measure the respiration rates of nematodes. However, the sensitivity and ease of operation of the polarographic oxygen-sensing equipment currently available offers a technique of great future value to plant nema-tologists. Our recent experience with the YSI Model 53 Biological Oxygen Monitor (Yellow Springs Instrumen...
Corn yields were measured after application of nematicides in 16 experiments, mostly in medium-to-heavily textured soil, at 12 locations in Iowa during 1973-1976. The average maximum yield increase in plots treated with nematicides was 21% over yields in untreated plots. Yields were correlated negatively with nematode numbers or nematode biomass in nearly all comparisons. Correlations of nemato...
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