Infestation

About: Infestation is a research topic. Over the lifetime, 8308 publications have been published within this topic receiving 82305 citations.

Interactions of aphid herbivory and nitrogen availability on the total foliar glycoalkaloid content of potato plants.

Abstract: In plant growth room (PGR) and open-air pot (OAP) experiments, potato cvs King Edward and Maris Piper were grown under two nitrogen levels or two different nitrogen release patterns. Plants were subjected to infestation by peach potato aphids Myzus persicae (Homoptera: Aphididae). Total glycoalkaloid (GA) levels were measured in the foliage of both infested and non-infested plants, before, during and after aphid infestation. In the PGR experiment, aphid infestation reduced the amounts of total GAs in both cultivars. This reduction is attributed to the sugar deficiency induced in the plants owing to the dense aphid colonization. Results from the OAP experiment showed a temporal increase of GAs produced by potato cv. King Edward plants subjected to aphid infestation. Elevated amounts of nitrogen in the nutrient solutions (PGR experiment) reduced total GAs, while no differences were observed between manure and fertilizer treated plants (OAP experiment). It is concluded that the source of available nitrogen does not affect foliar GA synthesis in potatoes, and as a consequence, does not affect its endogenous chemical defense against insect herbivory. The case for insect-induced chemical defense mechanisms as triggered by low rates of aphid infestation is discussed.

Frequency of intestinal parasitic infestation in children of 5-12 years of age in Abbottabad.

Abstract: Background: Worm infestation is a major problem in children from developing countries due to bad hygienic conditions. It produces nutritional deficiencies and anaemia in children, especially when hookworm infestation is present. Methods: This cross-sectional study deals with investigation of the frequency of intestinal parasitic infestation in children between the ages 5–12 years. A total of 283 subjects were tested and screened for different intestinal parasites at of Department of Physiology, Ayub Medical College, Abbottabad. Negative cases were re-examined and if found free of intestinal pathogenic parasites were labelled as negative. Results: Of the 283 children examined, 230 tested positive for various intestinal parasites. The frequency of helminthic infestation was found to be above 81%. There were 8 different species of helminths and protozoa found in the specimens. By far the highest frequency of 48% was noted for Ascaris lumbricoides while 6.9% (16 cases) of the specimens examined had mixed infestation. The mean Haemoglobin (Hb) level was found to be 9.82 g/dl in males and 9.0 g/dl in females. Virtually no Hookworm infestation was found which may be the reason of not so low Hb level of the subjects. Conclusions: A very high percentage (81%) of children from suburbs of Abbottabad have intestinal worm infestation and majority of them (48% of positive cases) have Ascaris lumbricoides. Children were not very severely anaemic because of virtually no hook worm cases. Key Words: Anaemia, Ascaris lubricoides, Helminths, Intestinal disease parasitic, Child nutritional disorders, Hookworm infestations.

Community structure of the Fusarium complex on wheat seed in Italy

Abstract: The objective was to quantitatively document the pathogen community associated with the Fusarium head blight complex in Italian wheat. The observational study was prompted by increased concerns about mycotoxin contamination coupled with a surge in organically grown wheat. During the three-year survey (2004 to 2006) in three geopolitically defined zones (north, centre, south), seedborne pathogens associated with Fusarium head blight in organic bread and durum wheat were assayed by the freezing blotter method and identified to species based on morphological features. The four most abundant species overall, in order from highest to lowest, were Fusarium poae, Microdochium nivale, F. verticillioides and F. graminearum. Environment was more influential than wheat cultivar in determining the variances in seed infestation counts. Counts of infested seeds were higher (and more variable) in the north and centre zones than in the south zone. The odds of observing any seed infestation was significantly higher in both the north and centre zones (compared with the south zone) for F. avenaceum, F. graminearum, F. poae, and M. nivale in durum wheat. There was a significant nonlinear relationship between seed infestation prevalence and incidence, with evident separation of species along the prevalence-incidence curve. Species co occurrence was observed, but associations shifted with wheat type, over years, and among zones. F. poae was not positively associated with any other species.

Plant Damage and Yield Response to the Russian Wheat Aphid (Homoptera: Aphididae) on Susceptible and Resistant Winter Wheats in Colorado

Abstract: Plant damage and yield response to the Russian wheat aphid, Diuraphis noxia (Mordvilko), were evaluated on a susceptible (TAM 107) and a resistant (RWA E1) winter wheat, Triticum aestivum L., in three Colorado locations in the 1993 and 1994 crop years. Russian wheat aphid was more abundant on TAM 107 than on RWA E1. Russian wheat aphid days per tiller were greater at the higher infestation levels. Yield losses as a result of Russian wheat aphid infestation occurred most of the time with TAM 107 but rarely with RWA E1. Seed densities were reduced at higher infestation levels in TAM 107 at two locations. Russian wheat aphids per tiller had a negative relationship to yield in TAM 107 but not in RWA E1. In TAM 107 yield decreased as aphid densities increased, but yield remained constant regardless of initial aphid abundance on RWA E1 in all environments. Seed densities were reduced at higher infestation levels in TAM 107 at two locations. The resistance conferred by the Dn4 gene seems to be an effective management approach across a range of field conditions.