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Theses

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1995 - 199912000 - 20021
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Subject: Plant Biochemistry × End date: 2002 × Type: Thesis × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Parasitism of Hirsutella thompsonii Fischer var. synnematosa Samson, McCoy & O`Donnell on coconut eriophtid mite Aceria guerreronis (Keifer)
    (Department of Plant Pathology, College of Horticulture, Vellanikkara, 2002) Shabnaz Padiyath; KAU; Beena, S
    An investigation on "Parasitism of Hirsutella thompsonii Fischer var. synnematosa Samson, McCoy & O'DonneU on coconut eriophyid mite Aceria guerreronis (Keifer)" was carried out at the Department of Plant Pathology, College of Horticulture, Vellanikkara. The main objectives of the study were to explore the cultural, physiological, toxicological characters of the fungus, compatibility of the fungus with pesticides and botanicals and mass multiplication characteristics of the fungus, which could be used as an efficient biocontrol agent on coconut mite. The results of this investigation revealed the following conclusions. From the mite infested young nuts collected from the coconut garden of College of Horticulture, Vellanikkara, the acaropathogen H. thompsonii var. synnematosa was isolated and its pathogenicity on mite was proved. Sabouraud's maltose agar + yeast was selected as the most suitable solid medium for the growth and sporulation of the fungus. Maximum number of fruiting bodies called synnemata were produced in Richard's medium. Correlation study revealed a significant positive correlation between mycelial growth and sporulation. Ninety six per cent germination of spores of the fungus grown in solid medium was recorded after eight hours of incubation. In the different liquid media tried, Sabouraud's maltose+yeast was selected as the best for maximum dry mycelial weight and sporulation. Only twenty five per cent germination was recorded after eight hours of incubation of spores of the fungus grown in liquid medium. Maximum sporulation and germination percentage of spores of the fungus were recorded in solid media compared to liquid media. Microscopic observations showed that in all the solid media the hyphae were hyaline, septate, smooth and branched producing conical to flask shaped phialides with narrow neck. Phialides were branched often once. Spores were spherical, verrucose and hyaline. Hyphal width, phialide width and spore diameter , ranged between 3.33 urn to 3.76 urn in different solid media. Maximum number of phial ides in a unit length of hypha was in Sabouraud's maltose agar + yeast. The fungus preferred an alkaline pH of 9. But it gave satisfactory growth on a wide range of pH from 5 to 9. Growth of the fungus was recorded only in temperatures of 25 and 30oe. No significant difference was recorded in the fungal growth at humidity levels of 50 to 90 per cent. Both exotoxin and endotoxin were extracted from the liquid culture of the fungus. In closed perianth condition there was no significant difference in the per cent mortality of mites due to spraying with both the toxins, but it was superior than spraying with water (control). In open perianth condition there was no significant difference in the percentage mortality of mites on spraying with both the toxins and water. The decreasing order of the inhibition of fungal growth by insecticides/acaricides was dicofol, carbaryl, triazophos, wettable sulphur and endosulfan. The fungicides bordeaux mixture and copper oxychloride showed cent per cent inhibition of fungal growth whereas potassium phosphonate (akomin) recorded minimum inhibition over control. Among the botanicals, maximum inhibition of fungal growth was with garlic + neem oil and azadirachtin showed least inhibition. In the two phase mass production study, wheat was identified as the most promising raw substrate for sporulation and germination percentage of spores of the fungus. In the powdered substrates tried, growth was present only in loose substrates like rice bran and tea waste.
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    ThesisItemOpen Access
    Identification, bionomics and control of infective larvae of common nematodes of domestic ruminants
    (Department of Parasitology, College of Veterinary and Animal Sciences, Mannuthy, 1995) Jeyathilakan, N; KAU; Sathianesan, V
    An investigation by coprological examination and copro – culture into the occurrence of common nematodes of cattle buffaloes and goats, specific identity and bionomics of their infective larvae and assessment of ovicidal and larvicidal properties of common fertilizers like urea, ammonium sulphate, quick lime and ash for their control were carried out. The prevalence was highest in goats with strongyle having highest percentage and Haemonchus being the commonest nematode involved. As per the specific identity Haemonchus contortus, Oesophagostomum radiatum, Cooperia punctate, Trichostrongylus axei, T. colubriformis, Bunostomum phlebotomum and Strongyloides papillosus, H. contortus, O. radiatum, T. colubriformis and S. papillosus and H. contortus, O. columbianum, O. asperum, T. colubriformis, T. axei, B. trigonocephalum and S. papillosus were the species of nematodes encountered in cattle, buffaloes and goats respectively. Regarding bionomics none of the larvae showed phototropism and the highest and shortest viability was for Oesophagostomum species and Strongyloides species respectively. Urea and ammonium sulphate (1%) were found to have the highest ovicidal property (100%) with ash having the lowest, when mixed with faeces. The larvicidal property was 100% for quicklime (1%) with no efficacy for other fertilizers, when treated with larval suspension. Scanning electron microscopic study of some of the infective larvae was also carried out.