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Theses

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1990 - 19985
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Subject: Entomology × Author: KAU × End date: 1999 × Start date: 1990 ×
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Now showing 1 - 5 of 5
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    ThesisItemOpen Access
    Effect of organic amendments on plant parasitic nematodes and soil micro-organisms
    (Department of Entomology, College of Agriculture, Vellayani, 1992) Ajith, K; KAU; Sheela, M S
    Field experiments conducted to evaluate the effect of neem and eupatorium leaves at two levels on plant parasitic and non-parasitic nematodes and soil micro-organisms in the rootzone of bhindi and cowpea in rainy and summer seasons revealed that neem and eupatorium leaf treatments (300g/plant or 15 t/ha) were found effective in controlling Helicotylenchus spp., R. reniformis and M. incognita in the rootzone. Lower dose (150g/plant) of neem was found sufficient to suppress the Helicotylenchus spp. In the rootzone of bhindi. Effect of these treatments persisted up to 75 D A S in rainy season and 45 DAS in summer season. The effect of lower doses also persisted up to 30 DAS. The predatory and saprophytic nematode population build up in the rootzone was enhanced by higher dose of eupatorium. The effect on predatory fauna persisted up to 75 D A S in the rootzone of two crops. But in cowpea the effect on saprophytic fauna persisted only up to 60 D A S. The microbial populations (bacteria, fungi and actinomycetes) were increased in the rootzone of bhindi and cowpea in two seasons by the application of eupatorium leaf at higher dose where as neem leaf (higher dose) reduced the microbial population. Only the fungal population increased by the application of neem leaf at higher dose during rainy season. There was seasonal variation in population build up of fungi and maximum effect was seen in rainy season. The biometric characters (number of leaves, height of plant, root weight and shoot weight) and yield of bhindi and cowpea increased significantly by the higher dose of neem and eupatorium leaf. For increasing the height, lower dose of neem, and, for yield lower dose of neem and eupatorium also were found effective. The population of nematodes in the roots at the termination of experiment was significantly reduced by the higher dose of neem and eupatorium in bhindi while lower dose was found effective protecting cowpea roots.
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    ThesisItemOpen Access
    Evaluation of Bacillus thuringiensis Berliner for the management of rice leaf folders
    (Department of Agricultural Entomology, College of Horticulture,Vellanikara, 1998) Asha, R; KAU; Babuphilip, M
    The study was conducted with the objective of survey and identification of the natural enemies of leaffolder and other lepidopterous pests of rice and to evaluate the efficacy of B. t. formulations against the leaffolders of rice. The survey was conducted at the Agricultural Research Station, Mannuthy and the Kerala State Agricultural Department Seed Farm, Mannuthy. The field trials to evaluate the efficacy of rice leaffolders were conducted at the Agricultural Research Station, Mannuthy during Kharif 1995 and Kharif 1996 . .. The present study revealed the occurrence of five viroses, two bacterioses and a nematode infection in the various lepidopterous pests of rice. Four Braconids, three Ichneumonids one Eulophid, one Chalcid and a Bethylid parasite were also recorded from various lepidopterous pests of rice. The B.t. formulations tested were found to be effective against the leaf folders on rice. The percentage of leaf damage during Kharif 1995 showed the B.t. formulations Biotox, BTT, Biolep to be the best treatments. With respect ~to the grain yield, BTT was the best treatment followed by Dipel, Biolep and Biotox. During Kharif 1996, Dipel followed by Biotox and monocrotophos were found to be the best in terms of percentage of leaf damage. Based on the yield during 1996, BTT was found to be the superior one followed by monocrotophos. B. t formulations were found to be safe to predatory spiders, other predators and paras i toids of folders. the leaf The combination of BTT and C.m. GV was able t.o reduce the leaf damage and data on larval mortality showed the leaf folder larvae to be susceptible to the combination of BTT and C.m. GV. The GV of C. medinalis was found to be highly host specific.
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    ThesisItemOpen Access
    Control of root-knot nematode (Meloidogyne incognita Kofoid and White, Chitwood) infesting black pepper (Piper nigrum L.) by bacterial pathogens
    (Department of Entomology, College of Horticulture, Vellanikkara, 1990) Sheela, M S; KAU; Venkitesan, T S
    A survey was carried out to study the occurrence and association of bacterial pathogens of the root-knot nematode Meloidogyne incognita infesting the black pepper (Piper nigrum L) covering ten major pepper growing districts namely Kannur, Eranakulam, Idukki, Kollam, Kottayam, Kozhikode, Pathanamthitta, Thiruvanandapuram, Thrissur and Waynad. The survey revealed that six species of bacteria were associated with the nematode namely, Bacillus subtilis.B. .pumilus, B. coagulans, B. macerans. B. circulans and E. licheniformis. B. subtilis, B . pumilus and B. licheniformis were found associated with egg masses, second stage juvenile and adult females while B. coagulans. B. macerans aud circulans were obtained from egg masses and adult females only. These six Bacillus spp. showed ovicidal and larvicidal effect against M. incognita. The pathogenic effect tested with the six Bacillus spp. on M. incognita on tomato as host plant showed that B. circulans (0.9x10^ cells per pot) and B._ macerans (0.8x10 cells per pot) compared with treatment of carbofuran 500 ppm were on par in reducing the larval stage of the nematode population in soil. However among the five species all were equal except B. subtilis (1.8x107 cells per pot) and carbofuran treatment in reducing the root-knot population in roots. Eight common host plants of root-knot nematode were tested for pathogenicity with the five Bacillus spp., B. subtilis (1.5x106 cells/ml), B. punilu3 (1.8x106 cells/ml) B. coagulans (1.2x10 cells per ml), B. macerans (0.8x10 cells per ml) and B. circulans (0.9x106 cells per ml). None of these plants showed any symptom of pathogenesis, withering or disease. Safety testing of these Bacillus spp. carried out by oral administration and subcutaneous injection, on two week old chicks, did not produce any bacterial infection indicating that itwas not injurious.
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    ThesisItemOpen Access
    Infestation reactions and management of Helopeltis theivora (Waterhouse) (Miridae:Hemiptera) in cocoa clones
    (Department of Entomology, College of Horticulture, Vellanikkara, 1998) Beena Nair; KAU; Baby, P Skaria
    Investigations were carried out at the College of Horticulture, Vellanikkara to identity sources of resistance to the cocoa mirid bug He/ope/lis theivora (Waterhouse) among the various high yielding cocoa clones and also to develop an effective and safer management strategy against the pest using insecticides. In the field trial, seven hybrids and eight parental clones were evaluated for their tolerance to the mirids at different developmental stages of the pods and on flushes. The pod damage intensity was moderate to low, the range being 0.25 to 5.84 per cent and in this situation the resistance traits could not be properly quantified. However, the parental trees 01-5.9 and GYl-68 and the hybrids involving these trees showed a moderate level of resistance. The clones M-l3.12 and GI-15.5 were found to be relatively more susceptible to the pest. The correlation studies have established the positive correlation between the yield of pods on the one hand and the intensity of damage to the pods and the vegetative flushes on the other. The various pod characters such as length, width, weight, pericarp thickness, wet bean weight and number of beans per pod did not show any influence on the intensity of pod infestation. 'The performance of the various clones in respect of the yield of pods and beans have been discussed in the light of variations in the intensity of damage to the pods and vegetative flushes. The susceptibility of clones with higher number of pods was detected in the correlation studies. The hybrid GI-S.9 x GVI-68 which produced 23 pods per tree on an average showed lower levels of damage by the mirid bug on the pods and also on flushes indicating a moderate level of resistance coupled with high pod number in this clone. The pod number was also found correlated with total wet bean yield per tree, height and spread of the tree. With respect to higher wet bean yield the parental clone GYI-68 ranked first with 1937.47 g followed by M-13.12, GVI-64, GVI-6I, M-13.J2 x GJ-S.9 and GI-S.9 x GVI-68. The crosses GJ-IO.3 x GVI-61 and 01-5.9 x GVl-54 recorded very low bean yields. However, the high yielding and low yielding clones showed varied reactions to the infestation by H. theivora. With regard to the management of H. theivora using insecticides the spray application of carbaryl at 1.25 kg ai/ha and monocrotophos at 0.5 kg ai/ha was most effective. However, considering the higher persistent toxicity of monocrotophos, carbaryl is recommended for field applications.
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    ThesisItemOpen Access
    Biology and management of orchid pests
    (Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1998) Sajitha Kumari; KAU; Lyla, K R
    In a survey conducted during 1996-97 in Kerala to study the various pests associated with orchids with reference to their biology, morphology, nature of damage and preliminary management studies on the selected pests, a total of thirteen pests were recorded. The grasshopper, Oxya chinensis (Thunberg); spiralling whitefly, Aleurodicus dispersus Russell; bihar hairy caterpillar, Diacrisia obliqua W alker; were recorded from the leaves of Spathoglottis spp. The larvae and adult of Megalurothrips distalis Karny was found infesting the buds and flowers of Dendrobium spp. and Spathoglottis spp. resulting in the destortion of buds and flowers. The tobacco catterpillar, Spodoptera litura F. was recorded from the flowers of Spathoglottis and Dendrobium spp. The ant, Monomorium indicum Forel was recorded to damage the roots of the plants. An unidentified species of Lema was recorded damaging the flowers of Spathoglottis spp. and Epidendrum spp. The grubs and adults of an unidentified curculionid was reported to cause considerable damage to Dendrobium spp. by feeding on the pseudobulbs. The banded blister beetle, Mylabris pustulata (Thunberg) was found as an occasional feeder of Spathog/ottis spp. The other pests observed during the survey were sowbug, Oniscus asellus L., land snail Ariophanta sp., black slug, Anon sp. and grey slug, Limax sp. During the studies on the morphology and biology of M distalis, the eggs were found to be bean shaped and the immature stages can be differentiated by the presence of wing pads or wing sheaths and antennal sheaths. The females inserted the eggs in the tissues of the petals and the whole life cycle ranged from 17-32 days. The adults of A. dispersus laid eggs singly covered with wax in loose whorls like fingerprints on the lower surface of the leaves. Incubation period was 5 days and the mean life cycle was found to be 45 days. During the drier conditions of the atmosphere the population of M. distalis and A. dispersus increased and there was a decline after heavy summer showers. Efficacy of insecticides against A. dispersus and insecticides and molluscide against slugs were tested. Among the insecticides tested, quinalphos , brought the highest mean mortality of the nymphs of A. dispersus (48%). In the case of slugs, 5 per cent metaldehyde bait and metaldehyde mixed carbaryl bait (2.5- 2.5%) gave the highest mean mortality of 44.44 per cent within 24 hrs of treatment. Treatment with 1 g phorate showed the highest mean mortality of 66.67 per cent after 48 hrs of treatment.