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Theses

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2000 - 20023
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Subject: Entomology × End date: 2002 × Start date: 2000 × Type: Thesis ×
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    ThesisItemOpen Access
    Ecofriendly pest management in Brinjal (Solanum melongena L.)
    (Department of Entomology, College of Agriculture,Vellayani, 2000) Annie Bernice, T S; KAU; Krishnakumar, R
    A survey was conducted in the important brinjal growing tracts of Thiruvananthapuram district to study the population dynamics of the pests and their natural enemies in the brinjal ecosystem. Laboratory experiment and field experiments were conducted in the College of Agriculture, Vellayani to assess the deterrency and toxicity of the different treatments on aphids, epilachna and Leucinodes which were identified as important pests of brinjal from the survey and the effective treatments as identified from the laboratory experiment were carried out in the field. =<; Malathion alone or with garlic was found to be toxic to aphids. Epilachna and Leucinodes. The treatments with neem oil and Hyptis suaveolens either alone and in combination were found to have deterrent and toxic effects on aphids, Epilachna and Leucinodes in the laboratory experiment. However, the effect was much pronounced when neem oil activated with garlic was used in combination with Hyptis suaveolens. In the field, though malathion was found to contain the pests, the effect was not persistent for a long time and hence was not effective in the long run. The combination of neem oil + garlic plus Hyptis suaveolens was found to offer protection for the pest for a long period of time. On par with it were combination of nee m oil plus Hyptis suaveolens + garlic and combination of neem oil + H. suaveolens. The botanicals were also found to be safe for the natural enemies like coccinellids, staphylinids and spiders. This treatment was also found superior to other treatments in terms of net income and benefit cost ratio and the lower unit cost of the treatment with high yield was precisely the reason for its superiority.
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    ThesisItemOpen Access
    Evaluation of potential botanical pesticides gainst tobacco cutworm
    (Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 2002) Suresh, S; KAU; Jim Thomas (Guide), Thomas (Guide)
    Investigations were carried out on the "Evaluation of potential botanical pesticides against tobacco cutworm, Spodoptera litura (Fab.)" in the Department of Entomology, College of Horticulture, Vellanikkara during 2000-2001. The objectives of this study were to screen the botanicals with biological resources such as ovipositional deterrency, ovicidal action, antifeedancy, morphogenic disruptions, insecticidal properties, etc. on the enigmatic and polyphagous caterpillar pests such as S. litura. Ovipositional deterrency test was conducted with aqueous plant extracts and essential oils. Azadirachta indica and Hyptis sauveolens aqueous extracts allowed lower rate of oviposition (as evidenced by their lower average score values of 3 to 6) on the treated surface at five and ten per cent strengths. Similarly, the essential oils viz., Cinnamomum zeylanicum and Cymbopogon martinii showed pronounced ovipositional deterrency even at 0.5 per cent level. Aqueous extract of Azadirachta indica gave higher ovicidal action as high as 61.43 and 88.39 per cent hatching inhibitions at five and ten per cent concentrations respectively. Among" the six tested essential oils, Cinnamomum zeylanicum and Cymbopogon martinii exhibited cent per cent egg mortality at 0.5 per cent strength each. Citronella winterianus oil, Kaempferia galanga oil and :4. indica aqueous extract exhibited higher leaf protection of 62 to 77 per cent at three per cent concentration each. Oils of Kaempferia galanga and Cymbopogon martinii and aqueous extract of Azadirachta indica induced larval starvation of 56 to 70 per cent at the same concentration of three per cent each. Among the solvent extracts of the botanicals tested, acetone extract of Andrographis paniculata exhibited larval starvation of 63 per cent at its two per" cent concentration, while, dichloromethane extract of the same produced 63 per cent leaf protection at the same strength. Vitex negundo extract in methanol afforded leaf protection to the level of 64.31 per cent and larval starvation of 55.99 per cent at its five per cent level. Chloroform extract of Azadirachta indica at four per cent level produced more than 70 per cent leaf protection as well as larval starvation. The Approximate Digestibility (AD) was lower in aqueous extracts of Andrographis panicufata, Thevetia nerifolia, Clerodendron infortunatum and Strychnos nux-vomica at one and three per cent strengths on the treated insects, highlighting their inhibitory action during digestion process, whereas, the essential oils viz., Citronella winterianus, Cymbopogon martinii and Kaempferia galanga treatments at three and five per cent inhibited the assimilation of ingested and digested food into body matter as indicated by their lower ECl and ECD values. The third instar larvae when fed on host leaves treated with oils of Cymbopogon flexuosus and Kaempferia galanga and aqueous extracts of Strychnos nux-vomica, Vitex negundo, Azadirachta indica and Andrographis paniculata (@ 1, 3 and 5% levels each) were found to be inducing pupal and adult malformations (7.53 to 16.67% total malformations). The chloroform extract of Azadirachta indica and acetone extract of Vitex negundo on exposure on host plants, induced higher rate of deformities at the time of pupation and eclosion to the extent of up to 30.8 per cent. Cymbopogon martinii oil had the lowest LCso value of 178 ppm as compared to other oils viz., Mentha piperita, Cymbopogon flexuosus and Citronella winterianus (with- their respective LCso values of 273, 311 and 370 pp m) indicating its significant insecticidal and insectistatic properties and offer their scope for lPM strategies.
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    ThesisItemOpen Access
    Management of banana pseudostem weevil Odoiporus longicollis Olivier (Coleoptera: Curculionidae) with induced resistance and epideictic compounds
    (Department of Entomology, College of Horticulture, Vellanikkara, 2002) Raihana, K C; KAU; Ranjith, A M
    The present investigation on management of banana pesudostem weevil Odoiporus longicollis Olivier (Coleoptera:Curculionidae) with induced resistance and epideictic compounds was undertaken in the Department of Entomology, College of Horticulture, Vellanikkara during 2000-2001. Extraction of epideictic pheromone associated with the weevil, evaluation of the resistance of the moisture stressed Nendran plants to the attack of the weevil and the resistance offered by the progenies of tissue cultured plants of infested plants were considered for the study . Females of 0. longicollis at different population intensities were released on cut pseudo stem of Nendran in the laboratory to arrive at the minimum pest load at which the concentration of epideictic pheromones would deter further oviposition. The results indicated that the weevil numbers above five per pseudostem was deterrent to conspecific emales. Pest load which would deter oviposition on banana was also be assessed by artificial confined release of females in the field. With increase in the pest loads on the plants there was a deterrency effect in the oviposition by the weevils. The maximum oviposition was observed by two weevils per plant (4.25). Even with twenty females per plant the oviposition count was very less (1.75). The oviposition deterrency was due to the deposition of the epideictic pheromone by the conspecific females after egg laying. It was seen that the acetone and ether extracts of pseudo stem pieces of 10 cm where five pairs of weevils had laid their eggs, when sprayed after air drying and dilution with water deterred the oviposition by other females. The acetone extract, air dried and diluted with water was the most effective for the extraction of the pheromone. Identification of the chemical composition of pheromones will help in their utilisation against the weevil. No-choice tests were designed to study the resistance of moisture stressed plants to the weevil attack. The weevil infestation was absent in those plants which received the minimum quantity of water though their yield was low. However, the plants which received slight reduction in the moisture (0.9 IW/CPE) •. gave a yield similar to those plants grown with normal irrigation. Only 40 per cent of these plants was infested when comparing with 90 per cent infestation in control plants. Rind-pulp ratio was also in par with control plants. The results indicated that the plants which receive a slight moisture stress from 6th month onwards at least in the outer sheaths will escape :from the attack of the weevil without affecting the yield adversely. No-choice experiment was conducted on the progemes of infested tissue cultured plants to evaluate the resistance to the weevil attack. The tissue cultured plants was found very resistant to the weevil attack. The experiment was started from the flower bud initiation stage (February). No plant was infested .upto three months after artificial infestation. Infestation was noticed during rainy period. The grades of infestation (0\ and O2) were very low in all the experimental plants.