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Subject: Agricultural Entomology × End date: 2004 × Start date: 2004 × Type: Thesis ×
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    ThesisItemOpen Access
    Bioecology and management of spiralling whitefly Aleurodicus disperus Russell (Homoptera : Aleyrodidae)
    (Department of Agricultural Entomology, College of Agriculture, Vellayani, 2004) Rani, J; KAU; Anitha, N
    A study on bioecology and management of spiralling whitefly, Aleurodicus dispersus Russell was carried out in laboratory and pot culture experiments at the Department of Entomology, College of Agriculture, Vellayani, Thiruvananthapuaram during the period 2003-2004. The survey conducted in the instructional Farm, College of Agriculture, Vellayani for a period of one year revealed that Aleurodicus dispersus attacked 50 host plants belonging to 30 families. Averrhoea bilimbi L, Capsicum chinense Jacq., Vigna unguiculata (L.) Walp. Vitis vinifera Linn, Passiflora edulis L., Jacquemontia violaceae Choisy, Spathoglottis aurea Lindle, Ixora chinensis Lam, Alysicarpus vaginalis (L.) DC Chromolaena odorata (L) King and Robinson, and Phaseolus sp, were reported for the first time in India as host plants of spiralling whitefly in the present study. Biology of A. dispersus on cassava, tomato and chilli revealed that cassava was the most susceptible host plant with shorter developmental period and longer adult period and higher fecundity. The eggs were laid on the under surface of leaves in characteristic spiral manner. Eggs were stalked, elliptical and light yellow to tan coloured. There were three nymphal instars and a pupal stage. Adult resembled tiny moths. The wings were clear first, later covered with a waxy powder. The nymphs and adults caused damage to the plants by sucking cell sap from the tender parts of the plants. They excrete honey dew which served as the substrate for the development of sooty mould. Heavy infestation of A dispersus combined with sooty mould infection resulted in loss of plant vigour, unsightly appearance and reduction in yield. The predators reported during the survey were Allograpta javana Wiedemann (Syrphidae; Diptera ), Axinoscymnus puttarudriahi Kapur and Munshi (Coccinellidae; Coleoptera), Cybocephalus indicus Tian and Ramani (Nitidulidae; Coleoptera) and spiders. Two doses each of the formulation viz., Neemazal, Econeem, and plant extract of Andrographis paniculata and Hyptis suaveolens were evaluated with Dimethoate 0.05 per cent as check against A. dispersus on tomato. Three sprayings were given at 45, 60 and 75 days after transplanting. Among the formulated neem products, Neemazal 4 ml 1-1 recorded highest population reduction of eggs, nymphs and adults of A. dispersus on tomato. The neem products were of only moderate efficiency in reducing various life stages of the pest compared to Dimethoate. However, the products can be included in the integrated management of this whitefly, considering the lower toxicity to the natural enemies and environmental safety. Based on the results of the present study, destruction of weed host plants and use of neem products can be suggested for the management of A. dispersus, as an adhoc recommendation.
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    ThesisItemOpen Access
    Management of insect pest complex in okra
    (Department of Agricultural Entomology, College of Agriculture, 2004) Thamilvel, D; KAU; Naseema Beevi, S
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    ThesisItemOpen Access
    Impact of different insecticides on pest natural enemy and neutral complex in rice ecosystem
    (Department of Agricultural Entomology, College of Agriculture, Vellayani, 2004) Smitha, Gopan; KAU; KAU; Nalinakumari, T
    Investigations were carried out during the second crop season of 2003-2004 at CSRC, Karamana, to assess the status of pests, natural enemies and neutrals in the rice ecosystem and to evaluate the efficacy of different insecticides on these organisms. The results revealed that pests dominated in the rice ecosystem followed by predators, neutrals and parasitoids. The sizeable population of pests recorded were Cnaphalocrocis medinalis (Guenee), Leptocorisa acuta (Thunberg), Hydrellia philippina Ferino, Oxya chinensis (Thunberg) and Nephotettix spp. Predators were present in fairly good number. Parasitoids and neutrals were comparatively less. The neutrals observed in the study came under the family Chironomidae, Culicidae, Tanyderidae, Otitidae and Sciomyzidae. Arthropod population showed a fluctuating trend and the highest population of pests, predators, parasitoids and neutrals were at 45, 30, 60 and 15 DAT respectively. Chlorpyrifos 50 EC + cypermethrin 5 EC was the most effective and persistent insecticide in suppressing C. medinalis. It effectively suppressed the other pests also and the persistent toxicity against them was comparatively less. It was toxic to the beneficial organisms; with shorter persistence on predators and parasitoids and the effect on neutrals was same as in carbaryl and monocrotophos. Acephate was found to be equally effective as carbaryl against C. medinalis and H. philippina. The other pests were also suppressed with the insecticide but the persistent toxicity was less. The insecticide was observed to be toxic to predators and neutrals and safe to parasitoids. Highest toxicity of imidacloprid was observed on Nephotettix spp., and was same as that of monocrotophos. The insecticide was found to be equally toxic to C. medinalis, H. philippina and L. acuta and the toxicity was less persistent on O. chinensis. It was toxic to all the three groups of beneficial organisms and toxicity was for a shorter period. Carbofuran granule showed immediate toxic effect only to neutrals and the delayed toxicity was exhibited on Nephotettix spp. and L. acuta. The granule was observed to be safe to predators and parasitoids. Azadirachtin suppressed the population of pests effectively and the effect was for a shorter period. This botanical insecticide was comparatively lower in toxicity to predators, parasitoids and neutrals. Among the insecticides tested, Bacillus thuringiensis var. kurstaki showed lower percentage mortality of C. medinalis, H. philippina, O. chinensis and L. acuta and no toxic effect on Nephotettix spp. This insecticide was safe to parasitoids and less toxic to predators and neutrals. The overall effect of these insecticides on the total population of four groups of arthropods showed that all the insecticides significantly suppressed the population of pests and predators. Acephate and Bacillus thuringiensis var. kurstaki were safe to parasitoids while azadirachtin and Bacillus thuringiensis var. kurstaki were less toxic to neutrals. The grain and straw yield recorded and the percentage abundance of the total population of four groups of arthropods were same in all treatments including control. The study emphasizes the need for cultivation of tolerant varieties and periodical field assessment of arthropod community. If the pest population is high and beneficial organisms are very low, pocket application of appropriate insecticides can be resorted to. The study once again asserts that insecticidal interventions are rarely needed and the four groups of arthropods regulate themselves and manage the pests and maintain the yield.
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    ThesisItemOpen Access
    Host-parasite relationship and management of important nematodes associated with chethikoduveli, Plumbago rosea L.
    (Kerala Agricultural University;Thiruvananthapuram, 2004) Santhosh Kumar, T.; KAU; Sheela, M.S.
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    ThesisItemOpen Access
    Synergistic interaction of biocides and insecticides on tomato fruit borer, Helicoverpa armigera (Hubner)
    (Kerala Agricultural University;Thrissur, 2004) Levin, Lily; KAU; Ranjith, A.M.