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1983 - 198911
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Subject: Entomology × End date: 1989 × Start date: 1983 × Type: Thesis ×
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    ThesisItemOpen Access
    Biological activity of different plant extracts with particular reference to their insecticidal,hormonal and antifee ding actions
    (Department of Entomology, College of Agriculture, Vellayani, 1989) Saradamma, K; KAU; Mohan Das, N
    Twenty locally available plants were screened for their antifeedant activity against three important crop pests of Kerala using water, acetone, benzene and petroleum other as extractants. Benzene was, in general, the best extractant and as a test insect H. vigintioctopunctata was more sensitive than S. litura or P. ricini. Among the twenty plants screened all the extracts of C. infortunatum, A.indica, T.neriifolia and E.odoratum and benzene and ether extracts of N.oleander gave high leaf protection against H.vigintioctopunctata. Against S.litura benzene and ether extracts of C.infortunatum, A.indica, T.neriifolia and N.oleander were effective. Water extract of E.odoratum and acetone extract of C.infortunaturm, A.indica and T.neriifolia also had high antifeedant activity against S.litura. All extracts of A.indica and water, benzene and acetone extract of N.oleander had antifeedant effect on P.ricini. High larval starvation was caused by most of the plant extracts which showed antifeedant action. But some extracts ineffective as antifeedant also caused high larval starvation. Eight essential oils obtained from the country were screened for feeding deterrency against P.ricini. Citronella oil, geranium oil and camphor oil gave significant protection, but the dosages required were too high to indicate possibilities of practical exploitation of essential oils as antifeedants for pest control. Based on PC 95 values worked out through bioassay studies using H.vigintioctopunctat as test insect N.oleander ranked first as antifeedant. It was followed by C.infortunatum, A.indica, T.neriifolia and N.odoratum. Based on larval starvation these plants had different ranking. Antifeedant activity of the extracts of T.neriifolia and N.oleander persisted up to 22 days on brinjal on field while that of C.infortunatum, E.odoratum and A.indica persisted up to 18 days. On the basis of PT indices the treatments were ranked as water extract of T.neriifolia > benzene extracts of N.oleander > C.infortunatum > E.odoratum > A.indica. The insecticidal effects of the plant extracts on D.cingulatus, H.vigintioctopunctata and S.litura were low. However, extracts of A.indica, T. neriifolia, P.odoratissimus and C.gigantea showed significant toxicity to A.craccivora. But their LC 50 values ranged from 34 to 93 per cent. Benzene extracts of C.infortunatum, A.indica, T.neriifolia and E.odoratum had high systemic action on different nymphal instars of D.cingulatus. Fourth instar nymphs were more tolerant to the insecticidal action of the extracts. The essential oils included in the experiment did not show insecticidal activity on D.cingulatus and S.litura while some caused significant mortality of A.craccivora at high doses. Sixteen out of twenty plants tested had significant juvenomimetic effect on D.cingulatus in one or more than one of the extracts tested. When the different extracts were ranked on the basis of percentage of normal adults and their sterility (an index of the possible build up of the post treatment populations of the test insect) benzene was found to be the best and it was followed by water while acetone and ether were on par and far less effective. T.neriifolia, A.indica and E.odoratum caused 100 per cent sterility of D.cingulatus in water and benzene extracts and above 90 per cent sterility in other two extracts. C.infortunatum and N.oleander caused 100 per cent sterility in acetone, benzene and water extracts. The juvenomimetic effect of S.litura was much lower than that on D.cingulatus. All the extracts of A.indica and N.oleander, water and acetone extracts of T.neriifolia and V.negundo, benzene and acetone extracts of A.vesica, acetone extract of E.odoratum, ether extract of M.esculenta and C.variegatum caused 100 per cent sterility to the insect and hence the treatment would limit the contribution from the treated insects to the next generation to zero level. Bioassay studies showed that acetone extracts of C.infortunatum had highest juvenilising effect on D.cingulatus. It was closely followed by A.indica. T.neriifolia, N. oleander and E.odoratum were much less effective than A.indica and C.infortunatum. Benzene extracts were more active than acetone extracts and were ranked as A.indica > C.infortunatum > N.oleander > E.odoratum > T.neriifolia. Considering both the extracts C.infortunatum came on par with A.indica. N.oleander and E.odoratum were also found promising. The essential oils caused morphogenetic abnormalities in the developing numphs of D.cingulatus. The dosage at which high sterility could be obtained were too high to ensure economic viability of its use in field. Lower effective dosages, cheaper and comparably effective oils may have to be found out for wide use of essential oils for pest control. Benzene extracts of A.indica, E.odoratum, C.infortunatum, T.neriifolia and N.oleander and water extracts of T.neriifolia as 2% emulsions reduced the populations of H.vigintioctopunctata, C.insolitus and A.gossypii on brinjal and H.vigintioctopunctata on bitterground significantly in the field experiments. All the treatments (except T.neriifolia againist A.gossypii) came on par with the insecticide check, carbaryl 0.2 per cent suspension, in reducing the population. The studies have thus established that the antifeedant and juvenoid effects of five plants screened out from the local flora were as promising as those of A.indica, the well recognized plant source for such activity and the extracts of these plants can be exploited effectively in the integrated control of crop pests.
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    ThesisItemOpen Access
    Integrated control of fruit fly Dacus cucurbitae Coq: Trypetidae: Diptera on bitter gourd
    (Department of Entomology, College of Agriculture, Vellayani, 1989) Jalaja, P N; KAU; Remamony, K S
    Bittergourd is very popular among the vegetable growers in Kerala. Fruit flies take a heavy toll of this crop and intense use of pesticides is a common practice of cultivators often leading to serious residue hazards in the marketed fruits. In the present investigation an attempt was made to standardise non-insecticidal methods of control for tackling this pest problem. Laboratory evaluation of potential attractants of fruit flies viz. eugenol, eucalyptus oil, citronella oil, borar, ammonium phosphate, vanilla essence, jaggery, sugar, vinegar, honey, toddy and bittergourd fruits were screened for baiting the adults of D. cucurbitae. Eugenol, eucalyptus oil, citronella oil, borax, ammonium phosphate and vanilla essence did not show any attractiveness to the flies. Three graded concentrationsof honey, sugar, jaggery, toddy and vinegar were tested for their attractiveness to the files in the laboratory. The result showed that (1) honey at the highest concentration of 1% attracted the maximum number of flies (2) toddy was not effective for attracting D. cucurbitae. (3) immature stages of bittergourd fruits showed poor aatraction and (4) ripe bittergourd fruits showed poor attraction and (4) ripe bittergourd fruits showed maximum attraction to the files up to 12 h of exposure.
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    ThesisItemOpen Access
    Control of vegetable pests using chitin synthesis inhibitors
    (Department of Entomology, College of Agriculture, Vellayani, 1983) Rajapadmanabhan Vivek, A; KAU; Mohandas, N
    The dose-effect relationship of two chitin synthesis inhibitors diflubenzuron and triflumuron against three vegetables pests viz., Sylepta derogata, Epilachna vigintioctopunctata and Psera basalis was assessed in terms of the average survival periods when the different larval instars were exposed on treated food materials in the laboratory. The results showed that the earlier instars . In general, the dose-effect relationship had a positive linear trend . The three test insects showed different susceptibility to the chitin sysnthesis inhibitors. S. derogata was least susceptible and it was followed by E. vigintioctopunctata and P. basalis in susceptibility. Besides the mortality observed, various malformations and deformities were also noted in the different life stages of the insects. At the various doses tried the mortality of the larval stages was , in effect, total. The later instars fed with lower cocentrations survived in small percentages and pupated. Some of these pupae were abnormal and some gave rise to abnormal adults fully or partly emerged from the pupal skin.
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    ThesisItemOpen Access
    Factors responsible for the population buid up of rice bug, Leptocorisa acuta Thunb and the control of the pest
    (Department of Entomology, College of Agriculture, Vellayani, 1986) Krishna Kumar, R; KAU; Visalakshi, A
    The rice bug Leptocoria acuta Thunb, was reared on the rice varieties Jaya, Jyothi, Triveni, Pavizham and Karthika in order to study the effect of varieties on the insect's biological features. Statistical analysis of the data obtained showed that varieties have no significant influence on the biological features of L. acuta. Studies made on the duration/survival of L. acuta on eleven common rice land weeds found in paddy fields showed that the bugscould complete their life cycle only on Echinoedria colonum and E. crusgalli. The bugs survived for short periods on a few of the otherweed hosts.
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    ThesisItemOpen Access
    Studies on insect pests and diseases of rice earhead and their control
    (Department of Entomology, College of Agriculture, Vellayani, 1987) Annie Thomas; KAU; Rajan Asari, P A
    A random sample survey on insect pests and diseases infesting rice during, flowering stage was conducted to collect information on the occurence of pests and diseases on rice earhead of different localities in Trivandrum district. Itcould be observed that L.acuta was the most important pest occurring throughout the area surveyed . The importance of rice bug was further proved by the mean number of insect present in different localities. The mean number of rice bug varied from 0.25 to 2.45 which showed the existence of considerable variation according to localities and varieties. The high yielding varieties invariably were seen more susceptible to the pest infestation than the local cultivars.
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    ThesisItemOpen Access
    Studies on the nature and extent of damage caused by insect pests to stored tapioca chips
    (Department of Agricultural Entomology, College of Agriculture, Vellayani, 1988) Ramla Beevi, S; KAU; Mammen, K V
    A survey on tho population of different stages of insect pests and the extent of damage caused by these insect to stored tapioca chips were conducted at monthly intervals for a period of four months from August 1984 to November 1934 in ten centres of Trivandrum District via. Palode, Parasala, Nedumangad, Venjaramood, Pothencode, Chirayinkil, Vembayon, Chalai, Sreekaryam and Mangalapuran, where tapioca chips wore stored. Among the various posts recorded three species viz. tapioca weevil
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    ThesisItemOpen Access
    Residue problems in the control of insect pests in processed food commodities using aluminium phosphide
    (Department of Agricultural Entomology, College of Agriculture, Vellayani, 1984) Rema Devi, K; KAU; Visalakshi, A
    Investigations were carried out to determine the bio-efficacy of fumigation with aluminium phosphide in controlling different species of insects feeding on stored wheat flour, maida, rice flour, rice, semolina, noodles, cattle feed, gram flour, soy beans, green gram, dhal, coffee, tea, cocoa powder, garlic, pepper and cumin under laboratory conditions at the doses 1.5, 3.0 and 4.5 g/m3 with an exposure period of 3 days. Studies revealed that the dose of 3.0 g/m3 was suitable for effective control of the pests and that the toxicity of the fumigant depended upon the media in which the insects were reared. Studies conducted on the relative susceptibility of different stages of insects feeding on different food commodities at the 3 doses revealed that adult stage was highly susceptible showing cent per cent mortality evenat the lowest dose of 1.5 g/m^. The egg stage of all the species in all the commodities was relatively resistant to the fumigant followed by pupae, larvae and adults in that descending order. The dose required for the elimination of the different life stages of different insects in different commodities varied depending upon the stage.Thus the percentage control of T. castaneum infesting seven food commodities varied from 92.49 to 100.00 per cent the percentage mortality of the egg ranged from 78*29 to 99.29* of larvae from 97*59 to 100.00 and of pupae from 93.29 to 100.00 per cent at the lowest dose of 1.5 g/m^,S. orvsae also, in three different products showed the same response where the percentage control varied from 93*09 to 97.00. In egg stage the variation in mortality was from 73.55 to 74.81 per cent, in larvae 85.06 to 86.98 per cent and in pupae the variation was from 76.00 to 78.05 per cent at the dose of 1.5 g/m . Similar results were obtained for A. fasoiculatus in three products, C. chinensis on pulses, C. cephalonica on rice flour and L. serricome on cumin.
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    ThesisItemOpen Access
    Use of organic amendments for the control of root-knot nematode In brlnjal
    (Department of Agricultural Entomology, College of Agriculture, Vellayani, 1986) Kamalakshi Amma, P L; KAU; Ravindran Nair, K K
    Two field experiments were conducted - one for evaluating oilcakes and another for evaluating organic wastes for the control of the root-knot nematode Meloldogyne incognita infesting brinjal, (These experiments were carried out in the Instructional Farm, College of Agriculture, Vellayani, in an area already infected by root-knot nematode. The experiments were laid out in randomised block design with three replications. In the first experiment there were ten treatments including the control and in the second experiment there were eleven.treatments including the control. Organic amendments were applied to the soil three weeks prior to planting and watering was done during this period for the proper, decomposition of these materials. Results were assessed in terms of yield, growth parameters, gall formation and population of nematode. Results indicated that the nematode population in roots as well as in soil was significantly reduced by the application of oilcakes and organic wastes. It was also observed that the intensity of gall formation on roots was considerably reduced as a result of application of organic amendments. Reduction in the population of the nematode and in the intensity of gall formation in turn resulted in bettor crop stand and increase in yield. (Different methods of application vis. application in the planting pit and broadcasting in the plot did not vary in efficacy.
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    ThesisItemOpen Access
    Crop loss caused by root-knot nematode (Meloidogyne incognita Kofoid) infesting Coleus parviflorus and its control
    (Department of Entomology, College of Agriculture, Vellayani, 1988) Sosamma, P; KAU; Ravindran, Nair K K
    Crop loss caused by the root-knot nematode Infesting Coleus parvlflorus and its control was studied in a pot culture experiment and a field experiment in the Department of Entomology, College of Agriculture, Vellayani, Trivandrum, during August to December, 1986. The number of leaves, shoot length, fresh shoot weight and weight of tubers obtained were less in inoculated plants than in control. The yield and growth parameters showed a negative correlation with the population of nematodes. A high positive correlation was noticed between tho tuber weight and the number of leaves and shoot weight of coleus. The shoot length did not influence the tuber yield significantly