Thumbnail Image

Theses

Browse

1982 - 199015
Reset filters
Subject: Entomology × End date: 1990 × Start date: 1982 × Type: Thesis ×
Reset filters

Search Results

Now showing 1 - 9 of 15
  • Thumbnail Image
    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.
  • Thumbnail Image
    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.
  • Thumbnail Image
    ThesisItemOpen Access
    Use of synthetic pyrethroides for the control of pests of bitter gourd (Momordica charantia L) and snake gourd (Trichosanthes anguina L)
    (Department of Entomology, College of Agriculture, Vellayani, 1982) Kosaraju Ravindra, Nath; KAU; Sasidharan Pillai, K
    In a field experiment conducted at the Instructional Farm, College of Agriculture, Vellayani, during the summer season in 1982, the efficacy of four synthetic pyrethroids viz. permethrin, fenvalerate, cypermethrin and deltamethrin, on the pests of bitter gourd and snake gourd in comparision with the standard, malathion, was evaluated. Both the crops were sprayed thrice on need basis for controlling the various pests which infested the crops at different growth stages. Spotted beetle observed on bitter gourd at the time of first spraying was controlled by all the synthetic pyrethroids along with the standard for a period of 23 days after spraying. Fruit fly of the bitter gourd also was controlled by all the three sprayings and all the insecticides were effective in most occasions. Cypermethrin at higher dose was superior to the standard during the first spraying followed by fenvalerate and deltamethrin. In the second spraying deltamethrin was not so effective whereas permethrin was found more effective. Again in the third spraying deltamethrin and fenvalerate were more effective . The fruit fly damage observed for the entire crop season revealed the superiority of fenvalerate, permethrin and deltamethrin at their higher doses over the standard. Jassid on bitter gourd was controlled by all the insecticides except permethrin and cypermethrin at their lower dose for a period of 2 days after the spraying . But aphid could be controlled only with permethrin and fenvalerate at their higher dose along with the standard malathion for a period of 2 DAS. The fruit set and the flowering pattern were not affected by any of these insecticides.
  • Thumbnail Image
    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.
  • Thumbnail Image
    ThesisItemOpen Access
    Insecticide deposits and residues on paddy with reference to volume of spray fluid applied at different growth stages of the crop
    (Department of Entomology, College of Agriculture, Vellayani, 1982) Thomas Biju, Mathew; KAU; Mohan Das, N
    A set of experiments were conducted for assessing the optimum volumes of carbaryl suspension required to spray rice at different growth stages of the crop, using a pneumatic knapsack sprayer and a mist blower. The levels of pesticide deposit formed by spraying the crop at varying levels of pesticide suspension were taken as the indices of bio efficacy and these were also correlated with the leaf area indices of the crop at different growth stages . The level of contamination of the rice eco-system was assessed in terms of pesticide residue in irrigation water of the treated plots. A correlation between different levels of pesticide deposits caused by varying the volumes of the spray fluid was assessed by trials conducted against leaf roller and case worm infesting rice. In the first experiment , the crop was sprayed with 100, 150, 200, 250, 300, 350, 400, 450, 500, 550 and 600 1/ha of 0.2% carbaryl suspension on using a pneumatic knapsack sprayer. Deposit on leaf and stalk of the plants, two hours after spraying , was estimated from the representative samples adopting the chemical assay method of Benson and Finocchiare (1965). The experiment was repeated at four different growth stages of the cropviz. 30, 45, 60 and 75 days after sowing. The results showed that the minimum levels of carbaryl suspension required to cause significantly higher levels of deposit on the leaves were 200, 300, 400 and 500 1/ha for the crop at 30, 45,60 and 75 days after sowing respectively.
  • Thumbnail Image
    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.
  • Thumbnail Image
    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.
  • Thumbnail Image
    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.
  • Thumbnail Image
    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