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ThesisItem Open Access Isolation of the bioactive pinciples of thevetia nerlifolia juss.(Apocynaceae) and determination of their biological activities(Department of Entomology, College of Agriculture, Vellayani, 1996) Hebsi, Bai; KAU; George, KoshyFresh and dried leaves and seeds of Thevetia neriifolia were evaluated for their antifeedant activity against Henosepilachna vigintioctopunctata, using acetone, benzene, ethanol, hexane, methanol and water as extractants. Based on the percentage of leaf protection, seed extracts were superior to the leaf extracts. Fresh leaf and dried leaf extracts were on par. Among the solvents, ethanol and methanol gave maximum leaf protection closely followed by water. Based on larval starvation, seed extracts were superior to leaf extracts and fresh leaf extracts were significantly better than dried leaf extracts. Water, methanol and ethanol were on par for extracting plant tissues. Soaking of powered plant material well in solvents for 48 hours and filteration was found as effective as soxhlet method for extracting antifeedant components from leaves and seeds of T. neriifolia. Leaves and seeds of the plant showed conspicuous hormonal/sterilant activity on Dysdercus cingulatus and the response was dose dependent. This was evident in post treatment larval mortality, prolonged preovipositional period, emergence of malformed adults and reduced fecundity. Adult longevity, incubation period and hatching percentage of eggs were not affected. Forty per cent and ten per cent of leaf and seed extracts as well as 20 and 5 per cent extracts of the same came on par in juvenomimetic effect. The results showed that seeds were four times more effective than the leaves in their juvenomimetic effect on D. cingulatus. The length of ovary, number of oocytes per ovariole and size of basal, penultimate and antepenultimate oocytes were significantly lower in seed and leaf extract treated females of D. cingulatus. Closer examination of the data revealed that growth of ovary was delayed rather than suppressed by the plant extracts. Levels of protein, glycogen and lipid contents observed on ovary, fat body and haemolymph of treated and untreated insects from first to fifth day after emergence indicated a delay in vitellogenesis and oocyte development in treated insects. Consequently previposition period was prolonged. The effect observed is similar to the effect of chemosterilants reported on some insects earlier. Results indicated that reduction in fecundity of D. cingulatus may be due to the chemosterilant action of T. neriifolia extracts. Bioassay studies in the laboratory revealed the low contact toxicity of leaf and seed extracts of T. neriifolia to S. litura and H. vigintioctopunctata. Chromatographic isolation of different fractions of ethanol extracts of fresh leaf and seed yielded six bioactive fractions from the leaf and four from the seed. Fractions III and IV were absent in seeds. Fractions IV, V and VI obtained from leaves and V and VI from seeds had far higher activity than the remaining fractions and they were on par in their antifeedant effect and larval starvation on H. vigintioctopunctata. Available active fractions were more concentrated in seeds than in leaves. Laboratory studies showed the safety of leaf and seed extracts of T. neriifolia at field doses to Chrysocharis johnsoni, the most important parasite of H. vigintioctopunctata in Kerala. Toxicological studies in albino mice and rats revealed that 400 mg/kg body weight was the LD50 dose of seed extract of T.neriifolia while doses upto 1000mg/kg body weight of leaf extract was not toxic to the animals. Haematological picture of animals chronically exposed to the extracts showed marginal deviations in the haemoglobin content, RBC count, serum cholesterol, SGOT levels in seed extract treated animals from the permissible safe range. Leaf extract treatment caused deviations in SGOT and serum cholesterol. Vacuolation, cytoplasmic acidophilia and degenerative changes in the liver and heart tissues and inflammation of kidney were observed in animals treated with seed extract. Adverse effects of leaf extract were negligible. Replicated field experiments were conducted for two seasons on bittergourd and amaranthus to evaluate the efficacy of crude extracts of T. neriifolia in controlling their major pests. All the extracts viz., ethanol and water extracts of dried and fresh leaves and seed reduced the pest population and the extent of leaf damage. Seed extract was on par with the insecticide check, carbary 1 (0.15 per cent) in bittergourd and malathion (0.1 per cent) in amaranthus. Fresh leaf extract was on par with the seed extract and was superior to extracts of dried leaf in reducing pest population and increasing yield of both the crops. Water extracts of leaves and seed were found equally good for checking the pest population and increasing yield. On cost benefit basis water extracts were found more advantageous to the farmer. Parasitization of egg masses, grubs and pupae in treated plots were on par with control while they were totally missing in the insecticide treated plots. Extracts of T.neriifolia were thus found to be safe to the non – target organisms too. An overall assessment of the results obtained revealed that water extracts of fresh leaf and seed in appropriate doses can be effectively and safely used for the control of important pests of bittergourd and amaranthus without any health hazards and adverse effect on the non target organisms in the agroecosystem. T. neriifolia can be considered as a plant suited for developing effective plant protection chemicals for replacing undersirable synthetic insecticides, especially in integrated pest control calendar.ThesisItem Open Access Screening medicinal plants for antihelminthic properties against different life stages of banana burrowing nematode radopholus similis [Cobb,1893] thorne 1949(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1996) Sreeja, P; KAU; Job Sathyakumar, CharlesExperiments were conducted at the department of Entomology, College of Horticulture, Vellanikkara to screen medicinal plants for antihelminthic properties against the infective stages of banana burrowing nematode R. similis. The effect of aqueous extract of different parts of 20 medicinal plants were treated at four dilutions and three exposure times. Nematicidal and nematostatic properties of these extracts were studied using the nematode culture developed on carrot callus. The study resulted in the following findings. 1. Extracts of A. indica and G. pentaphylla were highly nematicidal to infective stages of the nematode at all the tested doses. K. pinnata was significantly effective at all the tested doses except 1:40. P. longum resulted in significant mortality at all the tested doses against larval stages whereas only 1:5, 1:10 and 1:20 dilutions were effective against adult stages. Besides nematicidal effect 1:20 and 1:40 dilutions of G. pentaphylla and K. pinnata exhibited nematostatic effects. 2. Leaf extract of M. oleifera and M. piperita at 1:5 and 1:10 dilutions showed significant nematostatic effects against both larvae and adults. P. betle extract was equally effective at the three dilutions. 3. Leaf extracts of C. angustifolia, A. squamosa and L. inermis were not effective at all tested doses. 4. Fruit extract of M. azedarach was nematicidal at all the tested dilutions of 1:5, 1:10, 1:20 and 1:40. But extract of C. papaya was ineffective. 5. Seed extract of C. viscosa expressed nematostatic property at 1:5 and 1:10 dilutions against adult stages, but it was ineffective against larval stages. Treatment with seed extract of E. scandens was ineffective. 6. Rhizome extract of C. rotundus was equally effective against infective stages in causing mortality at 1:5, 1:10 and 1:20 dilutions. Besides nematicidal effects, the extract exhibited significant nematostatic effect. A. calamus extract was nematostatic at 1:5 and 1:10 dilutions. 7. Root extract of I. tinctoria was nematostatic at 1:5, 1:10 and 1:20 dilutions against both larvae and adults. In addition to immobility, it resulted in the death of adult nematodes at 1:5 and 1:10 dilutions. Extract of S. indicum showed significant nematostatic effect at 1:5, 1:10 and 1:20 dilutions against larval stages. But it was effective only at 1:5 and 1:10 dilutions against adult stages. 8. Plant extract of E. hirta expressed nematicidal property at 1:5, 1:10 and 1:20 dilutions against larval stages, but the same was effective only at the two lower dilutions against adult stagesThesisItem Open Access Evaluation of the active principles of the rhizome extracts of L. for the management of melon fly(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1996) Shakunthala, Nair; KAU; Jim, ThomasThe melon fruit fly Bactrocera cucurbitae : Diptera) is one of the highly destructive pest species attacking cucurbits. The larvae hatching from eggs deposited within the fruits, tunnel and feed on the internal contents. As a result of this, the fruits are severely damaged, rot and fall to the ground, where pupation takes place. As the recommended management practices against the melon fly are still proving inadequate, there is a need to devise newer and safer means to solve this problem. The latest trend in pest control is the use of natural products derived from plant and animal sources. Among the various plants tested, Acorus calamus L., is gaining importance owing to its insecticidal and insectistatic properties. The present study was carried out at the Department of Agricultural Entomology, College of Horticulture, Vellanikkara, during 1993-94, with the objective of evaluating the extracts of A. calamus for the management of the melon fly, B. cucurbitae. The experiments were conducted in order to assess effects like repellency, feeding deterrency, oviposition deterrency, ovicidal action, topical contact toxicity to larvae, pupae and adults and chemosterilant action. Water and organic solvents were used to prepare the A. calamus extracts. Among the organic solvents tested, methanol was selected, owing it’s the better effect. Melon flies (B. cucurbitae ) reared in the laboratory were used for all the tests, and the following results were obtained. The repellent and feeding deterrent effects of the extracts was proved by reduced alightment of flies on the treated substrates. The aqueous extracts were effective at 5%, while the methanol extract at 0.1% was highly repellent., proving the superiority of the methanol extract. In the oviposition deterrency test, the number of ovipunctures as well as the fecundity realization, showed a decreasing trend with the increase in concentration of the extracts. The methanol extract was found to be superior to the aqueous extract in deterring oviposition also, as it was effective at 0.25 %, while in case of the aqueous extract a significant effect was produced only at a concentration of 5 %. Toxicity tests were conducted on all life stages of the melon fly. The eggs were not affected by the aqueous extract upto 10%, but there was 100% egg mortality (inhibition of hatching) when 0.1% methanol extract was used. The LC50 of methanol extracts to the eggs was found to be 0.03%. Both the aqueous extract and the methanol extract were found to be ineffective in causing mortality to larvae and pupae, upto 10%. In the case of adult flies, there was no mortality upto 10% of the aqueous extract by topical application or residue film technique. Topical application with methanol extract could not be followed, as the solvent itself caused 100% mortality. However by residual film application, it was possible to obtain a range of mortalities, and the LC50 of methanol extract to adult flies was found to be 0.07%. The methanol extracts were found to inhibit mating completely, in adult flies fed with the extracts at 0.1 to 0.01 % from the day of emergence. The average survival period of these flies was also significantly lower, because of which, fecundity realization was not see. The sizes of reproductive organs in the treated flies were found to be considerably reduced, probably due to regression or oosorption in the ovaries, or general atrophy of the organs, caused by the feeding of the extracts. This damage to the reproductive organs might have caused a hormonal imbalance, which resulted in the mating being inhibitedThesisItem Open Access Fusarium pallidoroseum (Cooke) Sacc as a biocontrol agent for the pea aphid Aphis craccivora Koch(Department of Agricultural Entomology, College of Agriculture, Vellayani, 1996) Sunitha, V S; KAU; Susamma MathaiDetailed investigations were made on the entomogenous fungus Fusarium pallidoroseum (cooke) Sacc infecting cowpea aphid Aphis cracclvora koch. Field studies showed that spore suspension and wettable powder formulations were equally effective in controlling the pea aphid. 7 x 106 spores per ml suspension in water or a similar suspension of a wettable powder or quinalphos 0.05 per cent were found to be equally effective in controlling the aphids under field conditions. Spore suspension containing 3.5 x 106 spores per ml have shown similar results during the later half of the experimental period. Pot culture studies conducted to assess the influence of host plants of aphid on the efficacy of the pathogen revealed that there was no influence of host plant on the pathogenecity of F. pallidoroseum. The germination and viability of F. pallidoroseum in formulation was found to decrease with increase in storage period and the formulations retained its capacity for germination and viability for more than ten months under refrigeration. The fungus was found nonpathogenic to vegetables viz. as bhindi, brinjal, amaranths, tomato, chillies, snakegourd, bittergourd and medicinal plants, viz., adathoda, ocimum and notchi under field conditions. Besides it was found safe to natural enemies of aphids viz., Coccinella septumpunctata, Menochilus sexmaculata and Scymnus sp. The productive insects, honey bees and silkworms were not at all affected by this fungus. Cross inoculation studies using this pathogen showed that three species of aphids, viz., Toxoptera aurantii, Aphis gossypii and Aphis malvae were not infected. A strain of F. Pallidoroseum isolated from a weed plant water hyacinth(Eichhornia crassipes) was found to be non pathogenic to the aphid Aphis Crassivora. Similarly F. Pallidoroseum was observed non pathogenic to water hyacinth. These observations indicated that the above two strains of F. Pallidorosem are entirely different.ThesisItem Open Access Die- back in cashew incited by the tea mosquito bug, Helopeltis antonii Signoret as influenced by wound pathogens and plant biochemicals(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1996) Bindu, N; KAU; Pathummal Beevi, SExperiments were conducted at the College of Horticulture, Vellanikkara and in the cashew fields at Cashew Research Station, Madakkathara, to ascertain the intensity of shoot die-back symptoms in cashew incited by the TMB bug, Helopeltis antonii in association with the wound pathogens; to evaluate the selected plant products for their feeding detterrency to TMB; to study the variations in the major biochemical factors such as starch, sugars, phenol and OD phenol in the five susceptible and five less susceptible cashew types and the changes in these biochemical factors due to TMB feeding. The predominantly occurring fungus isolated from the necrotic lesions of the TMB affected shoots, panicles and nuts was Colletotrichum gloeosporioides. The involvement of the fungus in the die-back symptom development calls for appropriate modifications in the crop protection strategies particularly for younger cashew plantations. The necessary strategic shifts have been discussed. The role of this fungus in aggravating the seedling die-back when inoculated on the grafts infested by TMB has been established. Emulsions of neem and pongamia oil at 2 per cent and 5 per cent spray caused mortality of adult bug after 12 h of exposure. Significant variations in the biochemical constituents viz., starch, sugar, phenol and OD phenol content were detected in all the ten cashew accessions. Comparatively low starch content was noticed in most of the susceptible cashew types and high in the less susceptible type. The starch content increased during the 6 h followed by significant decrease during 12 and 24 h of infestation by TMB. Low sugar content was found in the less susceptible accessions. The sugar content showed significant decrease during 6,12 and 24 h of infestation by TMB. The phenol and OD phenol contents were lower in the susceptible cashew accessions than the less susceptible accessions. The phenol content showed an increasing trend at 6 h followed by a decrease during 12 h and again an increase during 24 h of infestation by TMB. The varietal variations and the time interval after the TMB infestation seemed to influence the rate of biochemical reaction rather than any specific biochemical changes induced by the interaction of varieties and TMB feeding.