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ThesisItem Open 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, NTwenty 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.ThesisItem Open 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 SBittergourd 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.ThesisItem Open Access Major pests of ginger in Kerala and their control(Department of Entomology, College of Agriculture, Vellayani, 1989) Rajan, Mathew; KAU; George, KosyA survey conducted in Kottayam and Idukki Districts (ginger tracts) of Kerala, adopting multistage random sampling technique, revealed that D. punctiferalis is the major pest infesting the crop in both the Districts. The first instar larvae bored in at the fourth or fifth leaf axil of the psuedostem and caused the drying up of the distal part. Then the larvae emerged out and tunneled in at the base of the psuedostem. The lower part of the stem did not dry up. The pest had a uniform distribution in the two Districts. The extent of shoot damage ranged between 23.59 and 24.92 per cent. The incidence of the pest was not significantly associated with the soil type in which the crop was grown or with the age of the crop. The damage observed was higher during August, September and October and started declining from November. The possible yield loss for the mean damage of 23 to 24 per cent of the psuedostem could be estimated as 25 per cent based on the observations of CPCRI (1981 a). A field experiment conducted in the two Districts showed that the avoidable yield loss caused by D. punctiferalis was around 40 per cent. Application of granules (carbofuran and phorate) caused initial reduction in the damage done by D. punctiferalis but it did not persist to reduce the final yield loss caused by the pest. Need based spraying of dimethoate or quinalphos 0.05 per cent emulsion controlled the pest effectively. Spraying of quinalphos was more economical. Studies on the nature of damage done by the rhizome maggot M. coeruleifrons revealed that the entry of the maggot in to the rhizome occurred only when there were mechanical injury at the collar region or the tissues at the point was softened by prior infection of bacteria or fungi. A pot culture study showed that the fly maggots invaded the rhizome infected by fungus and not vice versa. The fly was seen distributed in both the Districts, but the distribution was discontinuous. The incidence in the high ranges was very low. The incidence of the pest was positively correlated with the rhizome rot disease incidence. The biology of the pest was studied in detail and the life stages of the pest have been described in detail. The leaf roller U. folus was observed as a minor pest of ginger and it was distributed in a few locations covered in the survey. The leaf spot disease was prevalent in Idukki and Kottayam Districts the mean indices of the disease being 1.627 and 1.043 respectively. The disease commenced in July, reached the peak in September and continued up to November. Soft rot disease was prevalent in Idukki and Kottayam Districts; but the distribution was discontinuous. It was less in higher elevations of Idukki District. The peak incidence of the disease was in September. It was less common in forest lands. the relative humidity was positively correlated with disease incidence while the age of the crop had a negative influence. Meloidogyne sp and Radopholus sp were obtained from the root and soil samples collected from the different locations covered in the survey. But population was too low to cause significant crop loss. Low population of Helicotylenchus sp. in root and soil samples and Criconema sp, Xiphinema sp and Mononchus sp in soil samples were also recorded.