Thumbnail Image

Theses

Browse

1984 - 19875
Reset filters
Subject: Agricultural Entomology × Author: KAU × End date: 1987 × Start date: 1984 × Thesis Type: M.Sc ×
Reset filters

Search Results

Now showing 1 - 5 of 5
  • Thumbnail Image
    ThesisItemOpen Access
    Pest complex associated with mango inflorescence and their control
    (Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1984) Satheesan, N V; KAU; Abraham, C C
    In a survey conducted during 1982-83 in the State of Kerala to study the incidence of various insect pests associated with mango inflorescence with reference to their seasonal history, a total of ten insect pests were recorded. The hoppers idioscopus niveosparaus Leth. and I. clypealis Leth. were found to be widely distributed in the State. Significant variability was not detected among the population loads of I. niveosparsus in different districts, while in the case of I. clypealis such variations were significant. The heaviest populations of the latter was recorded from the Calicut District. The seasonal changes in I. clypealis populations were recorded only in the two Districts of Calicut and Trivandrum. I. niveosparsus showed a well defined peaks in the Palghat and Wynad districts. The fluctuations I. niveosparsus and I. clypealis populations have been discussed with reference environmental conditions. Procystiphora mangiferae Felt. is reported for the first time from the State from the Wynad and Cannanore Districts. Infestations by the pest led to transformation of the floral buds to conical galls. In the Wynad District, there was a well defind population peak in March, while in the Cannanore District a district crest waslacking. The mango blister midge, Erosomyia indica grover and Prasad was recorded to occur in association with P. mangiferae in these two districts. The larvae of E. indica tunnel into inflorescence axis and cause ovate galls thereby causing losses. Bombotelia jocosatrix Gn. was recorded from the Cannanore, Palghat, Trichur and Alleppey Districts throughout the flowering season. Eublemma anguilifera Moore as well as another unidentified spp. of Eublemma were recorded to occur throughout the State, except in the wynad District. The seasonal fluctuations of this pest were significant only in the Palghat District. An unidentified species of Cacoecia was recorded for the first time as a minor pest of mango inflorescence. The larvae fed on flowers and floral buds. The other pests observed during the course of the survey were Rapala manea Hewitson, Haplothrips ganglbaueri Schmutz, Dichocrosis punctiferalis Guenee and an unidentified Geometrid. The bio-efficiency of monocrotophos applied by two methods, namely, stem injection and stem banding, against the Idiocerine hoppers infesting mango inflorescence was evaluated in a separate experiment. The relative toxicity of the insecticide was determined from the time- mortality relationship between the insecticide reaching the inflorescence of treated trees and the mortality of the fourth instar nymphs of I. niveosparsus. The LT -50 values of the nymphs following application of the insecticides by the stem injection method was found to be substantially lower than the corresponding values for the stem banding method of application. It was thus evident that the toxicant moved at a faster pace when administered by the stem injection method. The variations in the pattern of translocation of the toxicant under the two methods of administration have been discussed. The residues of monocrotophos on freshly formed mango fruit at five weeks after application by the stem injection method at 4 ml and 2 ml ai/tree were 0.3600 ppm and o.3750 ppm respectively. The corresponding residues in the mango fruit consequent on stem banding method of administration were 0.0550 ppm. The implications of the above results in formulating control methods against Idiocerine hoppers infesting mango inflorescence have been discussed.
  • Thumbnail Image
    ThesisItemOpen Access
    Taxonomic studies of leaf and plant hoppers associated with paddy in Kerala
    (Department of Entomology, College of Horticulture, Vellanikkara, 1984) Abdulla, K; KAU; Mammen, K V
    Taxonomic study on the leaf and plant hoppers of paddy was conducted to find out the various specious of leaf and plant hoppers associated with paddy in Kerala. Paddy fields from two important paddy growing tracts of Kerala viz., Trichur and Palghat were selected and weekly collections of hoppers were made. Collections were made with a fine mesh hand net for the entire cropping season from transplanting upto harvest. Fixed numbers of sweeps were taken from the same field in order to get an idea about the population fluctuations. Collections from each field for each week were separately preserved in homeopathic vials with collection data. Later insects in all vials were sorted out, number of specimens collected in each week were noted, sexes separated, and each species were preserved in separate vials. Vials were serially numbered and collection data were noted under each serially numbered species. Genitalia of males as well as general form and colouration of all species were stidied. However genitalic studies of Exitianus indicus (Dist.) and Nisia nervosa (Motsch.) could not be conducted for want of male specimens. Altogether nine species were collected viz., Nephotettix Virescens (Dist.), N. nigropictus (Stal), Recilia dorsalis (Motsch.) and Exitianus indicus (Dist.) coming under Cicadellidae, Nilaparvata lugens (Stal), Sogatella furcifera (Horv.),Matutinus pusanus (Dist.) belonging to Delphacidas and Nisia nervosa (Leth) under Meenoplidas. Among these species all but M. pusanus were reported to be occurring on paddy in India and other East Asian countries, while E. indicus and N. nervosa were not observed by earlier workers from Kerala. Apart from these, two male and two female specimens of Nephotettix showing variations in characters from N. nigropictus and N. virescens were also obtained. These may be natural hybrids between N. virescens and N. nigropictus. Certain morphometric studies were conducted using head measurements viz., eye diameter to interocular distance and /or vertical distance next to eye to median length of Vertex. It was found that there is difference between male specimens of N. virescens and N. nigropictus with regards to the ratio of vertical distance next to eye to median length of vertex; and in females of these species there is difference between the ratios of eye diameter to interocular distance. Similarly there is difference between male specimens of N. lugens and S. furcifera with regards to the ratio of eye diametor to interocular distance. Studies on the seasonal abundance of leaf and plant hoppers revealed that there is variation in the predominant species present in each area.
  • Thumbnail Image
    ThesisItemOpen Access
    Joint action of nuclear polyhedrosis virus of Spodoptera (Fabricius) with insecticides and its applicability in pest control
    (Department of Agricultural Entomology, College of Agriculture, Vellayani, 1984) John, V Cherian; KAU; Vasudevan Nair, K P
    Experiments were conducted to study the joint action of nuclearpolyhedrosis virus (NPV) of Spodoptera litura (Fabricius) and five insecticides viz., quinalphos, carbaryl, BHC, monocrotophos and permethrin. The investigation carried out included bioassay of the virus and insecticideson third instar larvae of S.litura, effect of different combinations of the virus and insecticides on larval mortality and the effect of simultaneous and sequential application of virus and insecticides for the control of pest.
  • Thumbnail Image
    ThesisItemOpen Access
    Crop loss caused by the root-knot and reniform nematodes in brinjal and control of the pests
    (Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1986) Jiji, T; KAU; Venkitesan, T S
    Two pot culture experiments were laid out i) to study the pathogenic effect of different inoculam levels of root-knot and reniform nematodes on brinjal, alone or in combination each at 100, 500 and 1000 nematodes/plant comprising 10 treatments and 10 replications and ii) to study the effect of four granular chemicals viz. carbofuran, aldicarb, phorate and quinalphos at the rate of 1.0 and 1.5 kg ai/ha against the above two nematodes alone or in combination, comprising of twentyfive treatments and five replications. The results brought forth the adverse effect induced by the highest inoculum levels of two nematodes either alone or in combination on plant growth characters of brinjal even after 45 days of inoculation. The reniform nematode seems to have more pathogenic effect than root-knot nematode at the same inoculum level. The results obtained from the second experiment indicated that carbofuran or aldicarb at the rate of 1.0 and 1.5 kg ai/ha were found to be the best treatments resulting in increase in plant growth characters and yield and in reducing the nematode population in roots and soil. Phorate and quinalphos were found least effective in promoting growth of plants and in reducing nematode infestations. However the application of phorate or quinalphos at the rate of 1.5 kg ai/ha was found to have equal effect as that of carbofuran or aldicarb up to 15 days of their application.
  • Thumbnail Image
    ThesisItemOpen Access
    Effect of varying volumes of pesticide spray fluid on the control of rice pests
    (Department of Entomology, College of Agriculture, Vellayani, 1987) Viswanathan, G; KAU; Mohan Das, N
    A series of field experiments were conducted in the Instructional Farm attached to the College of Agriculture, Vellayani, during 1984-85 for evaluating the bioefficacy of pesticide suspension/emulsions sprayed in varying volumes at different growth stages of rice crop for the control of various pests and diseases keeping the concentrations of the toxicants in the spray fluid at the recommended levels. A parallel series of experiments were conducted with similar volumes of spray fluids which were in different concentrations for maintaining the doses in all treatments at constant recommended level . the experiments were conducted in an area under bulk planting of rice (planted and maintained as per the package of practices recommended by the Kerala Agricultural University) by peg marking adequate number of plots at locations where pest incidence occurred in sufficient intensity. Randomised block design was adopted in all the experiments. At tillering phase of the crop the incidence of the case worm, N.depunctalis, leaf roller C. medinalis and brown leaf spot disease were observed. Against N.depunctalis HCH suspension 0.2 percent was used in varying volumes in one experiment and the same at a fixed dose of 1.25 kg ai/ha and in varying volumes a parallel experiment. For the control of C. medinalis quinalphos 0.05 per cent emulsion was tried in varying volumes and the fixed dose of 0.25 kg ai/ha was also used in varying volumes. The treatment for the disease was with Dithane M 45 at a concentration of 0.4 per cent and at a dose of 2.0 kg/ha in similar range of volume. The volumes of spray fluid used were 300,350,400,450,500 and 550 1/ha and for each treatment there were three replications. Plots sprayed with water alone were retained as controls. The results were assessed in terms of the reduction /increase in the populations of the pest or on the intensity of the damage caused by the pest, observed at different intervals after spraying. Results of the experiment showed that 350 1/ha was the optimum volume of spray fluid for the control of the pests and diseases occurring at tillering phase of the crop. In the second series of experiments where the recommended doses of toxicants per unit area were used in varying volumes of water the bioefficacy of the pesticides varied with the volumes of spray fluid used per unit area. At the tillering phase of the crop a formulation with 3501/ha of the water gave the maximum effect. At bootleaf stage the crop was infested by the leaf roller C. medinalis and the stem borer S. incertulas. Quinalphos 0.05per cent emulsion was sprayed in varying volumes ranging from 450 to 700 1/ha. In both the experiments 550 1/ha of the spray fluid was found as the optimum volume with reference to the reduction in the extent of damage caused by the pests. Even when the quantity of pesticide applied per hectare was maintained at the fixed level of 0.25 kg ai the efficacy was varying with the volume of spray fluid used. The volume of 550 1/ha was found to be the optimum for the control of both the pests. In the bootleaf stage the incidence of sheath blight and sheath rot were observed and for controlling the disease Bavistin 0.1% suspension was sprayed at varying volumes ranging from 450 to 700 1/ha. In another experiment the pesticide was applied in the same range of volumes but maintaining the dose at the fixed rate of 0.5kg/ha in all treatments. From the results 5501/ha could be fixed as the optimum volume for maximizing the bioefficacy of the pesticide against the two diseases. The overall assessment of the data obtained from the experiments conducted at the bootleaf stage of the crop revealed that 550 1/ha of the spray fluid should be used for the control of the pests and diseases occurring at the stage and that the recommendation of a fixed quantity of pesticide per unit area will not be adequate unless it is used in 550 1/ha of water. Only pest which occurred during the heading stage of the crop was the rice bug L. acuta . When methyl parathion 0.05% emulsion was applied at varying volumes ranging from 450 to 700 1/ha, 550 1/ha gave the highest initial reduction in population and maintained the effect up to the fifth day after treatment. Even when the quantity of insecticide was kept at a fixed dose of 0.25 kg ai/ha the volume of water to be used was found to be 550 1/ha for maximizing the bioefficacy of treatment. In a separate series of experiments the influence of varying volumes of spray fluid on the coverage and deposit formation on different growth stages of the crop was ascertained using safranin as tracer. The data showed that the volume required for maximum deposition at tillering , bootleaf and heading stages of the crop were 350, 550 and 5501/ha respectively. These volumes were corresponding with the volumes of pesticide formulations required for maximizing the bioefficacy against the pests at different growth stages of the crop.