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ThesisItem Open Access Effect of phorate applied for the control of bunchy top vector of banana Pentalonia nigroneroosa Coq. on the plant and in the soil environment(Department of Agricultural Entomology, College of Agriculture, Vellayani, 1989) Sitarama Rao, D; KAU; Mohandas, NA series of experiments were carried out for ascertaining the basic problems related to the current recommendations for managing bunchytop disease of banana through the application of phorate. The absorption, translocation and metabolism of phorate applied in the soil was influenced more by the condition and age of the plant than by the dose of the insecticide. Since the application of 2.50 g ai/plant did not result in corresponding increase in the residue content or the bioefficacy in the early phases of crop growth, when compared to the 1.25 dose, the latter can be used without significant loss in efficacy. A definite dose-effect relationship existed between the phorate content of plant and the mortality of P.nigronervosa confined at feeding sites. The median lethal doses of the insecticide content of the plant tissue were higher during declining phase of absorption as compared to those obtained during the active absorption phase. The result indicated the lesser toxicity of some components in the total residue during the later phase of the crop. Application of phorate granules in leaf axils was less effective than the treatment done in the soil and hence the current recommendation to use less quantity of insecticide when applied in the leaf axils has to be altered. A simple technique for the separation, identification and quantification of phorate and its metabolites was developed. Phorate and phorate sulfoxide contents of the total residue showed inverse relationship with each other while the other metabolites did not exhibit a clear relationship among them. Phorate and phorate sulfoxide exhibited more positive direct influences on the morality of the vector than the other metabilites. The absorption and toxicity of the insecticide content in plants did not vary significantly up to 174 DAP, when applied @ 2.50 g ai/plant at different intervals after planting. Absorption was very low when the insecticide was applied at 180 and 210 DAP. For ensuring residues within tolerance limits (0.10ppm) in raw fruits, the insecticide treatment has to be limited to 150 DAP and for ripe fruits the limit can be extended up to 180 DAP. The absorption and persistence of phorate and metabolites was significantly higher in plants grown in summer season than in those grown in rainy season. The absorption of insecticide was high in sandy soils and it was lowest in black cotton soils during the active absorption phase. The insecticide persisted at effective levels for 75 days in sandy, 90 days in lateritic upland and 105 days in black cotton soil. Sulfoxidation of the thioether moiety was the dominent metabolic pathway in sandy soil while desulfuration pathway was predominent in the other three soils. Application of phorate at planting, @ 2.50 g ai/plant, did not adversely affect the soil microflora as observed at the time of harvest of the crop.ThesisItem Open Access Studies on the extent of damages caused by pests of stored copra and controle of the important pests(Department of Agricultural Entomology, College of Agriculture, Vellayani, 1989) Nalina kumari, T; KAU; Mammen, K VThe magnitude and intensity of insect pest attack in stored copra, in the Southern Districts of Kerala, were assessed in an elaborate survey, adopting a random sampling technique for two years. The survey revealed that insects cause significant damage even in well preserved good quality copra stocked for more than five months. N. rufipes, O. surinamensis, A. advena and L. serricorne were the major pests recorded. The immature stages of N. rufipes, adults and immature stages of the other pests were seen inside the tunnels made between the endosperm and testa. N. rufipes and O. surinamensis were distributed widely, while the predominant insects observed at Nedumangad were A. advena and L. serricorne. All the insects were found breeding on copra from June to October. A positive correlation between moisture content of copra and the insect incidence was observed in the studies. The influence of A. flavus on the extent of damage caused by these pests showed that the presence of the mould was not a predisposing factor for insect attack. The extent of damage in copra due to the infestation by N. rufipes was 12.2 per cent at the end of sixth month whereas O. surinamensis caused only three per cent damage. When combind with fungus, the damage caused by N. rufipes was reduced by 50 per cent. This effect was not observed on O. surinamensis. The infection by the fungus adversely affected the oil content of copra and this effect was not altered by the preceeding or succeeding infestation of the insect. The insect attack alone caused significant reduction in oil yield of copra during the sixth month after exposure only. The quality of oil was adversely affected when infested by insects and fungus independently. The infestation of insects preceeding or succeeding fungal infection did not alter the adverse effect caused by them independently. The quantitative loss caused by the attack of N. rufipes and O. surinamensis to copra obtained from different varieties of coconut did not show significant variations. Among the different varieties tested LM and LO were more favourable to N. rufipes and DxT and TxD to O. surinamensis. Two to six fold increase in the longevity of the adults of N. rufipes was observed when they were provided with immature stages in addition to copra for feeding. N. rufipes and O. surinamensis caused significantly greater damage to copra under eight per cent and six per cent moisture levels respectively. The development of N. rufipes was totally arrested in copra with four per cent moisture content. The development of immature stages and adult population of N. rufipes were higher in copra containing eight per cent moisture level and those of O. surinamensis in copra containing six per cent moisture. The response to moisture fluctuations was more conspicuously seen in O. surinamensis than in N. rufipes. Though the population of insects were found to be high in reused gunny bag followed by heap storage, the extent of damage was higher in heap storage than in reused gunny bags. High populations of N. rufipes and O. surinamensis were recorded from heap and reused gunny bags respectively. Low populations of insects were recorded in copra stocked in polythene/alkathene lined gunny bags and netted polythene bags. But the oil extracted from copra stored in these types of bags gave significantly higher acid values. In the trials done to find out a safe prophylactic method of control against pests of copra, malathion and phoxim proved more toxic to N. rufipes and malathion and fenitrothion to O. surinamensis. When these insecticides were evaluated for their persistence on gunny bags, malathion 0.4 per cent gave protection up to five months and fenitrothion 0.8 per cent up to six months. The residues of malathion and fenitrothion came below tolerance limits, 15 and 60 days after treatment respectively . For complete control of the major pests of copra 4.5 g/m (2.5 g ai/m ) of aluminium phosphate with one day exposure period was found adequate. The residue of phosphine in the copra fumigated as above was below tolerance limit.ThesisItem Open Access Resurgens of brown planthopper Nilaparvata Lugens (stal) on rice treated with various insectisides(Department of Agricultural Entomology, College of Agriculture, Vellayani, 1989) Thomas biju, Mathew; KAU; Mohan das, NA series of green house experiments were carried out for screening the insecticides, fungicides and herbicides recommended for the control of pests, diseases and weeds infesting rice in Kerala, for their resurgence inducement in N. lugens. Among the thirteen insecticides screened, each at three doses and applied at three critical growth stages of the crop as well as at their possible combinations, methyl parathion, deltamethrin, fenitrothion, fenthion, quinalphos and carbaryl were identified as resurgence inducing insecticides with no apparent differences among themselves in the intensity of resurgence caused, HCH, dimethoate, monocrotophos, phosphamidon, phorate, BPMC and carbofuran were found to be free from resurgence inducement and some of them even exerted a significant suppressing effect on the progeny production of N. lugens. There was no carry over of resurgence effect over generations. The results of the experiments also revealed that: 1. The manifestation of resurgence inducing property of insecticides was more at the higher doses than at the field doses or lower doses. 2. The frequency of occurrence of resurgence among the different treatments with resurgence inducing insecticides showed that a single application at any of the three critical growth stages of rice and two applications combining any two of the three growth stages were on par while three consecutive treatments covering all the three growth stages was more favourable for manifestation of resurgence. 3. The growth stages of the host plant had significant influence on the manifestation of resurgence inducement of insecticides. It varied with the properties of insecticides used. Some manifested resurgence at tillering, some at panicle initiation and none at booting stage. 4. The resurgence effect induced by the insecticides was found to last in the treated plants for a period of 15 to 20 days after treatment and the results indicated, that there was no cumulative effect by repeated treatments on insect populations. In the light of the above findings the method of screening resurgence inducing insecticides in the green house was standardized as the application of the insecticide at doses higher than the field doses thrice covering the tillering, panicle initiation and booting stages preceeding the exposure of insects for assessment of progeny production which may be done at 15 days after the third application. In further screening adopting the procedure standardized above malathion, methyl demeton, FMC 35001, fenvalerate, permethrin and cypermethrin were found inducing resurgence in N. lugens. The granular insecticides were screened giving two treatments (tillering + panicle initiation) and exposing insects at 30 DAT for egg laying. Results revealed that diazinon, phorate, cartap and carbofuran caused resurgence of N. lugens. Endosulfan, formothion, phosalone, methamidophos, chlorophyriphos, DDVP and their combinations with HCH or carbaryl (liquid formulations), aldicarb, quinalphos and sevidol (granular) were free of resurgence hazard. At the recommended doses and methods of application of fungicides zineb, mancozb, captafol, ediphenphos, kitazin, carbendazim and carboxin and the herbicides 2, 4-D (sodium salt and ester), pendimethalin, fluchloralin, butachlor, propanil and thiobencarb did not post any resurgence problem. The inducement of resurgence by insecticide was seen significantly influenced by the variety of host plants of the insects involved. The levels of plant mediated resurgence inducement and resistance of the plants to insect attack were not mutually related. In screening insecticides for the control of a pest in an agroecosystem, the interaction of the popular varieties of the crop available in the area with resurgence inducement also should be studied. The resurgence inducing mechanism of six identified insecticides was studied in detail. The results of a series of green house and laboratory experiments revealed that : 1. Resurgence inducing insecticides brought about some morphological changes in the crop causing some improvements in the stand but the magnitude of the changes were not adequate to influence the attraction of the insects or build up of the pest population. 2. The application of the insecticides caused significant variations in the nutrient content and biochemical constituents of treated plants causing consistent changes in the total nitrogen, free sugars and free amino acid contents. 3. The feeding of N. lugens on treated plants was significantly higher as indicated by the feeding indices. 4. The correlation studies and path coefficient analysis of the data relating to the magnitude of changes in the above factors caused by the application of insecticides could be attributed as the major cause of plant-mediated resurgence inducement. The direct application of resurgence inducing insecticides revealed that some of the insecticides which showed plant mediated resurgence (methyl parathion, deltamethrin and carbaryl) had direct stimulating effect also on the progeny production of N. lugens at sublethal doses while some (fenthion and fenitrothion) did not show any increase in progeny production and some (quinalphos) showed only marginal effect. While carbaryl and methyl parathion were more stimulatory at lower levels, deltamethrin stimulated reproduction at both the lower and higher levels. The field experiment revealed that the resurgence observed in the field was the added effect of plant-mediated resurgence observed in green house experiments and the direct effect of the pesticides caused by their sublethal doses. In general the conclusions from the green house experiments were in agreement with the results obtained from the field. It was seen that the changes in predatory population in field caused by the application of pesticides did not contribute significantly to the inducement of resurgence in N. lugens. It was also observed that the assessment of plant induced resurgence of insecticides in green house experiments and the direct effects of the toxicants on the insects will serve as an effective alternative elaborate field experiments for evaluating the resurgence effect of insecticides.ThesisItem Open Access Persistence and metabolism of phorate in rice plants and in different soil types of Kerala and its effect on non target organisms(Division of Agricultural Entomology, College of Agriculture, Vellayani, 1987) Naseema Beevi, S; KAU; Visalakshi, AThe uptake, persistence and metabolism of phorate in rice plants and in different types of soil, viz., alluvial, sandy and lateritic loam when applied at 3 doses and 3 growth stages of the crop were studied by conducting field experiments. In these studies, the insecticides was applied as granules at 3 doses of 1.0, 1.25 and 1.5 kg ai/ha at 20, 40 and 60 days after planting. The residues were estimated colorimetrically and by bioassay. The metabolites in plants and soil were separated by T.L.C and further estimated colorimetrically at intervals of 2,7 and 14 days after application. The ultimate residues of the insecticide in grain and straw also were determined.ThesisItem Open Access Nuclear polyhedrosis of Opisina arenosella WLK. (= Nephantis serinopa Meyr;) (Cryptophasidae: Lepidoptera) and its utility for the control of the pest(Department of Agricultural Entomology, College of Agriculture, Vellayani, 1985) Babu, M Philip; KAU; Mohandas, NThe black headed caterpillar, Opising arenosella Hlk. (= Nephantis serinopa Meyrick) is a serious pest of coconut. The slender caterpillars found under the leaves in galleries made of silk and foreign matter feed on the chlorophyll tissues . Philip et al., (1982) reported the occurrence of a nuclear polyhedrosis virus in the larvae of O. arenosella. Basic information for judging the suitability of this pathogen for the control of the pest were lacking. Hence detailed studies were made on the symptamatology, morphology of the pathogen, histopathology, mode of transmission of the virus to the progeny, cross infectivity to other species of lepidoptera, bioassay of the virus , persistence of the virus on coconut foliage , effect of physical factors on the persistence of the virus, safety of the pathogen to non target organisms and the efficacy of the virusin controlling the pest in field.ThesisItem Open Access Biology, Bionomics and control of coconut cockchafer Leucopholis coneophora Burm.(Division of Agricultural Entomology, College of Agriculture, Vellayani, 1983) Abraham, V A; KAU; Mohan Das, MThe biology of the coconut cockchafer Leucopholic coneophora Burm. was studied in detail for the first time. Techniques for rearing the pests from egg to adult in potted palnts kept in field were standardized. The egg laying behaviour of adults was observed. The morphological changes off eggs, different instars of grubs and pupae during development were studied in detail. The changes in immature stages of male and female insects were traced separately. The general morphology of different instars of the grubs was studied in full with a view to finding distinct identifying characters for each.ThesisItem Open Access Effect of sub-lethal doses of decamethrin and carbaryl on the orientation, feeding reproductive rate and survival of key pests of brinjal, Solanum melongena L.(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1989) Sheila, M K; KAU; Abraham, C CThe effect of sub-lethal doses of decamethrin and carbaryl at their LD5, LD10, LD25 and LD50 levels on orientational stimuli, feeding, reproductive potential and survival of the three important pests of brinjal, namely, the epilachna beetle H.28 punctata, the aphidsA. gossypii and the leaf hopper A. b. bicuttula have been studied in the laboratory. In all the three test insects, positive orientational stimuli were not detected at all the tested sub-lethal levels of the two insecticides. A decrease feeding rate in H. 28 punctata was detected when the insects were exposed to the sub-lethal dose treatments. In A. crossypii and A. b. biguttula, the reduction in the feeding rate was more pronounced at the LD 50 level of both insecticides.ThesisItem Open Access Host resistance in brinjal varieties to the fruits and shoot borer Leucinodes orbonalis Guen ( Lepidoptera: pyralidae)(Department of Agricultural Entomology, College of Horticulture, Vellanikkara, 1983) Madhavan, Nair G; Abraham, C CIn studies on the host plant resistance in brinjal (Solanum melongena L.) against the shoot and fruit borer, Leucinodes orbonalis Guen. (Lepidoptera : Pyralidae), germplasm materials were screened to identify sources of resistance and an attempt was made to investigate the mechanisms of resistance involved. Forty accessions of brinjal and related species were initially screened in a field trial conducted during the monsoon season of 1982 and these were classified into highly susceptible, moderately susceptible, moderately resistant and resistant classes. The accessions SM-6, SM-56, SM-72 and SM-74 from the highly susceptible group; SM-1, SM-45, SM-48 and SM-71 from in moderately susceptible group; SM-65, SM-68, SM-97 and SM-105 from the moderately resistant group and SM-67, SM-88, S.indicum and S.incanum from the resistant group were further field tested during the summer season, 1982-83 and were evaluated for the levels of resistance. Under artificial infestation of caged single plants of the accessions by the first instar larvae of L. orbonalis, the susceptibility spectrum was found to be similar to the trend noticed in the field trials. In the resistant types, the infestation by L. orbonalis occurred for a relatively shorter duration than in the susceptible ones. In studies on the antibiosis, it was found that the resistant accessions gave rise to larvae and pupae of reduced weights which took longer durations as compared to the highly susceptible accessions. The larval survival was lower in the resistant types. The highly susceptible accessions produced more females than did the resistant line. There was no significant variation in the fecundity of second generation females. In multiple-choice and no-choice tests, the females of L.orbonalis showed a clear preference for the highly susceptible and moderately susceptible accessions for oviposition. Correlation studies revealed that the density of trichomes on the shoot apex, lower leaf surface and lower surface of midribs exerted considerable influence on the ovipositional response of the female moth, the relationship between oviposition and trichome density being of a negative nature. Among the biophysical characters, the higher density of trichomes on shoot apex and lower midrid; lower pith area, lingnified selerenchymatous hypodermis and compact vascular bundles in shoot apex and tight or semi-tight calyx in fruit were found to impart resistance to borer infestation. Positive correlations were detected between the mean percentages of total sugars, crude protein, total ash, nitrogen, potassium and calcium in the fruit on the one hand and fruit infestation on the other. The contents of total ash, calcium, magnesium and iron in shoots on the one hand and shoot infestation on the other were also found to be positively correlated, while silica, zinc, copper and crude fibre contents were negatively correlated with shoot infestation.The implications of the findings have been discussed.ThesisItem Open Access Use of insecticides as granules for protecting paddy crop against pests(Division of Agricultural Entomology, College of Agriculture, Vellayani, 1981) Sasidharan, Pillai K; KAU; Gopalakrishnan, Nair N R
