Browsing by Author "Subaharan, K."

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    Bioefficacy of insecticides against white grub Leucopholis lepidophora Blanch infesting arecanut palm
    (2007-02-08) Subaharan, K.; Vidyasagar, P.S.P.V.; Mohammad Basheer, B.M.
    The root infesting scarabaeid white grub Leucopholis lepidophora Blanch is a major pest on arecanut in Western ghats area of Karnataka. In an attempt to identify an insecticide with enhanced bioaction against L. lepidophora four insecticides viz. carbosulfan tefluthrin chlorpyriphos and phorate (standard insecticide) were screened for their toxicity in the laboratory and in the field. In laboratory bioassay studies, the order of toxicity observed was carbosulfan > tefluthrin > chlorpyriphos > phorate. On relative toxicity, carbosulfan was 4.2 times more toxic as compared to phorate followed by tefluthrin (2.8) and chlorpyriphos (1.9) in the case of II instar grubs. In III instar nubs carbosulfan was 13 times more toxic than phorate whereas, tefluthrin and chlorpyriphos were 12.5 and 2.7 times more toxic than phorate, respectively. A replicated field trial was taken up at arecanut gardens in Sringeri 1(Kamataka) for two years and the treatments were imposed during post monsoon season (1999 and 2000). Carbosulfan [ @ 20 g / palm during first and second years effected a mean reduction in grub population to a tune of 80.6 % and 66 I % , respectively. Chlorpyriphos @ 8 ml/ palm and carbosulfan @ 10 g / palm caused > 60 % reduction in grub population during both the years of study. The standard insecticide phorate @ 10 g / palm caused a mean reduction of ; 36.43% and 44% during the respective years.
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    Coconut community in India -a profile
    (CPCRI, 2001-09) Arulraj, S.; Rajagopal, V.; Sairam, C.V.; Thamban, C.; Anithakumari, P.; Dhanapal, R.; Bosco, S.J.D.; Subaharan, K.; Naresh Kumar, S.; George V. Thomas; Vinayaka Hegde; Kumaran, P.M.; Parthasarathy, V.A.
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    A comparative study of insect odorant protein binding (OBP) genes and isolation of a practical OBP gene from coconut red palm weevil rhynchophorus ferrugineus F.
    (2008-12) Rajesh, M.K.; Subaharan, K.; Ritto Paul; Sathish Kumar, R.; Bobby Paul; Sreesmitha, V.; George V. Thomas
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    Digital phenotyping of coconut and morphological traits associated with eriophyid mite (Aceria guerroronis Keifer) infestation
    (2013-12) Arunachalam, V.; Augustine Jerard, B.; Elain Apshara, S.; Jayabose, C.; Subaharan, K.; Ravikumar, N.; Palaniswami, C.
    Observations were recorded on traits associated with mite infestation related at two stages of button on six different coconut cultivars over three years. Highly significant correlation was found between mite damage score with color or weight of tepal. Step-wise multiple regression of the data analysis showed color of inner tepal as major trait associated with infestation by eriophyid mite. Other traits are ratio of tepal weight to tepal area, per cent of buttons with pink discoloration or with resin, tepals of regular aestivation and gap between fruit and tepal. Digital phenotype data of 83 image files were used to calculate color signature and correlated the same to mite damage score over three years. Red spectral values were found to vary from 14 to 251, green values to 12 to 237 and blue to vary from 5 to 183. Spectral values red max, green max, 3* Red + Green max had high significant negative correlation (>-0.4) with mite damage. Color and firmness of fruits and tepals of three coconut varieties were further analyzed where, fruits and tepals of COD variety showed high red/green (a* value of Hunterlab) >12. Firmness of 3 month old tepal and fruit of Benualim (BGRT) tall variety was (penetrometer reading >38) higher than other varieties.
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    Dynamics of rhinoceros beetle damage as influenced by pheromone trapping
    (2016-12) Joseph Rajkumar, A.; Subaharan, K.; Chandrika Mohan; Shanavas, M.; Sunny Thomas; Nampoothiri, C.K.
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    Electrohysiological and behavioral response of Goniozus nephantidis Muesbeck, to plant and host volatiles
    (2011) Subaharan, K.; Ravikumar, N.; Prasad, A.R.
    Experience of parasitoids with host and host related products have effects on their behavior. Learning can be induced by conditioning parasitoids at various stages i.e. pre imaginal or imaginal (after eclosion). Here we studied the volatiles from damaged, undamaged coconut leaflets and Opisina arenosella larval frass that cause electrphysiological and behavioural response in the bethylid parasitoid Goniozus nephantidis. The possibility of using the host frass for conditioning the parasitoids was explored. The damaged coconut leaflets released cyclopentanone, butanol, and alpha pinene and these compounds were absent in undamaged leaflets. Z-3 hexenol, a green leaf volatile was trapped form both damaged and undamaged plants. Alpha pinene released form undamaged leaflets caused the highest electroantennogram (EAG) peak amplitude (O.330mV) in female antennae. This was followed by cyclopentanone (O.30mV), hexanone (O.29mV) and hexanal (O.29mV) which were all at par. G nephantidis reared on Corcyra cephalonica conditioned with the larval frass of O. arenosellla when provided a choice preferred to parasitize O. arenosella as compared to C. cephalonica. Conditioned parasitoids when released in the field caused 59 per cent reduction in larval population per leaflet as compared to 29 per cent reduction by unconditioned parasitoids two months after release. Conditioning of G nephalliidis with odors of O. arenosella will aid to enhance the host searching ability of the parasitoids that were reared on C. cephalonica.
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    Homology modeling and docking studies in an odorant binding protein from palm weevil
    (2008) Sreesmitha, V.; Rajesh, M.K.; Subaharan, K.; Sathish Kumar, R.; George V. Thomas
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    Isolation of microbial pathogens of Aceria gaerreronis, the coconut eriophyid mite
    (2003) Murali Gopal; Rohini Iyer; Vinayaka Hegde; Subaharan, K.; Sosamma, V.K.; Alka Gupta; Chandrika Mohan; Nair, C.P.R.; Gunasekaran, M.; Chandramohanan, R.
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    Isolation of microbial pathogens of Aceria guerreronis,the coconut eriophyid mite
    (2007-02) Chandrika Mohan; Murali Gopal; Chandra Mohanan, R.; Gunasekaran, M.; Radhakrishnan Nair, C.P.; Koshy, P.K.; Alka Gupta; Sosamma, V.K.; Subaharan, K.; Vinayaka Hegde; Rohini Iyer
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    Leaf eating caterpillar - a menace to coconut cultivation
    (2009-03) Subaharan, K.; Ravindran, P.
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    Molecular Identification of Entomopathogenic Nematode Isolate and its Virulence to White Grub, Leucopholis burmeisteri (Coleoptera: Scarabaeidae)
    (2016) Rajkumar; Rachana, K.E.; Rajesh, M.K.; sabana, A.A.; Nagaraja, N.R; Shahin, S.; Subaharan, K.
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    Occurrence and distribution of entomopathogenic nematodes in white grub endemic areas of Kerala
    (2004-12) Gulsar Banu, J.; Subaharan, K.; Rohini Iyer
    A random survey was conducted in White grub endemic areas (Kasaragod and Nileshwararn) in Kerala , India to know the occurrence and distribution of Entomopathogenic nematodes. A total of 100 samples were collected from different soil types. Steinernema sp. was recorded in seven per cent samples and Heterorhabditis sp. in 11 per cent samples. The pH of the positive samples ranged from 4.93 - 6.39. Based on the rnorphometric analysis all the Heterorhabditis were identified as Heterorhabditis indica. Entomopathogenic nematodes were isolated from the rhizosphere of coconut and clove.
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    Olfaction in Drosophila melanogaster
    (2004) Subaharan, K.
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    Olfactory conditioning in Goniozus nephantidis (Musebeck) a parasitoid of coconut black headed caterpillar, Opisina arenosella Walker
    (2007-02) Subaharan, K.; Raveendran, P.; Md. Basheer, B.; Sujatha, A.; Ponnamma, K.N.
    Egg maturation and behavioral response to imaginal conditioning was studied on bethylid, Goniozus nephantidis, a parasite of coconut black-headed caterpillar, Opisina arenosella. Age and feeding had influence on G. nephantidis reared on O. arenosella. Eclosed females of 0-24 h had no mature eggs. Maximum numbers of mature eggs in the abdomen were observed 10 days after eclosion. Parasitoids that emerged from Corcyra cephalonica when offered a choice to parasitize C. cephalonica and O. arenosella showed preference to C. cephalonica, the host on which it was reared (Unconditioned response). Though unconditioned, they had 32 per cent response to O. arenosella and this is termed innate response. But when they were conditioned to odour of O. arenosella and then provided a choice, they preferred to parasitize O. arenosella as compared to C. cephalonica. Hence, it is clear that attraction to odours in imago that develops after eclosion is partly induced and partly Constitutive. © 2005 Association for Advancement of Entomology.
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    Ostrinia revisited: Evidence for sex linkage in European Corn Borer Ostrinia nubilalis (Hubner) pheromone reception
    (2010) Shannon B. Olsson; Subaharan, K.; Astrid T. Groot; Teun Dekker; David G. Heckel; Bill S. Hansson
    Background: The European Corn Borer, Ostrinia nubilalis (Hubner), is a keystone model for studies on the evolution of sex pheromone diversity and its role in establishing reproductive isolation. This species consists of two sympatric races, each utilizing opposite isomers of the same compound as their major pheromone component. Female production and male response are congruent in each race, and males from each strain exhibit phenotypic differences in peripheral physiology. Both strains possess co-localized pheromone-sensitive olfactory sensory neurons characterized by a larger amplitude action potential (spike) responding to the major pheromone component, and a smaller spike amplitude cell responding to the minor component, i.e. the opposite isomer. These differences in amplitude correspond to differences in dendritic diameter between the two neurons. Previous studies showed that behavioral response to the pheromone blend was sex-linked, but spike amplitude response to pheromone components matched autosomal, not sex-linked inheritance. Results: As part of a larger study to finely map the loci responsible for pheromone communication in this species, we have reanalyzed peripheral physiology among parental, and first and second generation hybrids between the two pheromone strains using tungsten electrode electrophysiology. Our results reveal that differences in spike amplitude ratio between male pheromone-sensitive sensory neurons in O. nubilalis races are controlled, at least partially, by sex-linked genes that exhibit E-strain dominance. Conclusions: We propose that peripheral olfactory response in O. nubilalis may be affected both by autosomal and sex-linked genes exhibiting a cross-locus dominance effect, and suggest that the genetic basis for pheromone reception and response in the species is more closely linked than previously thought.
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    Preliminary studies on wilt disease complex in cocoa
    (2006) Kannan, C.; Subaharan, K.
    The wilt disease complex ofcocoa was first noticed in India in 1998. in Karnataka. The leaves became yellow or brown, branches wilted and finally the plant died. Pods of the affected trees did not show any external symptoms, but shrivelled slowly leading to the death of the trees. The affected plants were consistently associated with Xylosandrus beetles which inhabited short pin hole borings made by them. Several fungi were found associated with the disease of which Ceratocystis sp.? was found to be consistently present. Pathogenicity trials with inoculation of Ceratocystis sp.? by wound inoculation-cotton plugging method produced internal symptoms of wilt in the seedlings. Field trials with systemic chemicals showed that the diseased plants recovered when Propiconazole @ 0.2 %, and Imidacloprid @ 0.2 % were used simultaneously as whole plant drenching. The incidence of fresh infection was Jess when compared with the other treatments.