Browsing by Author "Fernando, L.C.P."

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    Advances in research on biological control of the coconut mite, Aceria Guerreronis Keifer in Sri Lanka
    (2009) Aratchige, N.S.; Fernando, L.C.P.; Kumara, A.D.N.T.; Suwandharathne, N.I.; Perera, K.F.G.; Hapuarachchi, D.C.L.; de Silva, P.H.P.R.
    Biological control is considered as the most economical, sustainable and environment-friendly approach for the control of coconut mite, Aceria Guerreronis Keifer. In Sri. Lanka, several research have been done on the local predatory mite, Neoseiulus baraki Athias-Henriot and the entomopathogenic fungus, Hirsutella thompsonii Fisher to evaluate their effectiveness against the coconut mite in an augmentative biological control approach. This paper reports the development in research on N. baraki and H, thompsonii in Sri Lanka as potential biological control agents of the coconut mite. Two technologies, "dry culture" arena method and the "sachet" method were developed for mass rearing of N. baraki. The effect of a single augmentative release of N. baraki in the field to reduce the coconut mite populations was not consistently significant. Release of N. baraki at the rate of 5000 mites/ palm in two-months intervals increases the number of nuts with discontinued damage scars and reduces the number of nuts that are sold at half-price in the harvest. H. thompsonii isolate IMI 391722 showed the highest efficacy in reducing the coconut mite populations. Single application of//. thompsonii in the field is effective only for a short duration. Application of the fungus both at 2- and 3-month intervals caused similar mortality levels of the coconut mites. Perspectives of these findings in the biological control of coconut mite are discussed.
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    Effect of Application Frequency of the Entomopathogenic Fungus Hirsutellathompsonii (Fisher) on Damage Levels of Coconut Mite Aceriaguerreronis (Keifer)
    (2012) Fernando, L.C.P.; Hapuarachchi, D.C.L.; Waidyarathne, K.P.
    The effect of application interval of H. thompsonii(Fisher) on damage caused by the coconut mite,Aceriaguerreronis(Keifer) (Acari: Eriophyidae) in two coconut plantations in Sri Lanka was evaluated.In each plantation, coconut palms infested by coconut mite were treated with H. thompsonii isolate IMI 391722 at 2- and 3-monthly intervals and the fruits with H. thompsonii-infected coconut mite cadavers and percentage of harvested fruits in different damage categories were assessed.Infected coconut mite cadavers were found on up to 60% of the fruits treated with the fungus in both plantations at treatment frequencies. The effect of the treatments was site-specific.The treatments reduced the percentage of damaged-small size harvested fruits to half that of the untreated control in both plantations irrespective of the frequency of treatment.At one plantation, the percentages of undamaged fruits and fruits with discontinued damage were nearly doubled to that of untreated fruits .
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    Portable acoustic device for detection of coconut palms infested by Rynchophorus ferrugineus (Coleoptera: Curculionidae)
    (2010) Siriwardena, K.A.P.; Fernando, L.C.P.; Nanayakkara, N.; Perera, K.F.G.; Kumara, A.D.N.T.; Nanayakkara, T.
    Acoustic methods have been developed and used to detect insects in concealed habitats. The larvae of red palm weevil, Rynchophorus ferrugineus (Olivier), a serious pest of the coconut palm, Cocos nucifera L. feed on the soft tissues inside the stem and bud region. Detection of infested coconut palms in the early stages by the conventional method of checking for external symptoms is time consuming, labour intensive and costly. This paper describes the development of a portable and efficient acoustic device and its potential in detection of infested palms in the field. The device comprises a sensor to mount on the palm and to acquire the sounds of red palm weevil larvae, an electronic unit that processes the acquired sounds and a set of headphones to receive the output sound by the listener. It is light weight, user-friendly andpowered by batteries. The highest accuracy of identifying infested palms was obtained when the palm was checked at four positions; either side of palm base and bases of the two lowermost leaves. The infested palms were detected with over 97% accuracy, while the probability of not detecting uninfested palms was over 92%. A second check increased the rate of accuracy. Many difficulties encountered with conventional methods could be overcome by the use of this device.
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    Rearing of coconut mite Aceria guerreronis and the predatory mite Neoseiulus baraki in the laboratory
    (Springer Science, 2008) de Silva, P.H.P.R.; Fernando, L.C.P.
    A method was developed for the rearing of coconut mite, Aceria guerreronis Keifer (Acari: Eriophyidae), and its predatory mite Neoseiulus baraki (Athias-Henriot) (Acari: Phytoseiidae) on embryo culture seedlings of coconut (Cocos nucifera) in the laboratory. Seedlings in the ages of <2, 2–4 and 4–6 months were infested with 75 Weld- collected coconut mites and the population growth was determined up to six weeks after introduction. The populations of coconut mites increased exponentially up to Wve weeks after introduction and declined thereafter on seedlings of all ages with signiWcant diVer- ences among the three groups of seedlings occurring over time. At week 5, a signiWcantly higher mean number (§SE) of coconut mites (20,098 § 3,465) was bred on 4–6-month-old seedlings than on smaller seedlings, and on the largest seedlings the numbers were highest at all time intervals, except at week 2. Neoseiulus baraki was reared on embryo culture seedlings of the three age groups infested with coconut mites, by introduction of Wve female deutonymphs and one male, three weeks after introducing coconut mites. Predator numbers progressed signiWcantly over time, but the size of seedlings did not signiWcantly inXuence the numbers. On all groups of seedlings, the mean number of N. baraki increased up to two weeks after introduction on to seedlings and then declined. Many coconut mites were successfully reared in the laboratory for a longer period by this method and it could also be used as an alternative method to rear N. baraki. Development of this method may contribute to the progress of studies on the biology and ecology of coconut mite and its interactions with natural enemies.
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    Toxins Produced by Fusarium Species in Leaf Scorch Decline Affected Coconut Palms (Cocos nucifera L.): Quantitative Analysis of Fusaric Acid, Zearalenone and T-2
    (2009) Siriwardhana, P.H.A.P.; Fernando, L.C.P.; Jayasundara, J.M.M.A.
    Leaf Scorch Decline (LSD) is a disorder of coconut (Cocos nucifera L.) prevalent in Sri Lanka, for which the etiology is yet unknown and hence a study was conducted to identity the toxins produced by Fusarium spp. associated with LSD-affected palms. Root, stem and leaf tissues of LSD-affected and healthy palms were used to analyze the toxin content. Gas Chromatographic (GC) analysis carried out for Fusaric acid (FA), Zearalenone (ZEA) and T-2 (a Trichothecene) revealed the presence of FA in stem or leaves of many affected palms, but not in any of the roots. Total FA in stem and leaves was significantly higher (p>0.01) in affected palms than in healthy palms. Healthy palms were free of FA. Although ZEA and T-2 were present in both healthy and affected palms, the only significant difference between the two groups was ZEA in stem tissues. A strong association between FA and the presence of ZEA suggest they influence the production of LSD symptoms. The similarity of symptoms of Fusarium wilt diseases in other plants and LSD are discussed.
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    Use of polypropylene bags for mass rearing Neoseiulus baraki (Acari: Phytoseiidae), a predatory mite of Aceria guerreronis Keifer (Acari: Eriophyidae)
    (2014) Kumara, A.D.N.T.; Fernando, L.C.P.; Suwandhrathne, N.I.; Aratchige, N.S.
    An efficient, low cost and practicable mass rearing method for the predatory mite, Neoseiulus baraki Athias-Henriot (Acari: Phytoseiidae) was developed using a bag made of two-ply polypropylene (gauge 150, 24 cm × 36 cm) sheets. Introducing 20 N. baraki females into the bag produced a mean number 5218 ± 212.10 offspring in 6 weeks with a 260-fold increase of the initial population.