Browsing by Author "Hapuarachchi, D.C.L."

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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 .