Further investigations on the development of insecticide resistance in Helopeltis theivora (Heteroptera : Miridae) from cocoa estates of Peninsular Malaysia. - (:unkn) unknown (My University)
Seven populations of Helopeltis theivora from cocoa estates of Peninsular Malaysia were assayed for resistance to insecticides using the FAO continuous exposure method. Insecticides tested were gamma-HCH, cypermethrin, deltamethrin, alpha-cypermethrin and lambda-cyhalothrin. LT50s so obtained were compared with that for a susceptible population collected from the ornamental plant Acalypha sp. Resistance ratios of 5.62, 5.64, 3.78 and 3.29 were obtained for gamma-HCH from the Sitiawan, Estate A Bagan Datoh, Estate B Bagan Datoh and Teluk Intan populations respectively. These ratios represented clear resistance to meaningful tolerance to have set in with the mirid populations. Such results agreed with reports of increasingly poor control with gamma-HCH in these estates in the early 1990s. All Helopeltis populations tested showed no resistance to the synthetic pyrethroids. This provided support for the appropriateness of the Malaysian cocoa industry's move towards the use of this group of insecticides as alternatives to gamma-HCH for mirid control, this being especially significant in the light of recent legislature disallowing use of gamma-HCH in the crop.
22 ref.
Seven populations of Helopeltis theivora from cocoa estates of Peninsular Malaysia were assayed for resistance to insecticides using the FAO continuous exposure method. Insecticides tested were gamma-HCH, cypermethrin, deltamethrin, alpha-cypermethrin and lambda-cyhalothrin. LT50s so obtained were compared with that for a susceptible population collected from the ornamental plant Acalypha sp. Resistance ratios of 5.62, 5.64, 3.78 and 3.29 were obtained for gamma-HCH from the Sitiawan, Estate A Bagan Datoh, Estate B Bagan Datoh and Teluk Intan populations respectively. These ratios represented clear resistance to meaningful tolerance to have set in with the mirid populations. Such results agreed with reports of increasingly poor control with gamma-HCH in these estates in the early 1990s. All Helopeltis populations tested showed no resistance to the synthetic pyrethroids. This provided support for the appropriateness of the Malaysian cocoa industry's move towards the use of this group of insecticides as alternatives to gamma-HCH for mirid control, this being especially significant in the light of recent legislature disallowing use of gamma-HCH in the crop.
Keywords: Aia.; Arthropoda.; Helopeltis.; Hemiptera.; Heteroptera.; Insecta.; Insecticidas.; Miridae.; Plaguicidas.; Resistencia a agentes dañinos.; resistencia quimica; Sterculiaceae.; Theobroma cacao.; Theobroma.