Malays. Appl. Biol. (1998) 27(1 & 2): 83-85
STUDIES ON THE RESISTANCE STATUS OF COCOA MIRID TO ?-HCH, CYPERMETHRIN AND DELTAMETHRIN
DZOLKHIFLI OMAR1*, RITA MUHAMAD1 and LIEW VOON KHEONG2
1Dept. of Plant Protection, Faculty of Agriculture, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor
2Pusat Perkhidmatan Pertanian Tun Razak, Sg Tekam, Jerantut, Pahang, Malaysia
ABSTRACT
Phe response of the cocoa mirid, Helopeltis theivora, collected from Sungai Tekam areas to ?-HCH, deltamethrin and sypermethrin was determined through continuous exposure to a single concentration. The lethal time taken to knockdown 50% of the tested mirid (LT50) was obtained by probit analysis. The LT500 values of the cocoa mirids collected from an area of PKT 3, 4 and 8/18 to ?-HCH were high compared with the pooled natural population indicating a greater tolerance of the populations. The LT to cypermethrin could not be established for the mirid collected from PKT 4 and 8/18 as nc knockdown was observed after 600 min of exposure. Nevertheless, the mirids from these areas were still susceptible tc deltamethrin as there was only slight increase in the LT50 values compared with the pooled population. The high degree of tolerance exhibited by the cocoa mirid to ?-HCH and cypermethrin indicates a possible development of resistance.
ABSTRAK
Respon kepinding nyamuk, Helopeltis theivora yang dikutip dari kawasan Sungai Tekam terhadap ?-HCH, deltametrin dan sipermetrin telah ditentukan melalui pendedahan berterusan kepada satu kepekatan. Masa yang diambil untuk merebahkan 50% kepinding nyamuk yang diuji (LT50) diperolehi melalui analisis probit. Nilai LT50 kepinding nyamuk yang dikutip dari kawasan PKT 3, 4 dan 8/18 terhadap ?-HCH adalah tinggi berbanding kepada populasi yang digabung. Ini menunjukkan ketahanan yang tinggi populasi tersebut terhadap ?-HCH. Nilai LT50 kepinding nyamuk yang dikutip dari PKT 4 dan 8/18 terhadap sipermetrin tidak boleh ditentukan disebabkan tiada kerebahan yang dicatat 600 minit selepas rawatan. Walau bagaimanapun, kepinding nyamuk dari kawasan ini masih peka terhadap deltametrin di mana hanya terdapal sedikit pertambahan nilai LT50. Ketinggian darjah ketahanan yang ditunjukkan oleh mirid terhadap ?-HCH dan sipermetrin menunjukkan kemungkinan perkembangan keresistanan.
Key words: Cocoa mirid, cypermethrin, deltamethrin, ?-HCH, resistance
REFERRENCES
Busvine, J.R. 1980. Recommended methods for measurement of pest resistance to pesticides. FAO Plant Production and Protection Paper No. 2I.FAO, Rome, 132pp.
Dzolkhifli, O., Khoo, K.C., Muhamad, R. and Ho, C.T. 1986. The susceptibility of 3 strains of Helopeltis theobromae Miller (Hemiptera: Miridae) to gamma-HCH, propoxur and dioxacarb. In: Cocoa and Coconuts: Progress and Outlook, (eds. E. Pushparajah and P.S. Chew), pp. 317-323, Kuala Lumpur: Incorporated Society of Planters.
Finney, D.J. 1971. Probit Analysis, 3rd ed. Cambridge University Press, Cambridge. 333 pp.
Lok, Y.F. 1985. Resistance of Helopeltis theobromae Miller (Hemiptera: Miridae) to insecticides. B.Sc. Project, Faculty of Agriculture, UPM. 20 pp.
Muhamad, R. and Dzolkhifli, O. 1997. Susceptibility of the cocoa mirid, Helopeltis theivora Waterhose, to y-HCH, cypermethrin and deltamethrin. Resistant Pest Management, 9: 34-36.
Muhamad, R. and Khoo, K.C. 1983. A technique for rearing the cocoa mirid, Helopeltis theobromae Miller, in captivity. MAPPS Newsletter, 7(11), Supplement: 8-10.
Way, M.J. and Khoo, K.C. 1989. Relationships between Helopeltis theobromae damage and ants with special reference to Malaysian cocoa smallholding. Journal of Plant Protection in the Tropics. 6: 13-18.
