Temephos-resistant larvae of Simulium sanctipauli associated with a distinctive new chromosome inversion in untreated rivers of south-western Ghana
Item
Title
Temephos-resistant larvae of Simulium sanctipauli associated with a distinctive new chromosome inversion in untreated rivers of south-western Ghana
Date
2000
Language
English
Abstract
Larvae of the Simulium damnosum Theobald complex (Diptera:Simuliidae) were sampled in June 1996 from two sites in south-west Ghana where larviciding has not been applied: Sutri Rapids on the Tano river (05°23¢ N02°38¢ W) and Sekyere-Heman on the Pra river (05°11¢ N 01°35¢ W). All specimens were identi®ed as Simulium sanctipauli Vajime & Dunbar sensu stricto (Diptera:Simuliidae). Bioassays with temephos (organophosphorus larvicide employed by the Onchocerciasis Programme for systematic treatment of most rivers across West Africa since the 1970s) showed about ®ve-fold resistance in the Tano population (LC95 2.37±3.14 mg/L) and slight tolerance to temephos in the Pra population (LC950.67±0.76 mg/L), vs. the diagnostic concentration of 0.625 mg/L. Larval salivary polytene chromosomes of S. sanctipauli showed ®xed inversions 1S-24/24, standard IIL-6 and a new inversion IL/36 polymorphism at Sutri on the Tano. These karyotype characteristics differ from those of temephos-resistant S. sanctipauli in rivers of CoÃte d'Ivoire and other sites on the Tano in Ghana. Thus, temephos resistance in S. sanctipauli at Sutri is associated with distinct chromosomal configurations, showing that immigration was unlikely. This resistance could have been locally selected by exposure of S. sanctipauli larval populations to agrochemicals run-off from cocoa, coffee and oil plantations flanking the rivers.
Collection
Citation
“Temephos-resistant larvae of Simulium sanctipauli associated with a distinctive new chromosome inversion in untreated rivers of south-western Ghana,” CSIRSpace, accessed September 19, 2024, http://cspace.csirgh.com/items/show/2068.