Yebakima A

References (3)

Title : GENE-dosage effects on fitness in recent adaptive duplications: ace-1 in the mosquito Culex pipiens - Labbe_2014_Evolution_68_2092
Author(s) : Labbe P , Milesi P , Yebakima A , Pasteur N , Weill M , Lenormand T
Ref : Evolution , 68 :2092 , 2014
Abstract : Gene duplications have long been advocated to contribute to the evolution of new functions. The role of selection in their early spread is more controversial. Unless duplications are favored for a direct benefit of increased expression, they are likely detrimental. In this article, we investigated the case of duplications favored because they combine already functionally divergent alleles. Their gene-dosage/fitness relations are poorly known because selection may operate on both overall expression and duplicates relative dosage. Using the well-documented case of Culex pipiens resistance to insecticides, we compared strains with various ace-1 allele combinations, including two duplicated alleles carrying both susceptible and resistant copies. The overall protein activity was nearly additive, but, surprisingly, fitness correlated better with the relative proportion of susceptible and resistant copies rather than any absolute measure of activity. Gene dosage is thus crucial, duplications stabilizing a "heterozygote" phenotype. It corroborates the view that these were favored because they fix a permanent heterosis, thereby solving the irreducible trade-off between resistance and synaptic transmission. Moreover, we showed that the contrasted successes of the two duplicated alleles in natural populations depend on genetic changes unrelated to ace-1, confirming the probable implication of recessive sublethal mutations linked to structural rearrangements in some duplications.
ESTHER : Labbe_2014_Evolution_68_2092
PubMedSearch : Labbe_2014_Evolution_68_2092
PubMedID: 24494966

Title : Evolution of resistance under insecticide selection pressure in Culex pipiens quinquefasciatus (Diptera, Culicidae) from Martinique - Yebakima_2004_J.Med.Entomol_41_718
Author(s) : Yebakima A , Marquine M , Rosine J , Yp-Tcha MM , Pasteur N
Ref : Journal of Medical Entomology , 41 :718 , 2004
Abstract : Population surveys of Culex pipiens quinquefasciatus carried out in 1991 and 1999 were compared with data collected in 1990 before the beginning of the control program against this mosquito. Larval samples collected in 1999 displayed resistance to the four tested insecticides: permethrin, propoxur, temephos, and chlorpyrifos. Temephos resistance ratio at LC50 (RR50) ranged between 8.1- and 42-fold compared with 2.9- and 4.6-fold in 1990, and chlorpyrifos RR50 ranged between 8.6- and 123-fold compared with 6.4- and 19-fold in 1990. This increased resistance to organophosphorus insecticides was associated with a sharp decrease of susceptible genotypes at two loci (Ester and ace-1), as well as to an allele replacement at the Ester locus.
ESTHER : Yebakima_2004_J.Med.Entomol_41_718
PubMedSearch : Yebakima_2004_J.Med.Entomol_41_718
PubMedID: 15311466

Title : Resistance to organophosphorous insecticides in Culex pipiens quinquefasciatus (Diptera: Culicidae) from Martinique - Yebakima_1995_J.Med.Entomol_32_77
Author(s) : Yebakima A , Raymond M , Marquine M , Pasteur N
Ref : Journal of Medical Entomology , 32 :77 , 1995
Abstract : Before beginning a widespread control program against Culex pipiens quinquefasciatus in Martinique, resistance to temephos, chlorpyrifos, and two organophosphorous insecticides, was investigated at seven breeding sites. At LC95, populations exhibited resistance ratios between 6.9 and 11.6 for temephos and between 6.4 and 51.4 for chlorpyrifos. Overproduced esterases A2-B2 and B1, known to be involved in organophosphorous-resistance, were present at all breeding sites; esterases A2-B2 frequency was > 50% at all sites but one; and esterase B1 frequency was < 7%. Experimental treatment of three breeding sites with temephos induced no significant increase in resistance, but our esterase studies indicated a significant increase in the frequencies of esterase B1 and of a new highly active esterase C2. These results indicate that a large-scale C. p. quinquefasciatus control program with organophosphorous insecticides will induce a rapid increase of these resistance genes throughout Martinique. However, this may not necessarily result in high levels of resistance, because, at present, the level of gene amplification of esterase B still appears to be low.
ESTHER : Yebakima_1995_J.Med.Entomol_32_77
PubMedSearch : Yebakima_1995_J.Med.Entomol_32_77
PubMedID: 7541837