Knockdown Resistance (knockdown + resistance)

Distribution by Scientific Domains


Selected Abstracts


X-linked QTL for knockdown resistance to high temperature in Drosophila melanogaster

INSECT MOLECULAR BIOLOGY, Issue 4 2007
F. M. Norry
Abstract Knockdown Resistance to High Temperature (KRHT) is an adaptive trait of thermotolerance in insects. An interval mapping was performed on chromosome X of Drosophila melanogaster to search for quantitative trait loci (QTL) affecting KRHT. A backcross population was obtained from two lines that dramatically differ for KRHT. Microsatellites were used as markers. Composite interval mapping identified a large-effect QTL in the region of band 10 where putative candidate genes map. To further test for this QTL a set of recombinant (but non-inbred) lines was obtained from backcrosses between the parental lines used for the interval mapping. Recombinant line analysis confirmed that one QTL is targeted by band 10. We identify and discuss candidate loci contained within our QTL region. [source]


Knockdown resistance to DDT and pyrethroids: from target-site mutations to molecular modelling

PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 11 2008
TG Emyr Davies
Abstract Naturally derived insecticides such as pyrethrum and man-made insecticides such as DDT and the synthetic pyrethroids act on the voltage-gated sodium channel proteins found in insect nerve-cell membranes. The correct functioning of these channels is essential for the normal transmission of nerve impulses, and this process is disrupted by binding of the insecticides, leading to paralysis and eventual death. Some insect pest populations have evolved modifications of the sodium channel protein that inhibit the binding of the insecticide and result in the insect developing resistance. This perspective outlines the current understanding of the molecular processes underlying target-site resistance to these insecticides (termed kdr and super-kdr), and how this knowledge may in future contribute to the design of novel insecticidal compounds. Copyright 2008 Society of Chemical Industry [source]


X-linked QTL for knockdown resistance to high temperature in Drosophila melanogaster

INSECT MOLECULAR BIOLOGY, Issue 4 2007
F. M. Norry
Abstract Knockdown Resistance to High Temperature (KRHT) is an adaptive trait of thermotolerance in insects. An interval mapping was performed on chromosome X of Drosophila melanogaster to search for quantitative trait loci (QTL) affecting KRHT. A backcross population was obtained from two lines that dramatically differ for KRHT. Microsatellites were used as markers. Composite interval mapping identified a large-effect QTL in the region of band 10 where putative candidate genes map. To further test for this QTL a set of recombinant (but non-inbred) lines was obtained from backcrosses between the parental lines used for the interval mapping. Recombinant line analysis confirmed that one QTL is targeted by band 10. We identify and discuss candidate loci contained within our QTL region. [source]


New methods for the detection of insecticide resistant Myzus persicae in the U.K. suction trap network

AGRICULTURAL AND FOREST ENTOMOLOGY, Issue 3 2008
James A. Anstead
Abstract 1,Myzus persicae is a highly polyphagous pest of U.K. agriculture. It presents particular control difficulties because it has developed resistance to several insecticide classes. 2,For almost 20 years, M. persicae collected in the U.K. suction trap network have been analysed for insecticide resistance and the data disseminated to growers via a resistance bulletin. These data are generated by the biochemical analysis of individuals for two major resistance phenotypes: (i) elevated carboxylesterase and (ii) modified acetylcholinesterase (MACE). 3,The development of new polymerase chain reaction (PCR)-based technologies using fluorescently labelled probes has allowed other resistance mechanisms, such as knockdown resistance to pyrethroids (kdr/super-kdr), to be detected and has greatly increased the speed and accuracy of resistance monitoring. Unfortunately, these newer PCR-based assays are incompatible with the older biochemical assays. 4,The present study describes the development and testing of new compatible methods for detecting elevated carboxylesterases and MACE for use on M. persicae caught in the field or suction traps. 5,These new tests have significant advantages over present methodologies by allowing individual aphids to be tested for three resistance mechanisms quickly and accurately on a single platform. [source]


Widespread distribution of knockdown resistance mutations in the bed bug, Cimex lectularius (Hemiptera: Cimicidae), populations in the United States

ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY (ELECTRONIC), Issue 4 2010
Fang Zhu
Abstract We previously reported high deltamethrin resistance in bed bugs, Cimex lectularius, collected from multiple areas of the United States (Romero et al., 2007). Recently, two mutations, the Valine to Leucine mutation (V419L) and the Leucine to Isoleucine mutation (L925I) in voltage-gated sodium channel ,-subunit gene, had been identified to be responsible for knockdown resistance (kdr) to deltamethrin in bed bugs collected from New York (Yoon et al., 2008). The current study was undertaken to investigate the distribution of these two kdr mutations in 110 bed bug populations collected in the United States. Out of the 17 bed bug populations that were assayed for deltamethrin susceptibility, two resistant populations collected in the Cincinnati area and three deltamethrin-susceptible lab colonies showed neither of the two reported mutations (haplotype A). The remaining 12 populations contained L925I or both V419L and L925I mutations in voltage-gated sodium channel ,-subunit gene (haplotypes B&C). In 93 populations that were not assayed for deltamethrin susceptibility, 12 contained neither of the two mutations (haplotype A) and 81 contained L925I or V419L or both mutations (haplotypes B-D). Thus, 88% of the bed bug populations collected showed target-site mutations. These data suggest that deltamethrin resistance conferred by target-site insensitivity of sodium channel is widely spread in bed bug populations across the United States. 2010 Wiley Periodicals, Inc. [source]


Direct and correlated responses to selection for longevity in Drosophila buzzatii

BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2009
ALEJANDRA C. SCANNAPIECO
The possible associations between longevity, early fecundity, and stress-resistance traits were explored using artificial selection on longevity in a laboratory population of Drosophila buzzatii. Three replicated lines were selected for increased lifespan (L lines) and compared with the respective unselected controls (C lines) after the 14th generation of selection. Mean longevity exhibited a significant response to selection. The baseline mortality tended to decrease in the L lines and a negative correlated response to longevity selection was found for early fecundity. Egg-to-adult developmental time increased in L lines. Longevity selection increased stress resistance for both high and low temperatures, as measured by heat knockdown resistance and chill-coma recovery. Starvation resistance also tended to be higher in L than in C lines. The results obtained are consistent with the hypothesis of trade-offs between longevity and early fecundity, and also suggest a trade-off association between adult longevity and developmental time. Correlated selection responses were generally consistent with correlations among the traits previously inferred from altitudinal clines for longevity and stress-resistance phenotypes. 2009 The Linnean Society of London, Biological Journal of the Linnean Society, 2009, 97, 738,748. [source]