The culture filtrate of a plant pathogenic fungus that infected Zinnia elegans and Hydrangea macrophylla was investigated for mosquitocidal constituents by bioassay guided isolation. The fungus responsible for the pat...The culture filtrate of a plant pathogenic fungus that infected Zinnia elegans and Hydrangea macrophylla was investigated for mosquitocidal constituents by bioassay guided isolation. The fungus responsible for the pathogenic effects on Zinnia elegans and Hydrangea macrophylla plants had been identified as Nigrospora spherica by molecular techniques. The mosquito adulticidal constituent in the culture filtrate was identified as phomalactone by spectroscopic techniques. Laboratory bioassays showed that phomalactone had larvicidal activity against permethrin susceptible and resistant Aedes aegypti larvae and topical adulticide activities on permethrin susceptible and resistant Aedes aegypti and Anopheles quadrimaculatus mosquitoes. Phomalactone was effective as a topical adulticide against the standard Orlando reference strain of Ae. aegypti with an LD50 of 0.64 μg/org. Activity against An. quadrimaculatus was 0.20 μg/org.展开更多
This study examines the genetic variations and mechanisms involved in the development of permethrin resistance in individual mosquitoes from a field population of Culex quinquefasciatus, HAmCq^G0, and characterizes su...This study examines the genetic variations and mechanisms involved in the development of permethrin resistance in individual mosquitoes from a field population of Culex quinquefasciatus, HAmCq^G0, and characterizes susceptible reference lines of mosquitoes with a similar genetic background to the field HAmCq^G0 strain. Six upregulated cytochrome P450 genes, CYP9M10, CYP9J34, CYP6P14, CYP9J40, CYP6AA7, and CYP4C52v1, previously identified as being upregulated in the larvae of resistant HAmCq68 mosquitoes were examined in the larvae of 3 strains （susceptible S-Lab, parental HAmCq^G0 and permethrin-selected highly resistant HAmCq68） and 8 HAmCq^G0 single- egg raft colonies, covering a range of levels of susceptibility/resistance to perrnethrin and exhibiting different variations in the expression of A and/or T alleles at the L-to-F kdr locus of the sodium channel. The 2 lines with the lowest tolerance to permethrin and bearing solely the susceptible A allele at the L-to-F kdr locus of the sodium channels, from colonies Cx_SERC5 and Cx_SERC8, showed lower or similar levels of all 6 of the P450 genes tested compared with the S-Lab strain, suggesting that these 2 lines could be used as the reference mosquitoes in future studies characterizing insecticide resistance in HAmCq mosquitoes. This study also provides a detailed investigation of the mechanisms involved in insecticide resistance in individuals within a population： individuals with elevated levels of resistance to permethrin all displayed one or more potential resistance mechanisms-either elevated levels of P450 gene expression, or L-to-F mutations in the sodium channel, or both.展开更多
文摘The culture filtrate of a plant pathogenic fungus that infected Zinnia elegans and Hydrangea macrophylla was investigated for mosquitocidal constituents by bioassay guided isolation. The fungus responsible for the pathogenic effects on Zinnia elegans and Hydrangea macrophylla plants had been identified as Nigrospora spherica by molecular techniques. The mosquito adulticidal constituent in the culture filtrate was identified as phomalactone by spectroscopic techniques. Laboratory bioassays showed that phomalactone had larvicidal activity against permethrin susceptible and resistant Aedes aegypti larvae and topical adulticide activities on permethrin susceptible and resistant Aedes aegypti and Anopheles quadrimaculatus mosquitoes. Phomalactone was effective as a topical adulticide against the standard Orlando reference strain of Ae. aegypti with an LD50 of 0.64 μg/org. Activity against An. quadrimaculatus was 0.20 μg/org.
文摘This study examines the genetic variations and mechanisms involved in the development of permethrin resistance in individual mosquitoes from a field population of Culex quinquefasciatus, HAmCq^G0, and characterizes susceptible reference lines of mosquitoes with a similar genetic background to the field HAmCq^G0 strain. Six upregulated cytochrome P450 genes, CYP9M10, CYP9J34, CYP6P14, CYP9J40, CYP6AA7, and CYP4C52v1, previously identified as being upregulated in the larvae of resistant HAmCq68 mosquitoes were examined in the larvae of 3 strains （susceptible S-Lab, parental HAmCq^G0 and permethrin-selected highly resistant HAmCq68） and 8 HAmCq^G0 single- egg raft colonies, covering a range of levels of susceptibility/resistance to perrnethrin and exhibiting different variations in the expression of A and/or T alleles at the L-to-F kdr locus of the sodium channel. The 2 lines with the lowest tolerance to permethrin and bearing solely the susceptible A allele at the L-to-F kdr locus of the sodium channels, from colonies Cx_SERC5 and Cx_SERC8, showed lower or similar levels of all 6 of the P450 genes tested compared with the S-Lab strain, suggesting that these 2 lines could be used as the reference mosquitoes in future studies characterizing insecticide resistance in HAmCq mosquitoes. This study also provides a detailed investigation of the mechanisms involved in insecticide resistance in individuals within a population： individuals with elevated levels of resistance to permethrin all displayed one or more potential resistance mechanisms-either elevated levels of P450 gene expression, or L-to-F mutations in the sodium channel, or both.
