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Insecticide susceptibility of field-collected populations of Culex tritaeniorhynchus in the Republic of Korea.

Yoo DH, Shin EH, Lee DK, Ahn YJ, Chang KS, Kim HK, Kim SY, Park C - J. Insect Sci. (2013)

Bottom Line: Extremely high to low levels of susceptibility were measured: bifenthrin, susceptible ratio (SR) = 2.7-896.3; β-cyfluthrin, SR = 1.8-633.3; α-cypermethrin, SR = 1.2-1,051.9; deltamethrin, SR = 1.3-711.1; permethrin, SR = 1.5-1,053.4; etofenprox, SR = 2.2-29.3; chlorfenapyr, SR = 5.1-103.6; chlorpyrifos, SR = 2.3- 337.0; fenitrothion, SR = 2.0-142.3; and fenthion, SR = 1.4-186.2.Cx. tritaeniorhynchus populations from rice paddies had been under heavy selection pressure due to the agricultural insecticides, and that's why the mosquito species demonstrated high resistance to pyrethroids, which were used for a long time to control agricultural pests in the localities.These results indicate that careful selection and rotational use of these insecticides may result in continued satisfactory control against field populations of Japanese encephalitis vector mosquitoes.

View Article: PubMed Central - PubMed

Affiliation: Division of Medical Entomology, National Institute of Health, Chungcheongbuk-do 363-951, Republic of Korea.

ABSTRACT
The toxicities of 10 insecticides were examined against late third instar Culex tritaeniorhynchus Giles (Diptera: Culicidae) using the direct-contact mortality bioassay. Six geospatially-distant field mosquitoes were collected from Chuncheon-si, Hwaseong, Seosan. Jeonju, Daegu, and Busan in the Republic of Korea. Marked regional variations of insecticide susceptibility were observed. Field populations of Seosan, Jeonju, and Daegu from agricultural areas showed higher to extremely higher insecticide susceptibility to pyrethroids than those of Chuncheon-si, Hwaseong, and Busan strains from non-agricultural areas. Extremely high to low levels of susceptibility were measured: bifenthrin, susceptible ratio (SR) = 2.7-896.3; β-cyfluthrin, SR = 1.8-633.3; α-cypermethrin, SR = 1.2-1,051.9; deltamethrin, SR = 1.3-711.1; permethrin, SR = 1.5-1,053.4; etofenprox, SR = 2.2-29.3; chlorfenapyr, SR = 5.1-103.6; chlorpyrifos, SR = 2.3- 337.0; fenitrothion, SR = 2.0-142.3; and fenthion, SR = 1.4-186.2. Cx. tritaeniorhynchus populations from rice paddies had been under heavy selection pressure due to the agricultural insecticides, and that's why the mosquito species demonstrated high resistance to pyrethroids, which were used for a long time to control agricultural pests in the localities. These results indicate that careful selection and rotational use of these insecticides may result in continued satisfactory control against field populations of Japanese encephalitis vector mosquitoes.

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Locations of larvae collections. High quality figures are available online.
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f01_01: Locations of larvae collections. High quality figures are available online.

Mentions: Six different colonies of Cx. tritaeniorhynchus were established from larvae collected near rice paddy fields and cow sheds in Chuncheon (designated CC-CT; 37° 52′ 56.19″ N, 127° 46′ 12.16″ E), Hwaseong (HS-CT; 37° 12′ 18.40″ N, 126° 50′ 53.19″ E), Busan (BS-CT; 35° 12′ 21.73″ N, 129° 12′ 5.31″ E), Seosan (SS-CT; 36° 42′ 27.49″ N, 126° 28′ 23.97″ E), Jeonju (JJ-CT; 35° 54′ 54.63″ N, 127° 0′ 31.23″ E), and Daegu (DG-CT; 36° 8′ 47.78″ N, 128° 21′ 57.27″ E) from early August to mid-September 2011 (Figure 1). Field strains of CC-CT and HS-CT were collected from small swamps near hog barns, which were surrounded by mountains and at least 3km from a farming village. The BS-CT collection site was an area of small swamps near a hog barn along an urban area, and was surrounded by factories. Field strains of SS-CT, JJ-CT, and DG-CT were collected from small swamps near hog barns, which were surrounded by rice paddies and far from villages. The collected larvae were transferred to an insect rearing room at the Korean National Institute of Health Larvae were reared in plastic trays (27 × 15 × 4 cm) containing 0.5 g of sterilized diet (Vivid S:Super Terramin, 4:1 by weight) (Sewhapet, http://sewhapet.en.ec21.com/). Adult mosquitoes were maintained on a 10% sucrose solution, and were allowed to blood-feed on mice under an approved animal use protocol. All cages were maintained at 27 ± 1° C, with 65–75% relative humidity (RH) and a 12:12L:D photoperiod.


Insecticide susceptibility of field-collected populations of Culex tritaeniorhynchus in the Republic of Korea.

Yoo DH, Shin EH, Lee DK, Ahn YJ, Chang KS, Kim HK, Kim SY, Park C - J. Insect Sci. (2013)

Locations of larvae collections. High quality figures are available online.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3735112&req=5

f01_01: Locations of larvae collections. High quality figures are available online.
Mentions: Six different colonies of Cx. tritaeniorhynchus were established from larvae collected near rice paddy fields and cow sheds in Chuncheon (designated CC-CT; 37° 52′ 56.19″ N, 127° 46′ 12.16″ E), Hwaseong (HS-CT; 37° 12′ 18.40″ N, 126° 50′ 53.19″ E), Busan (BS-CT; 35° 12′ 21.73″ N, 129° 12′ 5.31″ E), Seosan (SS-CT; 36° 42′ 27.49″ N, 126° 28′ 23.97″ E), Jeonju (JJ-CT; 35° 54′ 54.63″ N, 127° 0′ 31.23″ E), and Daegu (DG-CT; 36° 8′ 47.78″ N, 128° 21′ 57.27″ E) from early August to mid-September 2011 (Figure 1). Field strains of CC-CT and HS-CT were collected from small swamps near hog barns, which were surrounded by mountains and at least 3km from a farming village. The BS-CT collection site was an area of small swamps near a hog barn along an urban area, and was surrounded by factories. Field strains of SS-CT, JJ-CT, and DG-CT were collected from small swamps near hog barns, which were surrounded by rice paddies and far from villages. The collected larvae were transferred to an insect rearing room at the Korean National Institute of Health Larvae were reared in plastic trays (27 × 15 × 4 cm) containing 0.5 g of sterilized diet (Vivid S:Super Terramin, 4:1 by weight) (Sewhapet, http://sewhapet.en.ec21.com/). Adult mosquitoes were maintained on a 10% sucrose solution, and were allowed to blood-feed on mice under an approved animal use protocol. All cages were maintained at 27 ± 1° C, with 65–75% relative humidity (RH) and a 12:12L:D photoperiod.

Bottom Line: Extremely high to low levels of susceptibility were measured: bifenthrin, susceptible ratio (SR) = 2.7-896.3; β-cyfluthrin, SR = 1.8-633.3; α-cypermethrin, SR = 1.2-1,051.9; deltamethrin, SR = 1.3-711.1; permethrin, SR = 1.5-1,053.4; etofenprox, SR = 2.2-29.3; chlorfenapyr, SR = 5.1-103.6; chlorpyrifos, SR = 2.3- 337.0; fenitrothion, SR = 2.0-142.3; and fenthion, SR = 1.4-186.2.Cx. tritaeniorhynchus populations from rice paddies had been under heavy selection pressure due to the agricultural insecticides, and that's why the mosquito species demonstrated high resistance to pyrethroids, which were used for a long time to control agricultural pests in the localities.These results indicate that careful selection and rotational use of these insecticides may result in continued satisfactory control against field populations of Japanese encephalitis vector mosquitoes.

View Article: PubMed Central - PubMed

Affiliation: Division of Medical Entomology, National Institute of Health, Chungcheongbuk-do 363-951, Republic of Korea.

ABSTRACT
The toxicities of 10 insecticides were examined against late third instar Culex tritaeniorhynchus Giles (Diptera: Culicidae) using the direct-contact mortality bioassay. Six geospatially-distant field mosquitoes were collected from Chuncheon-si, Hwaseong, Seosan. Jeonju, Daegu, and Busan in the Republic of Korea. Marked regional variations of insecticide susceptibility were observed. Field populations of Seosan, Jeonju, and Daegu from agricultural areas showed higher to extremely higher insecticide susceptibility to pyrethroids than those of Chuncheon-si, Hwaseong, and Busan strains from non-agricultural areas. Extremely high to low levels of susceptibility were measured: bifenthrin, susceptible ratio (SR) = 2.7-896.3; β-cyfluthrin, SR = 1.8-633.3; α-cypermethrin, SR = 1.2-1,051.9; deltamethrin, SR = 1.3-711.1; permethrin, SR = 1.5-1,053.4; etofenprox, SR = 2.2-29.3; chlorfenapyr, SR = 5.1-103.6; chlorpyrifos, SR = 2.3- 337.0; fenitrothion, SR = 2.0-142.3; and fenthion, SR = 1.4-186.2. Cx. tritaeniorhynchus populations from rice paddies had been under heavy selection pressure due to the agricultural insecticides, and that's why the mosquito species demonstrated high resistance to pyrethroids, which were used for a long time to control agricultural pests in the localities. These results indicate that careful selection and rotational use of these insecticides may result in continued satisfactory control against field populations of Japanese encephalitis vector mosquitoes.

Show MeSH
Related in: MedlinePlus