Impact of aerial spraying of pyrethrin insecticide on Culex pipiens and Culex tarsalis (Diptera

Culicidae) abundance and West Nile virus infection rates in an urban/suburban area of Sacramento County, California

Dia Eldin A. Elnaiem, Kara Kelley, Stan Wright, Rhonda Laffey, Glenn Yoshimura, Marcia Reed, Gary Goodman, Tara Thiemann, Lisa Reimer, William Reisen, David Brown

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

In response to an epidemic amplification of West Nile virus (family Flaviviridae, genus Flavivirus, WNV), the Sacramento and Yolo Mosquito and Vector Control District (SYMVCD) sprayed ultralow-volume (ULV) formulations of pyrethrin insecticide (Evergreen EC 60-6: 6% pyrethrin insecticide, 60% piperonyl butoxide; MGK, Minneapolis, MN, applied as 0.003 kg/ ha [0.0025 lb/acre]) over 218 km2 in north Sacramento and 243.5 km2 in south Sacramento on three consecutive evenings in August 2005. We evaluated the impact of this intervention in north Sacramento on the abundance and WNV infection rates of Culex pipiens L. and Culex tarsalis Coquillett. Mortality rates of caged Cx. tarsalis sentinels ranged from 0% under dense canopy to 100% in open fields. A comparison of weekly geometric mean mosquito abundance in CO2-baited traps in sprayed and unsprayed areas before and after treatment indicated a 75.0 and 48.7% reduction in the abundance of Cx. pipiens and Cx. tarsalis, respectively. This reduction was statistically significant for Cx. pipiens, the primary vector of WNV, with highest abundance in this urban area, but not for Cx. tarsalis, which is more associated with rural areas. The infection rates of WNV in Cx. pipiens and Cx. tarsalis collected from the spray zone were 8.2 and 4.3 per 1,000 female mosquitoes in the 2 wk before and the 2 wk after applications of insecticide, respectively. In comparison, WNV infection rates in Cx. pipiens and Cx. tarsalis collected at same time interval in the unsprayed zone were 2.0 and 8.7 per 1,000, respectively. Based on the reduction in vector abundance and its effects on number of infective bites received by human population, we concluded that the aerial application of pyrethrin insecticide reduced the transmission intensity of WNV and decreased the risk of human infection.

Original languageEnglish (US)
Pages (from-to)751-757
Number of pages7
JournalJournal of Medical Entomology
Volume45
Issue number4
DOIs
StatePublished - Jul 1 2008

Fingerprint

Culex tarsalis
suburban areas
West Nile virus
Pyrethrins
Culex
Culex pipiens
Virus Diseases
Insecticides
pyrethrins
Culicidae
Diptera
spraying
insecticides
Infection
infection
Human Bites
Flaviviridae
Piperonyl Butoxide
Mosquito Control
aerial application

Keywords

  • California
  • Control
  • Mosquitoes
  • Vector-borne disease
  • West Nile virus

ASJC Scopus subject areas

  • Parasitology
  • veterinary(all)
  • Insect Science
  • Infectious Diseases

Cite this

Impact of aerial spraying of pyrethrin insecticide on Culex pipiens and Culex tarsalis (Diptera : Culicidae) abundance and West Nile virus infection rates in an urban/suburban area of Sacramento County, California. / Elnaiem, Dia Eldin A.; Kelley, Kara; Wright, Stan; Laffey, Rhonda; Yoshimura, Glenn; Reed, Marcia; Goodman, Gary; Thiemann, Tara; Reimer, Lisa; Reisen, William; Brown, David.

In: Journal of Medical Entomology, Vol. 45, No. 4, 01.07.2008, p. 751-757.

Research output: Contribution to journalArticle

Elnaiem, Dia Eldin A. ; Kelley, Kara ; Wright, Stan ; Laffey, Rhonda ; Yoshimura, Glenn ; Reed, Marcia ; Goodman, Gary ; Thiemann, Tara ; Reimer, Lisa ; Reisen, William ; Brown, David. / Impact of aerial spraying of pyrethrin insecticide on Culex pipiens and Culex tarsalis (Diptera : Culicidae) abundance and West Nile virus infection rates in an urban/suburban area of Sacramento County, California. In: Journal of Medical Entomology. 2008 ; Vol. 45, No. 4. pp. 751-757.
@article{518743d3672e48ba809e5272b9419b0a,
title = "Impact of aerial spraying of pyrethrin insecticide on Culex pipiens and Culex tarsalis (Diptera: Culicidae) abundance and West Nile virus infection rates in an urban/suburban area of Sacramento County, California",
abstract = "In response to an epidemic amplification of West Nile virus (family Flaviviridae, genus Flavivirus, WNV), the Sacramento and Yolo Mosquito and Vector Control District (SYMVCD) sprayed ultralow-volume (ULV) formulations of pyrethrin insecticide (Evergreen EC 60-6: 6{\%} pyrethrin insecticide, 60{\%} piperonyl butoxide; MGK, Minneapolis, MN, applied as 0.003 kg/ ha [0.0025 lb/acre]) over 218 km2 in north Sacramento and 243.5 km2 in south Sacramento on three consecutive evenings in August 2005. We evaluated the impact of this intervention in north Sacramento on the abundance and WNV infection rates of Culex pipiens L. and Culex tarsalis Coquillett. Mortality rates of caged Cx. tarsalis sentinels ranged from 0{\%} under dense canopy to 100{\%} in open fields. A comparison of weekly geometric mean mosquito abundance in CO2-baited traps in sprayed and unsprayed areas before and after treatment indicated a 75.0 and 48.7{\%} reduction in the abundance of Cx. pipiens and Cx. tarsalis, respectively. This reduction was statistically significant for Cx. pipiens, the primary vector of WNV, with highest abundance in this urban area, but not for Cx. tarsalis, which is more associated with rural areas. The infection rates of WNV in Cx. pipiens and Cx. tarsalis collected from the spray zone were 8.2 and 4.3 per 1,000 female mosquitoes in the 2 wk before and the 2 wk after applications of insecticide, respectively. In comparison, WNV infection rates in Cx. pipiens and Cx. tarsalis collected at same time interval in the unsprayed zone were 2.0 and 8.7 per 1,000, respectively. Based on the reduction in vector abundance and its effects on number of infective bites received by human population, we concluded that the aerial application of pyrethrin insecticide reduced the transmission intensity of WNV and decreased the risk of human infection.",
keywords = "California, Control, Mosquitoes, Vector-borne disease, West Nile virus",
author = "Elnaiem, {Dia Eldin A.} and Kara Kelley and Stan Wright and Rhonda Laffey and Glenn Yoshimura and Marcia Reed and Gary Goodman and Tara Thiemann and Lisa Reimer and William Reisen and David Brown",
year = "2008",
month = "7",
day = "1",
doi = "10.1603/0022-2585(2008)45[751:IOASOP]2.0.CO;2",
language = "English (US)",
volume = "45",
pages = "751--757",
journal = "Journal of Medical Entomology",
issn = "0022-2585",
publisher = "Entomological Society of America",
number = "4",

}

TY - JOUR

T1 - Impact of aerial spraying of pyrethrin insecticide on Culex pipiens and Culex tarsalis (Diptera

T2 - Culicidae) abundance and West Nile virus infection rates in an urban/suburban area of Sacramento County, California

AU - Elnaiem, Dia Eldin A.

AU - Kelley, Kara

AU - Wright, Stan

AU - Laffey, Rhonda

AU - Yoshimura, Glenn

AU - Reed, Marcia

AU - Goodman, Gary

AU - Thiemann, Tara

AU - Reimer, Lisa

AU - Reisen, William

AU - Brown, David

PY - 2008/7/1

Y1 - 2008/7/1

N2 - In response to an epidemic amplification of West Nile virus (family Flaviviridae, genus Flavivirus, WNV), the Sacramento and Yolo Mosquito and Vector Control District (SYMVCD) sprayed ultralow-volume (ULV) formulations of pyrethrin insecticide (Evergreen EC 60-6: 6% pyrethrin insecticide, 60% piperonyl butoxide; MGK, Minneapolis, MN, applied as 0.003 kg/ ha [0.0025 lb/acre]) over 218 km2 in north Sacramento and 243.5 km2 in south Sacramento on three consecutive evenings in August 2005. We evaluated the impact of this intervention in north Sacramento on the abundance and WNV infection rates of Culex pipiens L. and Culex tarsalis Coquillett. Mortality rates of caged Cx. tarsalis sentinels ranged from 0% under dense canopy to 100% in open fields. A comparison of weekly geometric mean mosquito abundance in CO2-baited traps in sprayed and unsprayed areas before and after treatment indicated a 75.0 and 48.7% reduction in the abundance of Cx. pipiens and Cx. tarsalis, respectively. This reduction was statistically significant for Cx. pipiens, the primary vector of WNV, with highest abundance in this urban area, but not for Cx. tarsalis, which is more associated with rural areas. The infection rates of WNV in Cx. pipiens and Cx. tarsalis collected from the spray zone were 8.2 and 4.3 per 1,000 female mosquitoes in the 2 wk before and the 2 wk after applications of insecticide, respectively. In comparison, WNV infection rates in Cx. pipiens and Cx. tarsalis collected at same time interval in the unsprayed zone were 2.0 and 8.7 per 1,000, respectively. Based on the reduction in vector abundance and its effects on number of infective bites received by human population, we concluded that the aerial application of pyrethrin insecticide reduced the transmission intensity of WNV and decreased the risk of human infection.

AB - In response to an epidemic amplification of West Nile virus (family Flaviviridae, genus Flavivirus, WNV), the Sacramento and Yolo Mosquito and Vector Control District (SYMVCD) sprayed ultralow-volume (ULV) formulations of pyrethrin insecticide (Evergreen EC 60-6: 6% pyrethrin insecticide, 60% piperonyl butoxide; MGK, Minneapolis, MN, applied as 0.003 kg/ ha [0.0025 lb/acre]) over 218 km2 in north Sacramento and 243.5 km2 in south Sacramento on three consecutive evenings in August 2005. We evaluated the impact of this intervention in north Sacramento on the abundance and WNV infection rates of Culex pipiens L. and Culex tarsalis Coquillett. Mortality rates of caged Cx. tarsalis sentinels ranged from 0% under dense canopy to 100% in open fields. A comparison of weekly geometric mean mosquito abundance in CO2-baited traps in sprayed and unsprayed areas before and after treatment indicated a 75.0 and 48.7% reduction in the abundance of Cx. pipiens and Cx. tarsalis, respectively. This reduction was statistically significant for Cx. pipiens, the primary vector of WNV, with highest abundance in this urban area, but not for Cx. tarsalis, which is more associated with rural areas. The infection rates of WNV in Cx. pipiens and Cx. tarsalis collected from the spray zone were 8.2 and 4.3 per 1,000 female mosquitoes in the 2 wk before and the 2 wk after applications of insecticide, respectively. In comparison, WNV infection rates in Cx. pipiens and Cx. tarsalis collected at same time interval in the unsprayed zone were 2.0 and 8.7 per 1,000, respectively. Based on the reduction in vector abundance and its effects on number of infective bites received by human population, we concluded that the aerial application of pyrethrin insecticide reduced the transmission intensity of WNV and decreased the risk of human infection.

KW - California

KW - Control

KW - Mosquitoes

KW - Vector-borne disease

KW - West Nile virus

UR - http://www.scopus.com/inward/record.url?scp=49249088350&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=49249088350&partnerID=8YFLogxK

U2 - 10.1603/0022-2585(2008)45[751:IOASOP]2.0.CO;2

DO - 10.1603/0022-2585(2008)45[751:IOASOP]2.0.CO;2

M3 - Article

VL - 45

SP - 751

EP - 757

JO - Journal of Medical Entomology

JF - Journal of Medical Entomology

SN - 0022-2585

IS - 4

ER -