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 language | English (US) |
|---|---|
| Pages (from-to) | 751-757 |
| Number of pages | 7 |
| Journal | Journal of Medical Entomology |
| Volume | 45 |
| Issue number | 4 |
| DOIs | |
| State | Published - Jul 1 2008 |
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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 journal › Article
}
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 -