RESEARCH: WEST NILE VIRUS IN ILLINOIS
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CHAMPAIGN-URBANA CROSSOVER MODEL
Experimental Data, for Champaign-Urbana Only — 2019
Models from
Previous Years:
Culex pipiens - Northern House Mosquito.
Photo courtesy Robin McLeod.
The white-spotted mosquito Culex restuan and the northern house mosquito Culex pipien are believed to maintain the natural transmission cycle of West Nile Virus between birds and mosquitoes in Illinois. During the spring and early
summer, the white-spotted mosquito is the dominant species and is responsible for mosquito-bird-mosquito transmission of WNV. As the weather warms, the northern house mosquito becomes more dominant. The female of this later species is probably responsible for the rapid amplification of the arbovirus among birds and may act as the major bridge vector to mammals, including humans in the Midwest. Two temperature-based climate models were developed to estimate the likely date when the northern house mosquito begins to become the dominant species, and thus when the risk of WNV to horses, humans, and other wildlife is likely to increase.
The information provided here is based on research conducted by scientists at the Midwestern Regional Climate Center at the Illinois State Water Survey and in the Entomology Laboratory of the Illinois Natural History Survey. This research is described in the following publication:
Kunkel, K.E., R. Novak, R. Lampman, and W. Gu, 2006: Modeling the impact of variable climatic factors on the crossover of Culex Restuans and Culex Pipiens (Diptera Culicidae) vectors of West Nile Virus in Illinois. American Journal of Tropical Medicine and Hygiene, 74, 168-173.
Westcott, N.E., and S.D. Hilberg, R.L. Lampman, B. W. Alto, A. Bedel, E.J. Muturi, H. Glahn, M. Baker, K.E., Kunkel, R.J. Novak, 2011: Predicting the Seasonal Shift in Mosquito Populations Preceding the Onset of the West Nile Virus in Central Illinois, Bulletin of the American Meteorological Society, 92,1173-1180.
8/4/2019 - the crossover date has been reached by both models for the 2019 season
MAXIMUM TEMPERATURE EXCEEDANCE MODEL (Threshold of 80°F):
How to interpret the model results -
| 81°F MAX TEMP MODEL - CURRENT MODEL RUN: | 7/31/2019 |
| Based on this model, there is: | |
| • a 50 percent chance that the crossover date will be later than | July 31, 2019 |
| • a 90 percent chance it will be earlier than | July 31, 2019 |
| • and a 10 percent chance it will be earlier than | July 31, 2019 |
| • The current run of the model has a median crossover date of | July 31, 2019 |
| • The earliest crossover date projected by the current model run is | July 31, 2019 |
| • The latest crossover date projected by the current model run is | July 31, 2019 |
Model Run History for the Current Year -
| 81°F Max Temp Model | |||||||
| Model Run Date 2018 | Probability that crossover will occur earlier than given date | ||||||
| Earliest | 10 percent | 25 percent | MEDIAN | 75 percent | 90 percent | Latest | |
| 5/1 | 7/11 | 7/24 | 7/30 | 8/9 | 8/21 | 8/29 | 10/1 |
| 5/8 | 7/18 | 7/27 | 8/2 | 8/12 | 8/24 | 9/2 | 10/8 |
| 5/15 | 7/14 | 7/20 | 7/25 | 8/1 | 8/14 | 8/21 | 9/21 |
| 5/22 | 7/16 | 7/22 | 7/26 | 8/1 | 8/12 | 8/19 | 9/18 |
| 5/29 | 7/25 | 7/29 | 8/3 | 8/10 | 8/21 | 8/30 | 9/27 |
| 6/5 | 7/28 | 8/1 | 8/6 | 8/13 | 8/20 | 8/31 | 9/25 |
| 6/12 | 7/30 | 8/1 | 8/5 | 8/11 | 8/19 | 8/28 | 9/17 |
| 6/19 | 8/4 | 8/6 | 8/10 | 8/14 | 8/23 | 8/31 | 9/23 |
| 6/26 | 8/9 | 8/11 | 8/13 | 8/19 | 8/27 | 9/2 | 9/21 |
| 7/3 | 8/9 | 8/10 | 8/12 | 8/17 | 8/24 | 8/30 | 9/15 |
| 7/10 | 8/9 | 8/9 | 8/11 | 8/15 | 8/21 | 8/28 | 9/12 |
| 7/17 | 8/9 | 8/9 | 8/10 | 8/13 | 8/18 | 8/23 | 9/5 |
| 7/24 | 8/10 | 8/10 | 8/10 | 8/12 | 8/16 | 8/20 | 9/1 |
| 7/31 | 7/31 | 7/31 | 7/31 | 7/31 | 7/31 | 7/31 | 7/31 |
DEGREE DAY MODEL:
How to Interpret the Model Results -
| DEGREE DAY MODEL - CURRENT MODEL RUN: | 8/7/2019 |
| Based on the current model run there is: | |
| • a 50 percent chance that the crossover date will be later than | August 4, 2019 |
| • a 90 percent chance it will be earlier than | August 4, 2019 |
| • and a 10 percent chance it will be earlier than | August 4, 2019 |
| • The current run of the model has a median crossover date of | August 4, 2019 |
| • The earliest crossover date projected by the current model run is | August 4, 2019 |
| • The latest crossover date projected by the current model run is | August 4, 2019 |
Model Run History for the Current Year -
| Degree Day Model | |||||||
| Model Run Date 2018 | Probability that crossover will occur earlier than given date | ||||||
| Earliest | 10 percent | 25 percent | MEDIAN | 75 percent | 90 percent | Latest | |
| 5/1 | 7/10 | 7/24 | 8/2 | 8/12 | 8/24 | 8/31 | 9/20 |
| 5/8 | 7/14 | 7/25 | 8/3 | 8/14 | 8/26 | 9/3 | 9/22 |
| 5/15 | 7/12 | 7/21 | 7/29 | 8/9 | 8/20 | 8/30 | 9/16 |
| 5/22 | 7/13 | 7/24 | 7/31 | 8/8 | 8/18 | 8/28 | 9/15 |
| 5/29 | 7/20 | 7/31 | 8/8 | 8/17 | 8/26 | 9/3 | 9/18 |
| 6/5 | 7/24 | 7/30 | 8/8 | 8/18 | 8/28 | 9/4 | 9/17 |
| 6/12 | 7/25 | 8/1 | 8/8 | 8/18 | 8/26 | 9/1 | 9/17 |
| 6/19 | 7/27 | 8/8 | 8/15 | 8/21 | 8/31 | 9/5 | 9/20 |
| 6/26 | 7/30 | 8/11 | 8/17 | 8/25 | 9/1 | 9/7 | 9/18 |
| 7/3 | 8/5 | 8/10 | 8/14 | 8/21 | 8/27 | 9/2 | 9/14 |
| 7/10 | 8/6 | 8/9 | 8/14 | 8/19 | 8/25 | 9/1 | 9/12 |
| 7/17 | 8/7 | 8/11 | 8/14 | 8/18 | 8/23 | 8/28 | 9/6 |
| 7/24 | 8/9 | 8/11 | 8/12 | 8/15 | 8/18 | 8/21 | 9/1 |
| 7/31 | 8/13 | 8/13 | 8/14 | 8/15 | 8/16 | 8/19 | 8/25 |
| 8/7 | 8/4 | 8/4 | 8/4 | 8/4 | 8/4 | 8/4 | 8/4 |
These graphs show the results of the individual model runs so far this season. As more of the “actual” weather is included in the model runs (i.e. as the summer progresses) and less “probable” weather (i.e. past climatology) is included, the plots of the dates will tend to converge on the crossover date.
NOTE: These models were derived from Champaign-Urbana, Illinois data. The threshold temperature may vary regionally.
