1. Degree-Days, Climate and Mosquito Risks – Some Guidelines and Tools For Decision Support Len Coop, Integrated Plant Protection Center, Oregon State University, Corvallis OR Oct 17, 2013

2. Phenology and degree-day concepts Some features of the IPPC "Online weather data and degree-days" website at http://uspest.org/weahttp://uspest.org/wea Published results on mosquito phenology, weather, climate & habitat associations, other basic biology Topics for today's session: News this week: 46 million year-old blood-engorged mosquito (only 19 million yrs after dinosaurs went extinct)

3. "Who?" and "What?" Identification keys, diagnostic guides, management guides "When?" Phenology models (crops, insects, weeds), Risk models (plant diseases) "If?" Economic thresholds, crop loss models, sampling calculators, other decision tools "Where?" GIS, precision agriculture Typical IPM questions/decision tools:

4. Insects have complex life cycles e.g. Typical mosquito Eggs Larvae Pupae (most) Adults -Timing of stages *is often* predictable using degree-days, which are a two dimensional “heat unit“ of development for cold blooded organisms

5. Degree-day calculations – method varies: Simplest: (daily max + min)/2 – low threshold Single triangle compared with typical daily fluctuation How fast are they going?

6. Weather and Degree-day Concepts 1)Degree-day models: accumulate a daily "heat unit index" (DD total) until some event is expected (e. g. egg hatch) 38 20 18 32 14 22 20 26 daily: cumulative: 20 70 84 106 126 152 Eggs hatch: 152 cumulative DDs Eggs start developing: 0 DDs 70 o(avg) - 50 o(threshold) =20 DD

7. Degree-day model development: A bit more detail

8. Developing degree-day models from lab studies

9.  Degree-day models: x-intercept method (Arnold 1959) x-intercept ~ Tlow = 37 F 1/slope = 1/0.0011 = 920 ~ DD requirement

10. Monitoring data required for model building, validation and (sometimes) initiation to supply a “BIOFIX” starting date Trap data showing later emergence dates in N. Calif.

11. Need at least 3-4 years data from a variety of locations Doug fir needle midge – mostly from 1 trap/field, more than 20-47 fields 2009-2011 (provided by D. Silen) Plus data from OSU Extension 1990 Method is to vary the lower threshold and start date and use the value that provides lowest error Phenology Models – can bedeveloped from field data using lowest error methods

12. Here is how version 1 of the model looks w/2012 data: Phenology Models – developed by field data using lowest error methods

13. Mosquito Climate & Degree-days – Cornell 1. DDs in past week Tlow=50F

14. Mosquito Climate & Degree-days – Cornell 2. Date 1 st reaching 230 Dds - Normals Tlow=50F for planning – expected 1 st date of adult activity range of nearly 3 months in New England

15. Mosquito Climate & Degree-days – Cornell 3. Recent frost to suggest lowered risk

16. Mosquito Climate & Degree-days – Cornell 4. Normals – last Spring freeze to help control operations

17. Mosquito Climate & Degree-days – Cornell 5. Moisture Index in past week (Precip-PET) (high moisture may support breeding habitat)

18. Mosquito Climate & Degree-days – Cornell 6. Moisture Index over past season (Precip-PET) (high moisture may correlate with WNV reports)

19. Mosquito Climate & Degree-days – Cornell 7. Modeled relative abundance for current week (Experimental from Gong et al.)

20. Mosquito Climate & Degree-days – Cornell 8. Modeled seasonal abundance relative to Normals for a single station (Experimental from Gong et al.)

21. Focus on Culex tarsalis: (from Chen et al. 2013; modeling studies for the Canadian Prairies) Both Cx. tarsalis abundance and West Nile Virus infection rates were successfully modeled using 1 to 3 month prior temperatures/degree-days and precipitation, and land cover (agricultural, forest, and water). Implications for: -warning systems -climate change studies

22. Focus on Culex spp.: (another study from Chen et al. 2013; modeling studies for Pennsylvania; no time to digest this paper!)

23. http.uspest.org/wea

24. PNW Insect Management Handbook – ID photos and DD model links

25. New interface to DD Models – Douglas-fir needle midge http://uspest.org/cgi-bin/ddmodel.us?spp=dnm Google maps for location selection Nothing else to do but click “Calc”

26. DD model example output – Corvallis 2013

27. DD model output (cont.)

28. DD model output (cont.)

29. DD model output (cont.)

30. DD model output (cont.)

31. Watch for missing data/bad QA (quality assurance) reports e.g. Albany Weather Underground Flag for missing/interpolated data QA report not bad in this case

32. Focus on Culex tarsalis: (from Reisen et al. 2006) -Undergoes fall-winter reproductive diapause which interrupts arbovirus transmission. Diapause termination is temperature driven. -So a Degree-day model of C. tarsalis springtime activity is likely to be helpful. (e.g. Cornell 230 DDs after March 15 Tlow=50)

33. Focus on Culex tarsalis: (ex. Lab. Data from Reisen 1995 California-2 locations) Temperature-development rates 1. Immature Development: Tlow= 46F, 460 DDs Larval Stage

34. Focus on Culex tarsalis: (from Reisen 1995 California data) Temperature-development rates 2. Adult female life expectancy and generation time vs. temperature: Tlow= 46F, 401 & 948 DDs.

35. Focus on Culex tarsalis: (ex. from Reisen et al. 2006; California studies) Temperature-development rates 3. Gonotropic cycle: Tlow= 46F, 140 DDs blood meal to mature eggs

36. Focus on Culex tarsalis: (ex. from Reisen et al. 2006; California studies) Temperature-development rates 4. Extrinsic Incubation Rate: Tlow= 58F, 124 and 210 DDs for 20% and 50% WNV incubation (dissemination) rate.

37. Focus on Culex tarsalis: (mostly from Reisen et al. 1995 & 2006) Preliminary Basis for Degree-day Model (L. Coop)

38. Approximate Status of mosquito-relevant Degree-Days: 2013 CRVO Agrimet Corvallis OR DD accumulation on 10-15-13: 3259 (Tlow 46F), ca. 3 to 4 full generations of Culex tarsalis This year is about versus -------------------------- ---------- 50 days ahead 2012(3271 DDs Dec 31) DDs exceed full yr 2011(3050 DDs Dec 31) DDs exceed full yr 30-yr normals (3167 DDs Dec 31) This year (2013) has been the warmest in W. Oregon since 2003 (3277 DDs Oct 15; 3550 DDs Dec 31) (First WNV reported in Oregon in 2004)

39. Focus on Culex spp. (pipiens, restuans, tarsalis, stigmatosoma) -short days trigger overwintering for many species -overwinter as inseminated adult females in basements, outbuildings, subterranean locations w/high humidity (do not tolerate winter drought) -feed on carbohydrates (including flower nectar) for overwintering (not interested in a blood meal starting around Oct. 1 in this climate)

40. Focus on Culex spp. (pipiens, restuans, tarsalis, stigmatosoma) -larvae do not survive the winter here (too cool for development unless an artificially heated water source) -larvae have wide tolerance for organic matter and pollution -urban C. pipiens bite humans; rural C. pipiens mostly bite birds

41. Focus on Culex tarsalis: -females do not require blood meal for 1 st egg batch if conditions are favorable -prefer birds during spring, feed just after sunset; by late summer switch to mammals; a major cause of human disease by this vector -can fly 1-17 miles to find hosts -tolerate pollution, fresh & saline wetlands, prefer seasonal/intermittant rather than permanent water systems: is an early colonizer -most important vector of arboviruses in W. N. America: St. Louis, W. Equine Encephalitis, WNV; also vector of Llano Seco, Turlock, Gay Lodge, Hart Park virus, avian malaria,

42. Focus on Culex tarsalis: -rare East of Mississippi River -active during winter in S. California -larvae habitats shared w/Culiseta inornata, C. quinquefasciatus, C. pipiens, C. stigmatosoma, C. erythrothorax, C. restuans, sev. Spp. Aedes and Anopheles

43. Suggested improvements to a risk index (MA Dept Public Health, June 2012) - above average rainfall in the prior fall and spring, - mild winters with insulating snow cover, - infection activity in the previous year, - any arbovirus isolations from mosquitoes prior to July 1, - isolation of arbovirus from a mammal-biting species of mosquito, - infection of a human prior to mid-August, and - higher than average summer temperatures which accelerate the mosquito reproductive and development cycle and shorten the time interval between a mosquito becoming infected with EEE virus and when it becomes capable of transmitting the virus.

44. WNV Risk Index approaches: -Vector (mosquito) abundance only approach (using CO 2 trap counts for example) – Gujral et al. 2007 -Vector Abundance (A) x Infection Prevalence (P)(Vector index) (Kilpatrick et al. 2005)

45. Potential Indicators of Mosquito Risks: -Favorable weather for larval habitats Rainfall – Evapotranspiration -Favorable weather & bird counts for high Culex spp. mosquito numbers -Relatively warm temperatures for virus replication in mosquitoes: 58 degrees F and higher, (the higher outdoor temps, the faster WNV replication) (Reisen et al. 2006) -Cool evenings (temps < 50F) present lowered risk of WNV mosquito bites -Some risk in fall continues until a hard frost occurs (< 28F)

46. -From a study in S. Dakota, Cx. tarsalis associated w/grass&hay fields, cropland, and wetland, whereas A. vexans associated w/wetland, urban, and deciduous forest habitats (Chuang et al. 2011, J. Med. Entomol.)

47. Left: Culex pipiens Right: Aedes vexans (major vector) (not a major vector; may be a bridge vector)

48. Factors affecting West Nile Virus - Climate: – Worse during hot,wet summers in temperate climates – 2012 was worst year in US thus far (first cases NYC 1999); 2012 was hottest year E. of Rockies in a long time – Southern parts of US have been most heavily impacted (more generations, frequent summer rains)

49. Some mosquito notes: - New York City – 311 calls to report standing water – issue citations for violations (927 issued in 2012) – Ground (sewer catch basins) and aerial (large marsh areas) application of larvicides – Bird malaria (found to make birds more attractive to uninfected Cx. pipiens mosquitoes) (Cornet et al. 2013) – Lymphatic filariasis (yikes)

50. Summary Points: - Looks like good chance we can build a simple DD model of Culex spp. Springtime phenology and potential generation build-up & use in risk models. WNV extrinsic incubation threshold (58F) is significantly higher than life cycle of Cx. Tarsalis (46F), need a more complex model to account for both. With some good trapping data; we can continue building models for Oregon! Recent temps/DDs/rainfall/ET other measures of climate and weather show excellent prospects for online decision tools for mosquito/arbovirus risks. IPPC uspest.org/wea has evolved as a hybrid for support of State, Regional, and National needs (>100 models, 17,000 weather stations).