IPPC Degree-Day Models including Douglas-Fir Needle Midge

(Contarinia spp.)

Len Coop, IPPC, OSU CorvallisFeb 22, 2013

Phenology and degree-day concepts

Some features of the IPPC "Online weather data and degree-days" website at http://uspest.org/wea

Development and use of the Douglas-fir needle midge model

Topics for today's session:

"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:

Insects have complex life cyclese.g. Douglas-fir needle midge

(Contarinia spp.)EggsLarvaePupae (most)Adults

-Timing of stages *is often*predictable using degree-days, which area two dimensional “heatunit“ of development for cold blooded organisms

Degree-day calculations – method varies:Simplest: (daily max + min)/2 – low

threshold

Single triangle compared with typical daily fluctuation

How fast are they going?

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

70o(avg)-50o(threshold)=20DD

Degree-day model development: A bit more detail

35 40 45 50 55 60 65 70 75 80 85 90 950

25

50

75

100

125

150

175

200

Temperature vs. development time

Development time (days)

Temperature (F)

Day

sDeveloping degree-day models from lab studies

35 40 45 50 55 60 65 70 75 80 85 90 950

0.005

0.01

0.015

0.02

0.025

0.03

0.035

0.04

0.045

0.05

0.055

0.06

Temperature versus development

Development time (days)

Rate (1/days)

Temperature (F)

Ra

te (

1/d

ays

)Degree-day models: x-intercept method (Arnold 1959)

x-intercept ~ Tlow = 37 F

1/slope = 1/0.0011 = 920 ~ DD requirement

Pest Management: Monitoring plays a major role

especially since populations are cyclical (due to natural enemies or to swarming conditions

perhaps?)2012: 22 traps in 22 fields, 44 flies total

2011: 23 traps in 22 fields, 206 flies total2010: 21 traps in 20 fields, 2 flies

total2009: 47 traps in 47 fields, >500 flies total; swarming notedBox

trapSticky trap

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 – developed by field data using lowest error methods

Here is how version 1 of the model looks:

Phenology Models – developed by field data using lowest error methods

Here is how version 1 of the model looks w/2012 data:

Phenology Models – developed by field data using lowest error methods

http.uspest.org/wea

DFNM linked from PNW Insect Management Handbook – ID photos and DD model

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”

DD model example output – Corvallis 2013

DD model output(cont.)

DD model output (cont.)

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

What the model is telling us: timing can vary by 5 weeks or more

for cool vs. warm years

Pest Management: Spray or let natural enemies do their job? (avoid late sprays to protect later-emerging

parasitoids) Genus Platygaster

Genus GastrancistrusParasitoid wasp - family Pteromalidae

Parasitoid wasp - family Platygastridae

- Economic thresholds are lacking for christmas tree pests in general, would be especially helpful for DFNM

- More work should be conducted to distinguish the ID, biology, phenology, and parasitism of the three or more Contarinia species

Pest Management: Other considerations (cont.)

Summary Points:

IPPC uspest.org/wea has evolved as a hybrid for support of State, Regional, and National needs (>100 models, 17,000 weather stations)

New model interface uses Google maps for easier weather station selection

The new Douglas-fir needle midge DD model appears to succeed in taking on much of the 4-5 week year-to-year variability caused by weather.

Further work on biology of this pest complex is recommended!