Phenology models predict timing of events in an organism's development. For many organisms which cannot internally regulate their own temperature, development is dependent on temperatures to which they are exposed in the environment.
Information in this database comes from published articles. It may be used in conjunction with field monitoring and a degree-day calculator.
Note: Before using a model that was not field tested in your location, you should test the model for one or more seasons under your conditions to verify that it will work for you.
Model 1
Pickel, C., N. C. Welch, and D. B. Walsh. 1990. Timing Lygus sprays using degree-days in Central Coast Strawberries. Santa Cruz County Agricultural Extension Publication.
- Location of study: Santa Cruz County, California (field studies)
- Lower developmental threshold: 54.0°F (12.2°C)
- Method of calculation: Single Sine
Degree-day accumulations required for each stage of development
Host: Strawberries
- Eggs: 252.0 (°F) 140.0 (°C)
- Nymphs: 371.0 (°F) 206.1 (°C)
- Generation time (egg to adult): 623.0 (°F) 346.1 (°C)
- Pre-egglaying adults: 176.0 (°F) 97.8 (°C)
- Generation time (egg to egg): 799.0 (°F) 443.9 (°C)
- Lygus develop on weeds in the spring. When they migrate to strawberries they are pests.
Biofix: First Lygus adult found in strawberries
Host: Strawberries
- Time to treat: 252.0 (°F) 140.0 (°C)
- This is when nymphs are hatching from eggs laid by first adults.
- Next time to treat: 1051.0 (°F) 583.9 (°C)
- This is when the next generation of nymphs will be hatching.
Biofix: First Lygus nymph found in weeds
Host: Weeds
- Pretreat interval: 799.0 (°F) 443.9 (°C)
- This is when the next generation of nymphs start hatching. TREAT 5-7 DAYS LATER.
Model 2
Sevacherian, V., V. M. Stern, and A. J. Mueller. 1977. Heat accumulation for timing Lygus control measures in a safflower-cotton complex. J. Econ. Entomol. 70: 399-402.
- Location of study: Westside of San Joaquin Valley, California (field studies)
- Lower developmental threshold: 52.0°F (11.1°C)
- Method of calculation: Double Triangle
Degree-day accumulations required for each stage of development
Start date: April 1
Host: Safflower
One generation develops on the safflower in the spring. The resulting adults then migrate to cotton where they are pests.
- Optimum time to treat: 668.6 (°F) 371.5 (°C)
- This is when 50-70% of the Lygus are 3rd to 5th instar nymphs.
Model 3
Champlain, R. A., and G. D. Butler, Jr. 1967. Temperature effects on development of the egg and nymphal stages of Lygus hesperus (Hemiptera: Miridae). Ann. Ent. Soc. Amer. 60: 519-521.
- Location of study: Tucson, Arizona (laboratory studies)
- Lower developmental threshold: 46.4°F ( 8.0°C)
- Upper developmental threshold: 104.0°F (40.0°C)
- Method of calculation: not specified (UC IPM recommends Single Sine)
- Cutoff method: not specified (UC IPM recommends Vertical)
Degree-day accumulations required for each stage of development
Host: Green beans
- Eggs: 259.2 (°F) 144.0 (°C)
- Nymphs: 507.8 (°F) 282.1 (°C)
- Generation time (egg to adult): 767.0 (°F) 426.1 (°C)
