Research and IPM

Phenology Model Database

Corn Earworm, Cotton Bollworm, Tomato Fruitworm

Scientific name: Helicoverpa (Heliothis) zea

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.

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 of 3

Hartstack, A. W., Jr., J. P. Hollingsworth, R. L. Ridgeway, and J. D. Lopez. 1976. MOTHZV-2: A computer simulation of Heliothis zea and virescens population dynamics. User manual. 1976. U.S.D.A. ARS-S-127.

Location of study: College Station, Texas (field studies)

Developmental threshold

Lower:	54.7°F	(12.6°C)
Upper:	91.9°F	(33.3°C)

Method of calculation:	Single sine
Cutoff method:	Intermediate cutoff

Degree-day accumulations required for each stage of development

	DD (°F)	DD (°C)
Eggs:	72.9	40.5
Small larvae (1st - 3rd instars):	147.1	81.7
Large larvae (4 & 5th instars):	217.1	120.6
Pupae:	323.1	179.5
Generation time (egg to adult):	760.1	422.3
Pre-egglaying adults:	112.7	62.6
Generation time (adult to adult):	872.8	484.9

Model 2 of 3

Coop, L. B., B. A. Croft, and R. J. Drapek. 1993. Model of corn earworm (Lepidoptera: Noctuidae) development, damage, and crop loss in sweet corn. J. Econ. Entomol. 86: 906-916.

Location of study: Western Oregon (field and laboratory studies)

Method of calculation: Single Sine

Developmental threshold

Lower:	54.5°F	(12.5°C)

Degree-day accumulations required for each stage of development

Host: Cotton	DD (°F)	DD (°C)
Larvae:	360.0	200.0

Model 3 of 3

Butler, G. D., Jr. 1976. Bollworm: Development in relation to temperature and larval food. Environ. Entomol. 5: 520-522.

Location of study: Tucson, Arizona (laboratory studies)

Developmental threshold (Cotton)

Lower:	45.8°F	(7.7°C)
Upper:	93.2°F	(34.0°C)

Degree-day accumulations required for each stage of development

Host: Cotton	DD (°F)	DD (°C)
Larvae:	778.3	432.4

Developmental threshold (Corn)

Lower:	54.14°F	(12.3°C)
Upper:	93.2°F	(34.0°C)

Degree-day accumulations required for each stage of development

Host: Corn	DD (°F)	DD (°C)
Larvae:	491.6	273.1

Developmental threshold (Wheat germ media)

Lower:	54.86°F	(12.7°C)
Upper:	93.2°F	(34.0°C)

Degree-day accumulations required for each stage of development

Host: Wheat germ media	DD (°F)	DD (°C)
Larvae:	372.6	207.0
Pupae:	280.8	156.0