Research and IPM

Phenology Model Database

Twospotted Spider Mite

Scientific name: Tetranychus urticae

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 2

Carey, J. R., and J. W. Bradley. 1982. Developmental rates, vital schedules, sex ratios, and life tables for Tetranychus urticae, T. turkestani and T. pacificus (Acarina: Tetranychidae) on cotton. Acarologia 23: 333-345.

Location of study: Five Points, California (laboratory studies)

Developmental threshold

Lower:

53.1°F

(11.7°C)

Method of calculation: not specified (UC IPM recommends Single Sine)

Degree-day accumulations required for each stage of development

Host: Cotton	DD (°F)	DD (°C)
Eggs:	83.0	46.1
Larvae:	39.4	21.9
Protonymphs:	34.2	19.0
Deutoymphs:	38.7	21.5
Generation time (egg to adult):	195.5	108.6
Pre-egglaying adults:	21.4	11.9
Generation time (egg to egg):	216.9	120.5

Model 2 of 2

Herbert, H. J. 1982. Biology, life tables, and innate capacity for increase of the twospotted spider mite, Tetranychus urticae (Acarina: Tetranychidae). Can. Ent. 113: 371-378.

Location of study: Kentville, Nova Scotia (laboratory studies)

Developmental threshold

Lower:

50.0°F

(10.0°C)

Method of calculation: not specified (UC IPM recommends Single Sine)

Degree-day accumulations required for each stage of development

Host: Apple	DD (°F)	DD (°C)
Females:
Generation time (egg to adult):	260.1	144.5
Pre-egglaying adults:	45.5	25.3
Generation time (egg to egg):	305.6	169.8