Article

Physiological Time Model for Predicting Adult Emergence of Western Corn Rootworm (Coleoptera: Chrysomelidae) in the Texas High Plains

Department of Entomology, Texas Cooperative Extension, The Texas A&M University System, 115-A Agronomy Field Laboratory, Texas A&M University, College Station, TX 77843-2488, USA.
Journal of Economic Entomology (Impact Factor: 1.51). 11/2008; 101(5):1584-93. DOI: 10.1603/0022-0493(2008)101[1584:PTMFPA]2.0.CO;2
Source: PubMed

ABSTRACT

Field observations at three locations in the Texas High Plains were used to develop and validate a degree-day phenology model to predict the onset and proportional emergence of adult Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) adults. Climatic data from the Texas High Plains Potential Evapotranspiration network were used with records of cumulative proportional adult emergence to determine the functional lower developmental temperature, optimum starting date, and the sum of degree-days for phenological events from onset to 99% adult emergence. The model base temperature, 10 degrees C (50 degrees F), corresponds closely to known physiological lower limits for development. The model uses a modified Gompertz equation, y = 96.5 x exp (-(exp(6.0 - 0.00404 x (x - 4.0), where x is cumulative heat (degree-days), to predict y, cumulative proportional emergence expressed as a percentage. The model starts degree-day accumulation on the date of corn, Zea mays L., emergence, and predictions correspond closely to corn phenological stages from tasseling to black layer development. Validation shows the model predicts cumulative proportional adult emergence within a satisfactory interval of 4.5 d. The model is flexible enough to accommodate early planting, late emergence, and the effects of drought and heat stress. The model provides corn producers ample lead time to anticipate and implement adult control practices.

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    • "The rate of development of codling moth is governed by environmental temperature (Rock and Shaffer, 1983;Ranjbar Aghdam et al., 2009). The concept of using heat unit accumulation or degree days to explain codling moth activity originated in to develop from one point to another in its life cycle is called physiological time and is calculated as degree-days (DD) or more precisely based on degree-hours (DH) unit (Roltsch et al., 1999;Howell and Neven, 2000;Stevenson et al., 2008). Many mathematical methods are developed to estimate more precisely growing degree days (GDD) or growing degree hours (GDH) (Roltsch et al., 1999). "
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    • "Ávila et al. (2002) observed 449 SET DD based on the average daily soil temperature above 11.04°C at 0.10 m depth under maize canopy. Stevenson et al. (2008) calculated the sum of degree-days for phenological events from the emergence onset to 99% adult WCR emergence. According to this model, the initial occurrence of WCR (1% occurrence ) is expected after the air SET above 10°C and 600 DD. Baker et al. (2003) and MacLeod et al. (2007) used a CLIMEX model to identify the critical parameter to define the northward limit of WCR distribution in North America, i.e. an accumulated temperature threshold, and then applied this model to the United Kingdom at improved spatial and temporal resolutions under current and future climates. "
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    ABSTRACT: The sum of effective temperature (SET) of adult Western Corn Rootworm (WCR) occurrence was determined based on several criteria. The risk of WCR occurrence was mapped, and the areas of continuous reproduction of WCR in the Czech Republic were identified. The daily soil SET, until the initial adult WCR occurrence was observed, ranged from 414 degree days (DD) when the lower threshold temperature (LTT) 12.5°C at 0.02 m depth to 719 DD (LTT of 10°C at a depth of 0.05 m). The daily air SET ranged from 415 DD (LTT 12.5°C at a height of 2 m) to 726 DD (LTT of 10°C at a height of 0.05 m).
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