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
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.
Available from: H. Ranjbar Aghdam
- "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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DESCRIPTION: Applying a precise forecasting method is necessary to achieve acceptable results in IPM programs. Performances of the wing and delta pheromone traps for forecasting the codling moth phenology were compared with physiological time data based on Degree-Hours. Six pheromone traps (three wing and three delta style) were applied for the monitoring of the codling moth population. Traps were placed in an apple orchard in Tehran Province, Damavand region by the start of bloom. All traps were checked every week and the number of moths caught was recorded. Physiological time was estimated by using hourly recoded temperature, considering temperature thresholds for codling moth development. The results showed that the delta style traps statistically caught more male moth than wing traps. It was also shown that the results of the pheromone traps data were affected severely by weather conditions. Moreover, false fluctuations in recorded data from pheromone traps made some false population peaks, the interpretation of which was very hard. On the other hand, forecasting model based on the physiological time data, was not affected by the mentioned conditions and its results was easy to use for determination of the pest phenology without further interpretations.
Available from: Tomáš Středa
- "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).
Available from: Phil J. Lester
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ABSTRACT: Mechanistic models for predicting species’ distribution patterns present particular advantages and challenges relative to models developed from statistical correlations between distribution and climate. They can be especially useful for predicting the range of invasive species whose distribution has not yet reached equilibrium. Here, we illustrate how a physiological model of development for the invasive Argentine ant can be connected to differences in micro-site suitability, population dynamics and climatic gradients; processes operating at quite different spatial scales. Our study is located in the subalpine shrubland of Haleakala National Park, Hawaii, where the spread of Argentine ants Linepithema humile has been documented for the past twenty-five years. We report four main results. First, at a microsite level, the accumulation of degree-days recorded in potential ant nest sites under bare ground or rocks was significantly greater than under a groundcover of grassy vegetation. Second, annual degree-days measured where population boundaries have not expanded (456–521 degree-days), were just above the developmental requirements identified from earlier laboratory studies (445 degree-days above 15.9°C). Third, rates of population expansion showed a strong linear relationship with annual degree-days. Finally, an empirical relationship between soil degree-days and climate variables mapped at a broader scale predicts the potential for future range expansion of Argentine ants at Haleakala, particularly to the west of the lower colony and the east of the upper colony. Variation in the availability of suitable microsites, driven by changes in vegetation cover and ultimately climate, provide a hierarchical understanding of the distribution of Argentine ants close to their cold-wet limit of climatic tolerances. We conclude that the integration of physiology, population dynamics and climate mapping holds much promise for making more robust predictions about the potential spread of invasive species.
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