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: 1.6). 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.

  • [Show abstract] [Hide abstract]
    ABSTRACT: BACKGROUND: Diabrotica speciosa (Germar) is an important pest in South America. Both the adults and the larvae are polyphagous, and its most susceptible host is maize. Factors behind the appearance of adults in the field and geographical variations in voltinism are unknown. This hinders the chances of implementing rational control strategies. RESULTS: This study compiles field collection data from four agricultural regions of Argentina to examine the number of generations and phenology of D. speciosa in the field. These data are correlated with climatic data in order to provide evidence of regional variations and probable environmental causes for the appearance of adult generations in the field. Results indicate that temperature has an important role in the appearance of new generations in the temperate distribution areas of D. speciosa, but not within its subtropical range, where teneral adults appeared all year round. CONCLUSION: Results suggest that the emergence of adults may be elicited by weekly average temperatures above 13 °C. In the temperate distribution areas of D. speciosa there could be at least three generations a year, and in the subtropical region at least five. No obvious or discrete voltinism pattern could be observed for D. speciosa in southern South America. © 2013 Society of Chemical Industry.
    Pest Management Science 01/2013; · 2.59 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    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).
    Plant Protection Science 01/2013; 49(2):89-97.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Field observations from pecan, Carya illinoinensis (Wangenh.) Koch, orchards in Texas were used to develop and validate a degree-day model of cumulative proportional adult flight and oviposition and date of first observed nut entry by larvae of the first summer generation of the pecan nut casebearer, Acrobasis nuxvorella Nuenzig (Lepidoptera: Pyralidae). The model was initiated on the date of first sustained capture of adults in pheromone traps. Mean daily maximum and minimum temperatures were used to determine the sum of degree-days from onset to 99% moth flight and oviposition and the date on which first summer generation larvae were first observed penetrating pecan nuts. Cumulative proportional oviposition (y) was described by a modified Gompertz equation, y = 106.05 x exp(-(exp(3.11 - 0.00669 x (x - 1), with x = cumulative degree-days at a base temperature of 3.33 degrees C. Cumulative proportional moth flight (y) was modeled as y = 102.62 x exp(- (exp(1.49 - 0.00571 x (x - 1). Model prediction error for dates of 10, 25, 50, 75, and 90% cumulative oviposition was 1.3 d and 83% of the predicted dates were within +/- 2 d of the observed event. Prediction error for date of first observed nut entry was 2.2 d and 77% of model predictions were within +/- 2 d of the observed event. The model provides ample lead time for producers to implement orchard scouting to assess pecan nut casebearer infestations and to apply an insecticide if needed to prevent economic loss.
    Journal of Economic Entomology 06/2010; 103(3):735-43. · 1.60 Impact Factor