Degree-day accumulation to time initiation of sampling for alfalfa weevil using on-site, near-site, and regional temperature data Academic Article uri icon

abstract

  • In northern Wyoming alfalfa hay fields, on-site, near-site, and regional temperature data for accumulating degree-days was compared with the goal to initiate sampling for alfalfa weevil larvae after egg hatch and before the occurrence of third and fourth instars. On-site and near-site temperature data recorded every 30 min were obtained from portable recorders placed in selected fields, and regional data consisted of daily high and low temperatures recorded from weather stations located 1.5 to 16 km from the fields. For second instars, observed degree-days calculated from on-site and near-site data were associated with a 2-week period of highest occurrence of second instars. This observed degree-day window using on-site and near-site data overlapped with the expected degree-days for peak occurrence of the second instar (prediction based on a thermal summation model using a development-survival threshold of 10C) in 9 of 10 fields. Similarly, the observed degree-day window, calculated from the regional data, overlapped with the expected peak occurrence at all 10 fields. For third and fourth instars, the overlap of observed and expected degree-days also was similar using the regional data and the on-site and near-site data. Initiating sampling at the beginning of the degree-day window for second instars, the regional data would have triggered sampling about 1 week earlier than when using the on-site and near-site data. In regard to initiating sampling after egg hatch and before occurrence of the more damaging large larvae, use of on-site, near-site, and regional temperature data were equally as valuable. Given the complexities of the techniques and our application, use of the regional data from weather stations is preferable to on-site and near-site data for timing initiation of sampling for alfalfa weevil larvae.

published proceedings

  • Journal of Agricultural and Urban Entomology

author list (cited authors)

  • Brewer, M. J., & Hoff, K. M.

complete list of authors

  • Brewer, MJ||Hoff, KM

publication date

  • July 2002