Dectes stem borers, Dectes texanus texanus LeConte, can cause serious lodging in soybean. Beetle numbers can be estimated using a sweep net, but these numbers can be very small and do not predict soybean damage. We examined two sampling techniques over 7 weeks of beetle activity and at 4 times of the day to see how these variables affected the number of beetles collected. Sweep net samples indicated beetle numbers increased from 0 on 3 July to 2.9 beetles/50 sweeps on 24 July and then decreased slowly to 0.1 beele/50 sweeps on 21 Aug. Visual samples indicated beetle numbers increased from 0 on 3 July to 3.4 beetles / 50 ft on 10 July and then decreased rapidly to 0 to 1 / 50 ft after that. In samples taken at different times of the day, sweep net samples did not differ significantly across four sample times, but the 10:30 am samples were the highest. In visual samples the 10:30 am sample was significantly higher than the three other sample times. Beetle counts in visual samples were higher than sweep net samples on one sample date, but on other dates they were very low. Beetle counts in sweep net samples were relatively low throughout the season, but at the end of the season 71% of the soybean plants were infested.
Species 1: Coleoptera Cerambycidae Dectes texanus texanus (Dectes stem borer, Soybean stem borer)
Keywords: Soybean IPM
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