Host preference, seasonal dynamics and management in soybean of Megacopta cribraria (Hemiptera: Plataspidae)
Blount, Joni Loran
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Megacopta cribraria (F.) also known as the kudzu bug, was introduced into the United States in 2009 from Asia. M. cribraria develops on two primary hosts, kudzu and soybean. Since its introduction M. cribraria has become a major pest of soybean and has increased in range from nine original counties in Georgia to 13 states. Field and greenhouse trials were conducted to evaluate the developmental host range of M. cribraria. Effects of planting date and maturity group on soybean yield response to injury by M. cribraria were also evaluated in replicated trials. How geographic region influences development of M. cribraria was examined in kudzu and soybean. Effects of single insecticide applications to soybean for control of mid-season M. cribraria were evaluated. Combined effects of M. cribraria and defoliating lepidopterans on yield were evaluated. Population changes by year were determined monitoring by kudzu from 2012 to 2015. Relative sampling was conducted weekly to bi-weekly depending on study and consisted of sweep samples, drop clothes, cross-vane flight intercept traps, and whole plant counts. Out of the 23 species and varieties evaluated, soybean, edamame and pigeon pea were show to be developmental hosts of M. cribraria. Two generations developed in early planted soybean and one developed in late planted soybean. Greater yield reductions occurred in April and May planted soybean than later plantings. Maturity group did not affect M. cribraria populations and yield reduction was comparable between comparisons. Geographic region has no consistent effect on development of M. cribraria. Comparisons of weeks at which 50% of nymph populations were present coincided with a four week period in July when a single insecticide application suppressed mid-season M. cribraria populations. M. cribraria populations decreased substantially in 2014 and 2015 compared to early years when monitored in kudzu from 2012-2015 and soybean sampled from 2011-2014. Threshold levels of M. cribraria and subthreshold levels of lepidopterans did not affect yield, suggesting economic thresholds for M. cribraria management may require re-evaluation. Studies conducted in this work provide useful information for understanding and managing M. cribraria as it persists in its North American range.