Using climatology to predict the first major summer corn earworm (Lepidoptera: Noctuidae) catch in north central Illinois
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One of the largest food production companies in the United States, with sales in the billions of dollars, must closely monitor anything that may affect their vegetable crops. This includes harmful insects, such as the corn earworm (CEW) (Helicoverpa zea), that can reduce sweet corn yields and cause losses of approximately 12 million dollars annually in the Midwest. For this study, a major sweet corn production area located in north central Illinois was used to evaluate CEW moth flight characteristics. The initial major CEW catch (i.e. when 10 or more CEWs were caught in a field trap within a 24 h period) occurs on average around 20 August. However, during the period from 1960 to 2005 the first major catch occurred between 1 August and 16 September. If climatological information can be used to anticipate the initial major CEW arrival, then pest management strategies can be better implemented and field losses reduced. Seven of 13 years with an early first major CEW arrival (1 to 15 August) occurred when accumulated growing degree days (GDDs with a base of 10 °C) were >917 and the number of warm nights (minimum temperatures ≥18.3 °C) was above average (>21 days) from 1 May to 31 July, while 7 of 13 years with a late first major CEW arrival (24 August to 16 September) occurred when accumulated GDDs <853, the number of warm nights was <18 days, and the number of days with an average air flow from the south was <30 between 1 May and 31 July.