Population Dynamics of Heliothis zea (Lepidoptera: Noctuidae) as Influenced by Selected Soybean Cultural Practices

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Abstract
Corn earworm (CEW), Heliothis zea (Boddie), third filial egg and larval populations were monitored in field trials during 1980–82 in eastern North Carolina to investigate the effects of soybean planting date, cultivar, phenological stage, and degree of canopy development on CEW oviposition and survival. In 1982, soybeans were sampled every 3–4 d during the entire CEW F3 generation. This allowed for calculation of total within-generation production of eggs, egg parasitism, and stage-specific mortality. Planting date and phenological stage were the most important factors affecting CEW oviposition and survival. Late-planted soybeans had more eggs and higher insect survival than did early-planted soybeans, and treatments beyond the pod-set stage received few eggs. The highest correlations were found between the number of eggs and the number of plant terminals (r = 0.7) and flowers (r = 0.79). Greatest CEW mortality occurred between the egg stage and the third instar. Total incidence of natural enemies was higher in early-planted soybeans.