Identification of potential predators of western bean cutworm (Striacosta albicosta) in field corn through molecular gut-content analysis

Abstract

Western bean cutworm, Striacosta albicosta (Smith; Lepidoptera: Noctuidae), is a major pest of corn and dry beans in its historic and expanded ranges in the North American western Great Plains and Great Lakes Region, respectively. In corn, S. albicosta ear feeding damage can significantly reduce yield and introduce avenues for secondary fungal infections. Management practices currently rely on transgenic crops expressing effective Bacillus thuringiensis (Bt) protein, of which only the VIP3A protein is effective against S. albicosta, and/or labor-intensive scouting and chemical control. However, limited research on biological control options for this critical pest has been conducted. This study identifies key trophic interactions between S. albicosta and predatory arthropods in corn fields. Field surveys identified a community of 21 predator taxa present in Nebraska corn fields where S. albicosta eggs and larvae were present. The most common taxa were as follows: Hippodamia convergens (Guérin-Méneville; Coleoptera: Coccinellidae), Coleomegilla maculata (De Geer; Coleoptera: Coccinellidae), Orius insidiosus (Say; Hemiptera: Anthocoridae), and green lacewings (Neuroptera: Chrysopidae). Additionally, molecular gut-content analysis via PCR confirmed the predation of S. albicosta by several well-known biological control agents, including H. convergens, O. insidiosus, C. maculata, and Chrysopidae larvae and adults. Coleomegilla maculata consumed more S. albicosta eggs and larvae than H. convergens in feeding trials, although egg consumption by C. maculata was unaffected by the presence of corn pollen, an important supplemental food for this species. Exploring the trophic interactions between S. albicosta and its predators will provide information necessary to improve conservation biological control for S. albicosta integrated pest management.