Biology, ecology, and management of walnut husk fly (Diptera: Tephritidae)

Walnut husk fly, Rhagoletis completa (Cresson), is a major pest of English walnut, Juglans regia Linn. This pest is native to Southern and Central United States, and has since spread to many parts of North America. Walnut husk fly is also considered an invasive species and significant pest in many walnut-growing countries in Europe. Walnut husk fly larvae feed directly on the fruit’s husk (mesocarp) tissue, and can cause shell (endocarp) staining, kernel (seed) shriveling and darkening, and increased adherence of hulls which can interfere with nut processing. Growers typically rely on monitoring and well-timed insecticide applications to control husk fly adults, though stricter regulations on insecticides limit their spray options. Since the current options for biological and cultural control are limited, the use of novel lure types and entomopathogens are being explored in recent research. The shifting economic market, stricter regulations, and nontarget pesticide effects highlight a need for a deeper understanding of this pest, robust monitoring tools, and alternative management methods. This study discusses the life history, biology, seasonal ecology of walnut husk fly, and current integrated pest management practices in walnut orchards.