Thrips species, population dynamics, and seed treatment effectiveness in dry beans

Dry bean (Phaseolus vulgaris L.) is an economically significant crop in the Midwest.Thrips can injure dry bean plants by feeding and ovipositing on leaves and flowers and transmit viruses causing diseases.Thrips are considered perceived pests in dry bean, because whether their injuries on dry bean cause any economic losses is unknown. In addition, whether dry bean varieties differ in their suitability as host for thrips has never been investigated. This study evaluated host suitability of six dry bean varieties for Western flower thrips, Frankliniella occidentalis, and onion thrips, Thrips tabaci, the top two species colonizing dry bean, under laboratory and field conditions. Thrips developmental time and reproduction rate on bean leaves were estimated through laboratory bioassays for six dry bean varieties, and thrips abundance on same varieties were compared under field conditions. Laboratory bioassays revealed that a great northern variety ‘Coyne’ and a pinto variety ‘Othello’ had the highest and lowest reproduction rate, respectively. Developmental time varied significantly among varieties by one day for F. occidentalis and one to two days for T. tabaci. In the field trial, a black bean variety ‘Eclipse’ had the highest thrips density, while a pinto variety ‘Wildcat’ had the lowest. The observed variations in thrips fitness and abundance across dry bean varieties suggest that certain varieties provide more favorable conditions for thrips population growth, whereas others exhibit traits limiting their development or survival.Overall, this study reveals varietal effects on thrips developmental and abundance and enhances understanding of thrips– dry bean interactions.