Susceptibility of sunflower inbred lines and putative resistance sources to Smicronyx fulvus LeConte (Coleoptera: Curculionidae)

Authors: Prasifka, Jarrad

Submitted to: Journal of Applied Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/6/2020
Publication Date: 6/5/2020
Citation: Prasifka, J.R. 2020. Susceptibility of sunflower inbred lines and putative resistance sources to Smicronyx fulvus LeConte (Coleoptera: Curculionidae). Journal of Applied Entomology. 144(7):632-636. https://doi.org/10.1111/jen.12772.
DOI: https://doi.org/10.1111/jen.12772

Interpretive Summary: The red sunflower seed weevil is beetle that feeds on seeds of cultivated sunflowers in North America. Some wild and cultivated sunflowers have resistance that causes them to be less damaged by the beetles than other sunflowers. Beetles were confined on several different types of sunflower including a new line, HA 488, developed to be resistant to the red sunflower seed weevil. Over two years of testing, inbred lines developed before HA 488 had 20-40% damaged seed. Seed damage to HA 488 was about 5%, and two other sunflower varieties believed to be resistant showed 13-14% damage. The results show that resistance in the new line, HA 488, can reduce damage from these seed-feeding beetles, a benefit that should work both with and without application of the insecticides commonly used to limit damage by the beetles.

Technical Abstract: The red sunflower seed weevil, Smicronyx fulvus LeConte (Coleoptera: Curculionidae), is a primary seed-feeding pest of cultivated sunflowers, Helianthus annuus L., in North America. Host plant resistance is one tool available to complement insecticide-based management of S. fulvus. Artificial infestations of 30 adult weevils per head were used to determine whether variation for susceptibility to S. fulvus exists in previously-released inbred lines, and how a new weevil-resistant line, HA 488, compares with other putative sources of resistance. Correcting for the number of seeds per head, 13 older inbred lines showed variation in percent seed damage from 20-38%, with two lines (HA 412 HO, HA 821) being more damaged than most of the tested lines. Among four resistance sources, HA 488 was significantly less damaged (5%) than two previously identified open-pollinated varieties (PI 170424, PI 253417, with 13-14% seed damage) while the source of the resistance in HA 488, PI 431542, was statistically intermediate (12%). While the resistance to S. fulvus available in HA 488 is a marked improvement, potentially reducing damage per weevil by two thirds or more, additional work on genetic markers for resistance, economic thresholds, and basic weevil biology (e.g., degree-day models for adult emergence) is needed to support implementation of integrated pest management for this key sunflower pest.