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ARS Home » Plains Area » Fargo, North Dakota » Edward T. Schafer Agricultural Research Center » Sunflower and Plant Biology Research » Research » Publications at this Location » Publication #338402
Title: Reassessment of resistance to sunflower stem weevil, Cylindrocopterus adspersus LeConte (Coleoptera: Curculionidae), in cultivated sunflower germplasm

Author
item Prasifka, Jarrad
item BRADSHAW, JEFFREY - University Of Nebraska
item AIKEN, ROBERT - Kansas State University

Submitted to: Journal of Kansas Entomological Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/12/2017
Publication Date: 6/12/2018
Citation: Prasifka, J.R., Bradshaw, J.D., Aiken, R.M. 2018. Reassessment of resistance to sunflower stem weevil, Cylindrocopterus adspersus LeConte (Coleoptera: Curculionidae), in cultivated sunflower germplasm. Journal of Kansas Entomological Society. 90(3):204-210. https://doi.org/10.2317/0022-8567-90.3.204.
DOI: https://doi.org/10.2317/0022-8567-90.3.204

Interpretive Summary: Sunflower stem weevil larvae feed within sunflower stems, causing stalk breakage and loss of harvestable yield. Previous studies found evidence that some sunflowers had useful resistance to the weevil, but the earlier studies did not compare the materials they identified as resistant to current inbreds or hybrids; they also did not account for the possibility that stem thickness helps determine the number of weevil larvae found in each stem. Field trials in Kansas (2012) and Nebraska (2015) showed that entries previously identified as resistant were only better (i.e., had fewer weevil larvae) than a handful of sunflower hybrids, and this seemed to be because the hybrids had thicker stalks. Though resistance to sunflower stem weevil and other stem-feeding pests may be possible, the cost and difficulty of developing host plant resistance, declining severity of the pest, and availability of other simple management options are significant disincentives to additional research.

Technical Abstract: Sunflower stem weevil, Cylindrocopturus adspersus LeConte (Coleoptera: Curculionidae), larval feeding on pith and vascular tissues can weaken stalks of cultivated sunflower, leading to breakage and loss of harvestable yield. Previous research has suggested host plant resistance (HPR) to this pest is possible, but results have been difficult to interpret because of limited comparisons to cultivated inbreds and hybrids, along with possible confounding effects of stem diameter. Trials in Kansas (2012) and Nebraska (2015) were used to help reassess the value of germplasm with putative resistance to sunflower stem weevil. Field tests in 2012 included 28 inbreds and hybrids and three entries previously identified as resistant; while a putative resistance source, PI 386230, was infested with fewer weevil larvae per stem than several hybrids, differences primarily appeared to be due differences in stem diameter, which is strongly correlated with the number of weevil larvae per stem. A follow-up trial in 2015 suggested differences in larval infestation were not attributable to other qualities in groups of germplasm that differ in stem diameter (i.e., males, females or hybrids), but that changes in plant density predictably alter both stem diameter and numbers of stem weevil larvae. Though resistance to sunflower stem weevil and other stem-feeding pests may be possible, the cost and difficulty of developing HPR, declining severity of the pest, and availability of other simple management options are significant disincentives to additional research.