Artificially Infesting Sunflower Helianthus annus L. Field Plots with Sunflower Stem Weevil Cylindrocopturus adspersus (LeConte) (Coleoptera: Curculionidae) to Evaluate Insecticidal Control

摘要

The sunflower stem weevil Cylindrocopturus adspersus (LeConte) (Coleoptera: Curculionidae) prevents harvest of cultivated sunflower, Helianthus annuus L., by causing preharvest lodging. Adult sunflower stem weevils emerge from early May to mid-June from the previous year's sunflower stalks and mate. Eggs are oviposited under the epidermis of the lower portion of sunflower main-stem where larvae tunnel and consume the pithy inside of the stalk. Mature larvae construct hibernacula (Rogers & Jones 1979,Charlet 1987) at or near the woody portion of the root crown. This structural damage at the base of the plant increases lodging, especially in combination with drought conditions and high winds that are common on the Central Great Plains. The sunflowerstem weevil is found infesting cultivated sunflower from Texas (Rogers & Jones 1979) to Canada (Arthur & Mason 1990). Native (uncultivated) sunflower has been implicated as a signifi-. cant alternate host of the sunflower stem weevil (Charlet 1983), butmany other annuals and perennials have also been validated as reproductive hosts (Mitchell & Pierce 1911, Pierce 1916, Goeden & Ricker 1975, 1976, Schulz 1978, Armstrong 1997).