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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 #121408
Title: SUNFLOWER STEM WEEVIL (COLEOPTERA: CURCULIONIDAE) AND ITS PARASITOIDS IN THE CENTRAL AND NORTHERN PLAINS

Author
item Charlet, Laurence
item ARMSTRONG, J - TEXAS TECH UNIVERSITY
item HEIN, G - UNIVERSITY OF NEBRASKA

Submitted to: BioControl
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/20/2001
Publication Date: 10/1/2002
Citation: CHARLET, L.D., ARMSTRONG, J.S., HEIN, G.L. SUNFLOWER STEM WEEVIL AND ITS LARVAL PARASITOIDS IN THE CENTRAL AND NORTHERN PLAINS OF THE USA. BIOCONTROL. 2002. V. 47 (5). P. 513-523.

Interpretive Summary: The sunflower stem weevil is a pest of cultivated sunflower from the southern to the northern Plains. The incidence of weevil infestation in fields from the six different states sampled during 1996 and 1997 ranged from 33% (Minnesota) to 100% (Kansas, Colorado, Nebraska). Weevil populations per stalk also were greatest in the central Plains (Colorado, Kansas, Nebraska)compared with the northern Plains (North and South Dakota, Minnesota). Parasitization of weevils varied from field to field ranging from 1 to 100%, but was usually less than 20%. A total of nine species of larval hymenopteran or wasp parasites were recovered during the study. The parasite, Nealiolus curculionis, was the most common species collected and was recovered from all the states sampled. Parasite diversity was greatest in the central Plains. The reduced number of parasitoid species found attacking the weevil in the north Plains may be related to factors including low host populations, slower migration of parasites into the region, or incompatibility with the climatic conditions present. Additional work is needed to understand the weevil parasite complex from the central and northern Plains and their population dynamics in order to manipulate the natural enemies to improve the biological control of the sunflower stem weevil.

Technical Abstract: The sunflower stem weevil, Cylindrocopturus adspersus (LeConte), is a pest of cultivated sunflower (Helianthus annuus L) from the southern to the northern Plains. The incidence of weevil infestation in fields from the six different states sampled during 1996 and 1997 ranged from 33% (Minnesota) to 100% (Kansas, Colorado, Nebraska). Weevil populations per stalk also were greatest in the central Plains (Colorado, Kansas, Nebraska) [1-68] compared with the northern Plains (North and South Dakota, Minnesota) [0-12]. Parasitization of weevils varied from field to field ranging from 1 to 100%, but was usually less than 20%. The nine species of larval parasitoids recovered were all Hymenoptera and included: Nealiolus curculionis (Fitch), N. collaris (Brues), Bracon sp. (Braconidae); Neocatolaccus tylodermae (Ashmead), Chlorocytus sp., Pteromalus sp. (Pteromalidae); Quadrastichus ainsliei Gahan (Eulophidae), Eurytoma tylodermatis Ashmead (Eurytomidae); and Eupelmus sp. (Eupelmidae). Nealiolus curculionis was the most prevalent parasitoid reared from C. adspersus, and it was recovered from all states sampled. Parasitoid species richness was greatest in the central Plains. The reduced number of parasitoid species found attacking C. adspersus in the north Plains may be related to factors including low host populations, slower movement by parasitoids into the region, or incompatibility with the climatic conditions present. Additional work is needed to understand the C. adspersus parasitoid complex from the central and northern Plains and their population dynamics in order to manipulate the natural enemies to improve the biological control of the sunflower stem weevil.