Influence of Centaurea biebersteinii patch size on Urophora quadrifasciata (Dipt. Tephritidae) in Michigan, USA

• Published in: Journal of applied entomology (1986) Vol. 130; no. 2; pp. 91 - 95
• Main Authors: Marshall, J.M, Storer, A.J
• Format: Journal Article
• Language: English
• Published: Berlin, Germany Berlin, Germany : Blackwell Verlag GmbH 01.03.2006; Blackwell Verlag GmbH
• Subjects: Asteraceae; biological control; biological control agents; capitula; Centaurea; Centaurea biebersteinii; Centaurea stoebe subsp. micranthos; dispersal behavior; exotic; fruit fly; host plants; infestation rate; inflorescences; invasive; larvae; overwintering; perennial weeds; plant-insect relations; population density; seed heads; spotted knapweed; stem density; stems; Tephritidae; Urophora quadrifasciata; weed control; Michigan; USA, Michigan
• ISSN: 0931-2048; 1439-0418
• DOI: 10.1111/j.1439-0418.2006.01033.x

Host plant patch size plays an important role in the distribution and densities of many insect species. Understanding how the host plant patch size influences the population of a biological control agent is necessary to monitor the success of a biological control programme. Urophora quadrifasciata (Dipt. Tephritidae) was released in the early 1970s to control the spotted knapweed, Centaurea biebersteinii (Asteraceae) in North America. The studies reported here investigated the influences of spotted knapweed patch size and stem density on U. quadrifasciata larval populations overwintering within capitula in the Upper Peninsula of Michigan, USA. An inverse relationship was found between the percentage of capitula with U. quadrifasciata larvae and spotted knapweed patch size in 2002 from Houghton county, MI. In 2003, an inverse relationship was also found in the south region of the study area in Houghton and Keweenaw counties, Michigan. The percentage of capitula with U. quadrifasciata larvae and spotted knapweed patch size were positively related for the central region. No relationship was found for the North region in 2003. Dispersal of U. quadrifasciata is directed north-east along the Keweenaw Peninsula, Michigan. With this directed spread, areas with well-established populations of U. quadrifasciata would provide source individuals for new colonization. Spotted knapweed patch size may play an important role in the overwintering populations of U. quadrifasciata as a result of dispersal.