ASSOCIATION AND SYNCHRONY OF SMICRONYX-GUINEANUS VOSS, SMICRONYX-UMBRINUS HUSTACHE (COLEOPTERA, CURCULIONIDAE), AND THE PARASITIC WEED STRIGA-HERMONTHICA (DEL) BENTH (SCROPHULARIACEAE)

Field experiments were conducted in 1992 and 1993 at Kaya, Burkina Fas o, West Africa, in fields of sorghum (Sorghum bicolor) and pearl mille t (Pennisetum americanum). Striga hermonthica (witchweed) was sampled weekly using a square-meter metal frame. Concurrently, adult populatio ns of the weevils Smicronyx guineanus Voss and S. umbrinus Hustache we re sampled weekly using a Univac portable suction sampler to assess th e synchrony of Smicronyx with Striga. chi(2) tests for independence of the populations of Smicronyx and Striga indicated a good synchrony of the active stages of the life cycle of the weevils with the period of occurrence of the witchweed. The Univac portable suction sampler meth od was also used to determine the degree of association between Smicro nyx and Striga. There was a positive association between the weevil an d the witchweed. The percentage of Striga plants bearing galls caused by Smicronyx was determined on 39 occasions and galls were found in ev ery field visited (n = 50). The mean galling percentage ranged from 1 to 84%. A search for alternate hosts was done by sampling weevil adult s on weeds surrounding the farmers' fields. No Smicronyx adult was cau ght on these weeds before the emergence of volunteer Striga plants. (C ) 1996 Academic Press, Inc.