Potential biological control agents of field bindweed, common teasel and field dodder from Slovakia.

Abstract

AbstractField explorations during 2001 to 2006 in Slovakia resulted in the discovery of several potential biological control agents of the three weeds, field bindweed, Convolvulus arvensis L.; common teasel, Dipsacus fullonum L.; and field dodder, Cuscuta campestris Yuncker. The five top candidates are described in the following. The larvae of the agromyzid fly Melanagromyza albocilia Hendel (Agromyzidae) mine in the stems and root crowns of field bindweed, causing the death of infested shoots. The number of infested plants ranged from 46.7% to 99.2% and the number of infested stems from 4.1% to 37.2% in southwest Slovakia. The larvae and adults of the tortoise beetle, Hypocassida subferruginea (Schrank) (Chrysomelidae), almost completely destroyed leaves of field bindweed in some uncultivated habitats in the warmest localities of Slovakia. Development of the species is rapid under favourable conditions and takes only 22 to 27 days; females have a high fecundity, and it is easy to rear. The most important natural enemy of H. subferruginea recorded in Slovakia was the egg parasitoid Brachista pungens (Mayr) (Trichogrammatidae). Adult moths of Endothenia gentianaeana (Hübner) and Cochylis roseana (Haworth) (Tortricidae) were reared in high numbers from flowerheads of common teasel during the study. Of E. gentianaeana, only one larva was found per flowerhead, feeding within the central cavity, while larvae of C. roseana were gregarious. Especially C. roseana was destroying a large number of seeds within the flowerheads of teasel. Considerable parasitization of E. gentianaeana by Glypta mensurator (Fabricius) (Ichneumonidae) was noted. Weevils from the genus Smicronyx (Curculionidae) were found to be the principal natural enemies of dodders in Slovakia. Larvae of Smicronyx spp. induce stem galls, which prevents flowering and fruiting of field dodder vines. Smicronyx jungermanniae (Reich) was the most abundant species, accounting for up to 96% of the total number of weevils (n=877) reared from field dodder galls.