Technical Notes: Direct effect of parasitism by Dinarmus acutus Thomson on seed predation by Acanthoscelides perforatus (Horn) in Canada milkvetch

Abstract

Canada milk-vetch (Astragalus canadensis L.) is a widespread North American legume considered to be good forage in some regions but potentially dangerous to livestock when it contains high levels of 3-nitropropionic acid. Larvae of the seed predator Acanthoscelides perforatus (Horn) (Coleoptera:Bruchidae) occurred in 77% of the mature pods from 10 genotypes of the legume growing in a nursery at Brookings, S. Dak., in autumn 1987. Dinarmus acutus Thomson (Hymenoptera: Pteromalidae) parasitized 48% of the A. perforatus larvae and reduced numbers of seeds consumed by A. perforatus larvae by 23%. This study identified D. acutus as a parasitoid of A. perforatus and indicated parasitoids may play an important role in recruitment of native legumes.