Mutualistic and antagonistic networks involving the rare silky prairie-clover (Dalea villosa var. villosa) and its co-flowering plants and insect visitors

Abstract

In Canada, silky prairie-clover (Dalea villosa var. villosa (Nutt.) Spreng) is a nationally rare plant, growing only in sand dunes in Saskatchewan and Manitoba. Previous research indicates that this species is incapable of self-pollination, making it dependent on insect pollinators for successful reproduction. The insect visitor community to D. villosa in Spruce Woods Provincial Park (SWPP), Manitoba, was documented and compared with that of 13 co-flowering plants that share some of its insect visitors. In total, 29 insect taxa were observed feeding on nectar or pollen from D. villosa. Hymenoptera were the most frequent visitors, comprising 60.7% of the taxa and making 93.5% of all visits. The visitation rate per stem to D. villosa (0.0042 stems·min–1) was the second highest of all of the plants with which it was compared. The insect visitor diversity was 4.0 (Simpson’s reciprocal index), and the constancy index was 0.72. The high visitation rate, diversity, and constancy to this species may be due to a lack of competition for pollinators. Over half of the insect visitor taxa (54%) and visits (68%) were by omnivorous insects, as opposed to herbivorous ones. This means that there is interconnectivity between a mutualistic network involving D. villosa and several antagonistic networks.