ARS | Publication request: Breeding biologies, pollinators and seed beetles of two prairie-clovers, Dalea ornata and D. searlsiae (Fabaceae: Amorpheae), from the Intermountain West USA

Submitted to: Western North American Naturalist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 5, 2011
Publication Date: March 15, 2012
Citation: Cane, J.H., Weber, M., Miller, S. 2012. Breeding biologies, pollinators and seed beetles of two prairie-clovers, Dalea ornata and D. searlsiae (Fabaceae: Amorpheae), from the Intermountain West USA. Western North American Naturalist. 72 (1):16-20.

Interpretive Summary: Two perennial prairie-clovers of the Intermountain West, Dalea ornata and D. searlsiae, represent a large genus of New World legumes that are common in prairies, deserts and adjacent biomes. Growers will be planting these prairie-clovers to produce seed that will be used to restore plant communities on western public rangelands. Our pollination experiments showed that both kinds of prairie-clover need bees to move pollen between plants; only limited seed set resulted from self-pollination. Honey bees and alfalfa leaf-cutting bees should be effective and manageable pollinators for seed farming. We also found that two species of seed beetles commonly infest seed of these two prairie-clovers. These beetles will need to be cleaned out or killed to limit infestations. Use of prairie-clover seed in restoration seed mixes will benefit a number of kinds of bees that also pollinate additional native wildflowers of the region.

Technical Abstract: Two prairie-clovers, Dalea ornata and D. searlsiae, are perennial forbs that flower during early summer throughout the Colombia Plateau and Great Basin of the western USA, respectively. Their seed is desirable for use in rangeland restoration. We experimentally characterized the breeding biologies of D. ornata and D. searlsiae, surveyed their pollinator guilds, and sampled for their seed predators. The two Dalea species have comparable pollination requirements, being primarily xenogamous; 39-42% of flowers manually pollinated with outcross pollen yielded plump seeds, on average. They are marginally self-compatible (7-11% of selfed flowers yielded seeds), a limited but valuable capability for colonization. Flowers that were not visited or manually pollinated rarely yielded mature seed (5-6% of flowers). Limited surveys of their pollinator guilds in ruderal or cheatgrass-infested habitats revealed sparse visitation solely by wild bees, primarily of the genera Anthidium, Colletes, Bombus, Eucera, and Melissodes. Beetles (Acanthoscelides oregonensis and Apion amaurum) infested seed from 3/4 of 25 D. ornata populations sampled across a 3-state region. Bees will need to be provided and seed beetles excluded or controlled to productively farm seed of these prairie-clovers destined for restoration efforts in the sage-steppe of western USA.