Comparison of Bee Composition in Sunn Hemp and Other Cover Crops

Cover crops can be planted in rotation with cash crops to improve soils, assist in weed growth prevention, and help suppress plant pathogenic nematode populations. Experiments were conducted in northern and north-central Florida to evaluate bee populations within cover crop plants, including sunn hemp (Crotalaria juncea L.), sorghum-sudangrass (Sorghum bicolor [L.] Moench × S. bicolor var. sudanense [Piper] Stapf.), and cowpea (Vigna unguiculata [L.] Walp.). Almost 150 bees in 10 species and over 700 bees in 15 species were collected in pan (bee bowls) and blue vane traps, respectively. Both sets of traps captured bees from within all cover crop plots, indicating that these bees forage in disturbed habitats. The dominant bees collected, Melissodes spp., are ground-nesting solitary bees which may have been utilizing the ground below the plants and the border plot areas as a nesting site. Only a subset of the species composition associated with the cover crops was relevant to the pollination of sunn hemp, which requires large-bodied bees such as species of Xylocopa and Megachile.