Documenting Potential Sunn Hemp (Crotalaria juncea L.) (Fabaceae) Pollinators in Florida

Area of Science:

• Agronomy
• Entomology
• Ecology

Background:

• Sunn hemp (Crotalaria juncea L.) is a versatile legume cover crop.
• It improves soil health by adding nitrogen and organic matter.
• It also aids in weed and nematode suppression.
• Sunn hemp flowers offer resources for pollinators and natural enemies.

Purpose of the Study:

• To evaluate bee populations visiting sunn hemp flowers.
• To compare pollinator activity in mixed plots and different sunn hemp germplasm lines.
• To assess the potential of sunn hemp cultivars for pollinator support and seed production.

Main Methods:

• Field experiments were conducted in Northern and North Central Florida.
• Bee populations were observed and collected from mixed plots of sunn hemp and sorghum-sudangrass.
• Collections were made from plots of two sunn hemp germplasm lines: 'AU Golden' and Tillage Sunn.
• Pollinator activity was monitored during different flowering periods.

Main Results:

• Key bee species identified included Xylocopa virginica, Xylocopa micans, Megachile sculpturalis, Megachile mendica, and Megachile georgica.
• These bees were abundant from May to July and again in October.
• Tillage Sunn, planted in March, showed low bloom and bee visits in May.
• 'AU Golden' produced early flowers, supporting pollinators and showing potential for seed production.

Conclusions:

• 'AU Golden' sunn hemp is a valuable early-season resource for pollinators in Florida.
• It offers significant potential for supporting bee populations and ensuring seed production.
• Cultivar selection is crucial for maximizing benefits to pollinators and agricultural systems.