Garden Mastery: San Diego Native Bees, Plants Are Linked For Life
Native bees belong to a group of animals we call pollinators, and they play a crucial role in the biodiversity of our plants, flowers, fruits, vegetables, landscapes and cultures that sustain our environment and our food supply. Other animals that we value as pollinators are non-native bees like honeybee, beetles, ants, birds, bats, and even mice.
Bees are extremely diverse, with approximately 20,000 species worldwide, of which approximately 3,600 species are native to North America and 700 species are found right here in San Diego. Since many native bees have become specialized pollinators of certain native plants, their size and appearance vary greatly. North American species range from as small as a twelfth of an inch to over 1 inch long. Their colors also range in hues from white to black, including red, brown, orange, yellow, blue, and even a metallic green.
Almost all species of flowering plants need pollination to produce new seeds and fruits and to maintain their genetics. Animals are more efficient than the wind for pollination. Plants attract pollinators by offering food in the form of pollen and nectar, shelter, nest building materials, and a place to find a mate.
The energy that fuels the survival of pollinators comes from the sugars in nectar and the proteins, fats, vitamins and minerals in pollen grains. Native bees exhibit a behavior called “flower constancy,” meaning that they repeatedly visit the flowers of a particular plant species during a given foraging trip. This makes them effective pollinators, delivering the right pollen to the right sources.
During your travels in San Diego, take the time to observe the many floral morphologies. You might see the tiny clusters of flowers on a ceanothe, a perfect fit for a butterfly’s mouthparts; a cactus flower visited by a digger bee Diadasia australis, specialist in cactus pollen; or perhaps the very large open petals of a California poppy, which is visited by a wider variety of pollinators. Each of these plants has a specific set of pollinators that can do the job.
San Diego’s native bees such as Andrena spharalcées, from the mining bee family, like to nest in sandy soil, another option in your garden for habitat variety. Mining bees (family Andrendiae), furrow bees (Halictus sp.) and many others mostly live solitary lives, with a single female doing all the work to build a nest, collect resources to feed the larvae, and lay eggs to start the life cycle over.
Two-thirds of native bee species live in underground nests in complex tunnel systems designed to protect the developing larva from predators, fungi, weather and other diseases. Other native bee species such as leafcutter bees and mason bees prefer hollow plant stems and twigs above ground to create nests. The female bee creates chambers in the hollow stem to lay her eggs, taking care to line each cell with waxy secretions, bits of leaves or flowers, mud, or chewed wood to protect her young.
Native pollinators in danger
Research shows significant declines in native pollinator populations around the world. Due to environmental stressors, including habitat loss, climate change, pests, parasites, exposure to pesticides and disease, up to 40% of pollinator species are at risk of extinction in years to come. come.
A recent analysis by the Xerces Society and the International Union for Conservation of Nature (IUCN) found that 28% of bumblebees in Canada, the United States and Mexico are in an IUCN threatened category. According to NatureServe, 50% of leafcutter bee species and 27% of mason bee species are “at risk”.
The secret bond of partnership is that neither plant nor pollinator populations can exist in isolation – if one goes extinct, the other is only a generation away from disaster.
Ways to help pollinators
Our native pollinating bees need flowering plants, nesting and overwintering sites, and pesticide-free habitat to survive. Choosing the right plants is an essential step in supporting pollinators. Native plants are adapted to our local unique soil and climate, require little or no supplemental water to sustain themselves, promote local biological diversity, and are attractive landscape plants. Visit one of San Diego’s many plant nurseries that specialize in native plant landscapes to incorporate a variety of native wildflowers, such as these:
- Pacific Bleeding Heart
- California poppy
- dwarf checkerboard
- silver lupine
- mountain blue penstemon
… and trees and shrubs:
- California faux indigo
- palo verde
- black sage
- Blue flower
A small gesture with a big impact is to provide bees, butterflies and other pollinators with a water source, such as a shallow pie dish with marbles, half filled. The marbles create a landing point and prevent accidental drowning.
Pesticides – organic or conventional – have huge impacts on non-target pests when not applied correctly. Follow all label directions on all products you use and implement an Integrated Pest Management (IPM) strategy to manage targeted pests while protecting beneficial insects and pollinators in your spaces. Pollinators also need advocates like you, who change their landscapes by creating and maintaining habitats that are optimized to support pollinators. Visit the resources of the UCCE San Diego Pollinator Project, the Xerces Society, and the California Native Plant Society – San Diego Chapter for more information on pollinator identification and planting guides.
Taylor is a master beekeeper and coordinating master gardener for the California program. For questions about home gardening, contact the UCCE Master Gardeners of San Diego County Hotline at (858) 822-6910 or email [email protected]