Native Plants Shown to Favor Beneficial Insects

One of the basic principles of permaculture farms is biodiversity. The same is true of a sustainable landscape with its call to use native plants to establish native habitat for native beneficial insect populations.

The ‘No-Till’ principle of gardening lets the soil build up healthy, cooperative systems to digest mulch and nutrients to pass on to your plants. In the same way, a healthy, diverse population of beneficial insects is critical to a (mostly) hands-off approach to gardening.

Native plants bring ‘hands-off’ insect control to your garden. Introducing native plants, which host their own defensive insects, bring that natural defense to your garden. Exotic plants host little other than exotic pests. We’ve known this for a long time.

The University of California’s Agriculture and Natural Resources Dept has validated that opinion.

In a recently released, peer-reviewed article, the authors stated, “hedgerows attracted more beneficial than pest insects” and that “replacing weedy areas at field crop edges with managed hedgerow plantings will sustain or increase beneficial rather than pest insects on farms”.

Hedgerows were planted bordering large commercial fields and proved to bring native beneficial insects to the fields. The hedgerows were 1,000 to 1,800 feet long and 30 feet wide. The authors sum up their findings, “Our results show that field edge plantings of native California shrubs and perennial grasses can enhance beneficial insect abundance.”

Abundant beneficial insects came to our rescue when aphids attacked our new community garden. You can have the reserve troops working in your home garden as well.

Continuing, “most beneficial insects require or benefit from nectar or pollen sources from flowering plants that hedgerows provide, helping them survive and reproduce, especially during times of prey scarcity.” Having predatory insects lurking ‘in the wings’ and waiting for dinner is critical to avoiding plant-killing infestations.

The test plantings “contained California lilac (Ceanothus griseus), coffeeberry (Rhamnus californica), California buckwheat (Eriogonum fasciculatum), toyon (Heteromeles arbutifolia), elderberry (Sambucus mexicana) and coyote brush (Baccharis pilularis). These are drought-tolerant native California shrubs that provide pollen and nectar for beneficial insects (Bugg et al. 1998; Long et al. 1998) and have successive and overlapping bloom periods”

Read the full article here: Hedgerows enhance beneficial insects on farms in California’s Central Valley

You don’t have to have acres of field to protect; many of these plants work great in  your garden, are drought tolerant and many attract birds as well as insects. This is the time of year to plant your natives, while we get rain. The free water while the roots are developing takes you even closer to a hands-off garden.

The plants listed in the study (with the exception of Toyon) are also good choices for many southern California homes. The California Lilac is covered with lilac blue flowers in the spring time, Coffeberry and Elderberry fruits feed local birds and Coyote brush is a low-growing ground cover listed by the Fire Department as fire-resistant.

The report summary says, “Of 10,323 total insects collected in the hedgerows during the growing seasons over 2 years, 78% were beneficial insects and 22% were pests. The abundance of beneficial insects was consistently greater than pests in the hedgerow shrubs compared to weedy areas during each season.”

The ‘weedy species’ noted in the study included black mustard, a very common plant in this area. Removing the mustard from near my own garden reduced the numbers of Harlequin Bugs from ‘overwhelming’ to ‘few’. Consider replacing your exotics with natives and see the benefits in your own yard.