Home gardens, whether a collection of potted plants on a lanai or a backyard with fruit trees, reflect an owner’s personality and interests. Urban gardens, with their splashes of color and scent, are also a source of nutrition for insect pollinators.
Recently though, gardeners on Oahu and Hawaii island have been noticing a large decline in pollinators. The surprisingly low number of honeybees in some areas is due primarily to a one-two punch caused by the arrival of new honeybee pests and an increase in viral diseases affecting the bee colonies. In addition, pesticide use can make urban gardens a potentially deadly feeding station for these insects.
Understanding what pollinators need can help us choose plants that improve the value of the garden to these insects. Collectively these small patches of greenery form the "urban meadow" for bees and other beneficial insects, and thus, home gardens play an important role in the survival of these invaluable insects in the urban landscape. Selecting the right plants and reducing pesticide input are two of the most important contributions a gardener can make to the preservation of pollinators.
The most common pollinators found on local gardens fall into three categories: bees, hover flies and butterflies. Not all flowers are equally profitable to these beneficial insects. Some common ornamentals may be very colorful and attractive to us but are meant to be pollinated by birds and provide little food for insect pollinators.
This is the case for bromeliads, bird of paradise and ginger plants. However, it’s possible to include "bee-friendly" plants in gardens by adding daisy-type flowers that are easily accessed by most pollinators. Many herb species are also great forage, especially for honeybees. Mint, sage, rosemary, oregano and thyme are a few of the many plants that can be used to attract pollinators.
Gardeners should also be aware of another particularly serious complication for the conservation of native forests in Hawaii. Exotics, many of which are loved by pollinators, may become invasive species and spread to native ecosystems.
Lantana and false heather (also known as Hawaiian heather) have diminutive flowers that are loved by many pollinators. Unfortunately, these two ornamentals are considered invasive. Another example of an invasive ornamental is wedelia, a popular ground cover.
Luckily, there are an number of native Hawaiian plants that can attract pollinators, including hardy species such as ohia lehua, naupaka and ilima. Many local nurseries sell these species and others that can be easily incorporated to the urban landscape.
Urban gardeners can contribute to the health of pollinators by following a few simple tips:
» Use a variety of plants rather than a single type. This will ensure there is always something in bloom in the garden and you are providing food for a variety of pollinator types.
» Plant the same species in clumps. As a rule, the larger the flower display, the more attractive the patch will be to the pollinators.
» Select simple flowers where pollen and nectar are easily accessible to all pollinators.
» Choose plants that are not susceptible to pests to reduce the need for pesticide.
» Reduce pesticide use and/or select the least toxic materials whenever possible.
» If using pesticides, read labels carefully and apply in the evening when most insects are not active.
Ethel M. Villalobos is a researcher and educator from the College of Tropical Agriculture and Human Resources in Manoa. She is in charge of the University of Hawaii’s Honeybee Project and is interested in the ecology and behavior of bees in native habitats and agricultural environments. Contact her at uhbeelab@gmail.com.
On the Net: » www.ctahr.hawaii.edu/UHMG/news/V3-Villalobos-bees.pdf
» www.plantpono.org/
» www.uhbeeproject.com/
