Native Pollinators: Their Value, Diversity, And Conservation

Written by B. Merle Shepard, Ph.D.

Native pollinators are critical to the environment and economy. They contribute to our food security and to the health of our agricultural and natural ecosystems. Nearly 75 percent of all flowering plants exist because of native pollinating species and three out of every four bites of food are brought to you by a pollinating species. Eighty percent of the food species depend on pollination. Worldwide, of the estimated 1,330 crop plants, 1,000 of them rely on pollinators to produce fruits, nuts, vegetables, oilseed, and medicinal crops. Below is a table developed by the National Resources Conservation Services of some of the major crops that are benefited by or depend upon pollination.

Legumes and relatives: Beans, Cowpea, Lima Beans, Lupines, Mung Bean/Green or Golden Gram, Soybean
Vegetables: Artichoke, Asparagus, Beet, Broccoli, Brussels Sprouts, Cantaloupes, Carrot, Cauliflower, Celeriac, Celery, Cucumber, Eggplant, Endive, Green Pepper, Leek, Lettuce, Okra, Onion, Parsnip, Pumpkin, Radish, Rutabaga, Squash, Tomato, Turnip, White Gourd
Fruits, berries, and nuts: Almonds, Apple, Apricot, Avocado, Blackberry, Blueberry, Cacao, Cashew, Cherry, Chestnut, Citrus, Coffee, Coconut, Crabapple, Cranberry, Currant, Date, Fig, Gooseberry, Grapes, Guava, Huckleberry, Kiwi, Kolanut, Litchi, Macadamia, Mango, Olive, Papaw, Papaya, Passionfruit, Peach, Pear, Persimmon, Plum, Pomegranate, Raspberry, Strawberry, Tung, Vanilla, Watermelon
Herbs and spices: Allspice, Anise, Black Pepper, Caraway, Cardamom, Chive, Clove, Coriander, Dill, Fennel, Lavender, Mustard, Nutmeg, Parsley, Pimento, Tea, White Pepper
Oils, seeds, and grains: Alfalfa, Buckwheat, Canola, Flax, Oil Palm, Safflower, Sesame, Sunflower
Clover and relatives: Alsike Clover, Arrowleaf Clover, Ball Clover, Berseem Clover, Black Medic/Yellow Trefoil, Cider Milkvetch, Crimson Clover, Lespedeza, Peanut, Persian Clover, Red Clover, Rose Clover, Strawberry Clover, Subterranean Clover, Sweet Clover, Trefoil, Vetch, White Clover
Other: Cotton, Kenaf
From: Natural Resources Conservation Management. Fish and Wildlife Habitat Management Leaflet No. 34. 2005.

In both natural and agricultural ecosystems, billions of dollars of “ecosystem services” are provided by pollinators. Yet many of both native and cultivated pollinators are in serious decline. This short article will explore diversity of pollinating species, mostly native bees, in the South Carolina Lowcountry, the causes for their decline, and how we might modify the environment to increase their numbers and biodiversity. This, in turn, will increase and improve the pollination services that are essential for sustainable agricultural production and the health of natural ecosystems.

An article in the Carolina Rice Foundation Newsletter for the Fall of 2014, explored the importance of pollinators in heirloom and domestic crops. Although there is a rich diversity of pollinators that includes flies, wasps, butterflies, moths, beetles, and birds, native bees are by far the most important and essential. However, we are losing our native bees at an alarming rate. Scientists indicate the following causes for the decline in pollinating species: 1) habitat loss, 2) fragmentation of existing habitat, 3) loss of genetic diversity due to fragmentation, 4) pesticides, and 5) diseases brought in by commercially produced bumblebees.

Attracting bees to an area requires that there are adequate sources of food, shelter, and nesting sites. General recommendations include: 1) use local native plants, 2) choose several colors of flowers, 3) plant flowers in clumps, 4) include flowers of different shapes and 4) have a diversity of plants flowering throughout the season.

One particular group of insecticides, the neonicotinoids (“neonics”), is particularly troubling regarding native (and cultivated) bees. Over 50 “over the counter” products contain neonics. Most of these materials are systemic, which means when they are applied to seeds, the materials are translocated by the plant from the seed coat to roots and then to all parts of the plant, and end up in pollen and nectar. Besides the direct effects of these insecticides on bees, there is evidence to suggest that low levels of neonics make bees more susceptible to diseases such as those caused by Nosema sp. Recent studies in the U.K. have strong scientific evidence that neonics are responsible of the serious decline in native bees in that country. 

A recent loss of thousands of honeybees due to aerial spraying of the organophosphate insecticide, Naled, for mosquito control, tells only part of the story.  It is likely that hundreds of species of non-target organisms, particularly pollinating species, were negatively impacted.  This includes many species of native bees and other beneficial organism.  Small, naturally-occurring insect parasitoids, that help to keep pests under control, were no doubt killed along with the cultivated honeybees.  All chemical insecticides should be avoided or care should be taken to use them in a way that is least damaging to bees (and other non-target and beneficial species).

 Rusty-patched bumble bee Photo by Johanna James-Heinz

Rusty-patched bumble bee Photo by Johanna James-Heinz

The rusty-patched bumble bee (Bombus affinis), was once abundant in our area and along the entire eastern seaboard, but during surveys that we carried out in the South Carolina Lowcountry for the past four years, we have not found this species. It is critically endangered existing only in small isolated populations further north, and is likely headed for extinction.

  Two-spotted long-horned bee

Two-spotted long-horned bee

Results of ongoing surveys of native bee populations in Coastal South Carolina revealed that the most abundant groups of native pollinating bee species included: The American bumble bee (Bumbus pensylvanicus), Southern plains bumble bee (Bombus fraternus), common Eastern bumble bee (Bombus impatiens), the Eastern carpenter bee (Xylocopa virginica), the Southern carpenter bee (Xylocopa micans) (See the Carolina Gold Rice Foundation Newsletter, Fall 2014) and the two-spotted long-horned bee (Melissodes bimaculata). We have photo-documented over 90 different pollinating species, so far.

Managing habitat for native bees is critical for their survival and to gain the benefit of the ecosystem services that they bring to us and to the stability of their own ecosystems.

Here is a list of some native plants for pollinators that have been known to grow in the South Carolina Lowcountry. The list was compiled by April Bisner, a member of the native plant society. This list is certainly not all inclusive. There are many more native perennial and annual plants that provide excellent pollen and nectar sources.

The North American Pollinator Protection Campaign (NAPPC) along with the Wildlife Habitat Council and the Xerces Society, has developed a list of pollinator friendly practices. The Xerces Society is an excellent source for information about attracting native pollinators (Attracting Native Pollinators: Protecting America’s Bees and Butterflies. 2011). The Native Plant Society (Charleston) can provide readers with a list of native plants that do well in the Lowcountry of South Carolina. The Xerces Society published a fact sheet entitled Southeast Plants for Native Bees by Eric Mader and Matthew Shepherd (www.xerces.org).

In the past, farmers relied only on native bee pollinators which provided adequate pollination for their crops. With larger, much less diverse farms and “clean” field borders, farmers rely more on domesticated bees. The Xerces Society has provided simple steps that may be taken to protect and enhance native pollinators that are already present on farms and gardens.  A booklet entitled “Farming for Bees: Guidelines for Providing Native Bee Habitat on Farms can be downloaded from the Xerces Society website.