Importance of wild bees in agriculture
Almost 60% of wild flowering plants on Earth exhibit entomophily (i.e., need insects to be pollinated), and about 80% of our crops depend on insects to be successfully pollinated and even to increase their commercial value. Certainly, bees deserve the first place among pollinators so they have been declared the most important living organisms. Although not all crops need to be necessarily pollinated by bees, the truth is that wild bees such as bumblebees and many other solitary bees are usually the most effective pollinators for many economically important crops.
The astonishing diversity of wild bees
There are common questions about wild bees such as: Do they produce honey, do they have queens, and do they live in hives? The answers are no. Wild bees are mostly solitary, this means females are in charge of building the nest, bringing food (pollen and nectar), and laying eggs. In the United States, over 4,000 species of wild bees are known! In fact, the southwestern region of the country is one of the largest bee biodiversity hotspots across the world (Figure 1).
What about our apple orchards and their pollinators?
Apple orchards are a good example of bee-pollinated systems. In other words, we have apples every year because of bees. In fact, a recent study suggested that apple production is driven by wild bees. This may be a well-known fact among horticulturists and apple farmers. Many apple growers spend thousands of dollars a year to rent or keep honeybee colonies, so their apples trees are pollinated, increasing yields. In Kentucky, apple production is mainly for retail (direct marketing) and the local demand for quality fruits is increasing. In this scenario, we could think about both honey bees and wild bees as an essential element in apple production. In western Kentucky, specifically at the Research and Education Center in Princeton, apple trees were blooming during mid-April (Figure 2). As expected, different wild bees were actively visiting the apple flowers during the sunny and warm days (Figures 3 to 7).
Among the bee species we found in the UK- Research and Education Center at Princeton there were honey bees (Figure 3), mason bees (Figure 4), two sweet bee species (Figures 5 and 6), carpenter bees (Figure 7), bumble bees, leaf cutter bees, and mining bees. This is just a glimpse of some of the most common bees found visiting the apple flowers. In one survey, 80 bee species were identified visiting apple orchards in Ithaca, NY. Although we all know the benefits of honey bees to agriculture, we should not overlook the diversity and importance of wild bees in our orchards.
We already know that too much of a good thing is never good, so a heavy use of honey bees can be adverse to the surrounding pollinator diversity.
Surrounding sources of pollen and nectar, namely annual blooming plants and forested landscapes, could increase the chances of having more wild bees visiting the apple flowers.
Pesticides are detrimental to bees and most beneficial insects. Their use must be applied according to the local legislation.
The U. S. Forest Service provides further information regarding the best gardening, landscaping, and conservation practices to keep our wild bees.
By Armando Falcon-Brindis, Research Analyst, and Raul T. Villanueva, Entomology Extension Specialist