A Measurement of the Pollination Success of Native Bees in North Georgia Apple Orchards: Is there a need for Commercial European Honeybees?

Honeybees pollinate 1/3 of all human food crops. The value of honeybee pollination to U.S. agriculture is over $15 billion each year. However, agricultural operations worldwide are facing a growing dilemma that threatens food production: the rapid decline of the Honeybee.

A solution to this problem is the diverse assortment of native bees. Many of these bees have the potential to supplement or replace the dwindling honeybee as the primary pollinator for a range of crops.

The focus of the current project was to identify the native bees present in North Georgia apple orchards, and to measure their pollination success.

Introduction

It is estimated that 35% of global food production is dependent on animal pollination. Animal pollination is essential or at least important in 87 of the 115 leading global crops. Insects, mainly bees, are the main animal pollinator in almost every animal pollinated crop [1].

Honeybees (Apis mellifera L.) are the most important insect pollinator for the majority of agriculture crops, excluding cereals. The yields of some crops decrease by more than 90% when honeybees are not present [2]. In the Unites States alone, honeybees contribute $14.6 billion in pollination services [3].

Reliance on a single insect species, the honeybee, for the pollination of over 1/3 of the human food supply can be dangerous. Indeed, this is especially true considering that honeybees are in trouble, thus putting the global food supply at risk. In the United States there has been a sharp decline in managed honeybee colonies, from 4 million honeybee colonies in the 1970’s to 2.4 million colonies in 2005 [4,5]. The losses in managed honeybee colonies and the disappearance of wild honeybee colonies has been attributed to several factors, which include increases in parasites, improper use of pesticides, genetic inbreeding, and many other factors [6]. In 2006, the situation worsened with a significant increase in honeybee losses (30-90% of a colony). These losses were documented particularly in the East Coast of the United States, due to the phenomenon labeled Colony Collapse Disorder (CCD) [7,8]. In 2007, CCD resulted in sharp declines in honeybees in at least 35 states. In the affected areas 50% of beekeepers reported significant colony losses [6].

The reduced availability of honeybee colonies has increased food production costs and reduced potential crop yields. Most farmers are dependent on rented honeybee hives in order to ensure their crops are fully pollinated. The shortage of honeybee colonies has resulted in a rapid increase in the cost of renting honeybee hives. For example, the cost of renting a single honey bee colony used in almond pollination in California increased from $35 in the early 1990’s to $150 per colony in 2007 [6].

The potential loss or reduction of the honeybee can have a devastating effect on agricultural production. We need to develop alternative strategies that are less dependent on the use of the honeybee in order to ensure long-term sustainably of insect pollinated crops.

The best alternative to honeybees is the native bees already present in the local environment. There are over 17,000 bee species in the world [9]. With nearly 3500 species in North America alone, the diversity of different forms (size, pubescence, etc.), pollen-strategies, and behaviors (early spring emergence, prolonged daily foraging, shorter inter-flower travel, etc.) of native bees provide a wide range of use for agricultural operations [10,11].

It is estimated that native bees already annually contribute $3 billion to U.S. agriculture [12]. Many native bees already play an important role in the pollination of blueberries [13], watermelons [14], and many other crops.

This natural reservoir of insect pollinators needs to be fully utilized in order to safeguard the sustainability of commercial agriculture. With little more than simple habitat alterations to encourage native bee colony growth, many native bee species have great potential to supplement or replace the dwindling honeybee as the primary pollinator for many diverse crops [1].

Every region, even every crop, has its own characteristic group of native bee pollinators. Data concerning regional make-ups of these native pollinator-guilds are severely lacking, which has led to our reliance on the European honeybees. In fact, across the continent, available information on native bees is spotty at best [15]. Therefore, research is needed to determine which native bees are present in a given region and how best to enrich the habitat (e.g. nesting areas) to increase target native bee populations.

In the following study, we have taken the first step to identify the native bees diversity and abundance in North Georgia Apple Orchards. We have investigated bee abundance and diversity in four North Georgia apple orchards during the entire 2011 growing season. It is believed that native bees can supplement or even replace the honeybee in apple pollination in Georgia.

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