Protecting Pollinators

There are many different kinds of pollinator species (butterflies, bees, moths, and more), including this monarch butterfly (Danaus plexippus) on rough blazing star.

There are many different kinds of pollinator species (butterflies, bees, moths, and more), including this monarch butterfly (Danaus plexippus) on rough blazing star.

Why Should We Care About Pollinators?

Ellen Jacquart, The Nature Conservancy of Indiana; Robert P. Jean, Environmental Solutions & Innovations, Inc.; Melinda M. Appold, Purdue Horticulture and Landscape Architecture; David Gorden, Mark M. Holeman, Inc.; Heather Reynolds, Indiana University Department of Biology and Stranger's Hill Organics


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Pollinators provide pollination services for wild plants and many of our crop species, too – one in three bites of food is due to cross-pollination by pollinators. Pollination is important for maintaining genetic diversity in plants and ensuring adequate fruit and seed production for crops, wildflowers, shrubs, and trees. Our forests, prairies, meadows, and gardens would look much different without the help of our pollinators.

Pollinators are also important prey resources for other organisms such as migrating birds, beewolves, praying mantises, and many spiders, which in turn become food for other animals. Furthermore, as a very species-rich group, pollinators are an important component of our state’s biodiversity. Indiana’s pollinators include 430 species of bees, 144 species of butterflies, more than 2,000 species of moths, and many species of flower-visiting flies, wasps, ants, and beetles.

Honey bees, one of the best-known pollinators, are actually not native to North America. About 2 percent of Indiana’s bee species are non-native.

Unfortunately, Indiana’s pollinator communities face many threats. In the last 15 years, researchers have documented reduced populations of honey bees, bumble bees, and several butterfly and moth species. This publication provides information about how to establish and conserve effective pollinator habitats in Indiana — from small-scale backyard improvements to large-scale plantings.

This publication explains some of the threats pollinators face. Other publications in this series describe steps you can take to protect pollinators.

Figure 1. A hummingbird clearwing (Hemaris thysbe) on common milkweed.

Figure 1. A hummingbird clearwing (Hemaris thysbe) on common milkweed.


Threats to Pollinators

Pollinators face three major threats.

1. Habitat Fragmentation and Loss

Indiana was once almost entirely forested, but today only 20 percent of the state is forested. Development and agriculture are the main causes behind this loss of habitat. The problem is compounded by landscaping practices that rely on lawns and non-native plant species, and by the decrease in hedgerows on farm lands. In addition, invasive plant species out-compete native plants in many natural areas. The changing dynamics of our plant communities directly affect our pollinators.

2. Pesticide Use in Agricultural and Urban Settings

Many pesticide applications are meant to control harmful insects, but a pesticide’s effects extend to beneficial insects, including pollinators. For example, a class of insecticides called neonicotinoids are known to harm pollinators, but they are still widely used as treatments on commercial seeds. Neonicotinoid insecticides applied to seeds can be transferred to the nectar and pollen in certain plants.

3. Parasites and Diseases

Many parasites and diseases attack honey bees, many bumble bees, and other native bees. Honey bee pests include Varroa mites, tracheal mites, American foul brood, European foul brood, African hive beetle, and twisted wing virus. Nosema bombii (a fungal pathogen) is known to attack bumble bees. People introduced many of these parasites to bee populations by moving commercial bees used for pollination around the world.

Native bees are also susceptible to brood parasite insects such as cuckoo bees (fully one-quarter of all bee species in Indiana are cuckoo bees) as well as strepsipterans (beetle-like insects), meloid beetle larvae, velvet ants, and hoverfly larvae. Butterflies and moths are also very susceptible as larvae (caterpillars) to parasitic wasps, fungi, bacteria, and viruses. Native parasites are considered part of the normal ecology and diversity of the pollinator system, and normally play a minor role in reducing populations.

Each one of these organisms threaten our pollinators. When combined, these threats interact to cause even worse effects. For instance, pesticides can significantly weaken our pollinators’ natural resistance to disease.


Pollinator Interactions

How Pollinators Interact with Plants

Pollinators interact with plants in various ways and each species has a fascinating story. In many cases, a pollinator’s larva has a different story than the adult of the same species.

Some examples of how pollinators and plants interact:

In addition to these pollinator-plant interactions, pollinator species vary greatly in the number of different plant species they will use for food. There are two basic kinds of feeding patterns.


Figure 2. This photo shows a syrphid fly (Toxomerus germinatus) on Ohio spiderwort.

Figure 2. This photo shows a syrphid fly (Toxomerus germinatus) on Ohio spiderwort.


Figure 3. A locust borer (Megacyllee robiiae) foraging on goldenrod.

Figure 3. A locust borer (Megacyllee robiiae) foraging on goldenrod.


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