How Ecologically Based Pest Management Works

To bring ecological pest management to your farm, consider three key strategies:

Select and grow a diversity of crops that are healthy, have natural defenses against pests, and/or are unattractive or unpalatable to the pests on your farm. Choose varieties with resistance or tolerance to those pests. Build your soil to produce healthy crops that can withstand pest pressure. Use crop rotation and avoid large areas of monoculture.

■ Stress the pests. You can do this using various management strategies described in this book. Interrupt their life cycles, remove alternative food sources, confuse them.

■ Enhance the populations of beneficial insects that attack pests. Introduce beneficial insects or attract them by providing food or shelter. Avoid harming beneficial insects by timing field operations carefully. Wherever possible, avoid the use of agrichemicals that will kill benefi-cials as well as pests.

EBPM relies on two main concepts:

Biodiversity in agriculture refers to all plant and animal life found in and around farms. Crops, weeds, livestock, pollinators, natural enemies, soil fauna and a wealth of other organisms, large and small, contribute to biodiversity. The more diverse the plants, animals and soil-borne organ

isms that inhabit a farming system, the more diverse the community of pest-fighting beneficial organisms the farm can support.

Biodiversity is critical to EBPM. Diversity, in the soil, in field boundaries, in the crops you grow and how you manage them, can reduce pest problems, decrease the risks of market and weather fluctuations, and eliminate labor bottlenecks.

Biodiversity is also critical to crop defenses: Biodiversity may make plants less "apparent" to pests. By contrast, crops growing in monocultures over large areas may be so obvious to pests that the plants' defenses fall short of protecting them.

Biological control is the use of natural enemies — usually called "beneficial insects" or "beneficials" — to reduce, prevent or delay outbreaks of insects, nematodes, weeds or plant diseases. Biological control agents can be introduced, or they can be attracted to the farming system through ecosystem design.

Naturally occurring beneficials, at sufficient levels, can take a big bite out of your pest populations. To exploit them effectively, you must:

1) identify which beneficial organisms are present;

2) understand their individual biological cycles and resource requirements; and

3) change your management to enhance populations of beneficials.

"It's a subtle effect, but over time the advantage increases. Your system moves slowly toward a natural balance and your pest problems decrease."

— Zach Berkowitz, California vineyard consultant

The goal of biological control is to hold a target pest below economically damaging levels — not to eliminate it completely — since decimating the population also removes a critical food resource for the natural enemies that depend on it.

In Michigan, ladybugs feed on aphids in most field crops or — if prey is scarce — on pollen from crops like corn. In the fall, they move to forest patches, where they hibernate by the hundreds under plant litter and snow. When spring arrives, they feed on pollen produced by such early-

biological control vocabulary

When farmers release natural enemies, or beneficials, to manage introduced pests, they are using biological control tactics. Classical biological control is the importation and release of beneficial insects against exotic pests. When farmers add a species of natural enemy to a field where it is not currently present, or present only in small numbers, they are using augmentation biological control: they can either inundate a field with large numbers of natural enemies or inoculate it with relatively few at a critical time. When they conserve the augmented natural enemies or the ones that are already present in and around their fields, they are using conservation biological control. Parasitoids — a class of beneficials — are parasitic insects that kill their hosts.

Debbie Roos, North Carolina Cooperative Extension

Debbie Roos, North Carolina Cooperative Extension

(above) Southern green stink bug eggs being parasitized by Trissolcus basalis.

Jack Kellv Clark, Univ of Calif

JéÊ

(above) Southern green stink bug eggs being parasitized by Trissolcus basalis.

(left) Assassin bug feeding on colorado potato beetle larva.

season flowers as dandelions. As the weather warms, they disperse to alfalfa or wheat before moving on to corn. Each component of biodiversity — whether planned or unplanned — is significant. For example, if dandelions are destroyed during spring plowing, the ladybugs lose an important food source. As a result, the ladybugs may move on to greener pastures, or fail to reproduce, reducing the population available to manage aphids in your cash crop.

Research shows that farmers can indeed bring pests and natural enemies into balance on biodiverse farms by encouraging practices that build the greatest abundance and diversity of above- and below-ground organisms (Figure 1). By gaining a better understanding of the intricate relationships among soils, microbes, crops, pests and natural enemies, you can reap the benefits of biodiversity in your farm design. Further, a highly functioning diversity of

THE PILLARS OF ECOLOGICAL PEST MANAGEMENT

agroecosystem health below ground

HABiTAT MANAGEMENT, bíota actívatíon AND

díversífícatíon (SoiL oRGANiC MATTER, NUTRiENT MANAGEMENT)

1 If below ground

HABiTAT MANAGEMENT, bíota actívatíon AND

díversífícatíon (SoiL oRGANiC MATTER, NUTRiENT MANAGEMENT)

soiL HEALTH

crop health soiL HEALTH

crop health

AGRoECoSYSTEM DESiGN

AGRoECoSYSTEM DESiGN

above ground

HABiTAT MANAGEMENT, PLANT díversífícatíon AND ENHANCEMENT oF benefícíal FAUNA

above ground

HABiTAT MANAGEMENT, PLANT díversífícatíon AND ENHANCEMENT oF benefícíal FAUNA

Figure 1. The pillars of ecological pest management, explained in this book, can be categorized into above-ground and below-ground principles and practices. Ecological pest management is based on the use of multiple tactics to manage pests in the agroecosystem, rather than a "silver bullet" to control them.

ENHANciNG ■ Diversify enterprises by including more aboveground species of cr°ps and livestock.

- ■ Use legume-based crop rotations and b|od|vers|ty: mixed pastures.

A cHEcKLIST ■ intercrop or strip-crop annual crops where for FARMERS feasible.

■ Use varieties that carry many genes— rather than just one or two—for tolerating a particular insect or disease.

■ Emphasize open-pollinated crops over hybrids for their adaptability to local environments and greater genetic diversity.

■ Grow cover crops in orchards, vineyards and crop fields.

■ Leave strips of wild vegetation at field edges.

■ Provide corridors for wildlife and beneficial insects.

■ Practice agroforestry: where possible, combine trees or shrubs with crops or livestock to improve habitat continuity for natural enemies.

■ Plant microclimate-modifying trees and native plants as windbreaks or hedgerows.

■ Provide a source of water for birds and insects.

■ leave areas of the farm untouched as habitat for plant and animal diversity. (see Chapter 4 to learn about enhancing belowground biodiversity)

crucial organisms improves soil biology, recycles nutrients, moderates microclimates, detoxifies noxious chemicals and regulates hydrological processes.

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