Resident Insects Protect Nearby Fields

photograph of wheat fields and green plants during the day

Biological Strategy

Insects

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Protect From Animals

Animals–organisms that range from microscopic to larger than a bus–embody a wide variety of harms to living systems, including other animals. They threaten through predation, herbivory, defense, and parasitism, and they compete for resources such as water, nutrients, and space. Any given living organism commonly faces threats from a variety of animals, requiring strategies that effectively defend from each. Trout and other bony fish, for example, escape predators by having scales made of very thin, flake-like pieces of bone covered with slippery mucus. They also have behavioral strategies such as camouflage, fast swimming, and twisting and turning to achieve release from a predator’s grip.

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Biological Control of Populations, Pests, Diseases

An ecosystem must prevent overpopulation of any given species within it, as well as the spread of pests and diseases, to allow organisms to survive without threatening extermination of other organisms or ecosystems. To control pests and diseases, living systems use such strategies as developing antibodies and killing or repelling pests or disease-causing organisms. Ecosystems have checks and balances to maintain populations, pests, and diseases. For example, in a lake, a balance of predators, prey, and nutrients is crucial for proper functioning of the ecosystem. Predatory fish keep down the numbers of smaller prey fish, which in turn keep populations of algae-eating zooplankton in check. When the levels of any of these organisms change, the change can disrupt the health of the entire ecosystem.

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Insects

Class Insecta (“an insect”): Flies, ants, beetles, cockroaches, fleas, dragonflies

Insects are the most abundant arthropods—they make up 90% of the animals in the phylum. They’re found everywhere on earth except the deep ocean, and scientists estimate there are millions of insects not yet described. Most live on land, but many live in freshwater or saltwater marshes for part of their life cycles. Insects have three distinct body sections: a head, which has specialized mouthparts, a thorax, which has jointed legs, and an abdomen. They have well-developed nervous and sensory systems, and are the only invertebrate that can fly, thanks to their lightweight exoskeletons and small size.

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Herbivorous insects in hedgerows in Bavaria help protect nearby wheat fields from aphids by attracting generalist predators that feed on them as well as the aphids.

“Hedgerows along the borders of fields in Bavaria date back hundreds of years. In a land where most forests have been converted to timber plantations, these hedgerows now represent Germany’s most diverse woody vegetation, containing as many as thirty species of woody plants. They also serve as prime habitat for herbivorous insects, most of which are highly specialized feeders that have no interest in nearby crops. Instead, their presence attracts generalist predators and parasites, which not only feast on them but consume aphids in the neighboring grain fields. Because of these insects, northeast Bavaria is one of the few parts of Germany where farmers have no need to spray for wheat aphids.” (Baskin 1997:65)

Last Updated August 18, 2016

References

Book

Work of Nature: How the Diversity of Life Sustains Us

Island Press | 01/01/1997 | Yvonne Baskin

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Reference

Book section

Functional aspects of landscape diversity: A Bavarian example. Pages 453-466 In Biodiversity and Ecosystem Function

Springer-Verlag | Schulze, E-D; Gerstberger, P

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