Ecosystems and Pest Organisms

1. Ecosystems and Pest Organisms Source: Norris, R. F., Caswell-Chen, E. P., & Kogan, M. (2003). Concepts in integrated pest management. Upper Saddle River, NJ: Prentice Hall.

2. Understanding Pest Organism Biology and Ecology • Fundamental underpinning to all pest management • Identification • Taxonomy • Classification and naming • Morphology and anatomy • Physical structure of organisms • Genetics • Characteristics passed from generation to generation • Reproduction and population dynamics • Factors that determine population size • Ecology • How organisms interact with the abiotic and biotic environment

3. Ecosystem Organization and Succession • Organisms in a community interact with each other • The direction and intensity of these interactions are governed by both abiotic and biotic factors • Understanding the levels of ecosystem organization is fundamental to pest management • WHY?

4. Levels of ecosystem organization • Individual • Single organism • Examples? • Population • All individuals of a species within a defined area • Examples? • Community • Assemblage of all species occurring together within a limited geographic area • In an agricultural field, what makes up a community? • Ecosystem • A community of organisms together with the abiotic environment • Dimensionally undefined • What would be included in an agroecosystem?

5. Levels of ecosystem organization • Ecoregion • Denotes areas of general similarity in ecosystems and in type, quality and quantity of environmental resources • Delineated by climate, topography, soil, vegetation, land use • Includes human settlement and resource use patterns • Biosphere • Global ecosystem

6. Definitions and Terminology • Herbivore and herbivory • Herbivores are organisms that destructively consume plants or plant parts • Herbivory is the act of feeding on plants • Phytophagy (phytophagous insects) • Carnivore • An organism that eats animals • Can be generalists or specialists • Omnivore • Feeds of plants and animals • Examples?

7. Definitions and Terminology • Monophagous • Organisms that eat only one or a few species in a genus • A desirable trait in most biological control agents • e.g., Boll weevil on cotton • Oligophagous • Organisms that eat a limited range of usually related organisms • e.g., Hesperotettixviridis– grasshopper that only feeds on members of Asteraceae family • Polyphagous • Organisms that each a range of taxonomically unrelated species • Wide range of insects (e.g., green peach aphid (Myzuspersicae) feeds on over 400 plant species)

8. Definitions and Terminology • Host • Describes organisms that serve as both food source and habitat for parasitic organisms • Prey • Organisms that serve as a food source for predators • Predator • Organisms that eat all or part of their prey, resulting in death of the prey individual • Parasites and Parasitoids • Organisms that live in or on a host from which they can obtain nourishment • Parasites cause harm but do not usually kill the host • Parasitoids develop in the host, usually killing the host • Both usually complete their life cycle while associated with a single host • Hyperparasites and hyperparasitoids • Parasites of parasites • Also called secondary parasites • Why might they be important?

9. Endodermic braconid wasps lay their eggs in caterpillars and other insects. Larvae chew their way out, all while feeding on the viscera of the host. After emerging, pupae spin cocoons until they are ready to hatch.

10. Biological control of wheat stem sawfly in using ectodermincbraconid wasps

11. Trophic relationships • The energy and food resources of organisms • Some organisms serve as food for other organisms

15. Competition • The simultaneous demand for by two or more organisms for a common resource in finite supply • What are some resources? • Light • Nutrients • Water • Physical space • Intraspecific • Occurs among individuals within a single species • Interspecific • Occurs among individuals within different species