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Introduction to Rangeland Insects: Diversity and Function

Introduction to Rangeland Insects: Diversity and Function. Steve Cook Department of Plant, Soil and Entomological Science University of Idaho. 1 October 2012. My Prejudice: I am an Entomologist: All of this other stuff is simply for growing insects – and it is not very good for that.

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Introduction to Rangeland Insects: Diversity and Function

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  1. Introduction to Rangeland Insects:Diversity and Function Steve Cook Department of Plant, Soil and Entomological Science University of Idaho 1 October 2012

  2. My Prejudice:I am an Entomologist:All of this other stuff is simply for growing insects – and it is not very good for that.

  3. The problem with plants as food:They are a sub-optimal food source – and – N is the issue • Chemical composition of plants varies by species and in both time and space. • Nutritional requirements of insects vary among species as well as developmental stage and environmental conditions. • N is essential to organic life on earth • It is a building block for proteins and proteins are the structural material for building insects • Cuticular proteins > 50% of cuticular dry weight • Bulk of plant tissue is comprised of carbohydrates (cellulose, lignin, etc)

  4. But – what is an insect? And – what is something else?

  5. Why study Insects?They have been around for a long time Fossil Dragonfly from Brazil Fossil in Amber from the Baltic

  6. This long period of time means they have had lots of time to evolve and diversify. • Insects are the most speciose of all identified organisms. • Because of their abundance and diversity, insects contribute to most ecosystem functions and can be heavily involved with ecosystem services. • Insects outnumber and outweigh all other terrestrial animals. • It’s just plain fun. ecommons2.library.cornell.edu/web_archive/explore.cornell.edu/scene3396html?scene+Beetle%20Science

  7. Along with being fun – There are a lot of them andthey are involved with just about everything Megachilidae During one, 2-year study we captured over 65,000 insects. Four Families of bees – none were European honey bees – all were native. Andrenidae Apidae Hallictidae

  8. Along with there being a lot of them:They are very diverse. Bumble bee species on a single site in SE Idaho during s single summer. Sampling occurred over 3, 5-day periods. Gause’s axiom states that no 2 species can coexist if their ecological niches completely overlap – so – there is some factor(s) that allow the species to exist together and exploit different facets of the system.

  9. Going back to my prejudice:Insects are not pests – pest is a human-defined characterization of any organism that interferes with our management objectives

  10. Basic Ecology:Functional roles of insect in rangeland systems • Herbivores • Carnivores • Decomposers • Nutrient cycling • Prey for vertebrate predators • Natural enemy of pest insects • Pollinators • Etc. Secondary consumers - carnivores Energy Primary consumers - herbivores Primary Producers - plants Biomass and energy decrease as energy moves up through the trophic pyramid.

  11. Basic Ecology:Insects in Food Chains Grazing Food Chain Detrital Food Chain Dead organic matter furnishes energy Decomposers (primary detrital consumers) convert dead material into organic bodies (again) 2nd-level detrital consumers feed on primary detrital consumers Plants (primary producers) capture energy from the sun Herbivores (primary consumers) feed on the plants and convert vegetative matter into animal bodies 1st-level carnivores feed on the herbivores 2nd-level carnivores feed on the 1st-level carnivores and the herbivores

  12. A simple grazing food chain Energy movement through the system

  13. American Burying Beetle has endangered species status. A community of carrion-feeding beetles

  14. Ecosystem services performed by insects:Decomposition and Nutrient Cycling Colony of Formica ants Subterranean termites are common in rangelands

  15. Ecosystem services performed by insects:Vertebrate Food and Pest Control

  16. Ecosystem services performed by insects:Pollination

  17. Insects as disturbance agents Grasshopper from “A Bug’s Life” Photo from: John Capinera

  18. Insect Response to Disturbance:Relative Abundance of Ants Following Burns Photographs by Frank Merickel *may contain multiple genera difficult to distinguish without counting antennal segments

  19. Insect Response to Disturbance:Relative Abundance of Ants Following Burns

  20. Insect Response to Disturbance:Colony Density Following Cattle Grazing

  21. Insect Response to Disturbance:Colony Density Following Cattle Grazing 50% of sage grouse scat pellets collected during our 2012 field season contained remnants of ants that the birds had obviously been feeding upon. Photograph by Frank Merickel

  22. Insect Response to Disturbance:A Love Story Fire Male Anthicus beetles ‘steal’ their nuptial gift from Blister beetles and present it to potential mates Grasshoppers increase following prescribed burns in response to changes in vegetation Blister beetles are egg parasitoids of grasshoppers and increase in Response to grasshopper increases

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