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06.06 Impacts of Insect Herbivores

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Bugs 101: Insect-Human Interactions

Universidad de Alberta

4.9 (136 calificaciones) | 7.4K estudiantes inscritos

Of all the animals on earth, which are the strongest for their size? What about the fastest? Who were the first animals to evolve flight? Insects take all of these titles and more! As the most abundant animals on the planet, insects and other arthropods affect our lives in so many ways. From beneficial interactions like pollination and biological pest control, to the transmission of life threatening diseases; this course will teach you about the big ways that these little arthropods impact our lives. In Bugs 101: Insect-Human Interactions, you will be plunged into the diverse (and sometimes alien) world of arthropods to learn how they work, what they do, and how insects and humans interact every day. After completing this course, you will be able to: Describe the evolutionary relationships between insects and their arthropod relatives Inventory major groups of insects and their diversity Demonstrate evolutionary adaptations that make insects successful Discuss insect biology and human-insect interactions Evaluate positive and negative interactions between insects and humans Propose practical and symbolic roles insects play in human societies

Destrezas que aprenderás

Biology, Entomology, Science, Ecology

Revisiones

4.9 (136 calificaciones)

5 stars
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LB

Sep 18, 2019

Fantastic course full of interesting and useful information that is presented in a structured and clear way. A big thank you to the course presenters and plethora of guest experts.

JK

Aug 19, 2019

I learned so much from this class. Most importantly, I appreciated the faculty that would answer my questions in the forum, it made me feel more connected to the course.

De la lección

Module 06: Plant Feeding and Impacts of Herbivory

This module focuses on the vegetarians of the insect world. A long evolutionary history with plants has led to the development of some interesting feeding strategies in insects, and some wild defenses in the plants they eat. Some of these herbivores can be important pests, and may change entire ecosystems through their feeding.

06.06 Impacts of Insect Herbivores5:23

Impartido por:

Dr. Maya Evenden
Professor of Entomology

Transcripción

Herbivorous insects have a part to play in the maintenance and healthy ecosystems. However, at high population densities, these insects can cause serious damage to plants that are used by humans for food and fiber production. Despite control efforts, insect pests destroy more than 15 percent of potential worldwide crop production every year and are therefore, some of our biggest competitors for food. Billions of dollars are spent annually to control herbivorous insects, and they regularly cause significant economic loss. Invasive herbivorous insects in particular, have important economic impacts in agriculture. The spread of such invasive species has been driven by many factors, including the modern technological revolution. With increased globalization and ease of travel, insects that avoid detection can be transported all over the world. Invasive species can threaten biodiversity, and the damage they cause to crops can be extensive compared to native species. This is especially true if a host plant has not had the chance to co-evolve with an invasive herbivore, or if natural predators are not yet adopted to feed on the invasive species. A current ecological disaster in the Mississippi River Delta is the result of an invasive scale insect that feeds on Roseau Cane, a common marshland plant. The feeding damage caused by the Invasive insect threatens coastal restoration efforts to protect shipping channels, shrimp fishing grounds, and oil extraction activities along the Louisiana coast line. Besides the introduction and spread of invasive insects species, there are other human-based activities that can promote populations of both native and invasive herbivorous insects to greater pest status. In managed ecosystems, plant monocultures can dominate the landscape as a result of planting preferences, and the reliance on mechanized agriculture by humans. Monocultures reduce the natural plant diversity in a region, as only a single plant species is planted over a large area that would otherwise support a great diversity. Even within a single crop species, the genetic diversity of a monoculture can be further limited through the selection of certain crop varieties. This provides a great resource for insect herbivores that are able to utilize the chosen plant. Monoculture plantings also support a lower diversity and abundance of predators and parasitoids that feed on insect herbivores. More food and fewer enemies can lead to a population boom for the insect herbivore that can ravage the crop and the resource being harvested. A good example of monoculture practices that resulted in massive pest outbreaks is the wide scale production of cotton. By planting only a single species of crop over large areas, the oversimplified agro ecosystem promoted the invasion and outbreak of a destructive pest, the cotton boll weevil to the southern United States. At peak populations in the 1970's, feeding damage caused by the cotton boll weevil cost US cotton producers around 200 million dollars every year. Although the cotton boll weevil has been eradicated in almost all cotton growing states in the US, this pest remains a concern and is carefully monitored to prevent reintroduction. The economic impact of insect herbivores isn't all doom and gloom however, as some herbivorous insects can be beneficial control agents of weeds. For example, in the 1940s, about 2.5 million acres of California range land was covered by a noxious weed, the European St. John's Wort. The weed is toxic to livestock and outcompetes native range land vegetation. To manage this spread of this noxious weed, and herbivorous veto, Chrysolina quadrigemena, the Klamath weed beetle was introduced into this state. It became established in the region, and has since been effectively controlling weed populations. This in turn led to the restoration of the native plant species composition across the range lands. We will discuss the use of insects in weed biological control and pest management in a later module.

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