Ch17 - Ent 100 Fall 2009 1 Lecture 17: How Insects Get...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
Ent 100 Fall 2009 1 Lecture 17: How Insects Get Around Dispersal is the capacity of an insect to move from its birthplace to new areas. This movement can be multidirectional or unidirectional. The consequences of the two are quite different. Unidirectional dispersal occurs when individuals in a species, like monarchs, migrate on a seasonal basis. They move in a focused manner in one direction. This makes it possible for species to leave habitats when conditions become too harsh to survive. Multidirectional migration occurs when individuals move away from their birth place. Dispersal is usually, but not always confined to the adult stage in insects, although there are many examples of juvenile stages that disperse. Dispersal is the normal part of the life cycle in many insects. Dispersal also occurs in response to habitat modification caused by natural or unnatural (human) processes. Dispersal is primarily an ecological process. Natural selection generally favors individuals that move away from their parents. By moving away from their birth site individuals avoid the potential competition between offspring and parents and among offspring that occurs close to the birth site. Dispersal can also be caused by changes in the environmental quality of the birth site, which may occur because of the numbers of individuals concentrated in that area. Major dispersal events also occur on a historical scale, although these are far less common. The most obvious examples involve colonization of "new" habitats, like oceanic islands, areas wiped clean by tsunami waves, or volcanoes, like Mt. St. Helens after it erupted. Mechanisms of dispersal There are two basic ways that insects disperse, active movement and passive . Active movement is done under the insect’s own muscular output, and consists of walking, running, jumping, flying and swimming. Passive movement involves the insect taking advantage of another animal or components of the physical environment to move, including. Hitchhiking (phoresy). Phoresy involves the use other organisms to move from place to place, without actually harming it. For example hummingbirds carry mites from flower to flower on their feathers. Booklice (Order Psocoptera) have been found clinging to the feathers of migratory birds. Cockleburs have specially barbed seeds that cling to fur or clothing and end up dislodged when the animal or person grooms. Aerial plankton . Aerial plankton consists of tiny animals, spores, tiny seeds and pollen, which are passively carried by air movement from one place to another, often at high altitudes. Tiny organisms are readily carried through the atmosphere by air currents because they are so light they can be moved by simple air currents. Examples of organisms that become aerial plankton include aphids, mites, thrips, spores, pollen, parasitoid wasps and orchid seeds. Sampling from jets flying 15,000 ft above Louisiana yielded 210 families and 18 orders of
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 12/03/2009 for the course ENT 100 taught by Professor Kimsey,r during the Fall '08 term at UC Davis.

Page1 / 5

Ch17 - Ent 100 Fall 2009 1 Lecture 17: How Insects Get...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online