ch20 - ENT 100 Fall 2009 1 Lecture 19 Parasites and...

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ENT 100 Fall 2009 1 Lecture 19: Parasites and Predators There are three different kinds of insects that feed on other insects or animals – predators, parasitoids and parasites. More than half the orders have parasitic or parasitoid species. Predators – one individual feeds on many hosts in any life stage, killing all of them. Parasites – one or more individuals feed on one host; usually do not kill the host. Parasitoids – many individuals feed on one host, without killing it. Some insects are predatory throughout their entire life history; others are mostly predatory but may be facultative herbivores, such as true bugs in the genus Geocris . There are two basic types of predator, sedentary, or sit and wait predators, such as mantids, or active foragers, such as dragonflies and ants. A variety of different life styles can be seen in parasites, and generally different life stages are involved depending on the group of insects. Some groups are parasitic in all life stages, others only as adults or only as larvae. A. All life stages parasitic Insects that have all life stages parasitic are all hemimetabolous, with one exception in the Coleoptera (the beaver beetle). The entire life cycle of these parasites is spent on the host or in the hosts “nest”. All of these insects are basically blood and/or skin-feeders. 1. Phthiraptera (lice) – In lice the body is flattened top to bottom. These insects are obligatory parasites, which means that the entire life cycle is spent on the host animal. Some have chewing mouthparts, others sucking mouthparts. Lice are very sensitive to temperature changes and soon die off the host body. They are also highly host specific. Human lice feed only on humans. Constant environmental conditions on the host usually allow continuous reproduction. One odd exception to this is can be seen elephant seal lice. Elephant seals in the Antarctic only leave the water twice a year for several weeks. Their lice must time their reproduction to this period. Lice are known to transmit only a few rickettsial diseases, such as louse-borne relapsing fever. 2. Hemiptera (bedbugs, kissing bugs, bat bugs). Parasitic bugs all live in or near the host nest. They feed only at night. Bed bugs feed on birds (e.g. swallows, wood ducks) and humans. Kissing bugs are notorious as carriers of Chagas’ Disease. They bite a wide range of mammals that build nests, including humans. Humans may be hypersensitive to kissing bug bites, and can suffer from anaphylactic shock when bitten. Bedbugs feed on humans, birds and bats. All parasitic bugs feed on blood their entire life cycle. Parasitic bugs (kissing and bed) have distinctive a odor. If you notice an odd smell in a motel room don’t sleep there. 3.
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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.

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ch20 - ENT 100 Fall 2009 1 Lecture 19 Parasites and...

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