Term
| The five generally accepted steps in the parasitoid foraging behavior paradigm |
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Definition
1) location of host habitat
2) location of hosts within the habitat
3) acceptance of the host for egg laying
4) the suitability of hosts for development of the parasitoid
5) in some cases the parasitoid has to manipulate the host to make it suitable for offspring development |
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Term
| some examples of parasitoids locating the host habitat |
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Definition
| -Leptopilina heterotoma using volatile odors from decaying fruit to find the Drosophila larvae they attack
-the use of sound by mole cricket parasitoids to locate their hosts’ habitats and the hosts within them |
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Term
| some examples of parasitoids locating the host within the habitat |
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Definition
-a parasitoid fly that attacks gypsy moth larvae. In this case the parasitoid forages in the habitat where the hosts are located, and places it takes on the portions of leaves where it finds fresh feeding damage. The gypsy moth larvae then consume the fly egg while they are feeding, the egg hatches inside of the caterpillar, and parasitism is underway. So, in this case the parasitoid locates the host habitat, finds locations where the host is feeding, then leaves little time bombs for the host.
-responding specifically to cues that direct them to their hosts within the habitat, such as a wasp attacking caterpillars that are significant pests in cotton, corn, peanuts, soybeans, tomatoes, tobacco, and other crops |
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Term
| some examples of parasitoids accepting the host |
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Definition
| -Telenomus heliothidis will sting non-host eggs if they are treated with material from the accessory glands of the normal host – Heliothis virescens
-Edovum puttleri will sting glass beads if they are treated with hexane wash of eggs of the normal host - Leptinotarsa decemlineata |
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Term
| some factors that affect host suitability |
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Definition
-Host age or life stage
-Host diet – Nicotine, e.g.
-Parasitization status of host
-Health of host |
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Term
| how the response of the host can help the parasitoid decide on the suitability of the host |
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Definition
-If the host exhibits a very vigorous defensive response, then the parasitoid gets very excited and recognizes that this is a healthy host and will attack it.
-If the pest response is subdued or nonexistent, and parasitoid use this test will reject the host. |
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Term
| some ways parasitoids can reduce the suitability of hosts for subsequent parasitoids |
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Definition
-Internal Host Discrimination
1. Marked Hosts
-Eliminate competitors
2. Physical attacks |
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Term
| an example of physical attacks |
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Definition
| Copidosompsis tanytmemus attacking moth eggs
This is a polyembryonic species that typically lays a single egg from which hundreds of larvae eventually develop. But one subset of those larvae becomes a group of defenders that aggressively attack and destroy any other parasitoids that try to develop in the host. These defenders will never become adults, but will spend their entire short lives defending their siblings within the host. This is a particularly interesting system because of its ramifications for genetic control of development. All of the siblings are clones of one another, yet one small group is directed to become defenders, whereas the majority go on to become normal wasps. |
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Term
| how parasitoids can use physiological suppression to reduce the suitability of hosts for subsequent parasitoids |
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Definition
-Oxygen depletion
-Inhibitory secretions |
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Term
| an example of using oxygen depletion to reduce the suitability of hosts for subsequent parasitoids |
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Definition
| depleting the oxygen to such a level that competitors suffocate, as is the case of the parasitoid Horogenes chrysostictos against it’s competitor Nemeritis canescens |
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Term
| an example of using inhibitory secretions to reduce the suitability of hosts for subsequent parasitoids |
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Definition
| In a few cases, such as that of the fruit fly parasitoid Leptopilina heterotoma, the developing larvae within the host produce inhibitory secretions that essentially poison their competitors. |
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Term
| multiple parasitism regarding parasitoids |
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Definition
| parasitoids of different species successfully completing development within the same host |
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Term
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Definition
| Host is infested by more parasitoids of the same species than the host can adequately support, in some cases resulting in total parasitoid death |
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Term
| an example of how symbiotic bacteria can confer resistance to certain parasitoids |
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Definition
| the pea aphid and its parasitoid Aphidius ervi |
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Term
| some means by which parasitoids regulate their hosts |
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Definition
-toxins injected into the host by the ovipositing female
-viruses which the female inserts into the host along with her eggs
-teratocytes, which are tiny cellular components of eggs that are released into the host when the egg hatches and which modify the nutrient quality of the host or suppress the host immune system
-other mechanisms |
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Term
| how parasitoids can use viruses for host regulagtion |
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Definition
| Viruses can contribute to specificity or breadth of host range |
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Term
| how endocrine interactions can be used by parasitoids to regulate hosts |
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Definition
| Parasitoids are also capable of modifying endocrine interactions with the host, affecting the ability of the host to develop, utilize food resources, and in some cases the parasitoid is able to usurp the hosts hormones for its own development. The hormonal interactions between parasitoids in the hosts have not been worked out in great detail as of yet, there are clear indications that these relationships are quite complex. |
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Term
| some details about Green Lacewing (Family Chrysopidae) |
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Definition
Our bug of the day is a very important natural enemy in many crop systems. They typically lay individual eggs, but they may also be clumped in some species. Eggs of nearly all species are laid on stalks, presumably to reduce predation risks. The larvae are very active predators of aphids and other soft-bodied insects. The last instar larva spins a small circular cocoon in which it pupates.
Here we have an image of a larva feeding on an aphid on the left, and the adult on the right. These are green lacewings. Adults of many of the common species are not predators, but there are many species that are predatory as larvae and as adults. A few species are available commercially and are used in biological control programs. |
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Term
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Definition
| Green Lacewing (Family Chrysopidae) |
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Term
| pictures of Green Lacewing (Family Chrysopidae) |
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Definition
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