Parasitoids

Parasitoid [ Biology ]	Dictionary of botanic terminology - index of names

The term parasitoid is usually referred to an an endoparasitic organism (fly larva or wasp larva) that, during its development, lives in or on the body of a single host individual, eventually killing that individual.

Parasitoids differ from parasites in their relationship with the host. In a truly parasitic relationship, the parasite and host live side by side with little or no damage to the host organism while the parasite takes enough nutrients to live on and reproduce without draining the host's reserves in full. In a parasitoid relationship, the host is usually killed after the full development of the other organism. Many people use the word parasite when they really mean parasitoid. This is unfortunate because it obscures the lethal effect of parasitoids.

Eretmocerus sp. and Encarsia sp. wasps are examples of parasitoids of whiteflies; whose larvae develop within and kill their host.

Most beneficial insects for plants are parasitoids (especially wasps or flies). It is known that plants have defensive mechanisms that act directly against herbivore and pathogen attack; however, recent studies have shown that a variety of herbivore-damaged plants emit chemical signals that attract parasitoids and predators to the herbivores.

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Holdfast roots [ Botany ]
Dictionary of botanic terminology - index of names

Some species of climbing plants develop holdfast roots which help to support the vines on trees, walls, and rocks. By forcing their way into minute pores and crevices, they hold the plant firmly in place.

Climbing plants, like the poison ivy (Toxicodendron radicans), Boston ivy (Parthenocissus tricuspidata), and trumpet creeper (Campsis radicans), develop holdfast roots which help to support the vines on trees, walls, and rocks. By forcing their way into minute pores and crevices, they hold the plant firmly in place. Usually the Holdfast roots die at the end of the first season, but in some species they are perennial. In the tropics some of the large climbing plants have hold-fast roots by which they attach themselves, and long, cord-like roots that extend downward through the air and may lengthen and branch for several years until they strike the soil and become absorbent roots.

Major references and further lectures:
1) E. N. Transeau “General Botany” Discovery Publishing House, 1994