Nematodes life cycle

Ivermectin has an extremely broad spectmm of antinematodal activity in a variety of domestic animals. Indeed, among the many nematodes against which it has been tested, none has been found that is not affected by ivermectin during at least one stage of the life cycle. In all but a few instances the dmg is highly active against both immature and mature worms (19). 

A parasite must reproduce to complete its life cycle successfully. In this sense, the ability of an H. glycines individual to parasitize a soybean plant is measured by reproduction. In general, resistant hosts do not permit the female nematode to develop to reproductive maturity. Parasitism is a qualitative trait that the individual nematode either does or does not possess. In addition, nematode populations may be described quantitatively by their level of reproduction on a given host plant. Field populations of H. glycines... 

Young, L.D. (1992) Epiphytology and life cycle. In Riggs, R.D. and Wrather, J.A. (eds) Biology and Management of the Soybean Cyst Nematode. APS Press, St Paul, Minnesota. 

Trichinellosis is caused by the parasitic nematode Trichinella spiralis. This parasite has a complex life cycle that alternates between intestinal and muscle cell compartments of the host. This nematode infection is unusual because 7. spiralis is an intracellular parasite of mammalian cells. In addition, the broad host range of this parasite includes most mammals. The disease in humans has intrigued parasitologists, other biologists and public health workers for over a century (Cambell, 1983). The attraction to trichinellosis pardy stems from the debilitating and sometimes fatal effects that characterize this disease. 

Till now not much extensive studies on Phasmarhabditis has been done, however, whatever the little information available indicates that life cycle of this nematode is dependent upon the slug species it encounters. Researchers have described three distinct life cycles of Phasmarhaditis sp. 

Grow the green manure mustard on the area. It is said to speed up the life cycle. Biological control The nematode used for vine weevil (q.v.) may have some effect against wireworms. 

This is an example of a practical problem of considerable importance, where the relevant research would certainly be described as applied . Yet it would require quite specialised inputs of scientific information (for example, the life-cycles of parasitic nematodes) to be harnessed within a systems context. We are thus brought back to the need for a systems approach to research and the questions here is how can that be organised and funded ... 

All nematodes that are parasites on plants have a hollow style which they use to puncture plant cells and feed on the cell contents. Nanatodes may develop and feed either inside or outside of a plant. They move with an eel-like motion in water, even water as thin as the film of moisture around plant cells or soil particles. Their life cycle includes an egg, several larval stages, and adult Most larvae look like adults, but are smaller. 

In adverse conditions, the females of some species, such as root knot and cyst nematodes, form an inactive, resistant form called a cyst. The cyst is the hard, leathery, egg-filled body of the dead female. It is difficult to penetrate with pesticides. Cysts may provide protection for several hundred eggs for as long as 10 years. Figure 3.10 shows the life cycle of a typical nematode. 

Figure 3.10 Life cycle of a disease-causing nematode.

Whether they feed above or below ground, most nematodes spend at least part of their life cycle in the soil. While they can t move very far under their own power, they can swim freely in water, and they move more quickly in moist soil. They are also spread by anything that can carry particles of infested soil, including tools, boots, animals, and infected plants. 

In contrast to the protozoa, helminths are multicellular with complex reproductive systems and life cycles involving intermediate hosts for the development of larval stages and a definitive host for the adult form. Adults may be dioecious with separate sexes or hermaphroditic. Helminths are flatworms and flukes such as nematodes and tapeworms. They are common enteric pathogens and can be transferred by directly eating or drinking parasite eggs, which may exist in polluted meat or water. 

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