In the Rough Science programme Call of the Wild, Rough Scientist Ellen has to develop a mosquito repellent. Zanzibar has a luxurious plant life and Ellen knows she can extract plant materials that will keep the mosquitoes at bay without making Kate smell too badly. However, the hard trick is proving the mosquito repellent works. Ellen will need to cover one of Kate’s arms with the repellent and leave the other arm clear, so she can show that only the arm without the repellent gets bitten. But that leaves another problem, mosquitoes carry diseases that they pick up from biting other people, so Ellen needs to raise mosquitoes from birth that haven’t bitten anybody yet and so will be disease free.

To find out more about the life cycle of the mosquito, read the following extract from the second level OU course Biology:Uniformity and Diversity (S204).

One of the most widespread infectious diseases of human beings is malaria, which kills more people than any other parasitic eukaryote, mainly in tropical countries. The agents which cause malaria are protoctists, Plasmodium spp. (phylum 11, Apicomplexa), whose life cycle provides a classic example in which there are several stages, each with a distinct morphology and function and is illustrated here.

Life cycle of a malarial parasite Plasmodium vivax. Purple indicates haploid stages and pink diploid stages. RBC=red blood cells.

Notice that there are two hosts: human beings, where one stage of the life cycle occurs in liver cells and another in red blood cells; and a mosquito (Anopheles spp.). The mosquito picks up the parasite when it feeds on the blood of an infected person and transmits it in saliva after the parasite has passed from the gut to salivary glands.

    next > Page 1 of 2

Comments