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Rough Science 5 Zanzibar: Video extras: Call of the Wild

Updated Wednesday, 2nd March 2005

Follow Ellen in this exclusive video extra as she makes mosquito repellent, as part of the fifth BBC/OU TV series Rough Science, based in Zanzibar

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This video dates from a time before the general availability of broadband and, as a result, has been quite heavily compressed.



Ellen: I want to prove to Kate that I've actually made mosquito repellent. And so the easiest way to do that is to catch the larvae and the pupae of mosquitoes, raise them up to adults and then I'll make a cage full of mosquitoes. Kate can put one arm in, with the repellent. And one arm in, without. Only this arm, without the repellent, should get bit.


Kate: If you tell me that I only have to drink that twice a day and a mosquito will never bite me again, I will not believe you!


Ellen: I was thinking of something else!


Kate: Why have you got a pot full of wriggly things?

Ellen: Well, because we need adult mosquitoes, -

Kate: Hang on, hang on, hang on, hang on - no. We need a mosquito repellent, we don't need any more mosquitoes! We've got plenty of mosquitoes!

Ellen: But if I'm going to make a repellent, I want to prove to you that it works.

Kate: Right.

Ellen: Therefore I need adult mosquitoes.

Kate: Mmm-huh.

Ellen: And I want adult mosquitoes that are disease free. Because - the way you get all these diseases, malaria, falaria - all the rest of them.

Kate: Mmm-huh.

Ellen: Is when an adult mosquito bites somebody that has a disease. And then bites another person who doesn't and it infects them.

Kate: Oh right.

Ellen: Okay? So the mosquito is basically the vector of all these diseases but it's got to bit someone with it and then someone without.

Kate: Okay. Sooo - where do these things come in then?

Ellen: Well, okay. So mosquitoes have laid their eggs in the water that I collected from today.

Kate: Yeah.

Ellen: They've developed into these larvae.

Kate: Those are the wiggly ones?

Ellen: Uh-huh.

Kate: Yeah.

Ellen: And then into the pupae, which are the little comma shaped ones.

Kate: Okay.

Ellen: And in the next couple of days adult mosquitoes will emerge, come out of, the pupae - the comma shaped ones.

Kate: Yeah.

Ellen: And I'll catch them in the cage.

Kate: And they are presumably totally disease free, because they haven't had a chance to bite anybody yet?

Ellen: Exactly.

Kate: So the first person they get to bite is me?

Ellen: Exactly! So I will put mosquito repellent on one arm.

Kate: Yeah.

Ellen: And not on the other.

Kate: Okay.

Ellen: And we'll compare. And what we should find is the one with repellent - no mosquito bites…

Kate: Doesn't get bitten. And this one gets bitten to death.

Ellen: Yes. And this way we do it safely for you.

Kate: Great! I'm going to remove all their teeth!

Ellen: They don't have teeth, Kate!





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