Operation Cat Drop
Read the following case study:
In the early 1950s, the people in Borneo experienced
severe problems with Malaria. This was due to the bomb
craters that acted as ideal breeding sites for mosquitoes.
Malaria is caused by the parasite Plasmodium falciparum.
The World Health Organization had a solution: they sprayed
large amounts of DDT to kill the mosquitoes which carried
the malaria. The mosquitoes died, the malaria declined; so
far, so good.
But there were side-effects. Among the first was that the
roofs of people's houses began to fall down on their heads
(the roofs were “thatch” which is made of plant leaves.) It
seemed that the DDT was also killing a parasitic wasp which
had previously controlled thatch-eating caterpillars. In
addition, flies and cockroaches were also killed.
All the insects that were killed by DDT were eaten by geckoes, which in turn accumulated
DDT. The geckoes did not die but became more lethargic (slow moving). Cats caught more
geckoes, ate them and died. Without a predator controlling their population, the rat
population increased dramatically. Rats harbour fleas, which are a carrier of another serious
human disease – Typhus (Typhus is caused by the parasite Pasturella pestis.) The World
Health Organization was obliged to parachute live cats in to Borneo.
Complete the following activity:
1. Start by listing all of the species mentioned in the case study.
2. Create a single food web that includes all of the species from your list. (NOTE: not
all of the species can be connected to the web, but draw them anyway)
3. Draw the Sun and use a big arrow to show where energy from the Sun enters into this
4. Use dots to represent the DDT. Clearly indicate the bioaccumulation and
biomagnification of the DDT in your completed food web.
5. Also indicate which organisms died as a result of the DDT.
I. There will be an Inquiry Mark out of 25 for the content and food web drawn.
II. There will be a Communication mark out 10 for how well you have communicated all
of the ideas presented in the paragraphs.
You should have a legend to indicate what the different colours and symbols mean.