Explain how using the SIT could reduce transmission of dengue.

Describe how the mark-release-recapture method could be used to determine the population of A. aegypti at the start of the investigation.

The release of radiation-sterilised A. aegypti has not been very successful in controlling the transmission of dengue.

Suggest one reason why.

Recently a new method was developed to control A. aegypti. Scientists produced transgenic males carrying a 'lethal gene' which kills their offspring before they can reproduce.

The scientists released transgenic males every week in one area of a city in Brazil. At regular intervals they determined the number of A. aegypti per km2 in the area where transgenic males were released and in a control area where no transgenic males were released.

Suggest why the scientists released more transgenic males every week.

The release of transgenic males proved successful in reducing the number of A. aegypti.

Describe how the results in Figure 2 support this conclusion.