Computer Science Principles
impact of Computing Solutions
Anopheles gambiae, or A gambae, is the scientific name of a mosquito found in Africa. The male of this species feeds on the sap of plants.
The female feeds on the blood of various mammals. As she does this, she also often spreads malaria.
What are possible constraints that would prevent the successful use of genetically modified (GM) A gambiae mosquitoes in the fight against
malaria? Choose all answers that are correct.
The A gambiae female lays her eggs in stagnant pools of water. The larvae develop quickly into adult mosquitoes that emerge from the water.
Their quick development helps the mosquito larvae to avoid predators.
inability of GM mosquitoes to tolerate various environments
inability of GM mosquitoes to produce a large number of eggs
This mosquito species has two strains, the Mopti (M) strain and the Savannah (S) strain. These two strains have different behaviors. M strain
mosquitoes lay a greater number of eggs than S strain mosquitoes. M strain larvae are usually found in permanently flooded areas like rice
fields. The larvae of the S strain are found in temporary sites such as puddles on the ground. M strain adults stay outside in bushes, while S
strain adults enter houses, often hiding under furniture
ability of GM mosquitoes to pass the modified gene to offspring
poor survival of GM mosquitoes in areas with heavy insecticide use
Environmental factors regulate the percentages of Mand S strain mosquitoes in the total population as shown in Figure 1.
inability of GM mosquitoes to mate with both forms of A gambiae in the wild
hong
Figure 1
Efect of Rainfall on the
Percentage Change of Mand S Strains
of A gamble
100
B
Percentage of Mosquito Strana
m.
2.12
Mean Daily Rainfall (cm)
M strain
S strain
People spray insecticides outside their houses and use mosquito nets treated with insecticides inside houses to kill the insects. However, the
mosquitoes still thrive in large numbers. Insecticide spraying can also lead mosquito populations to become insecticide-resistant. These
resistant mosquitoes breed with others found in the wild and can have offspring that are also insecticide-resistant
Recently, scientists have genetically modified the "doublesex"gene in A. gambiae mosquitoes. This gene controls the development of sex
characteristics. The modified gene causes no changes in males or females that carry only one copy. However, temales that carry two copies no
longer bite or lay eggs. When females with the doublesex" modification are introduced into a mosquito population, the modified gene spreads.
Production of normal females drops, and the population crashes after around eight generations. Figure 2 shows how the modified "doublesex"
gene spreads within an A gambiae population. The release of genetically engineered female mosquitos into an area affected by malaria could
