Biology Now, 2e

Zika-Busting Mosquitoes ■ 351

a line of mosquitoes that does not require the use

of an antibiotic to be kept alive in the laboratory,

which would be less expensive. “We are finish-

ing the lines now. They are very promising,” says

Capurro. Other genetic modification techniques

are being attempted in labs elsewhere to make

Anopheles incapable of carrying the malaria

parasite, for example.

More recently, Oxitec released Friendly Aedes

aegypti in a neighborhood of 5,000 residents

in the city of Piracicaba, Brazil, to combat the

spread of dengue virus. The company released

3–4 million mosquitoes per month over a period

1860 1880 1900 1920

Year

Number of hare (thousands)

0

40

80

120

160

Number of lynx (thousands)

0

3

6

9 The number of lynx

rises and falls with

the number of hare.

Figure 19.11

Populations of two species may

increase and decrease together

The Canadian lynx depends on the

snowshoe hare for food, so the number

of lynx is strongly influenced by the

number of hare.

Q1: During which years did the

hare likely have the greatest food

supply?

Q2: Besides the number of

hare, what other factors might

contribute to the number of lynx?

Q3: Can you draw an average

carrying-capacity line on these

graphs? Why or why not?

Margareth Capurro is a biochemist at the University

of São Paulo in Brazil. Starting in 2011, she led

two field releases of Oxitec’s genetically modified

mosquitoes in Brazil, and today she continues to

explore the best way to use GM mosquitoes to

control mosquito-borne viruses.

MARGARETH CAPURRO

of 10 months. The experiment reduced the

number of wild A. aegypti larvae in the area by

82 percent, and the neighborhood experienced a