Which of the following events prompted worldwide mosquito control efforts in the 20th century?

• A. The discovery that mosquitoes spread diseases like malaria and yellow fever
• B. The development of vaccines for mosquito-borne diseases
• C. The invention of modern pest control equipment
• D. The discovery that mosquitoes can feed on nectar

Answer: (C)

Understanding that mosquitoes are vectors of deadly diseases is what sparked worldwide mosquito control efforts in the 20th century. When scientists showed that diseases like malaria and yellow fever are transmitted by mosquitoes, public health programs shifted from merely reacting to nuisance bites to actively reducing mosquito populations to prevent outbreaks. This vector-disease link drove large-scale control campaigns, surveillance, habitat modification, and later widespread use of insecticides. The existence of vaccines helps prevent disease in individuals but doesn’t by itself trigger broad population-wide control programs. While modern pest-control equipment aids implementation, it didn’t start the global efforts. The idea that mosquitoes feed on nectar is unrelated to disease transmission and doesn’t prompt these control campaigns.