Final answer:
Mosquitoes play a crucial role in transmitting infectious diseases to humans, making statement 1 correct. Statements 2, 3, and 4 are incorrect because mosquitoes are vectors for various human infectious diseases.
Step-by-step explanation:
Mosquitoes play a crucial role in transmitting infectious diseases to humans. They are known as disease vectors because they carry and transfer pathogens from one host to another. For example, mosquitoes are vectors for diseases such as malaria, yellow fever, dengue fever, chikungunya, and West Nile virus. Therefore, statement 1 is correct.
On the other hand, statement 2 is incorrect. Mosquitoes are indeed vectors for various human infectious diseases.
Statement 3 is also incorrect. Mosquitoes do not contribute to a decrease in the spread of infectious diseases; rather, they actively contribute to their transmission.
Lastly, statement 4 is incorrect as well. Mosquitoes are associated with several infectious diseases that affect humans, not just non-infectious diseases.