Step 1: Understanding the Concept
A vector-borne disease is carried to humans by an organism such as a mosquito.
Step 2: Check each disease
Malaria is spread by Anopheles, dengue by Aedes and filariasis by Culex.
Ascariasis is caused by the roundworm Ascaris and spreads when eggs are swallowed with contaminated food, water or soil.
Step 3: Conclusion
Only ascariasis has no vector.
Final Answer:
Ascariasis is not vector borne.
\[ \boxed{\text{(D) }\text{Ascariasis}} \]