Question

Insectivorous plants placed in ecosystem at which trophic level

Answer 1

Technically it's a primary producer (first level), because they don't EAT the insect (like real insectivores), they take the basic components of their molecules and uses LIGHT to transform them into biomolecules. They do the same as other plants, they just have a different source of nitrogen and Phosphorus....An insectivorous animal, to be considered that, takes the insect's biomolecules and makes them it's own. 

Answer 2

Insectivorous plants occupy two tropic levels such as:

In Tropic level 1 as producers

In Tropic level 2 as insect eaters  

As producers, they prepare their own food via photosynthesis because they contain chlorophyll and as insect eaters, they get nitrogen from the insects they trap. Insectivorous plants display different colors which makes them look attractive to insects and become their prey.