Positive roles:

Insects: Pollination of plants, decomposition of organic matter, and serving as a food source for other animals.
Reptiles: Control of pest populations by preying on insects and rodents, and contributing to ecosystem balance.
Negative roles:

Insects: Some can transmit diseases to humans and animals, damage crops, and be nuisances.
Reptiles: Certain species may pose threats to humans, livestock, or other wildlife, and some can become invasive in certain ecosystems.