What are the contributions both advantages and disadvantages insects made on local, communal and global basis?

Question

what are the possible contributions both advantage and disadvantages insects have made to us? the repercussions of their loss and the effects this may have on present day and future socities?

Answer 1

Termites convert wood into methane, a powerful greenhouse gas.  

Grasshopper swarms can devastate food crops in large areas.

Answer 2

The biggest are bees for pollination (positive), and plant insect pests that harm agriculture and natural resources (negative).  These two BIGGIES cover the the local, regional and global theaters.

Future society have to create a way to compensate for a lack of bees and to fight explosive spread and growth of plant pest species.