reproductive habits of some insects are of critical importance in pest control in agriculture

natural product chemists (it's a subfield of organic chemistry) find and identify new weird shit in obscure organisms (esp marine organisms) all the time. because amounts are tiny, then their work is on synthesis of the same thing. some of these turn out to be useful

Its actually quite simple. Snaily often eat crops and thereby reduce the production of said crops. The more snails reproduce, the more crops will be eaten. When you know how their reproduction works you can start looking for solutions on how to reduce their reproduction (and so the production of crops).