Amigratory bat species pollinates agave plants in northern mexico on its way to the southwestern united states where it spends the summer eating insects and reproducing. farmers spraying pesticides affect these bats, which eat the insects and also feed them to the baby bats. this could be the start of a story about

This could be the start of a story about threats to a keystone species

Explanation:

The ecosystem  has some kinds of species that are essential for the survival of other species of the system. That is how the ecosystem keeps its balance.

Any sort of change on the environment can put those keystone species in risk.  That is why the scients have been studying them for a while and trying to develop ways to preserve them.

Predators help control the population of prey species, when the farmers sprayed pesticides they killed the bats that were responsible for the control of the insect population. The lack of bats, will increase the insects population and unbalace the ecosystem.