esnanees Wrote:The premise stating "In addition......often a particular toxin will kill pest species but not affect insects that prey upon the species" is a bit confusing to me with regards to ans choice D.
So if the species are killed, it means the insects have no food to keep them growing. How does ans D stating that the insects build more resistant to BT weakens the argument because the toxin does not affect the insects anyway.
Can someone help me understand what i am missing in the stimulus? Thanks.
I think you're confusing which particular insect species the stimulus is talking about. When the stimulus says that B.t. toxins kill "pest" species but not insects that prey upon "pest" species, it is talking about two types of insects - the pest species are the harmful kind but the "insects that prey upon (pest) species" are insects that eat the harmful pest insects, so in a way they are "beneficial". This is the reason why B.t. toxins are preferable to insecticides. Not only do the toxins kill the harmful pest insects but they also dont kill the insects that prey upon pest insects. So in a way they are doubly effective in killing the harmful pest insects.
Answer choice D weakens the argument because it is only talking about the harmful pest insects and not the insects that prey upon the pest insects. In other words, if the harmful pest insects develop resistance more readily to the B.t toxins compared to the insecticides then the advantage of using toxins is lost (or at least diminished). This weakens the argument.
I hope that clears it up for you!