https://en.m.wikipedia.org/wiki/Avermectin

https://en.m.wikipedia.org/wiki/Protostome

avermectins block the transmission of electrical activity in invertebrate nerve and muscle cells mostly by enhancing the effects of glutamate at the glutamate-gated chloride channel that is specific to protostome invertebrates, with minor effects on gamma-aminobutyric acid receptors. This causes an influx of chloride ions into the cells, leading to hyperpolarisation and subsequent paralysis of invertebrate neuromuscular systems; comparable doses are not toxic for mammals because they do not possess protostome-specific glutamate-gated chloride channels.