Hey,

Most dart frogs now are non-poisonous.
Non of the captive bred ones are poisonous since it is based on their diet.

Most dart frogs in captivity are fruit flies that are dusted with mineral and vitamin supplements.
If they do eat crickets, it would be pinhead ones. Very few dart frogs eat grown crickets.

I forgot were I read this, but there have been studies that have shown dart frogs stay poisonous for over a year, even after being fed non-poisonous insects.