a good way to keep the locusts and crickets in good condition is to house them in a small tommy-tank with a few toilet rool tubs so they can hide away in, feed the locusts on cabbage and carrots, with the odd peice of apple as a source of liquid and the crickets on watery things like apple, oranges grapes ect. also give them a bowl of brand or fish pellets. the toilet tubs will help u when you want to feed them to the leapords as you can pick up a tub shake it in a tub, dust the crickets with powder and throw into the tank for your gekco's
the mealworms sould only be as a treat for the geckos as they are very fattening but a good way to keep them is to also have them in a tommy-tank, with lots of bran. newspaper scrunched up for them to hide in and they will also feed on this (not sure why) you can also give them veg like carrot, parsnip ect.
its always a good idea to keep your insects on a heat mat as they should survive longer but make sure it doesnt get too humid as they dont like to be damp.
hope that helps