Topical application insect toxicity tests

If insects have no choice or if they are very hungry, the deterrency threshold value is much reduced, and they often feed on a diet with alkaloids that they would normally avoid 15,32). In this case we have the chance to test the toxicity of an ingested alkaloid. If insects do not take up alkaloid-containing food, alkaloid toxicity can be assessed to some degree by topical application or by injection (Table I). 

Insecticidal Activity. Adult houseflies and 3rd instar com earworm larvae were used to evaluate the light induced toxicity of a-T. Rose Bengal was used as the standard. Both species were treated with a series of doses of the test compounds by feeding. In addition, a-T was tested by topical application. Two sets of insects were treated, one of which was kept covered to serve as a dark control. 

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