Fig. 5—Identifying predators that destroy unwanted insects.
Aphids are made radioactive.
Larger insects found nearby are checked for radioactivity.
Bumblebee has not eaten radioactive aphids, but mantis has.
Helpful parasites and predators must first be identified before they can be used. In the case of small or nocturnal insects, this can be exceedingly troublesome. Tagging the pests with radioisotopes in order to identify the predators which consume them is much simpler because the most efficient predators contain the most activity.
With such techniques entomologists have studied insects and animals which prey on unwanted aphids, mosquitoes, blackflies, and roaches. Such experiments may lead to a deliberate increase of certain predators to control injurious insects.
Radioactive labeling is also valuable in studying helpful insects. In one case the indolence of drone bees was indicated by finding that even with adequate syrup in their cage they still received identical syrup from worker bees in an adjoining cage!