"Research must be done in repetitions to gain enough
data for statistical analysis," explains Martin. "We needed
to use five insects per leaf to equal one repetition. But with the freeze-dried
diet, using five insects equals five repetitions," thus five times
In tests, researchers found that bacteria that killed
beetles on leaves did not kill as many of them on the earlier, fresh,
diet. But when fed the freeze-dried diet containing toxic bacteria,
more insects diedand fasterthan those fed the same bacteria
mixed in fresh diet. According to Martin, the reason for this is that
the bacteria must be added to fresh diet while it's in its liquidand
hotstate. But the heat kills the bacteria, which reduces toxicity.
Bacteria added to the diet once it's cooled and solidified doesn't get
evenly incorporated into the food, and the bugs will not get a lethal
The new and convenient freeze-dried diet provides a way
to test a wider range of bacterial and fungal controls for the Colorado
potato beetle because the toxins can be safely added as the diet is
Finding ways to control Colorado potato beetles is vitally
important to commercial growers. Both immature and adult beetles feed
on leaves of eggplant and tomato as well as potato and have developed
resistance to most available insecticides.By Sharon
Durham, Agricultural Research Service Information Staff.
This research is part of Crop Protection and Quarantine,
an ARS National Program (#304) described on the World Wide Web at www.nps.ars.usda.gov.
Martin is at the USDA-ARS Insect
Biocontrol Laboratory, Center Rd., Beltsville, MD 20705-2350; phone
(301) 504-6331, fax (301) 504-8190.
"Colorado Potato Beetles Love Freeze-Dried Diet" was
published in the March
2004 issue of Agricultural Research magazine.