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The health of lab-reared Mediterranean fruit flies--and their
human handlers--is protected better with refinements ARS scientists
devised for the flies' food. Billions of sexually sterile medflies
are raised each year in labs in Hawaii and elsewhere to combat
medfly invasions in states such as California. When sterile male
flies mate with their wild female counterparts, no fertile offspring
result. The population dies out. But, in their mush-like meals
of wheat bran, sugar, yeast and water, the flies need healthful
acids. In the past, as the food fermented, natural bacteria would
produce acetic acid. But volatiles from this acid can exceed federal
standards for worker safety and irritate the eyes. Scientists
found that adding two antibiotics and pasteurizing the food helps
hold down the acetic-acid-making bacteria and other unwanted microorganisms.
And incorporating some citric acid meets the flies' acid needs.
Tests with more than 900 million medflies showed that keeping
their rations acid--pH 4.0 to 5.0--boosts size and survival about
15 to 20 percent. Though the idea of adjusting pH to increase
medfly survival in the lab isn't new, the ARS studies apparently
are the most extensive to date to explore pH options for the food
that is used at medfly-rearing labs in Hawaii.
Tropical Fruit and Vegetable Research Laboratory, Hilo, HI
Eric B. Jang, (808) 959-4340
Stored-grain pests may meet their match in high-power microwaves.
ARS scientists have teamed with the Oak Ridge National Lab at
Oak Ridge, TN, and Micro-Grain, Inc. of Clinton, WI, to demonstrate
the use of microwaves against insects. In preliminary ARS studies
two years ago, microwave energy killed 94 percent of the maize
weevil, Sitophilus zeamais, in samples of soft white wheat.
Samples of the wheat were placed in a microwave at a temperature
of 122 degrees F. Heating up to 145 degrees F kills all the insects,
but doesn't cook the grain. Micro-Grain will make metal applicators
to separate and apply microwave energy to the grain as it flows
from bucket elevators, through metal pipes and into storage. If
the technology is successful, the company could employ as many
as 40 people to manufacture the applicators. Micro-Grain, Inc.,
is seeking a patent on the applicator design.
Stored-Product Insects Research, Madison, WI
Wendell E. Burkholder, (608) 262-3795
Manna scale insects that fed the Israelites in the Old Testament
may become the newest biological control of an exotic tree that
invaded western states. Saltcedar (Tamarix) infests and clogs
river beds. It has become one of the worst weeds along western
streams where it was planted in the 1800s as an ornamental and
to stabilize stream banks. Manna is honeydew produced by five
species of Trabutina scale, a beneficial sap sucking insect from
the southern regions around the Dead Sea. Manna scale insect and
a leaf beetle, Diorhabda elongata, from China that eats
saltcedar leaves have potential as natural controls of the tree.
ARS scientists tested the beneficial insects at the University
of Tel Aviv, Israel; the ARS European Biological Control Laboratory
in Montpellier, France, and at the ARS Quarantine Facility at
Temple, TX. Studies indicate the insects could be alternatives
to herbicides and mechanical methods that suppress saltcedar but
also kill native vegetation. By the summer of 1996, scientists
expect to release manna scale egg sacs along the lower Gila River
in Arizona and along the Rio Grande River in western Texas.
Grassland, Soil and Water Research Laboratory, Temple, TX
Jack DeLoach, (817) 770-6531
Last updated: July 10, 1996
Return to: Quarterly
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