Ever capture a moth and accidentally rub the powdery coating off its wings and body? Well, picture thousands of moths all fluttering about at once, in one place—each shedding this powder made up of millions of tiny scales.
Scales and other insect debris kicked up during mass-rearing can trigger sneezing, bronchitis, asthma, or more severe allergic reactions in susceptible people, says ARS entomologist Frank M. Davis. He is at the ARS Crop Science Laboratory in Mississippi State, Mississippi.
It's an occupational safety concern for entomologists and workers in all insectaries—whether they mass-rear hundreds or millions of moths and other insects for use in scientific research and as biological controls for crop pests.
"But now we've developed a management system for dealing with these scales," says Davis. "We call it ALERT, for Advanced Lepidoptera Environment Rearing Technology.
'The system begins with housing scale-shedding insects in separate quarters. We keep them in specially designed cages that facilitate removal of scales as they are produced. And, day and night, we run an improved, state-of-the-art air filtration system."
Davis, along with supervisory maintenance mechanic Stan Malone and lab director Johnnie Jenkins, consulted with a private firm to improve the lab's existing filtration system and bolster its overall scale-removal efficiency. They also implemented exceptional housekeeping practices, such as locating the vacuum cleaner motor outdoors and piping the suction in through PVC tubing. Says Davis, "The ALERT system has solved a problem that's concerned us and others in insect-rearing for years."
According to a 1984 study by the Entomological Society of America, 60 percent of 136 federal and private insect-rearing institutions that were surveyed reported at least one individual experiencing allergic symptoms from insect debris. A 1993 Italian university survey found 7 out of 13 insectary workers suffered allergies.
But in laboratory tests conducted near 20,000 caged moths, the air filtration system cleared nearly 100 percent of scales from the surrounding air. A commercial laser counter used to confirm the system's effectiveness detected about 9,000 tiny 0.5-micron particles per minute in the air entering the system, but only 47 per minute after the filter went to work.
Placed behind moth-holding cages, the air-cleaning system comprises a series of ducts and a special blower to draw larger-sized scales into pre-filters. Smaller debris is forced into a final downstream filter that removes up to 99 percent of remaining particles.
The work has been reported in the Journal of Economic Entomology. Several private firms specializing in natural pest controls are interested in adapting the ARS ALERT technology to their insect-rearing operations. — By Jan Suszkiw, ARS.
"Insectary Workers Can Breathe Easier" was published in the May 1995 issue of Agricultural Research magazine.