Gamma radiation is what turned Bruce Banner into the hulk- so when I found this article, I immediately had to see what it could do to carpet beetles. Much to my initial disappointment, I learned it did not turn them large mean and green, but I digress.  

To get ourselves situated, beetles in the family Dermestidae are commonly called carpet beetles. Carpet beetles are common household pests, often being found in carpets as their name suggests. Outside of a regular home, these pests are particularly destructive in museums. The artifacts held in museums from papers, fabrics, taxidermy, and many other organic materials, are under consistent threat from these beetles. Think of all the priceless history we keep not only on display, but archived away for the future. The larvae of these destructive beetles will eat away organic material, and over time can completely destroy critical items that preserve the world’s cultural heritage.  

Carpet beetles, like many stored product pests, can have a long life cycle, taking even a few years to go from egg to larvae to adult.

 

The priceless artifacts of museums cannot be exposed to many products the structural pest management industry would usually use. The fragile nature of the artifacts, many of whom cannot be cleaned or have delicate chemical balances, prevent use of almost every product at a PMP’s disposal. Now as you know, PMP’s have more tools to use than just insecticides. In this case, there are other IPM options to control carpet beetles. One of these options that is emerging is gamma radiation. 

 

Gamma radiation must be very specifically measured to be implemented in only the dosage necessary for the life stage being targeted. The dosages are often measured in a unit called kilograys. The goal of the research was to determine the lethal and sterilizing doses of radiation specifically for the varied carpet beetle. Note that different species have different dosages needed, making this pest specific research necessary.

The researchers reared the carpet beetles in the lab and took groups of each life stage to test against the radiation. They took each group and exposed them to a period of radiation at 5 different levels. Radiation exposure was done in an enclosed machine to keep the personnel involved safe from the radiation. In parts of the experiment, the irradiated adults were mated to see the viability of their eggs.  

As you might expect with the larvae, there was a significant positive correlation with higher radiation killing more of them. The larvae also became increasingly deformed with higher radition. Radiation reduced pupal emergence but did not deform the adults. At higher levels the pupa did not emerge and instead disintigrated internally.  

The younger the beetle, the more sensitive it was to radiation which follows the established trend that the less differentiated the cells in an organism are, the more susceptible it is to radiation. So the most differentiated cells are in adults and those are the least sensitive to radiation needing 1 kilogray to get to 100% mortality in three weeks. Even younger pupae were greatly affected, but older pupae were less so as they were more differentiated.  

The takeaways here were that the sterilizing dose and lethal doses discovered could be a viable option for killing these pests. The sterilizing dose would prevent future larvae and when needed the lethal dose would kill all of them.

Now with all that being said, one thing you may be thinking is "How safe is this to perform or administer?" Well, the device that irradiates the samples also encloses them so that the radiation isn’t getting out to everyone nearby. In the context of museum pests, if you had an infested artifact, the idea would be potentially put the artifact in a radiation chamber leave it there for whatever time is needed for the beetles to die. and then wait till the artifact is safe again. Basically, this method, when regular precautions are taken, would not pose a risk to personnel involved.

Article by Ellie Lane, BCE-Intern

References

Hamza, A., Zahran, N. & shafeay, N.E. The lethal and sterile doses of gamma radiation on the museums pest, varied carpet beetle, Anthrenus verbasci (Coleoptera: Dermestidae). Sci Rep 13, 16984 (2023). https://doi.org/10.1038/s41598-023-43739-x 

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