MadSci Network: Zoology

Re: How much radiation can insets receive and survive?

Date: Mon Dec 22 16:33:26 2003
Posted By: John Moulder, Faculty, Radiation Biology, Medical College of Wisconsin
Area of science: Zoology
ID: 1071769457.Zo

irradiated insects

Steve, you ask:

I have heard that Cockroaches can withstand an extreme amount of [ionizing] radiation in comparison with humans.
How much radiation can insets receive and survive?
Is this due to their relatively small surface area, their exoskeleton or some other factor that prevents absorption, or can they absorb a lot of radiation without it affecting their tissue as greatly?

You are correct that cockroaches are much more resistant to ionizing radiation than humans. In fact most (perhaps all) insects are more resistant to ionizing radiation than all mammals.

For most insects a dose of about 500-700 Gy is required to kill them within a few weeks of exposure; although cockroaches require 900-1000 Gy (Hassett and Jenkins, Nucleonics, 1952). Killing insects in less than a few days requires much higher doses. These doses are for mature insects, the immature stages of some insects (I don't know of data on baby cockroaches) can be killed by doses as low as 40 Gy (Blaylock et al, Proc Hawaiian Acad Sci, 1952).

Some insects can be sterilized at even lower doses, and this has application in insect control. Screw-worms, for example, can be sterilized with doses of 25-50 Gy (Bushland and Hopkins, J Econ Ent, 1953).

By contrast, doses as low as 3 Gy caused death of humans in Hiroshima and Nagasaki (Levin et al, Health Phys, 1992) and doses of about 6 Gy caused death of fire fighters in the Chernobyl accident (Mould, 1988).

It is not exactly certain what the basis is for the resistance of insects to ionizing radiation.

So it is clear that insects are resistant to ionizing radiation and that this resistance is an inherent property of their cells. But it is not clear exactly what the basis of this cellular resistance is, although the dominant theory is that it relates to the relatively small amount of DNA in insect cells.

One of the difficulties is assessing possible mechanisms is that very little work on insect radiobiology has been done since the mid-80's. I looked at the past 40 years of papers in one of the main radiobiology journals, Radiation Research. I found 45 papers on insect radiobiology, but the last was published in 1992, and over half were published prior to 1975.

John Moulder
Professor of Radiation Biology
Senior Editor, Radiation Research
Medical College of Wisconsin


  1. TM Koval: Intrinsic resistance to the lethal effects of x-irradiation in insect and arachnid cells. Proc. Natl. Acad. Sci (USA) 80:4752-4755, 1983.
  2. DS Grosch and LE Hopwood: Biological Effects of Radiation, Academic Press, 1979.
  3. ZM Bacq and P Alexander: Fundamentals of Radiobiology, Pergamon, 1961.
  4. WD Clauss: Radiation Biology and Medicine, Addison-Wesley, 1958.

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