Murray State University

Poster Title

The Effects of Light Exposure on Immunity in Wax Moth Caterpillars

Institution

Murray State University

Abstract

The environment in which an animal lives may affect its immune system, and these effects can have far-reaching consequences. For example, animals living in poor quality habitats may have reduced immunity, presumably due to stress, and be more susceptible to disease. We are examining the impact of one environmental factor, light level, on the immune system of wax moth (Galleria mellonella) caterpillars. Caterpillars were reared in 24 hours light exposure or 24 hours dark exposure. Because wax moth caterpillars live inside beehives in their natural environment, we predicted that animals reared in a dark environment would be less stressed and have greater immunity. We examined two measures of immunity: levels of phenyloxidase (PO) – an enzyme important in invertebrate immune systems - and overall protein levels. Both of these parameters were measured in hemolymph (blood). We also measured animal size (head width and total length). We found that, per unit of hemolymph, both PO activity and protein levels increased with animal size. In addition, animals reared in light were significantly smaller, pupated at a smaller size and weighed less as newly emerged moths than animals reared in dark environments. These findings suggest that animals reared in light had reduced immunity compared to animals reared in more natural (i.e., higher quality) environments.

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The Effects of Light Exposure on Immunity in Wax Moth Caterpillars

The environment in which an animal lives may affect its immune system, and these effects can have far-reaching consequences. For example, animals living in poor quality habitats may have reduced immunity, presumably due to stress, and be more susceptible to disease. We are examining the impact of one environmental factor, light level, on the immune system of wax moth (Galleria mellonella) caterpillars. Caterpillars were reared in 24 hours light exposure or 24 hours dark exposure. Because wax moth caterpillars live inside beehives in their natural environment, we predicted that animals reared in a dark environment would be less stressed and have greater immunity. We examined two measures of immunity: levels of phenyloxidase (PO) – an enzyme important in invertebrate immune systems - and overall protein levels. Both of these parameters were measured in hemolymph (blood). We also measured animal size (head width and total length). We found that, per unit of hemolymph, both PO activity and protein levels increased with animal size. In addition, animals reared in light were significantly smaller, pupated at a smaller size and weighed less as newly emerged moths than animals reared in dark environments. These findings suggest that animals reared in light had reduced immunity compared to animals reared in more natural (i.e., higher quality) environments.