A protozoan parasite weakens the stress reaction of monarch butterflies

Jovani Raya, a student from Abaraham Baldwin Agricultural College, worked with Dr. Sonia Altizer and Dr. Andy Davis to study the effect of infection on the stress reaction of monarch butterflies.

Abstract:  The protozoan parasite Ophryocystis elektroscirrha (OE) affects the adult mortality, longevity, body size, and flight ability of monarch butterflies (Danaus plexippus). However, very little research on how the parasite influences the stress response in monarchs has been conducted. We examined the effects of parasite infection and larval rearing densities on the monarch stress response. Monarch larvae were inoculated with parasite spores and reared in low (2 larva) or high (10 larva) densities. When the monarch larvae reached pupation, we assessed their stress reactions. To produce the stress response in the pupae, physical disturbance was applied for 20 seconds. After the disturbance, the pupa was placed on a device that detects movement within animal tissue and can record the movements of the heartbeat. This recording allowed us to count the number of beats per minute. The result showed that infection was a significant predictor of the magnitude and duration of pupa HR; infected monarchs had lower reactions. Lower reactions would negatively affect how well infected monarchs could cope with daily stressors, especially during the arduous fall migration.

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