Detection of Yersinia pseudotuberculosis in Apollo Butterfly (Parnassius apollo, Lepidoptera: Papilionidae) Individuals from a Small, Isolated, Mountain Population

Yersinia pseudotuberculosis is a bacterium pathogenic to humans and other mammals; however, its insecticidal activity has also been documented in laboratory studies. A small population of Apollo butterfly (Parnassius apollo), reconstituted from less than 30 individuals in 1990s, occurs in Pieniny National Park (Poland). In this report, we demonstrate that a DNA fragment specific to Y. pseudotuberculosis could be detected in 40% of biological samples isolated from insects belonging to the Apollo butterfly population. Although Y. pseudotuberculosis DNA occurred in both normal and mal‐ formed insects, the difference between the fractions of infected individuals was statistically significant (p = 0.044 in the Fisher's exact test). No such DNA could be detected in analogous samples from other butterflies (Pieris napi, Pieris rapae, and Zerynthia polyxena) occurring in separate habitats (either a meadow near the city of Cracow, Poland, or in a mountain region of Greece). It is suggested that infection with Y. pseudotuberculosis might weaken the general condition of the P. apollo population from Pieniny and contribute to the appearance of developmental abnormalities of the butterflies. Thus, it appears that Y. pseudotuberculosis infections of insects may be of biological significance in natural environment.