Hygienic indicator bacteria in the 2 species of wild-caught Japanese cicadas, large brown cicadas and robust cicadas

Abstract

Entomophagy is considered a potent dietary practice to replace animal protein due to its highly nutritious and environmentally sustainable features. While entomophagy has many advantages, safety and security concerns still remain, especially for wild-caught insects, not farm-reared insects. This study aimed to clarify the potential microbiological hazards of eating wild-caught cicadas. Large brown cicadas and robust cicadas, which were commonly inhabited in Japan, were caught and examined the hygienic indicator bacteria, standard plate counts (SPC) and Enterobacteriaceae. Then, representative colonies of Enterobacteriaceae were identified. Also, the distribution of bacteria, i.e. the surface or inside the body of the cicadas, and the changes in the bacterial number during the storage of the dead cicadas were examined. SPC was in the range of 3.0 to 9.0 log CFU/g and Enterobacteriaceae was detected in the most of cicadas. Most of the Enterobacteriaceae species identified were biosafety level 2 pathogens or opportunistic pathogens. SPC and Enterobacteriaceae were distributed both on the surface and in the body of the cicadas. SPC and Enterobacteriaceae rapidly increased in the dead cicadas during the storage (at 25 °C). In this study, it is concluded that sufficient heat cooking and proper cold storage should be necessary for the safe consumption of cicadas as food.