Horizontal transmission of the microsporidium, Nosema adaliae, from the two-spotted lady beetle, Adalia bipunctata, to the green lacewing, Chrysoperla carnea

Abstract

The green lacewing, Chrysoperla carnea Stephens, and the two-­‐spotted lady beetle, Adalia bipunctata L., are two natural enemies commonly used in biological control in North America. They are used in greenhouses and agriculture through augmentative release, and are mass-­‐produced in commercial insectaries in Europe. Both have been found to host different species of microsporidia; however Nosema adaliae has been successfully identified and maintained within A. bipunctata, having a chronic effect on its host. Due to coexistence of the two insects, horizontal transmission of N. adaliae from A. bipunctata to C. carnea will provide knowledge of host specificity of the pathogen and lacewing susceptibility. The objective of this study is to determine if N. adaliae is successfully transmitted through oral consumption, if dose affects transmission, and if the pathogen has effects on C. carnea larval development. Three treatments of varying numbers of infected and non-­‐infected A. bipunctata eggs were fed to C. carnea larvae, and development was observed over 30 days. Experimental trials were conducted under controlled environmental conditions. Test larvae were examined for microsporidian spores upon death or after the 30 days trials had concluded. The microsporidium was transmitted to two lacewing larvae that died early in their development suggesting acute effects of the pathogen. Low pathogen transmission suggests pathogen resistance and poor susceptibility of C. carnea to N. adaliae.