Effects of a microsporidium pathogen, Nosema adaliae, on the general predator Chinese praying mantis, Tenodera sinensis

Abstract

Microsporidia are unicellular eukaryotic parasites that cause chronic diseases in invertebrates, as well as some other species in the animal kingdom, such as fishes, crustaceans and even humans. Microsporidia are known to cause a variety of effects to their hosts, such as increase in development time, increase in mortality, changes in feeding amounts, and increased likelihood of experiencing developmental abnormalities. Nosema adaliae is known to cause chronic disease to its natural host, the two-spotted lady beetle (Adalia bipunctata Linnaeus). N. adaliae may infect other lady beetles used as biological control agents. The focus of this study is to determine whether N. adaliae can be transmitted horizontally from A. bipunctata to the Chinese praying mantis (Tenodera sinensis Saussure) through direct feeding of infected beetle larvae. Horizontal pathogen transmission may occur as a result of intraguild predation, when these two biological control agents are used together for pest control. Three treatment groups were established from a population of T. sinensis, and each was provided with two second-instar A. bipunctata larvae: those from the Control group were provided two microsporidia-free A. bipunctata larvae, individuals from Treatment 1 were provided one uninfected and one microsporidia-infected A. bipunctata larva, and Treatment 3 individuals were provided two microsporidia-infected A. bipunctata larvae. Once these were eaten, T. sinensis nymphs were provided a diet of fruit flies (Drosophila hydei) and they were reared until they died. N. adaliae did not infect T. sinensis when infected beetle larvae were eaten. Mortality and longevity of T. sinensis did not differ significantly between groups. Failure of molt was significantly higher in Control individuals when compared to those of Treatment 1 or Treatment 2. Individuals of the Control group consumed significantly fewer fruit flies than did those from Treatment 1 or 2.