Effects of removal of Cardinium infection on fitness of the stored-product pest Liposcelis bostrychophila (Psocoptera: Liposcelididae)

Endosymbiotic bacteria that potentially influence reproduction and other fitness-related traits of their hosts are widespread in arthropods, and their appeal to researchers' interest is still increasing. In this study, the effects of removal of Cardinium infection on development, survival, and reproduction of Liposcelis bostrychophila Badonnel (Psocoptera: Liposcelididae) were investigated in the laboratory. The Cardinium-free strain was obtained by the removal of Cardinium infection by using 1% rifampicin treatment on the Cardinium-infected strain (control) for 4 wk, and no Cardinium gene product was detected in this strain throughout the experiment. The results showed that the removal of Cardinium infection had negative effects on fitness of L. bostrychophila. Compared with the control strain, the Cardinium-free strain (both in first [F1] and second [F2] generation) had a similar developmental time, reduced survivorship of immature stages, as well as reduced fecundity, which resulted in much smaller r(m) values. Using r(m) values, the fitness for Cardinium-free F1 and F2 relative to the control was calculated as 0.81 and 0.74, respectively. We concluded that the use of antibiotics combined with heat treatment might be a good control measure for L. bostrychophila.