Infection Patterns and Fitness Effects of and Symbionts in the Green Lacewing

Endosymbionts are widely distributed in insects and can strongly affect their host ecology. The common green lacewing () is a neuropteran insect which is widely used in biological pest control. However, their endosymbionts and their interactions with their hosts have not been very well studied. Therefore, we screened for endosymbionts in natural and laboratory populations of using diagnostic PCR amplicons. We found the endosymbiont to be very common in all screened natural and laboratory populations, while a hitherto uncharacterized strain was found only in laboratory populations. By establishing lacewing lines with no, single or co-infections of and , we found a high vertical transmission rate for both endosymbionts (>89%). However, we were only able to estimate these numbers for co-infected lacewings. negatively affected the reproductive success in single and co-infected , while showed no effect. We hypothesize that the fitness costs accrued by infections might be more tolerable in the laboratory than in natural populations, as the latter are also prone to fluctuating environmental conditions and natural enemies. The economic and ecological importance of lacewings in biological pest control warrants a more profound understanding of its biology, which might be influenced by symbionts.