Ecological impact of a secondary bacterial symbiont on the clones of Sitobion avenae (Fabricius) (Hemiptera: Aphididae)

Many insects harbor heritable endosymbionts, whether obligatory or facultative, and the role of facultative endosymbionts in shaping the phenotype of these species has become increasingly important. However, little is known about whether micro-injected endosymbionts can have any effects on aphid clones, which was measured using various ecological parameters. We examined the effects between symbiotic treatments and the vital life history traits generated by Regiella insecticola on the life table parameters of Sitobion avenae. The results showed that R. insecticola can decrease the intrinsic rate of increase (r), the finite rate of increase (λ) and birth rate and can increase the mean generation times (T) of S. avenae clones, suggesting that R. insecticola may decelerate the normal development of the hosts. No significant differences of these parameters were observed between the examined Sitobion avenae clones, and the symbiont treatment by genotype interaction affected only the net reproduction rate R(0), pre-adult duration and total longevity but not the other parameters. Additionally, a population projection showed that R. insecticola decelerated the growth of the S. avenae clones. The evocable effects of R. insecticola on the S. avenae clones may have significant ramifications for the control of S. avenae populations under field/natural conditions.