Meeting Abstract
Much is known regarding the impact of global climatic shifts on the stability of insect communities. However, the influence of rising temperatures on host-microbe interactions and their influence on reproduction is less understood. Pea aphids (Acyrthosiphon pisum) asexually produce offspring with distinct winged and wingless phenotypes when exposed to environmental stressors. Besides harboring the obligate bacterial symbiont, Buchnera aphidicola, which provides essential amino acids, some pea aphids can establish and maintain “secondary” facultative symbionts such as Regiella instecticola, which can provide protection against fungal pathogens. While winged and wingless individuals from the same mother are genetically identical, additional energy is required for wing production and maintenance. Such energy needs may be further impacted by the presence of secondary bacterial symbionts. By inducing production of winged offspring via crowding, and further exposing winged and wingless adults to heat-shock, we assessed the influences of heat stress, morphotype and secondary symbionts on reproductive ability and lifespan. Morphotype and stress treatment, but not symbiont status, significantly impacted aphid reproduction: winged, unstressed aphids reproduced more than their wingless sisters. In contrast, all three factors impacted survival, with symbiont status having the strongest source of effect: aphid lines containing fungal-protective Regiella, in addition to those without the secondary symbiont had the highest levels of survival. Our results suggest that upon environmental stress, morphotype is the main driver for adaptation. Furthermore, the energy spent on maintaining protective secondary symbionts may result in a tradeoff with decreased reproduction and overall lower life quality upon the absence of the pathogen.
