Intraspecific variation in facultative symbiont infection among native and exotic pest populations: Potential implications for biological control

Facultative bacterial symbionts can provide their host insects with protection from natural enemies. These symbionts are often found at low to intermediate frequencies among hosts in native populations, suggesting that fewer symbiont taxa (and their corresponding defensive properties) may be present in exotic populations, due to founder effects and drift in newly established populations. We tested this hypothesis by collecting aphid species from...