Wolbachia impacts vector ecology and transmission dynamics in the banana aphid, Pentalonia nigronervosa

Microbial symbionts of several crop pests and disease vectors mediate interactions with ecological communities, shaping several components of world agriculture. Among the best-studied are aphids, which vector damaging plant pathogens while harboring several heritable symbionts conferring protection against ecological threats. The bacterial symbiont, Wolbachia, is found in many economically important arthropod species, and while among the best-studied, Wolbachia biology in aphids remains obscure. Our recent findings indicate that Wolbachia is widespread in the banana aphid, Pentalonia nigronervosa, the vector of Banana bunchy top virus (BBTV; Nanoviridae) a major pathogen of Musaceae. Since Wolbachia is particularly known for anti-viral phenotypes, we investigate whether Wolbachia infection impacts within-vector dynamics of BBTV. Through quantitative PCR we discovered that BBTV accumulation and retention, over time, were much lower in aphids with Wolbachia compared to those without suggesting Wolbachia disrupts the transmission of BBTV. We also compared aphid fitness between those with and without Wolbachia and that fed on either healthy or BBTV infected banana plants (W-/Healthy W-/BBTV+; W+/Healthy W+/BBTV+). We found that W+/Healthy aphids outperformed W-/Healthy aphids indicating that Wolbachia infection improves aphid fitness. We also found that the fitness of W-/BBTV+ aphids was comparable to W+/Healthy aphids indicating symbiont-free aphids benefited from feeding on BBTV infected plants. However, it was Wolbachia-infected aphids who benefited the most when feeding on BBTV infected plants; W+/BBTV+ aphids developed faster and were more fecund than all other combinations. Our findings provide further understanding of how heritable microbes may impact vector transmission of plant diseases.