Wolbachia in a major African crop pest increases susceptibility to viral disease rather than protects

Robert I. Graham, David Grzywacz, Wilfred L. Mushobozi, Kenneth Wilson

Research output: Contribution to journalJournal Articlepeer-review

99 Citations (Scopus)


Wolbachia are common vertically transmitted endosymbiotic bacteria found in < 70% of insect species. They have generated considerable recent interest due to the capacity of some strains to protect their insect hosts against viruses and the potential for this to reduce vector competence of a range of human diseases, including dengue. In contrast, here we provide data from field populations of a major crop pest, African armyworm (Spodoptera exempta), which show that the prevalence and intensity of infection with a nucleopolydrovirus (SpexNPV) is positively associated with infection with three strains of Wolbachia. We also use laboratory bioassays to demonstrate that infection with one of these strains, a male‐killer, increases host mortality due to SpexNPV by 6–14 times. These findings suggest that rather than protecting their lepidopteran host from viral infection, Wolbachia instead make them more susceptible. This finding potentially has implications for the biological control of other insect crop pests.
Original languageEnglish
Pages (from-to)993-1000
Number of pages8
JournalEcology Letters
Issue number9
Publication statusPublished - Sept 2012
Externally publishedYes


  • African armyworm
  • Arthropod
  • Baculovirus
  • Insect outbreak
  • Male-killing
  • Nucleopolyhedrovirus
  • Parasite
  • Spodoptera
  • Symbiosis
  • Wolbachia


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