What happened to horse flies after the oil spill?

  • Immediately after the Deepwater Horizon oil spill in April 2010 the adult horse fly population crashed.
  • Fly counts in oiled areas were magnitudes lower than those in unaffected areas. Most likely, adults flies searching for water were attracted to the oil sheen, which mimics fresh water.
  • We frequently found larvae of tabanids and other immature insects in soil from unaffected areas. However, most soil samples from oiled areas did not contain any larvae. The lack of larvae in the sediment is likely caused by oil contamination killing the larvae and/or their food web they rely on for nutrition and/or the reduced number of breeders due to the adults' population crash.
  • The population crash in oiled areas left its mark on the genetic structure of tabanid populations (genetic bottlenecks, fewer breeding parents, reduced effective population size, lower number of families and fewer migrants among populations in oiled areas).

    Read the publication of the results of this study in Nature Scientific Reports.