Two Species Are Really One

PEPS study finds DNA barcoding cannot accurately ID fruit flies

  • 2 August 2022
  • Author: Mark Berthold
  • Number of views: 907
Two Species Are Really One

When two fruit flies look very different, it’s logical to conclude they’re from two different species, correct?

Au contraire, monsieur. A new study by the Dept. of Plant and Environmental Protection Sciences, using genomic sequence data, shows that what was previously thought to be two different pest fruit fly species in the mango fruit fly complex – are actually one.

“This is surprising because the adult flies have very different appearances and markings across their range, and some previous studies showed different host preferences,” says principal investigator Camiel Doorenweerd. “Nevertheless, the genome-wide DNA data we obtained shows the mango fruit fly (Bactrocera frauenfeldi) is a single widespread pest across Peninsular Southeast Asia, not separate from the white striped fruit fly (Bactrocera albistrigata).”

From his work in Dan Rubinoff’s Insect Systematics and Biodiversity Lab, Camiel also concludes that a highly popular molecular identification method called “DNA Barcoding,” which is used around the world for a wide variety of DNA identifications – including official plant protection protocols – cannot differentiate between the pests of the mango fruit fly complex.

“New methods will need to be developed, he says. “Accurate molecular identification methods can be particularly beneficial because they can identify maggots found inside fruit, rather than waiting for them to develop into adults.”

Fruit flies of the family Tephritidae include some of the most destructive agricultural pests worldwide. The mango fruit fly has invaded northern Australia and the Philippines in the last 10 years and has the potential to invade more regions.

Hawaiʻi currently has five species of tephritid fruit fly accidentally introduced in the last 70 years. These five species (Mediterranean fruit fly, Oriental fruit fly, solanum fruit fly, melon fly, and, since 2018, olive fruit fly) have greatly reduced the potential for commercial fruit export and profitable farming. And even more pest species could potentially be introduced into Hawaiʻi or the Mainland.

“Our research focuses on risk assessment and developing identification methods to enable early recognition of newly introduced pests,” says Camiel. “When a new pest arrives, there is only a short window for eradication before the pest becomes established and it is virtually impossible to get rid of it.”

Read the full “A phylogenomic approach to species delimitation in the mango fruit fly (Bactrocera frauenfeldi) complex: A new synonym of an important pest species with variable morphotypes (Diptera: Tephritidae),” which appears in a recent Systematic Entomology of the Royal Entomological Society.

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