True fruit flies in Pakistan are different, but there isnt even proper research done on them to even comment that HWT or Vapur heat treatment is not enough!! The US consulate general seems to be pulling one from his backside! Because there is no proper studies you cant make such stupid claims and USDA cant impose anything!
No studies, fruit flies?
Are you kidding?
Drosophilia and other 'fruit fly' families are used extensively in research and everything from their response to heat, drought, water stress, UV sensitivity, irradiation etc has been researched. Type Drosophilia into Google scholar and you'll get over 1 million hits.
In my first year as a post graduate research scientist, I used to perform gene knockout experiments on fruit flies! Most fruit fly species had their genomes completely mapped before the human genome.
The concerns in this instance of the US are completely valid.