How to search NCBI in bulk for a list of accession numbers?
After some trial and error in an interactive python shell and some documentation checking, I found that the relevant information is present in the genbank-formatted output (rettype="gb"), and this can be parsed using Entrez.read provided it is returned in "xml" mode (retmode="xml").

The following code that seems to work:



#!/usr/bin/env python3

from Bio import Entrez


Entrez.email = "Your.Name.Here@example.org"
id_list = ["KJ841938.1", "FJ911852.1"] # real list is about 500 elements

for accession in id_list:
    handle = Entrez.efetch(
        db="nucleotide", id=accession, rettype="gb", retmode="xml")
    gb_record = Entrez.read(handle)
    handle.close()
    organism = gb_record[0]['GBSeq_organism']
    print("{}\t{}".format(accession, organism))


(You don't need a while loop here, by the way: python has the more convenient forsyntax to loop over the elements of a list.)

Output:

KJ841938.1  Setoptus koraiensis
FJ911852.1  Gaeolaelaps aculeifer