Transposon-based genetic transformation has facilitated insect functional genomics and new strategies
of pest management. However, there is a need for alternative, site-specific approaches to overcome
limitations of random integration (and associated position-effects) and potential instability of inserted
transgenes. Here we describe a transposon-free, site-specific genetic transformation system mediated by
transcription activator-like effector nucleases (TALENs) in the silkworm, Bombyx mori, a lepidopteran
model insect. We successfully established a site-specific transgenic system with comparable transformation
efficiency to transposon-based genetic transformation through microinjection of TALENs
mRNA targeting the BmBLOS2 locus and a linearizable donor plasmid encoding an expression cassette of
the DsRed2 red fluorescent protein. This system provides a valuable approach for insect transgenesis and
will enable future functional gene analysis and generate novel applications in agricultural and medical
insect pest-management technologies.