Some academic references:
Jussi Parikka uses the term in his article: Insects, Sex and Biodigitality in Lynn Hershman Leeson’s Teknolust (2007) in an early iteration of his insect figuration (and returns to it in later work).
Luciana Parisi also discusses Biodigital Sex (the title of chapter 4 of her book Abstract Sex). In a kind of macro organic history of life she contrasts the primal bacteria of the past with the biodigital sex of the future
Nigel Thrift (2007) briefly touches on Parisi’s use of this term in his book: Non-representational theory: space, politics, affect
Martha Herbert uses the term biodigital to signal ‘the will to technologise biology’ in her chapter ‘More than code: from genetic reductionism to complex biological systems’ in a collection on Genetic Governance (Bunton and Peterson, 2005)