A biogenic charge was a hypothetical biogenic weapon devised as an assimilation method by the Borg Queen in 2375, intended for use against Humans, who had survived two previous direct assaults.
The method involved detonating the charge in Earth's atmosphere, subsequently infecting all inhabitants with nanoprobe viruses. The Queen suggested the biogenic charge to Seven of Nine, as part of her attempt to influence Seven to rejoin the Collective. The Queen assigned Seven the task of programming the nanoprobes and enhancing their viral sequencers, using her knowledge of Humans in order to maximize the process's efficiency. Despite Seven's insistence that the charge would prove inefficient due to the fact that the virus would take years to proliferate throughout Earth's ecosystem, the Queen maintained that the Collective had already displayed great patience in their efforts to assimilate Humanity, and was willing to wait for the end result. Before Seven could begin work on the charge, however, she was rescued by Captain Janeway and the crew of the USS Voyager. (VOY: "Dark Frontier")