Comment Virus and fungus? bah (Score 1) 347
The doctor already figured this one out!
Melissa Majoria was the homeworld of Bees, some of which made their way to Earth. In early 2009, the Bees sensed that a catastrophe was about to befall the Earth, and began to make their way back to Melissa Majoria. Donna Noble noticed this several times, and remarked on it to the Doctor, who also found it odd. (DW: Partners in Crime, Planet of the Ood)
The catastrophe was Davros moving the Earth to the Medusa Cascade. The bees' movement created a disturbance on the Tandocca Scale, which allowed the Doctor and Donna to trace their path towards the Earth. (DW: The Stolen Earth)
http://tardis.wikia.com/wiki/Melissa_Majoria