The word "unfertilized" means when something, like an egg or a plant, has not been joined with something else, like sperm or pollen, to start the process of growth or development.
This native South African bee reproduces through a specific type of parthenogenesis known as thelytoky, in which diploid females (which carry the normal double set of chromosomes) develop from unfertilized eggs. (sciencemag.org)
Schöler says the clusters are likely parthenotes, embryos that develop from unfertilized eggs. (sciencemag.org)
For instance, certain fish species produce no males, but the females must have sex to trigger parthenogenic development of unfertilized eggs; the female therefore «mates» with males of other species. (discovermagazine.com)