About the Cover
A parasitoid wasp, Encarsia pergandiella, laying an egg in a whitefly. This minute wasp is infected with Cardinium, an obligate intracellular bacterial endosymbiont that causes cytoplasmic incompatibility. When symbiont-free female wasps mate with infected males, most of their offspring die. See PERLMAN et al. (pp. 1003–1011). Photograph by Alex Wild.