For his dissertation research, Matt Doremus, Ph.D., studied how the bacterial symbiont Cardinium hertigii is affected by temperature in parasitoid wasps in the genus Encarsia. Using fluorescent imaging on dissected testes (male wasps’ sperm-producing organs), as in the image shown here, he discovered that the bacteria infects the wasps’ sperm in some species and the seminal vesicle in other species. These variations offer clues to how the symbiont affects the wasps’ reproduction.