Gender dimorphism in the virulence of a dioecious mistletoe.

Parasite virulence often differs between male and female hosts. However, less is known about how virulence might differ between male and female parasites. Here, I show that female plants of the dioecious mistletoe Misodendrum quadrifolium (Misodendraceae) grow larger than male plants. Correspondingly, females reduce the photosynthetic capacity of infected host branches more than males. Results indicate that in addition to playing an important role in determining host susceptibility to parasitism, gender can also play an important role in determining the virulence of dioecious parasites.