Host species influences body size and egg load of the bark beetle parasitoid Roptrocerus xylophagorum (Hymenoptera: Pteromalidae)

As early as 1844, it was stated that the size of the host may influence the size of parasitoid adults (Ratzeburg 1844) and that parasitoid size may affect fecundity (Salt 1941). Although positive relationships between host and parasitoid body size have been supported in the literature (Tillman and Cate 1993; Heimpel and Rosenheim 1995), this relationship is not universal to all host–parasitoid systems (King 1991; Morse 1994). Although the relationship between host size and body size of parasitoid adults has been observed for some bark beetle parasitoids (Bushing 1967; Samson 1984), the relationship between body size and fecundity has not been studied for bark beetle parasitoids. Roptrocerus xylophagorum Ratzeburg (Hymenoptera: Pteromalidae) is a bark beetle parasitoid with a wide host range that includes beetles in the genera Dendroctonus, Ips, and Scolytus (Bushing 1967).