PROC. ENTOMOL. SOC. WASH. 91(4), 1989, pp. 594-603 LIFE HISTORY OF PTEROMALUS COLORADENSIS (ASHMEAD) (HYMENOPTERA: PTEROMALIDAE) A PARASITE OF PARACANTHA GENTILIS HERING (DIPTERA: TEPHRITIDAE) IN CIRSIUM THISTLE CAPITULA David Headrick and Richard D. Goeden Department of Entomology, University of California, Riverside, California 92521. Abstract. —The biology and behavior of Ptcronialus coloradensis. a solitary larval-pupal parasite of Paracantha gcntilis, a thistle-capitulum-infesting tephritid, are described. Pter-omalus coloradensis. pre\ iously known from a single female collected in Colorado, is reported herein from California. We describe larval and pupal development using labo-ratory reared specimens, and oviposition. feeding, and reproduction from field and lab-oratory observations. Scanning Electron Microscopy of adult mandibles was used to determine the function of the dentition during emergence from the host puparium and overwintered capitula. Morphometric analysis of individual host puparia and parasites showed three distinct relationships between size and sex of the parasite to the size of the host puparium, substantiating predetermination of sex by the ovipositing female. Court-ship behavior and the side mounting of the female by the male during copulation have not been previously described for males in Plcroinalus. A description of the male is given. Key Words: Insecta, Paracaiit/ia. Cirsiuiu, Pteromalus, parasite, functional morphology, courtship behavior This study of Pteromalus coloradensis (Ashmead) was undertaken while working on the life history of its host, Paracantha gentilis Hcring, a stcnophagous capitulum-infesting tephritid on Cirsiiini thistle species in western North America (Foote and Blanc 1963, Goeden and Rickcr 1986a, b, 1987a, b). Ashmead (1890) described Pteromalus (= Rhopalicus) coloradensis from one fe-male specimen taken at West Cliff, Colo-rado; no rearing records were given. Rare is the opportunity to describe the life history of a parasite, but Pt. coloradensis lent itself well to study, thus we were able to obtain as complete a record of its biology and be-havior as known for any other North Amer-ican species in this family. Materials and Methods Cirsium californicum Gray capitula con-taining host puparia were collected from Mill Creek, San Bernardino National Forest, San Bernardino Co., California, 16 km N.E. of Mcntone, and Cirsium proteanum J. T. Howell capitula vere collected from Saw-mill Mt., Angeles National Forest, Los An-geles Co., California, 25 km S.E. of Gor-man, during the Spring and Summer of 1 987 and 1 988 (Headrick and Goeden 1 990). The capitula were dissected to remove the host puparia which were then individually placed in 60-ml clear plastic rearing vials. Newly emerged adults of Pt. coloradensis were maintained on a diet of honey which was streaked onto the inside of the vials. Cou-
Life history of Pteromalus coloradensis (Ashmead) (Hymenoptera: Pteromalidae) a parasite of Paracantha gentilis hering (Diptera: Tephritidae) in Cirsium thistle capitula
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