Biology ofCallirhytis cornigera(Hymenoptera: Cynipidae) and the Arthropod Community Inhabiting Its Galls

Abstract

Populations of Callirhytis cornigera (Osten Sacken) and its associated community of natural enemies and inquilines were monitored on pin oak, Quercus palustris Muenchhausen, in Lexington, KY, from 1997 to 1999. The gall wasp has alternating agamic and sexual generations that differ morphologically and develop in multichambered galls on branches and single-chambered galls on leaves, respectively. There was a strong association between maximum gall diameter and the number of total stem gall inhabitants, such that proportionately more C. cornigera survived and fewer were parasitized as stem gall diameter increased. The most abundant natural enemies of the agamic generation included the hymenopteran parasitoids Sycophila spp. (Eurytomidae) and Ormyrus labotus Walker (Ormyridae), and the clerid predator Phyllobaenus verticalis (Say). The most abundant inquilines in stem galls were the cynipids Synergus sp. near lignicola and Ceroptres sp., and the dogwood borer, Synanthedon scitula (Harris) (Lepidoptera: Sesiidae). In leaf galls, Aprostocetus sp. was the most abundant parasitoid, and Ceroptres sp. was the only inquiline. The unique aspects of the C. cornigera gall system are discussed, including the relative abundance, emergence phenology, and host relationships of C. cornigera and its associated natural enemies and inquilines.

A native and an introduced parasitoid utilize an exotic gall-maker host

“…O. labotus exploits more hosts than any other Ormyrus species (Hanson 1992). It is the most abundant parasitoid in galls formed by Callirhytis cornigera Osten Sacken (Hymenoptera: Cynipidae), and overwinters as pupae within C. cornigera stem galls on Q. palustris Muenchhausen (Eliason and Potter 2000). D. kuriphilus was introduced to North America in the 1970s, and is therefore a relatively new host for O. labotus (Cooper and Rieske 2007).…”

Spatial Distribution and Parasitism of Leaf Galls Induced byCallirhytis cornigera(Hymenoptera: Cynipidae) on Pin Oak

“…(Eurytomidae), Brasema sp. (Eupelmidae), and Ormyrus labotus Walker (Ormyridae) (see also Eliason and Potter 2000b). All were solitary ectoparasitoids that attacked older C. cornigera larvae and pupae, and tended to emerge before C. cornigera adults.…”

“…Pin (Quercus palustris Muenchhausen) and willow (Q. phellos L.) oak are most commonly attacked (Weld 1959, Johnson andLyon 1988). Development of the agamic and sexual generations requires about 33 mo and 9 wk, respectively (Eliason and Potter 2000b). Stem galls on tree branches are aesthetically disÞgur-ing, cause branch dieback, and heavy infestations may kill trees either alone or in combination with other environmental stresses (Whyte and Ford 1980, Johnson and Lyon 1988, Taft and Bissing 1988.…”

Life History and Natural Enemy Associations of Calico Scale (Homoptera: Coccidae) in Kentucky

“…The appropriate base temperature for use in heat summation models is the one yielding the lowest coefÞcient of variation in degree-days among years. This method has been used to predict emergence of other tree-inhabiting insects (Potter et al1989, Eliason andPotter 2000). Pruess (1983) recommended that DD models intended for use in pest management use standardized base temperatures as reported by the National Weather Service.…”