Interest in the natural enemies of proconiine sharpshooters has increased since the introduction and establishment of the glassy-winged sharpshooter, Homalodisca coagulata (Say), in California. Previous surveys of egg parasitoids of proconiine sharpshooters from Florida indicated several species in the families Mymaridae and Trichogrammatidae (Hymenoptera) as the most common (Triapitsyn et al. 1998; Triapitsyn & Hoddle 2001). Presently, classical biocontrol efforts to manage introduced populations of H. coagulata in California rely exclusively on inundative releases of egg parasitoids of the genus Gonatocerus. Triapitsyn (2003) created a key to the genera of trichogrammatid parasitoids of proconiine sharpshooter eggs in the southeastern US that included an unidentified species of the genus Paracentrobia Howard. Poor condition of type specimens of P. acuminata (Ashmead), deposited in the National Museum of Natural History, Washington, D.C., did not allow then for a positive identification of the Paracentrobia sp. from Florida and Georgia as P. acuminata (Triapitsyn 2003). More recently, specimens of Paracentrobia obtained from egg masses of Cuerna costalis (F.) and Homalodisca insolita (Walker) collected from Byron and Centerville, Georgia were identified as P. acuminata (Hoddle & Triapitsyn 2004). Additionally, specimens listed as P. acuminata, collected previously from Monticello, Florida, and Fort Valley, Georgia were verified by J. George (pers. comm.). We have reared another species of Paracentrobia, P. americana (Girault), that has not previously been reported from the southeastern United States. This parasitoid attacked the eggs of H. insolita that were cultured in cages of Johnson grass, Sorghum halepense (L.) Persoon.
Notes on Paracentrobia americana. This species was described from Salt Lake City, UT where it was reported to parasitize the eggs of an undetermined leafhopper found on Elymus sp. (Girault 1917). Prior to this study, the species description included the only published host association and distribution records for P. americana.
Material Examined. Paracentrobia americana: USA, Florida, Gadsden Co., Quincy, 30-IX-2004, C. Tipping, numerous females and males (emerged from egg masses of a culture of H. insolita reared on S. halepense). All specimens examined for this record were tentatively determined by S. V. Triapitsyn and then confirmed by J. George (Department of Entomology, University of California, Riverside); voucher material was deposited at UCRC (Entomology Research Museum, University of California, Riverside).
Notes on the Host, Homalodisca insolita. Prior to 1944, this species had a reported distribution that included Mexico, Arizona, New Mexico, and Texas. It was subsequently discovered in Georgia (Kaloostian & Yeomans 1944). By the late 1950s, its distribution was reported to include Louisiana, Arkansas, Tennessee, Mississippi, Alabama, Florida, Georgia, South Carolina, and North Carolina (Pollard et al. 1959). It has been reported to feed on many plants but prefers grasses (Turner & Pollard 1959), including Texas millet (Panicum texanum Buckley), crab grasses (Digitaria spp.), and Johnson grass (S. halepense (L.) Persoon). In north Florida, reproductive plant hosts of H. insolita include Johnson grass and southern sand spur, Cenchrus echinatus L. (Tipping et al. 2004). The most common parasitoid of H. insolita eggs in Florida is Acmopolynema sema Schauff (Hymenoptera: Mymaridae) (Triapitsyn et al. 2002).
H. insolita is a competent vector of Xylella fastidiosa bacterium, the causative agent of many plant diseases including phony peach, Pierce’s disease of grape, and plum leaf scald (Turner & Pollard 1955). Many of the grass and weed species fed upon by H. insolita are reservoirs of Xylella bacteria. While H. insolita feeds primarily on herbaceous hosts, we have documented that it also feeds on economically important hardwood species that are susceptible to X. fastidiosa such as peach and plum (Mizell & French 1987). Potentially, the parasitoid P. americana may serve as a management tool in combating the spread of X. fastidiosa diseases.
We thank Jeremiah George for confirmation of our initial identification of Paracentrobia americana, and Gisette Seferina, Brent Brodbeck, and Peter Andersen for editorial suggestions on an earlier version of this manuscript. The California Department of Food and Agriculture as well as the University of California, Davis provided funding for this research. Contribution of the Florida Agricultural Experiment Station Journal Series No. R-10891.
Summary
The trichogrammatid wasp, Paracentrobia americana (Girault), was reared from egg masses of the leafhopper Homalodisca insolita (Walker) maintained in culture at the University of Florida North Florida Research and Education Center in Quincy, Florida. This discovery is a new host record for P. americana. Parasitized egg masses were found on Johnson grass, Sorghum halepense (L.) Persoon.
