A NEW DISTRIBUTION AND HOST RECORD FOR GONATOCERUS TRIGUTTATUS IN FLORIDA, WITH NOTES ON ACMOPOLYNEMA SEMA (HYMENOPTERA: MYMARIDAE)

Abstract

Triapitsyn et al. (1998) reported results of the 1997 survey of egg parasitoids of the glassywinged sharpshooter, Homalodisca coagulata (Say) (Homoptera: Cicadellidae), in northern Florida. As part of an on-going classical biological control program against H. coagulata in California, two of the authors conducted a survey of egg parasitoids of proconiine sharpshooters (Cicadellidae: Cicadellinae: Proconiini) throughout Florida in August 2001 (Triapitsyn & Hoddle 2001). Among several species in the families Mymaridae and Trichogrammatidae (both Hymenoptera) that were collected (Triapitsyn & Hoddle 2001), there were two mymarid species on which the previously unknown information is given below. All specimens resulting from this study were determined by S. V. Triapitsyn; the vouchers of parasitoid species were deposited in the Entomology Research Museum, University of California at Riverside, California [UCRC] and those of proconiine sharpshooter species were deposited in the California State Collection of Arthropods, California Department of Food and Agriculture, Sacramento, California; also examined was the collection of Mymaridae at the Florida State Collection of Arthropods in Gainesville, Florida [FSCA]. Gonatocerus triguttatus Girault, originally described from specimens reared from an egg mass of an unidentified leafhopper on orange, Citrus sinensis (L.) Osbeck, in Trinidad (Girault 1916), was reared recently in northeastern Mexico from egg masses of H. coagulata, Oncometopia clarior (Walker), and an unidentified Oncometopia species (Triapitsyn & Phillips 2000, Triapitsyn et al. 2002). Gonatocerus triguttatus is also known from eggs of H. coagulata in Texas (Jones 2001, Triapitsyn & Hoddle 2001). In Apopka, Florida, we reared two females of G. triguttatus from an egg mass of the blackwinged sharpshooter, Oncometopia nigricans (Walker), laid in a leaf of crape myrtle, Lagerstroemia indica L., in the parking lot of the University of Florida Mid-Florida Research and Education Center. From the same plant and several adjacent crape myrtle trees, we also collected an adult specimen and several nymphs of 0. nigricans, which is the prevalent proconiine sharpshooter species on woody plants in central and southern Florida, whereas relative abundance of H. coagulata decreases from north-central Florida southward (Timmer et al. 1982), although it is known in southern Florida as far as Homestead (Turner & Pollard 1959). Gonatocerus triguttatus has not been known previously from Florida and 0. nigricans is a new host record for this parasitoid. Before our discovery, the only known record of an egg parasitoid of 0. nigricans was by Turner & Pollard (1959) who reported a Gonatocerus sp. (as Lymaenon sp.) in Plant City, Florida, from eggs of Oncometopia undata (Fabricius), that is an obvious misidentification of 0. nigricans following Young (1968). Material Examined. USA, Florida, Orange Co., Apopka, 21-VIII-2001, M. S. Hoddle and S. V. Triapitsyn, 2 females (emerged in UCR quarantine 30-VIII-2001 from an egg mass of 0. nigricans on crape myrtle) [UCRC]. Notes on Aemopolynema sema Schauff. This species was described from a large series of type specimens reared from eggs of the johnsongrass sharpshooter, Homalodisca insolita (Walker), in Fort Valley, Georgia (Schauff 1981). We reared A. sema from egg masses of the same host, laid in Johnson grass, Sorghum halepense (L.) Persoon, collected at the grounds of the University of Florida Everglades Research and Education Center in Belle Glade, Florida, on 19-VIII-2001 and brought under permit into UCR quarantine. Numerous specimens of H. insolita were collected from the same plants on which the egg masses were found. Following emergence, which began within the sealed containers while we still were in Florida and continued en masse in UCR quarantine, female and male parasitoids were given time to mate and then were exposed to H. coagulata eggs laid in leaves of Euonymus japonica Thunberg on 24-VIII-2001. The first generation (n > 100), which consisted of both females and males (the sex ratio was 4.3:1, respectively), was successfully obtained on 10-IX-2001 and exposed to the host on 12-IX-2001. The second generation, which emerged on 29-IX-2001, however, consisted of males only (n > 400), thus our colony ofA. sema was discontinued thereafter. We suspect that this was in response to the fact that H. coagulata is not the natural host for this parasitoid, which prefers to attack egg masses of H. insolita, a species that feeds and lays eggs on grasses (Turner &