Naturaliste can - 1 07: 87-93 (1980). PLANT BUG HOSTS (HETEROPTERA: MIRIDAE) OF SOME EUPHORINE PARASITES (HYMENOPTERA: BRACONIDAE) NEAR BELLEVILLE, ONTARIO, CANADA C. C. LOAN Biosystematics Research Institute, Agriculture Canada, Research Branch, Ottawa KlA 0C6 Resume Nous avons e'eve des Euphorines parasites (14 espbces de Peristenus et 4 de Leiophron) b partir de 28 especes de Mirides, recoltes pres de Belleville, Ontario. Nous avons, en plus, obtenu plusieurs immatures d'Euphorines indeterminees chez 24 autres espbces d'hotes. Les parasites de chaque espece se rencontrent dans les nymphes d'une ou plusieurs especes de mirides. La majorite des hates et tous les parasites nont qu'une seule generation annuelle. L'attaque des para- sites ne se produit que durant la periode nymphale de I'hote. Les adultes hivernent en diapause, dans les cocons. Le taux de parasitisme est de 16 6 64%. Abstract Euphorine parasites, comprising 14 species of Peristenus and four of Leio- phron, were reared from 28 plant bug species collected near Belleville, Ontario. Immature, unidentifiable euphorines were found in 24 other host species. Each of the parasite species attacked nymphs of one or more plant bugs. Most of the hosts, and all the parasites have one generation per year. Parasitism was limited to the portion of the season when the host(s) was in the nymphal stage. The over- wintered parasites were inactive as diapausing adults in cocoons until the growing season of the following year. From 16-64 per cent of host nymphs were parasitized. Introduction Materials and methods Species of the euphorine genera Periste- Plant bugs were collected during May- nus Foerster and Leiophron Nees parasitize August in representative habitats immediately nymphs of plant bugs (Miridae). The various north of Belleville, using a sweep net for parasite species ovoposit in the haemocoel low plants and a beating frame for higher of second and third instar nymphs. One ma- vegetation. Samples of plant bugs were main- ture parasite larva emerges from each para- tained on foliage in ice-cream cartons in the sitized nymph or teneral adult, spins a co- field and later were dissected to determine coon in soil, and develops to an adult which euphorine parasitism. If parasites were fou nd,/f': overwinters inside the cocoon. Parasite adults a sample of fifth instar host nymphs was emerge the following year. Occurrence, collected and these were reared to the adult hosts, and specificity of these parasites is stage. Parasite larvae that emerged were poorly known except for species that para- reared and cocoons were stored outdoors in sitize important pests such as lygus bugs on potted soil for the balance of the summer alfalfa (Clancy & Pierce, 1966). Near Belle- and over winter. The pots containi-ng the ville, Ontario, euphorine parasitism was cocoons were lifted from the ground in late found in plant bugs from a wide range of April and held until parasite adults had host plants in 1963-1970. The parasites are emerged. All indoor rearings of plant bugs listed in this paper with observations on their and cocons were at 21 0C. hosts, specifi city and seasonality. 88 LE NATURALISTE CANADIEN, VOL. 107,1980 TABLE Feeding habitats for the various parasitized subfamilies Plant growth- Mirinae Orthotylinae Phylinae Deraeocorinae Dicyphinae Bryocorinae forms Trees 8 2 1 3 0 0 Shrubs- vines 8 5 7 0 2 0 Grasses- herbs 8 5 2 0 0 0 Ferns -0 0 0 0 0 1 Total species 24 12 10 3 2 1 parasitized Results SPECIFICITY OF EUPHORINES Seven of the euphorine species parasitized PARASITES AND HOSTS plant bug species that occurred alone on Fourteen species of Peristenus and four host plants. Other euphorines parasitized of Leiophron were reared from 28 plant bugs one or more of a complex of host species species. Immature euphorine parasites were (Tables 1l-V). On forage crops in May and found in 24 other hosts species. Six families June, Leiophron trigonotylidis parasitized of Miridae were parasitized including a only Trigonotylus coelestialium from among species of Bryocorinae, Monalocoris ameri- a complex of mirid nymphs while Peris- canus. Euphorine parasitism of this subfamily tenus pal/ipes parasitized six species of plant previously was known only from Africa (Les- bugs but not T. coe/estialium or species of ton, 1959). The subfamily Mirinae contained Collaria, Irbisia, Litomeris, Stenodema or 48 per cent of the parasitized species. All Stenotus. Each of the major residents on of the parasitized hosts are phytophagous Solidago canadensis was parasitized by one except one species of Pilophorus and three or two species of euphorines: in June and of Deraeocoris, which are predaceous. July Slaterocoris spp. and Polymerus vena Feeding habitats for the various parasitized ticus by Peristenus solidaginis, Slaterocoris spp. P. spp. mirid subfamilies are by bicolor; and P/agiognathus listed in Table I. by P. reidi; in late summer Lygus vanduzeel SPECIFICITY OF PLANT BUGS by P. pseudopallipes and L. Iineolaris by P. The host plants of parasitized plant bugs pseudopa/lipes and Leiophron Iygivora. are listed in Tables Il-V. Some plant bug SEASONALITY species were found on only one species of host plant, e.g. Diaphnocoris chlorionis on The hosts and parasites found in May and Gleditsia triacanthos. Other species occurred early June, in late June and early July, and in on closely related plants, e.g. Dicyphus August are listed in Tables 11-V, respectively. simi/is on Rubus odoratus and R. ideaus, Lygus lineolaris and Adelphocoris lineolatus while still others had nymphal populations were the only host species with nymphs oc- limited to a type of vegetation, e.g. Lygus curring in early and again in late summer /ineolaris on forage crop legumes. The plant (Loan, 1965). Nymphs of ail others occurred bugs' specificity probably ensured that the only once on host plants, and developed from parasite adults emerged in proximity of host overwintered eggs whose hatch date de- nymphs. Hence, the level of parasitism by pended on the winter dormant period and euphorines may depend on the distribution developmental rates of the species (Reid et of the host plants of the plant bug as well al., 1975). 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