Tachinid Flies and Monarch Butterflies: Citizen Scientists Document Parasitism Patterns over Broad Spatial and Temporal Scales

Diversity of prominent moths (Lepi-doptera: Noctuoidea: Notodontidae) in the cloud forests of northeastern Ecuador, with descriptions of 27 new species. Annals of the Entomologi-cal Society of America. In press. Diversity cascades in alfalfa fields: From plant quality to agroecosystem diversity. Environmental Entomology 37:947-955. Synergistic effects of amides from two Piper species on generalist and specialist herbivores. Immunological cost of chemical defence and the evolution of herbivore diet breadth. Ecology Letters 12:612-621. Instant symposiuM T he Tachinidae represent the largest family of dipteran parasitoids, with ~10,000 species. Most of their hosts are Lepidoptera, and it is generally assumed that tachinid flies have wide host ranges (i.e., many suitable host species) (Stireman et al. 2006). However, it is likely that tachinid host ranges have been overestimated; in a long-term study of tachinid flies reared from hosts collected in Costa Rica, many species that appeared to be generalists were shown to be host-specific cryptic species (Smith et al. 2007). Lespesia archippivora (Riley) (Tachinidae) has been reported to parasitize larvae of 25 Lepidoptera species in 14 families, and one species of Hymenoptera (Arnaud 1978). It is widespread throughout North and Central America, has been found in Brazil (Arnaud 1978), and was introduced into Hawaii for biocontrol in 1898 (Etchegaray and Nishida 1975). Except for its occurrence in multi-host species-rearing projects, L. archippivora has only been studied in detail in monarchs (Danaus plexippus L.) and beet armyworms (Spodoptera exigua Huber). It parasitizes monarch larvae in the continental U.S. et al. 2007), with one long-term, broad-scale monitoring project documenting an overall parasitism rate of ~13% (Oberhauser et al. 2007). In the southern U.S., the beet armyworm is reported to be a preferred L. archippivora host (Stapel et al. 1997). North American monarchs complete multiple generations on their milkweed host plants (Asclepias spp.) within a summer breeding season, and overwinter in central Mexico (eastern migratory population) or coastal California (western migratory population). They remain in their wintering sites in a state of reproductive diapause from early November through mid-March, before returning to their spring breeding grounds. In the east, returning migrants lay eggs in the southeastern U.S. (Texas to Florida and Oklahoma to North Carolina) and their offspring recolonize the summer breeding range (roughly the northeastern quarter of the U.S. and southern Ontario and Quebec), where they undergo two to three non-migratory generations before the final generation returns to Mexico. There is some fall breeding by southward …