Appendix A. Natural history of plant and insect species studied.
The sea oxeye daisy, Borrichia frutescens (Asteraceae), is a perennial composite that can reach 1 meter or more in height. This species typically inhabits marsh zones just shoreward of the intertidal, so it receives irregular tidal inundation (Adam 1990). At our field site, Borrichia grows the closest to the sea of the five plant species examined. The most common herbivore on Borrichia is the planthopper Pissonotus quadripustulatus, whichis monophagous on this plant species (Denno 1978). It feeds on the phloem from the leaves, and lays its eggs in the stem below the epidermis. Pissonotus eggs are frequently parasitized by Anagrus sp. nr armatus (Hymenoptera: Mymaridae), with parasitism levels frequently reaching 50–80% (Moon and Stiling 2000, 2002b, c).
Another common herbivore on Borrichia is the gall fly Asphondylia borrichiae. Asphondylia oviposits in the apical meristem of Borrichia, inducing gall formation at the stem tip. Galls have an average of four chambers each, and each chamber contains a single larva (Rossi and Stiling 1995). Asphondylia larvae are attacked by four species of hymenopteran parasitoids- Rileya cecidomyiae and Tenuipetiolus teredon (Eurytomidae), Torymus umbilicatus (Torymidae), and the eulophid Galeopsomyia haemon. Aggregate levels of parasitism can be very high, usually between 50 and 100% (Stiling et al. 1992, Moon and Stiling 2002a). Parasitism of Asphondylia is easily determined in the field by examining emergence holes. Flies create large emergence holes with ragged edges and attached puparia, while parasitoids create small holes with smooth edges and no puparia (Stiling and Rossi 1997). Midge larvae developing within the galls may be killed by abortion of the gall by the host plant, parasitism by one of the four species of hymenopteran parasitoids, or occasionally by bird predation (Stiling et al. 1992, Stiling 1994, Stiling and Rossi 1996, 1997).
The third most common herbivore that feeds on Borrichia is the stem borer Argyresthia sp. (Lepidoptera: Argyresthiidae), which, in the larval stages, feeds on the tissue layers beneath the epidermis. The stem borer is parasitized by an unknown species of Eulophidae, although rates of parasitism have not been established. In Florida, these three herbivores are multivoltine with at least three overlapping generations per year, and are present year round, although the highest densities typically occur in spring and early summer (Rossi et al. 1992, Stiling 1994, Moon and Stiling 2000, 2002c).
Sea grape, Coccoloba uvifera (Polygonaceae), is a salt-tolerant tree that can grow in any coastal habitat from beach dunes to upland hammocks. Its leaves, which can be up to 25 cm wide, are frequently attacked by two unidentified species of lepidopteran leaf miners (Nepticulidae) that make serpentine mines. These two types of mines are easily distinguished by width, as the mines made by species 1 do not exceed 0.5mm in width except at the oval-shaped terminal chamber, while the mines made by species 2 are typically 2–3mm wide, and do not end in a widened chamber. A single leaf can support up to 100 mines, although the usual range is 10–40 (Moon and Stiling unpublished data). Both species of leaf miners are parasitized by multiple species of hymenopteran parasitoids (Braconidae and Eulophidae), with aggregate levels of parasitism averaging from 25–60% (Moon and Stiling unpublished data). Parasitism of both leaf miners can be detected by a characteristic round hole made away from the edge of the mine, while unparasitized leaf miners cut a semicircular hole at the edge of the mine to pupate. Leaf petioles and stems are also attacked by the lepidopteran stem borer Hexeris enhydris. Although attack rates of this species are relatively low (between 5 and 15% of petioles damaged), damage caused by this species can have significant effects on the plant, killing the leaf or even the entire branch distal to the damage. H. enhydris is parasitized by an unidentified species of Hymenoptera, but attack rates have not been determined. In Florida, these three herbivores are multivoltine with at least two generations per year, and are present year round, although the highest densities typically occur in spring and early summer.
The dioecious woody shrub Baccharis halimifolia can tolerate a wide range of salinities and can be found throughout the coastal gradient from the mean high water mark to upland habitats that experience no tidal influence. In west-central Florida it is most common shoreward of the Iva zone. The most common herbivores on B. halimifolia at our site are the gall-making fly Neolasioptera lathami (Cecidomyiidae), and the leaf mining flies Liriomyza trifolii and Amauromyza maculosa (Agromyzidae). All of these herbivores are most abundant in spring and early summer, but A. maculosa also exhibits a pulse in density in the fall, and N. lathami is present in lower densities year-round (Hudson and Stiling 1997). The gall-maker N. lathami is parasitized by three species of hymenopteran parasitoids, Torymoides sulcius (Torymidae), Sympiesissp. (Eulophidae), and an unidentified species of Platygastridae. Parasitism rates of N. lathami galls can be determined in the field by examining emergence holes, as described above for the galls of Asphondylia borrichiae. Aggregate levels of parasitism range from 30–70% (Moon and Stiling, unpublished data). Parasitism of L. trifolii by Closterocerus sp. (Eulophidae) ranges from 20–50%, and parasitism of A. maculosa by the eulophids Aprostocetussp. and Neochrysocharis sp. ranges from 40–80% (Moon and Stiling, unpublished data). Parasitism of both leaf miners can be detected by a characteristic round hole made away from the edge of the mine, while unparasitized leaf miners cut a semicircular hole at the edge of the mine to pupate. At our field site, the gall maker N. lathami is bivoltine, although the two generations overlap. The leaf miners are multivoltine with at least three overlapping generations per year. Densities of these insects typically fall to near zero by the end of September, and increase again in February.
Wax myrtle, Myrica cerifera (Myricaceae) is a common plant of upland hammocks of coastal habitats in Florida. The most common herbivores of this species are two species of lepidopteran leaf miners, Nepticula myricafoliella (Nepticulidae), which creates a serpentine mine, and an unidentified species, which creates a blotch shaped mine. Parasitism of N. myricafoliella by Zagrammosoma americanum (Eulophidae) ranges from 30–50%, while parasitism of the unidentified species averages 40–70%.
Parasitism rates of these leaf miners can be determined by examining the emergence holes created, as was described above. Wax myrtle leaves are also frequently attacked by an unknown species of lepidopteran (Hesperiidae) leaf tier, from which we have not yet reared parasitoids. At our field site, all three herbivore species are multivoltine with at least three overlapping generations per year. Densities of these insects typically fall to near zero by the end of September, and increase again in February.
Another common plant of upland hammocks is Red Bay (Persea borbonia). This species experiences significant chewing damage caused by katydids (Microcentrotus sp.), bush crickets, and lepidopteran larvae. Of these leaf chewers, only the moth Urodus parvula (Yponomeutidae) occurred frequently enough to yield meaningful counts. Urodus parvula caterpillars are parasitized by an unknown species of hymenopteran endoparasitoid, with parasitism levels ranging from 10–50%. Another common herbivore of P. borbonia is the leaf-galling homopteran Trioza magnoliae (Psyllidae), which creates large galls usually on the leaf margins, in which nymphs feed (Johnson and Lyon 1988). A single leaf can have as many as 8 galls, and as many as 80% of the leaves may contain galls. Trioza magnoliae is parasitized by Psyllaephagus sp. (Encyrtidae), with parasitism levels averaging 25–45%. Parasitized T. magnoliae can be easily distinguished by their dark color, although destructive sampling of galls is required in order to determine rates of parasitism. Another conspicuous herbivore feeding on the leaves of Persea is the leafminer Phyllocnistis magnoliella, which creates large serpentine mines. This leafminer is parasitized by an unidentified species of Eulophidae, and parasitism of mines can be determined by examination of emergence holes, as described above. At our field site, the leaf miner P. magnoliella and the moth U. parvula are bivoltine, although the two generations overlap. The gall maker T. magnoliae is multivoltine with at least three overlapping generations per year. Densities of these insects typically fall to near zero by the end of September, and increase again in February.
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