Abstracts for Oral Presentations at Florida Rare Plant Task Force Rare Plant Insect Interactions Thursday, May 9, 2013
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Abstracts for Oral Presentations at Florida Rare Plant Task Force Rare Plant Insect Interactions Thursday, May 9, 2013 Dr. Patti J. Anderson, Florida Department of Agriculture and Consumer Services, Division of Plant Industry, Gainesville, FL., [email protected] “Regulating Interactions: DPI, Rare Plants, and Insect Pests” Florida Department of Agriculture and Consumer Services Division of Plant Industry’s mission is to protect Florida’s native and commercially grown plants and the state’s apiary industry from harmful pests and diseases. Although much of DPI’s work focuses on pests of agricultural crops, rare plants can benefit from programs for biocontrol of pests and emergency programs to eliminate exotic pests, such as fruit flies. Plant pests can be generalists, damaging a broad range of plants, or specialists, concentrating on a single species, genus or family. Biocontrol projects that target pests of commercially grown plants also benefit their rare relatives. Several of these biological control agents are now considered established in Florida and no longer require special release by DPI. A new program to control air potato (Dioscorea bulbifera), an invasive weed that alters natural habitats, will benefit Florida’s native plants, both rare and not so rare. Dr. Mark Deyrup, Archbold Biological Station, [email protected] “Riddles of Rare Plants and Insects in Florida Scrub” Using studies from Archbold Biological Station and the unusual concentration of rare plants in the Florida scrub, I show that rare plants and rare insects are usually part of some huge generalist network. Insect-flower relationships, even those that include rare plants, are likely to be part of some highly resilient network of relationships. Rare plants must frequently compete with abundant species for pollinators, like a badminton club competing for event attendance with football in a Texas town. Rare plants may also have generalist insect enemies whose populations are kept high by common plants, like a poor homeowner who is a frequent victim of burglars attracted by a surrounding community of rich and careless movie stars. The complexity of these networks in normal natural habitats is so extraordinary that it would be impossible to recreate them or restore them if they were destroyed. From an ecological point of view individual rare species are seldom likely to be “keystone species,” but there are many more rare species than one might suppose, and in the aggregate they probably have an unexpectedly large impact on ecosystem function. There have always been rare plants; why do they even exist? There are also plants that have become rare very recently; will they face a different set of problems from the traditionally rare species? Stories from the Florida scrub may help answer these riddles. Dr. John Geiger, Florida International University, [email protected] “The endangered vine Ipomoea microdactyla (Convolvulaceae): Butterflies good, caterpillars bad, and fire best.” Ipomoea microdactyla, commonly known as wild potato morning-glory, man-in-the-ground, and ‘bejuco colorado’, is a woody, perennial vine found in Cuba, the Bahamian archipelago, and in Florida. In Florida, I. microdactyla is listed as a Florida state endangered species and is restricted to Everglades National Park and to 36 of the remaining ca 400 pine rockland fragments in Miami-Dade County. Population size in most fragments is less than 50 individuals. A study was conducted from 2002-2007 to gauge the demography of this species at 8 pine rockland fragments in Miami-Dade County and at 9 continuous pine forest sites on Andros Island, the Bahamas. Flowering and fruiting was associated with natural and prescribed fires in both regions. Synchronous flowering of individuals post-fire most likely helped overcome the self- incompatible breeding system of this species. Floral visitors were nearly exclusively hummingbirds on Andros Island, while hummingbirds were rarely observed visiting flowers in Miami-Dade, where native solitary bees, introduced honey bees, and butterflies were the predominant floral visitors. Caterpillars of the Arctiid moth, Syntomeida ipomoeae, were observed consuming leaves, green stems, and green fruits from plants at 3 of the 8 Miami-Dade County sites. A similar, unidentified moth species was observed at 6 of the 9 Andros Island sites performing the same behaviors. It appears that insects exert both positive (via pollination) and negative (via herbivory, specifically seed predation) influences on this species. Overall, the main finding of this study is the necessity of fire management to promote reproduction for this endangered species. Dr. Brenda Molano-Flores. University of Illinois, [email protected] “From the Midwest to the Florida Panhandle: rare plant/insect interactions” Regardless of the geographical location, rare plants share similar issues such as habitat loss and degradation. Changes to their habitat not only have an impact on the rare plants, but also on the insects that visit them (pollinators, herbivores and prey). Through a series of examples from previous research conducted in the Midwest to new research being conducted in Florida, an assessment of the benefits and challenges of habitat management on rare plant/insect interactions will be presented. In particular, I will discuss the relationship between Minuartia patula and pollinators, Agalinis auriculata and Synthris bullii and herbivores, and Pinguicula spp. and prey. I will examine the question: Do we need to make habitat management decisions for each species individually, or are there broad recommendations that we can make that will benefit rare plant/ insect interactions in general? Dr. Pedro F Quintana-Ascencio, Elizabeth Stephens, and Matthew Tye, Department of Biology, University of Central Florida, Orlando, FL., [email protected] “Experimental demography: How field experiments and population modeling can inform restoration and management of Florida Scrub” We conducted seed removal and germination experiments for five rare (Liatris ohlingerae, Eryngium cuneifolium, Polygonella basiramia, Hypericum cumulicola, Paronychia chartacea subsp. chartacea) and two common herbs (Chamaecrista fasciculata and Balduina angustifolia) to evaluate the effect of degraded and intact scrub and microsites (bare sand, litter only, and under shrubs with litter) on population dynamics. The species with the largest seeds (L. ohlingerae) was removed in higher frequency in degraded scrub, likely by vertebrates. H. cumulicola and P. chartacea had the smallest seeds and were removed by invertebrates and in higher frequency in intact scrub. E. cuneifolium germinated more in degraded scrub and P. chartacea had significantly more germination in intact scrub. E. cuneifolium, H. cumulicola and P. chartacea had higher germination in bare sand than in litter or under shrubs. We used data from field experiments coupled with observations on seed production and plant survival to parameterize matrix models exploring the effect of habitat and microsite on demography of the common herbs. Models evaluated scenarios of successional change associated to human disturbance. Population growth was greatest in degraded habitat for C. fasciculata and similar between habitats for B. angustifolia. Bare sand had the greatest positive contributions to population growth for B. angustifolia. Our results suggest that for our study species bare sand gaps in intact scrub may not be equivalent to bare sand areas in the degraded scrub. Our study further emphasizes intact scrub is ecologically complex and this is critical to consider in the process of habitat restoration efforts. Dr. Matthew L. Richardson, USDA-ARS, Port St Lucie, FL; [email protected] “Influence of habitat on pollinators and pollination success of Lakela’s Mint” Lakela’s mint, Dicerandra immaculata Lakela var. immaculata (Lamiaceae), is a critically endangered plant known only from a few locations in Florida scrub. I identified the natural habitat of Lakela’s Mint, insect pollinators, and possible influences of habitat on pollination. Lakela’s mint tended to grow in areas with open gaps at ground and canopy-level. Over 93% of the pollinators were honeybees, which are nonnative pollinators. Native pollinators included bumblebees, butterflies and moths, true flies, and a wasp. Honeybees were more likely to visit plants in sunny habitat and those with large floral displays, whereas native pollinators were only influenced by the size of the floral display. The number of flowers visited by a honeybee within a plant was not influenced by the size of the floral display or sunlight, but honeybees visited nearly three times more flowers within a plant than native pollinators. The number of calyxes on a plant, which is an indication of how many flowers were fertilized, was not influenced by sunlight, but was influenced by the size of the plant (i.e., larger plants had more calyxes per stem). Overall, these results indicate that 1) pollinators and pollination are not limiting in shaded habitat (and therefore do not drive the spatial distribution of Lakela’s Mint); 2) larger plants experience greater pollination; and 3) Lakela’s Mint may be pollinated primarily by nonnative honeybees. The efficiency of honeybees as pollinators as well as their influence on population genetics of Lakela’s mint (honeybees may promote more selfing) should be explored. Dr. Alex Segarra, Merari Feliciano & Rosa A. Franqui. Department of Crops and Agro- Environemntal Sciences.