Table 3 - uploaded by Jessica D Stephens
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With as little as 3% of southeastern Coastal Plain pitcher plant bogs remaining, it is important to understand the life-history aspects of the endemic organisms that comprise this community. In this study, we elucidate aspects of the life history of Exyra semicrocea (Pitcher Plant Moth) by incorporating unpublished portions of a thesis from 1978-19...
Contexts in source publication
Context 1
... in the egg stage was recorded at 56% in 1978-79 (Table 3). This rate of mortality is assumed to be the combined results of infertility, predation, fungal pathogens, and parasitism. ...
Context 2
... mortality is diffi cult to ascertain, as disappearance of larvae from tagged pitchers was often due to dispersal to nearby pitchers. Therefore, a disappearance rate was calculated at 60% and observed mortality at 15% ( Table 3). Predation of dispersing larvae was observed on multiple occasions between 1978 and 2010 by spiders (i.e., Peucetia viridans (Hentz) [Green Lynx Spider], Strotarchus piscatoria (Hentz) [Bent-leaf Spider], and Phidippus audax (Hentz) [Common Jumping Spider]) and Solenopsis invicta Buren (Formicidae; Red Imported Fire Ant). ...
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Citations
... Exyra semicrocea (Lepidoptera, Noctuidae), the pitcher plant moth, is a specialist that feeds on several species of Sarracenia (Jones 1907;Folkerts and Folkerts 1996;Lamb and Kalies 2020); only S. alata occurs in our study site. During the growing season, larval E. semicrocea feed on pitchers (Jones 1907;Stephens and Folkerts 2012;Carmickle and Horner 2019). Overwintering E. semicrocea larvae emerge from the bases of senesced pitchers and feed on S. alata flowers from early March to late April. ...
Losses of floral tissues to herbivory (florivory) can affect plant reproduction, population growth and structure, and community dynamics. Because carnivorous plants inhabit nutrient-poor environments and exhibit slow growth rates, losses to herbivory may be particularly costly. However, there has been no published study of florivory in carnivorous plants. We conducted a 2-year field study in Leon County, Texas USA, on the carnivorous Pale Pitcher Plant Sarracenia alata and its specialist herbivore Exyra semicrocea. We surveyed the proportions of flowers attacked and compared the mass of floral components (ovaries, anthers, petals, sepals, and style) between attacked and undamaged flowers. In 2017, a mean of 53% of flowers was attacked. The anther count and the masses of anthers, perianth (petals + sepals), and style were significantly lower in attacked flowers than in undamaged flowers, but ovary mass was not significantly affected. The total flower dry mass (without peduncle) of attacked flowers on the last collection date was 13.3% less than that of undamaged flowers, but this difference was not statistically significant. In 2018, a mean of 33% of flowers were attacked, with significant mass losses from all floral components, including ovaries. The total flower dry mass (without peduncle) of attacked flowers on the last collection date was significantly (48%) less than that of undamaged flowers. Herbivore population size, differences in emergence phenology of the host and/or herbivore, and differential defense of components may have contributed to differences between years in the proportion of flowers attacked and variation in the floral structures consumed.
... Closing off a pitcher opening by girdling or webbing ostensibly protects larvae from attack by predaceous insects, spiders, and parasitoids (Jones 1907), but also effectively prevents any further prey capture by that pitcher. Both larval and adult E. semicrocea possess trap avoidance mechanisms, including modified metatarsi that allow them to move freely inside S. alata pitchers (Jones 1921;Rymal 1980;Stephens and Folkerts 2012). Adults mate and oviposit within pitchers. ...
... mm; instar 4: 1.090-1.499 mm; instar 5: 1.500 mm and larger (adapted from Stephens and Folkerts 2012). Insufficient numbers of instars 3-4 were collected, so results of feeding trials are presented for fifth-instar larvae only. ...
... Movement among pitchers may be a strategy to avoid parasitism or predation, a response to induced plant defenses, or a means to reach more nutritious tissue. Green lynx spiders (Peucetia viridans) and parasitoids such as tachinid flies, which are known to prey on larvae (Stephens and Folkerts 2012), have been Fig. 3 Effects of E. semicrocea on pitcher growth per genet. a Mean sum of heights of all pitchers per genet. ...
Herbivory by the specialist herbivore Exyra semicrocea on the carnivorous plant Sarracenia alata results in loss of nutrients and photosynthetic tissue (direct losses) and diminished prey capture (indirect losses). Using a combination of field surveys in a bog in Leon County, TX USA, and laboratory assays, we examined the losses of tissue and nutrients to herbivory in a population of S. alata. In a field experiment in the same bog, we manipulated herbivore access, prey capture, and supplemental (compensatory) prey to examine the relative effects of direct losses, indirect losses, and their combination on plant growth. We hypothesized that the combined effect of direct and indirect losses would be greater than the effects of either direct or indirect losses alone. Approximately 86% of pitchers in the study population had evidence of herbivory by E. semicrocea. On average, 15% of each damaged pitcher was consumed. In the field manipulation experiment, both direct and indirect losses significantly reduced growth in S. alata, but there was no significant interaction effect. As predicted, pitcher production was lowest in plants experiencing both direct and indirect losses. These results demonstrate that herbivory by E. semicrocea can be widespread and have a significant negative effect on growth of S. alata. Future studies should examine the effects of herbivory on nutrient limitation, storage in rhizomes, and sexual reproduction.
... They are considered herbivores, where larvae are restricted to the pitchers and feed on the inner tissue of the leaf. Adult moths are often found inside the pitcher leaves during the day, and disperse to nearby pitchers within the bog at night (Stephens & Folkerts, 2012). Multiple mite lineages are known from this habitat, where they either scavenge on the prey mass or act as active predators (Fashing & O'Connor, 1984). ...
Aim
The Sarracenia alata pitcher plant and inquiline species comprise an ecological community. These inquilines span the continuum in their ecological association with the host pitcher plant, from species that contain little‐to‐no interaction with the plant to species that are completely dependent on the plant for their entire life cycle. We are interested in testing if degree of ecological dependence is positively correlated with a shared evolutionary history, and in identifying members of this community that display concordant phylogeographic structure.
Location
Southeastern United States.
Methods
We collected genome‐wide sequence data from a set of arthropods that are ecologically associated with the plant to estimate comparative phylogeographic patterns among the species. We estimated species tree distributions from biallelic unlinked SNP data and used phylogeographic concordance factors (PCFs) to test degree of phylogeographic concordance among community members. In addition, for each species we conducted an analysis of molecular variance and calculated FST values to identify population genetic structure across the landscape, and compared these traditional values to the tree‐based approach.
Results
Obligate members of the pitcher plant community display concordant phylogeographic patterns, suggesting their ecological dependence has manifested itself into a shared evolutionary history. In contrast, two spider species do not contain significant population genetic structure or similar phylogeographic histories, highlighting their loose association with the host pitcher plant.
Main conclusion
The S. alata pitcher plant system should be considered an evolutionary community, where multiple members sharing strong ecological interactions also display concordant phylogeographic structure. This work demonstrates that PCFs provide an important quantitative measure into assessing community structure and illustrates how simulations can be used to assess significance of shared patterns of phylogeographic structure across the landscape.
... Inquilines include the moth, which spends its entire life cycle in the pitcher plant leaves (Jones, 1921;Stephens, Santos, & Folkerts, 2011), and the flesh flies, which are also tightly associated with the plant leaves (Dahlem & Naczi, 2006). Notably, both the moth and flies are poor flyers and dispersal limited (Folkerts, 1999;Krawchuk & Taylor, 2003;Rasic & Keyghobadi, 2012;Stephens & Folkerts, 2012). In contrast, the spider species sampled here are widespread and opportunistic predators, abundant in the habitat but not dependent on S. alata, as either can be found in a variety of other microhabitat in the region. ...
Biogeographic barriers have long been implicated as drivers of biological diversification, but how these barriers influence co-occurring taxa can vary depending on factors intrinsic to the organism and in their relationships with other species. Due to the interdependence among taxa, ecological communities present a compelling opportunity to explore how interactions among species may lead to a shared response to historical events. Here we collect single nucleotide polymorphism (SNP) data from five commensal arthropods associated with the Sarracenia alata carnivorous pitcher plant, and test for co-diversification across the Mississippi River, a major biogeographic barrier in the southeastern United States. Population genetic structure in three of the ecologically dependent arthropods mirrors that of the host pitcher plant, with divergence time estimates suggesting two of the species (the pitcher plant moth Exyra semicrocea and a flesh fly Sarcophaga sarraceniae) dispersed synchronously across this barrier along with the pitcher plant. Patterns in population size and genetic diversity suggest the plant and ecologically dependent arthropods dispersed from east to west across the Mississippi River. In contrast, species less dependent on the plant ecologically show discordant phylogeographic patterns. This study demonstrates that ecological relationships may be an important predictor of co-diversification, and supports recent suggestions that organismal trait data should be prominently featured in comparative phylogeographic investigations. This article is protected by copyright. All rights reserved.
... Pitcher plants have no less than 17 arthropod symbionts, given relatively little study compared to the pitcher plants themselves ), among which are pitcher plant moths, Exyra (Grote) (Noctuidae) (Stephens & Folkerts 2012). Two of the three species of Exyra, the pitcher plant mining moth, E. semicrocea (Guenée) and Riding's pitcherplant looper moth, E. ridingsii (Riley) are prevalent in the pitcher plant savannas of the Southeast where they inhabit the pitcher plant savannas (Stephens & Folkerts 2012). ...
... Pitcher plants have no less than 17 arthropod symbionts, given relatively little study compared to the pitcher plants themselves ), among which are pitcher plant moths, Exyra (Grote) (Noctuidae) (Stephens & Folkerts 2012). Two of the three species of Exyra, the pitcher plant mining moth, E. semicrocea (Guenée) and Riding's pitcherplant looper moth, E. ridingsii (Riley) are prevalent in the pitcher plant savannas of the Southeast where they inhabit the pitcher plant savannas (Stephens & Folkerts 2012). The moths live out the majority of their life inside pitcher plants (Jones 1921), only emerging at night (Stephens & Folkerts 2012). ...
... Two of the three species of Exyra, the pitcher plant mining moth, E. semicrocea (Guenée) and Riding's pitcherplant looper moth, E. ridingsii (Riley) are prevalent in the pitcher plant savannas of the Southeast where they inhabit the pitcher plant savannas (Stephens & Folkerts 2012). The moths live out the majority of their life inside pitcher plants (Jones 1921), only emerging at night (Stephens & Folkerts 2012). The adults lay one egg in a plant. ...
Pine savannas in the Southeastern United States are subject to an historical regime of periodic fire, with many and varied ecological consequences. Insectivorous plants of the genus Sarracenia (L.) (Sarraceniaceae) often entirely lose their aboveground leaves to these periodic fires. During the growing season, these tubular leaves, which act as pitfall traps for insects, are host to pitcher plant moths, Exyra (Grote) (Noctuidae), which live their entire life cycle within the plant. This study tested the effect of smoke on a small sample of Exyra semicrocea in pitchers, and demonstrated that they respond quickly by flight.
... moths, which are obligate associates of many Sarracenia spp. (Moon et al. 2008;Stephens and Folkerts 2012). Third, how does resource availability and nutrient limitation alter the dynamics of these interactions? ...
Plants experience often opposing energetic demands and selective pressures-for instance, where plants need to attract an insect that is both the pollinator and herbivore, or alternately, where plants attract prey (due to limited resources) and pollinators. Together, these selective pressures can modify the volatile signals available to the plant's mutualistic and antagonistic partners. Nevertheless, it remains an open question how changes in the information content of volatile signals modify behavioral responses in mutualists and antagonists, and what the underlying neural bases of these behaviors are. This review focuses on two systems to explore the impact of herbivory and resource availability on plant-pollinator interactions: hawkmoth-pollinated hostplants (where herbivory is common), and carnivorous bee-pollinated pitcher plants (where the plants differentially attract bee pollinators and other insect prey). We focus on (1) the volatile signals emitted from these plants because these volatiles operate as long-distance signals to attract, or deter, insect partners, (2) how this information is processed in the hawkmoth olfactory system, and (3) how volatile information changes spatiotemporally. In both the plants and their respective insect partner(s), volatile signaling, reception and behavior are dynamic and plastic, providing flexibility an ever-changing environment.
... In the study by Stephens et al. (2011), the larvae were overwintering so they were unable to move but in our study, the timing of the burn and the adjacent habitats allowed E. ridingsii to disperse into the newly grown pitchers. Exyra semicrocea has been observed moving from pitcher to pitcher at night after feeding (Stephens and Folkerts 2012). Even though Exyra is a genus that exhibits low mobility, this does not prevent them from migrating to new habitats (Atwater et al. 2006). ...
Exyra ridingsii is a host-specific moth that spends its entire immature life cycle in the Sarracenia flava L. pitcher plant. Sarracenia flava requires a habitat that undergoes frequent fires and has acidic moist soil. During this investigation we studied the degree to which E. ridingsii damaged S. flava under different environmental conditions. From summer 2012 to fall 2013, five sites in the Croatan National Forest, North Carolina, were surveyed four times each year. At each site, 7 to 20 quadrats were randomly selected for sampling. In each quadrat, pitchers were counted and measured for height and whether the pitchers were affected by herbivory; the fraction affected was calculated (herbivory per clump). Median herbivory per clump at the burned sites ranged from 86-100%. All other sites ranged from 50-75% with the exception of the unburned pocosin site, which was the lowest at 32%. Herbivory per clump was found to differ by site, but because sites varied in environmental characteristics other than burn status, other factors playing a role in habitat status cannot be ruled out. Tallest median trumpet heights were found at the unburned sites. During this study, E. ridingsii repopulated S. flava pitchers in the burned sites less than two months after fire, suggesting that they persist as a metapopulation.
... Since then, more than 645 species have been described worldwide resulting from at least 6 independent origins (Albert et al. 1992). Recent strides in our knowledge and understanding of these remarkable plants has led to a clearer definition of phytocarnivory (Juniper et al. 1989), cost-benefit analyses of resource allocation (Givnish et al. 1984, Laakkonen et al. 2006, documentation of genetic and morphological variation (Bauer et al. 2011, Godt and Hamrick 1998, Lloyd 1942, descriptions of various symbiotic plant-arthropod interactions (Folkerts 1999, Stephens andFolkerts 2012), and resolution of phylogenetic relationships (Jobson et al. 2003, Meimberg et al. 2001, Stephens et al. 2015. However, the adaptive significance of trapping morphology and its relationship to prey capture remains poorly known. ...
Morphological differences in trapping mechanisms of carnivorous plants may be a response to selection pressure to reduce competition among species and even conspecifics. However, few studies have investigated whether variation in plant morphology is related to prey capture. Here, we measured height, peristome width, and outer-trichome density in pitchers of Sarracenia minor (Hooded Pitcher Plant) and its variety, S. minor var. okefeno-keensis (S. m. var. okefenokeensis). In addition, we compared arthropod-prey contents of pitchers between the typical short form and the tall Okefenokee variety and across seasons and sampling locations. Similar to findings in previous studies, we found that S. minor was an ant specialist with no influence of season or location. In contrast, S. m. var. okefenokeen-sis had a more generalist diet, and prey content varied across season and location. Pitchers of S. m. var. okefenokeensis were also significantly larger in height and peristome width with fewer outer trichomes than S. minor. Overall, differences in pitcher morphology appear to be correlated with prey contents. These results have important implications for our understanding of the evolution and diversification of carnivorous plants.
The Grand Canyon, a colorful maze of steep-walled canyons, isolated plateaus, and desert landscapes in the Colorado Plateau, is 446 km (277 miles) long, nearly 29 km (18 miles) wide, and over 1800 m (600 feet) deep. Caves can form in response to various geological processes, but many result from the dissolution of limestone producing a geological formation known as karst. Food chains in caves are short and consist mainly of generalists, species that take advantage of as many foods as possible from the limited supply in caves. More than 20 species of endemic plants occur on granite outcrops in the southeast, and most are federally protected. A distinctive cliff formation known as the Niagara Escarpment forms the exposed edge of an ancient seabed, the Michigan Basin, which formed more than 400 million years ago when a tropical sea receded and exposed the underlying sediments.
