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Capture Rates of Invertebrate Prey by the Pitcher Plant, Sarracenia purpurea L

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Abstract

I examined capture rates of invertebrate prey by pitchers of the purple pitcher plant Sarracenia purpurea, in western Newfoundland, Canada. While captures were diverse, Hymenoptera (mostly ants), Coleoptera and Gastropoda accounted for 69% of the total dry mass caught. Gastropoda decompose quickly and completely in pitchers, and their importance (20%) implies that prey sampling methods that do not survey freshly caught prey may seriously underestimate resource availability in pitchers. The average pitcher caught 11 mg dry mass of animal biomass over its lifetime, but capture rates were highly variable (range 0–67 mg). Pitchers opening earlier in the season caught no more or less than those opening late. Larger pitchers caught more than smaller ones, although size accounted for a small fraction of total variance. Capture rates changed with time, peaking in pitchers 12–33 days old; however, pitchers continued to catch prey through their 2nd season (i.e., after overwintering). In an average pitcher, 2nd-season captures made up nearly half of the total.
... For example, 115 insect families of 14 orders have been found in S. purpurea from North Carolina (Wray and Brimley 1943). In Canada, representatives of at least 12 insect orders and seven major invertebrate groups are reported from Newfoundland (Heard 1998), and at least 43 insect families and 13 higher-level invertebrate taxonomic groups have been found in Ontario (Judd 1959). Prey items in the plant's diet are predominantly Diptera, Hymenoptera, and Coleoptera (Cresswell 1993, Heard 1998. ...
... In Canada, representatives of at least 12 insect orders and seven major invertebrate groups are reported from Newfoundland (Heard 1998), and at least 43 insect families and 13 higher-level invertebrate taxonomic groups have been found in Ontario (Judd 1959). Prey items in the plant's diet are predominantly Diptera, Hymenoptera, and Coleoptera (Cresswell 1993, Heard 1998. Despite an apparently large search effort, there is a conspicuous absence of vertebrate prey (occurring with any level of regularity) reported in these plants. ...
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Botanical carnivory is an evolutionary marvel of the plant kingdom that has long fascinated general onlookers and naturalists alike. Darwin even dedicated serious study to these ‘most wonderful plants in the world’ (Darwin 1875; Ellison and Gotelli 2009). Carnivory in plants has evolved multiple times across the world, often in wet, open, and nutrient‐poor environments, as an alternative pathway of nutrient acquisition (Butler et al. 2005). Among carnivorous plants, the pitcher plants (family Sarraceniaceae), and specifically the northern pitcher plant (Sarracenia purpurea purpurea L.), intrigued early natural historians (e.g., Macbride 1815; Riley 1874; James 1883). This article is protected by copyright. All rights reserved.
... The purple pitcher plant, Sarracenia purpurea, is a low-lying herbaceous perennial that uses pitcher-shaped leaves to capture mostly arthropod prey (Schnell 2002). Common prey of S. purpurea include insects, spiders, harvestmen, mites, mollusks, and the occasional small vertebrate (Lloyd 1942, Wray and Brimley 1943, Judd 1959, Cresswell 1991, Heard 1998. Nectaries and pigmented lines may be used by S. purpurea to capture these prey (Juniper et al. 1989, Plachno 2007, Schaefer and Ruxton 2008, Bennett and Ellison 2009), although recent evidence points to the presence of nectar rather than pigment (Green andHorner 2007, Bennett and) as the defining difference between the capture rate of a S. purpurea pitcher vs. a cup in the ground (e.g., a pitfall trap). ...
... For example, Wray and Brimley (1943) studied the efficacy of spider capture by the plant but limited their examinations to only the spiders that were captured, ignoring the surrounding spider fauna. Other researchers studying this phenomenon have lamented the lack of data on the local arthropod fauna near S. purpurea populations and note that the inclusion of such data would allow for insights into the differences in prey capture among spatially separated S. purpurea populations (Heard 1998). In addition, such data could reveal if S. purpurea pitchers act as pitfall traps that catch a random subset of the surrounding spider assemblage, or selectively catch certain spider taxa. ...
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The purple pitcher plant, Sarracenia purpurea, is a low‐lying carnivorous plant that uses pitcher‐shaped leaves to catch arthropod prey for nutrition. Spiders make up a significant portion of these prey. To determine the tendency of specific spider taxa to be captured by the plant, we compared the composition (by taxonomic family) of three spider assemblages: those captured by the plant, those residing on or over the plant, and those found nearby in the local environment. Although there were some broad similarities within the three spider assemblages, significant differences existed when specific families and guilds were considered. While some families (e.g., Linyphiidae and Lycosidae) and guilds (e.g., low sheet/tangle weavers) were heavily represented in all three assemblages, other groups varied, and we found that the taxonomic makeup of victimized and resident spiders did not always reflect their environmental abundances. Moreover, spider assemblages captured by S. purpurea were extremely similar across distant locations regardless of environmental spider assemblage composition, suggesting that S. purpurea is very selective in its spider capture regimen.
... Pitchers 370 with a longer size and a larger aperture trapped significantly more prey in total. This is consistent with the 371 results of Cresswell (1993) and Heard (1998) Likewise, in Nepenthes liana, which explore both terrestrial and aerial strata, two pitcher types "lower" and 391 "upper" are produced, each one targeting a different group of prey, the "upper" type trapping more flying 392 insects than the "lower" type (Moran, 1996;Di Giusto et al., 2008;Gaume et al., 2016). Similarly, in long-393 . ...
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Sarracenia insectivorous plants show a diversity of visual features in their pitchers but their perception by insects and their role in attraction, have received little attention. They also vary in prey composition, with some species trapping more flying Hymenoptera, such as bees. To test the hypothesis of a link between visual signal variability and prey segregation ability, and to identify which signal could attract flying Hymenoptera, we characterised, the colour patterns of 32 pitchers belonging to four taxa, modelled their perception by flying Hymenoptera, and examined the prey they trapped. The pitchers of the four taxa differed in colour patterns, with notably two long-leaved taxa displaying clear areoles, which contrasted strongly in colour and brightness with the vegetative background and with other pitcher areas in the eyes of flying Hymenoptera. These taxa trapped high proportion of flying hymenoptera. This suggests that contrasting areoles may act as a visual lure for flying Hymenoptera, making plants particularly visible to these insects. Prey capture also differed according to pitcher stage, morphology, season and visual characteristics. Further studies on prey visitation are needed to better understand the link between prey capture and attraction feature.
... Characteristics of pitcher size, which include width of pitcher hood and pitcher length, were significant related positively. Similarly, Heard (1998) ;Nastase, De La Rosa, and Newell (1995) found that width of hood of pitcher was positively related with length and other pitcher measurements. The amount of dry detritus was indicated to have positively correlation with pitcher size and actual fluids (Nastase, De La Rosa, & Newell, 1995). ...
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This study examined the abundance of various immature mosquito species and ascertained selected environmental conditions in the pitcher. A total of hundred pitchers (Nepenthes mirabilis var. mirabilis), including 50 upper pitchers and 50 lower pitchers, were collected during rainy and dry seasons from Songkhla Province, Thailand. A total of 546 mosquito larvae belonging to two genera and three species were identified. Among the collections, 526 larvae of Tripteroides tenax (96.34%), followed by 11 larvae of Tripteroides sp.1 (2.01%), and nine larvae of Toxorhynchites albipes (1.65%) were identified. The abundance of mosquito larvae was noted to be higher during rainy season than during dry season. Mosquito larvae abundance positively correlated with pitcher size, amount of detritus present, pH of the medium, abundance of microorganisms, and amount of total fluid present in pitchers. Variation in abundance of mosquito larvae existing in pitchers is influenced by the presence of predators therein and different seasons.
... The mineralized nutrients are quickly assimilated and translocated to plant tissues (Butler et al., 2008). In the field, less than 1% of prey encounters result in successful capture (Heard, 1998;Newell and Nastase, 1998). With low detrital inputs and active photosynthesis by the plant, this aquatic microecosystem is normally in an oligotrophic state, with low prey abundance and dissolved oxygen (DO) close to 20% (where 21% = 100% air saturation). ...
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Incremental increases in a driver variable, such as nutrients or detritus, can trigger abrupt shifts in aquatic ecosystems that may exhibit hysteretic dynamics and a slow return to the initial state. A model system for understanding these dynamics is the microbial assemblage that inhabits the cup‐shaped leaves of the pitcher plant Sarracenia purpurea. With enrichment of organic matter, this system flips within three days from an oxygen‐rich state to an oxygen‐poor state. In a replicated greenhouse experiment, we enriched pitcher‐plant leaves at different rates with bovine serum albumin (BSA), a molecular substitute for detritus. Changes in dissolved oxygen (DO) and undigested BSA concentration were monitored during enrichment and recovery phases. With increasing enrichment rates, the dynamics ranged from clockwise hysteresis (low), to environmental tracking (medium), to novel counter‐clockwise hysteresis (high). These experiments demonstrate that detrital enrichment rate can modulate a diversity of hysteretic responses within a single aquatic ecosystem, and suggest different management strategies may be needed to mitigate the effects of high vs. low rates of detrital enrichment. Incremental increases in a driver variable, such as nutrients or detritus, can trigger abrupt shifts in aquatic ecosystems, which may exhibit hysteretic dynamics and a slow return to the initial state. We used the ecosystem found in the pitcher plant Sarracenia purpurea as a model system for understanding hysteretic dynamics by observing changes in a dissolved oxygen in replicated ecosystems enriched with bovine serum albumin, a molecular substitute for detritus. We observed clockwise and novel counterclockwise hysteresis and demonstrated that a complex range of hysteric dynamics can occur in a natural ecosystem in response to manipulation of a single driver variable.
... It has also been shown that Bombus spp. are the main pollinators of S. flava [43] and S. alata [44], and ants are the main prey of S. alata [45,46] and S. purpurea in some habitats [47,48], with Diptera being taken by S. purpurea growing in a different habitat [49]. Therefore, pollinator trapping is unlikely to occur in Sarracenia spp. ...
... It has also been shown that Bombus spp. are the main pollinators of S. flava [43] and S. alata [44], and ants are the main prey of S. alata [45,46] and S. purpurea in some habitats [47,48], with Diptera being taken by S. purpurea growing in a different habitat [49]. Therefore, pollinator trapping is unlikely to occur in Sarracenia spp. ...
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Article
Records of invertebrates that are able to surpass the capture mechanisms of carnivorous pitcher plants are rare. This work records for the first time land snails living inside the pitchers of Nepenthes graciliflora, a pitcher plant endemic to the Philippines widely sold in Brazil. These gastropods were found adhered in the slippery zone of pitcher and were identified as Gastrocopta pellucida hordeacella, extending ca. 500 Km the southern limit of this species in Brazil. The possible mechanisms that allow this interaction and their implications are discussed.
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Article
Factors determining the trapping success of Pinguicula vallisneriifolia, a carnivorous plant of southern Spain which grows in limestone rock walls are examined. Several ecological aspects are considered jointly, such as the abiotic environment in relation to spatio-temporal prey abundance, behaviour of prey and kleptoparasites, and plant traits that directly determine trapping efficiency, such as the amount and retention capacity of the mucilage under contrasting ecological conditions. Observations are combined with field experiments in four P. vallisneriifolia microhabitats differing in radiation and substrate wetness. The abundance of flying insects and the mucilage-retention capacity mainly determined differential prey captures between habitats, while kleptoparasitism had a similar quantitative effect in all habitats. Irradiance intensity and insect availability correlated negatively, i.e. in sunny, dry places, flying insects were scarce, whereas in shady, wet places, insects were abundant. Plant mucilage secretion also depended on light availability, and the adhesiveness of the droplets correlated negatively with insect availability (that is, more mucilage adhesiveness in the sunny and wall habitats, with fewer insects available, and vice versa in the shady habitat). As a result, plants growing at the extremes of the abiotic gradient (sunniest and shadiest habitats) trapped less animal biomass. This fact poses a schizophrenic problem for P. vallisneriifolia, which, as a green plant, needs both water and light for photosynthesis, and, as a carnivorous one, animal prey for nutrients.
Chapter
Two questions appear to us to be fundamental to the understanding of life history evolution. First, what sorts of selective forces are impinging on a species over its range or a given environmental gradient? Second, what is the response by this species to this gradient? As has often been pointed out, there is abundant theory relating to general (many assumptions) or special (very specific) circumstances but fewer direct answers to the two questions posed above. Before one can predict the outcome of selection, one must first know how selection is operating; only then can one test the predictions about what organisms ought to do by comparing these predictions with what one actually finds them doing.
Article
The insect prey of 214 pitchers of Sarracenia purpurea were monitored for 55 days. A total of 504 individual prey with a dry weight of 569.5 mg were recovered. The catch comprised individuals from 49 families and 13 orders, with most individuals from the Diptera. The distribution of the prey among pitchers was highly uneven; over 50% of pitchers caught nothing and about 8% of the pitchers caught 66% of the prey biomass. Experimental manipulations failed to produce an effect of pitcher density on prey capture rates. Indeed, no significant spatial variation in prey capture rates was found. Spiders that spun webs inside pitcher apertures prevented pitcher function on about 10% of trap days and may have imposed an important reduction on pitcher success.
Article
Larvae of the Diptera, Wyeomyia smithii and Metriocnemus knabi, accelerate the breakdown of prey and the rate of ammonia production in leaves of Sarracenia purpurea L. The leaves take up ammonia and carbon dioxide rapidly and infuse oxygen into the water contained in them. Brighter light and higher temperature promote more rapid uptake of ammonia. Thus, under the brightest, warmest times of day, inquiline metabolism and respiration can produce increased substrates for photosynthetic carbon reduction and nitrogen incorporation. These same conditions promote an aerobic metabolite-free environment within the leaves. When the system goes anaerobic as a result of superabundant prey decomposition, photosynthetic bacteria predominate and fulfill the roles of the previous aerobic inhabitants.
Article
The functional response of the carnivorous pitcher plant (Sarracenia purpurea L.) was determined using Drosophila melanogaster as prey These plants exhibit a sigmoid-shaped curve in response to an increase in prey availability Plants with newly opened leaves captured significantly more Drosophila in 24 hr than plants without new leaves. The number of Drosophila caught was related to the size of the leaf opening in plants that did not have newly opened leaves. This relationship did not occur in plants that had newly opened leaves. There was no increase in the number of Drosophila caught as the number of leaves per plant increased.
Article
Greenhouse experiments and field collections were used in investigating the ecological relationships of three species of Diptera, Blaesoxipha fletcheri (Aldrich) (Sarcophagidae), Wyeomyia smithii (Coquillett), (Culicidae) and Metriocnemus knabi Coquillett (Chironomidae), which inhabit the digestive fluid of the pitcher plant. Only newly opened leaves actively attract and capture insects. As the leaves age, the insect victims slowly decompose and the leaf fluid pH is lowered. Since the leaves of a pitcher plant are of different ages, each leaf differs in its ability to capture insects and in the degree of decomposition of its captured insects. The relative abundance of the insect inhabitants of a leaf depends upon the leaf age, because each insect species consumes captured insect remains at different stages of decomposition. The buoyant larvae of B. fletcheri feed upon newly captured insects floating upon the surface. As the victims decompose, free-swimming W. smithii larvae filter-feed upon the suspended particulate matter. Accumulated insect remains on the bottom of the leaf chamber provide food for M. knabi. Although all three species feed upon the remains of captured insects, they do so at different times and at different strata within the leaves.