Publications
Below each reference, I've provided a quick summary - if it sounds interesting, read the paper!
I'm happy to send pdfs to anyone interested, just shoot me an email (lopresti.eric@gmail.com).
2024
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In this paper, we show that the glandular trichomes of tarweeds - wonderfully sticky, fantastic little asters - do not seem to function as a resistance trait, bringing up the intriguing possibility that indirect defense via defensive mutualism is the evolved function of these hairs.
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2023
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Sierra found that pink-flowered Abronia fragrans in Texas received pollination by both moths and butterflies; both of these guilds were necessary for full seed set. In contrast, white-flowered plants in Kansas received only moth pollination. These results are interesting for two reasons: (1) a small amount of butterfly pollination may drive this floral color difference, and (2) it is not often thought that secondary pollinators increase seed set (and, rarely tested!).
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Pan, VS, A Pepi, EF LoPresti, R Karban. Virus as Bodyguards: Leaf Retention Increases Caterpillar Infection Risk. Oecologia. doi: 10.1007/s00442-023-05325-w
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In this study with very thought-provoking results, we found that leaf retention, a trait that varies across individuals and species, might affect the risk of disease to herbivores. Plants that hold their leaves longer infected more caterpillars; this led to decreased herbivory (standard perennial fitness caveats apply, but results are very suggestive!). Vincent argues that this may be common and consequential.
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LoPresti, EF, VS Pan†, C Girvin†, G Barber†, S Jaeger & JL Orrock. Sandy seeds: armor or invisibility cloak? Mucilage-bound sand physically protects seeds from rodents and invertebrates Journal of Ecology doi: 10.1111/1365-2745.14077
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In this series of experiments in Oklahoma grasslands and crosstimber oak forests, we show that sand bound to mucilaginous seeds protected them physically from both rodent and arthropod predation. Using a series of manipulations of sand color, we also tested - but found no support for - this substrate serving as camouflage against these guilds of granivores. So, like in our 2019 Ecology paper, we found that substrate entrapment functioned as armor, not an invisibility cloak.
A worldwide project describing patterns of spatial variation in herbivory patterns. I contributed herbivory data for ferns (a very interesting group of plants that are often neglected in studies on insect-plant interactions).
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​Salt bladders - little modified trichomes found on the leaves of many chenopods, including spinach and quinoa - were thought to be important mostly in osmoregulation. My previous worked showed their utility in plant defense; a very nice paper that came out (Moog et al 2023) recently went several steps farther, examining mechanisms of that defense and testing various physiological functions. In this commentary, I caution that assumed functions - even decades old and universally accepted - are not always right, as this recent paper demonstrated.
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In this study by a post-baccalaureate technician (Madi Stessman) and two undergrads (Ashlesha Sharma and Gabby Barber), we found that the substrate that a seed binds to affects its attachment strength and subsequent success. Using a number of species of seeds, various grits of sandpaper, and the incredible seed predators, harvester ants, Madi demonstrated the context-dependency in these interactions and that they were... mostly predictable (but, like all mucilage stuff we've studied, there were some interesting idiosyncracies as well!). ​
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2022
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Seed mucilage cements themselves to surfaces after a wetting/drying cycle, which protects them from herbivory. Vincent Pan noticed a few years ago that when put in a drying oven, they stuck much worse. With two fantastic undergrads, Madi Stessman and Sara Warren taking two of the parts of the study, we found that drying at higher temperatures strongly reduces attachment, that this effect is due to drying speed (Madi figured out how to dry them faster with vaccuums!), and that those seeds dried in vacuums or at higher temperatures are exploited more easily by granivorous ants.
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Pan, VS, C Girvin†, EF LoPresti. Anchorage by seed mucilage prevents dislodgement in high surface flow: a mechanistic investigation. Annals of Botany. 10.1093/aob/mcac045
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Many plants that grow in highly erosive environments (imagine steep roadsides, rocky hillsides, etc.) have mucilaginous seeds which allow them to stick to the ground, a phenomenon called antitelochory (anti-dispersal!). We tested seeds of 52 species in artificially simulated erosive conditions and monitored dislodgement for a week, finding that seeds that are "stuck" more tightly survive far better and that this is predicted best by mucilage volume, not drag, cross-sectional area, or any other metric we tested. We believe that among its many other functions, mucilage is an extremely important adaptation to this particular niche/life history for many plants.
2021
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Seeds with a mucilage layer become tightly bound to the ground after a wetting drying cycle; this is known to be defensive against harvester ants in a few species. We tested it in 53 species that differed in their attachment force; attachment force was a good predictor of the benefit. We also looked for environmental correlates of mucilage in a larger dataset, though we did not find any particularly strong correlates, we found a few that deserve increased attention.
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Toll K, EF LoPresti, DB Lowry. Inbreeding depression contributes to the maintenance of habitat segregation between closely related monkeyflower species. Evolution.
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Two species of monkeyflowers segregate despite some dispersal between the microhabitats and successful reproduction. Using reciprocal transplants lines with differing generations of selfing, we found that those immigrants are probably doomed because of inbreeding depression, and therefore this phenomenon contributes to the observed spatial segregation.
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2020
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LoPresti EF, Goidell J†, Mola JM*, Page ML*, Specht CD, Stuligross C*, Weber MG, Williams NM, Karban R. A lever action hypothesis for pendulous hummingbird flowers: experimental evidence from a columbine. Annals of Botany, 125: 59-65.
----> a really nice write-up by Alun Salt here.
Many hummingbird-pollinated flowers have downward-facing flowers, despite other studies showing that hummingbirds do not like to feed on flowers with this orientation. In a columbine, the hummingbirds lever the flower up, thus not feeding in the non-preferred orientation; we experimentally found that the levering increases pollination success. We hypothesize that this mechanism works only in actinomorphic flowers, but hope that this simple study inspires increased attention on this somewhat odd trait.
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Pearse IS, EF LoPresti, J Ali, J Bronstein, M Eubanks, K Mooney, P Ode, R Schaeffer, MG Weber, W Wetzel. Generalising indirect defence and resistance of plants. Ecology Letters, 23: 1137-1152.
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Reviews are difficult to summarize, but essentially, we tried to unite a disparate field of studies which examine how plants benefit from associations with insects that protect them from herbivores and pathogens. Our definition of indirect defense is more all-encompassing than previous examinations, but we feel it is more useful and consistent. We highlight (some of the many, many!) important research directions in indirect defense
for the future.
2019
LoPresti, EF, V. Pan†, J. Goidell†, M.G. Weber, & R. Karban. Mucilage-bound sand reduces seed predation but not by reducing apparency; a field test of 53 plant species. Ecology, e02809.
Mucilaginous seeds, when wetted and dried, get encrusted by substrate. This substrate encrustation reduced seed predation by ants in 48 out of 53 tested species; interestingly, when we manipulated the color and thus how "unapparent" (=camouflaged) the seed was, the effect seemed to be largely physical - but future work should use birds or mammals.
Karban, R. LoPresti, EF; Pepi, A* & P Grof-Tisza. (2019) Induction of the sticky plant defense syndrome in wild tobacco. Ecology. 100: e02746.
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When damaged, wild tobacco plants increase the stickiness on buds; this stickiness functions as a fly-trap and those dead insects feed a guild of scavenging predators that somehow increase plant fitness.
Karban, R; LoPresti, EF; Vermeij, GJ & R Latta. (2019) Unidirectional grass hairs usher insects away from meristems. Oecologia. 189: 711-718.
As you surely intuitively know, spines on most grass species face towards the tip. This is why you can run your fingers up a blade of grass but not down it. This orientation leads to herbivorous insects generally walking towards the tip of the grass, and away from the meristem (though a large caterpillar was not deterred). Field surveys and an experiment found more damage towards the tips of hairy grasses, but did not provide unequivocal evidence of a fitness effect.
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2018
​LoPresti, EF; Van Wyk, JI*.; Mola, JM*; Toll, K*; Miller TE & NM Williams. 2018. Effects of wildfire on floral display size and pollinator community reduce outcrossing rate in a plant with a mixed mating system. American Journal of Botany 105: 1154-1164
Wildfires have become a ubiquitous feature of California shrub and woodlands, and are likely incurring pervasive ecological & evolutionary consequences. After wildfires burned much of McLaughlin reserve (Lake Co., CA) in 2015, bee communities shifted towards larger-bodied species. Individual plants of the annual mint Trichostema laxum also got bigger due to increased water, light, and nutrient availability, producing far more flowers per plant. We found that these two changes altered the outcrossing rate of this mixed-mating species; post-burn populations had a ~25% lower outcrossing rate compared to unburned populations.
Manzanita shrubs (Ericaceae) are found across many habitats in California. The fruit of many manzanita species are sticky and entrap insects. We outline a series of hypotheses for the functional significance of sticky fruit, in addition to the old ‘tried-and-true’ hypothesis of epizoochory (seed dispersal via sticking to animals). We outline the natural history of two species of manzanita (Arctostaphylos viscida and A. hooveri), and detail some small experiments we did to test the hypotheses we proposed. While epizoochory certainly occurs in this and other systems, the other interactions modified by sticky fruit are quite understudied.
LoPresti, EF. Polyphagy by omnivory: scavenging expands host range of a polyphagous caterpillar. 2018. Oecologia 186: 1007-1015
Many herbivorous insects opportunistically scavenge or eat other insects, and macroevolutionary research has indicated that this omnivory may be linked to the ability to consume many different types of host plants (polyphagy, a rare, but very important trait of herbivorous insects). I tested the highly polyphagous tobacco budworm (Heliothis virescens) on ten plants of varying suitability. On each, I gave some caterpillars dead fruit flies, and fed others the plant alone. On host plants of lower quality, scavenging helped the caterpillars' growth rates; however, on hosts of good (or terrible) suitability, they had no effect. This suggests that opportunistic carnivory may expand the host range of herbivores to hosts of lesser suitability, though it cannot overcome all mechanisms of host plant resistance.
Plant defensive traits can mediate a surprising complexity of biotic interactions. In this paper, we detail a combination of observation and small experiments on two species of sticky tarweeds (Madia elegans and Hemizonia congesta). We first outline the interesting food webs found on these plants from our five years of work in these systems. Entrapped insects attract predators, and this protects the plant from caterpillars and weevil larvae. However, when multiple predators co-occur, they often eat each other (intraguild predation - the photo to the left shows a lynx spider eating a stilt bug). We added and subtracted carrion to explore these interactive effects, and found that the amount of intraguild predation depended on the amount of carrion. Interestingly, even at high levels of intraguild predation, the effect of predators on the plant was still beneficial, through reductions in herbivores.
LoPresti, EF; Grof-Tisza, P.; Robinson, M.; Godfrey, J. & R. Karban. 2018. Entrapped sand as a plant defence: effects on herbivore performance and preference. Ecological Entomology 43: 154-161
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Many sticky plants end up covered in windblown sand or other substrates. To explore the potential defensive role of this formidable armor, we examined effects of entrapped sand on the two herbivores with different feeding strategies: the externally-feeding sphinx moth, Hyles lineata, and an internally-feeding sun moth, Lithariapteryx abroniaeella. We showed that entrapped sand abraded the mandibles and caused reductions in growth rate and pupal weight of the sphinx moth Hyles lineata. When given the choice, Hyles caterpillars also preferred to consume nonsandy foliage. In contrast, the leaf mining caterpillar had no aversion to sand on the surfaces of the plant.
2017:
LoPresti, EF. Artificial rainfall increases herbivory on an externally-defended forb. 2017. Arthropod-plant Interactions 11: 871-874
Atriplex rosea, a California summer growing chenopod, is covered in a thin layer of exudates which protect it from herbivory. In the presence of artificial rainfall (it doesn't rain in the CA summer at this location), plants suffer increased herbivory from a leaf beetle. This simple experiment demonstrates that external defenses are liable to be changed by the abiotic environment in potentially important ways. ​
LoPresti, EF & Morse, DH. 2017. A parasitoid's odd pupal vigil. Ecology 98: 1722-1723
This short paper details our attempts to understand why some male Phaeogenes hebrus – a wasp that parasitizes Herpetogramma thesausalis moths at the pupal stage - clung to certain host moth pupae, even when the surrounding leaf shelter was manually opened. We found that those pupae contained pre-emergence female wasps. We did a little experiment and found that mating success of the male parasitoids was far higher in small containers than in progressively larger ones. The odd behavior of clinging to a female pupae for a day or more before emergence – mediated by the wasp’s ability to select pupae hosting a female conspecific – may increase male reproductive success by ensuring mating prior to their leaving the caterpillar shelters.
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Grof-Tisza, P; LoPresti, EF; Heath, SK & R Karban. 2017. Plant structural complexity and mechanical defenses mediate predator–prey interactions in an odonate–bird system. Ecology and Evolution. doi: 10.1002/ece3.2705
Dragonflies are very vulnerable to bird predation when they leave ponds to molt from their aquatic nymphal stage into winged adulthood. Following an observation that nymphs congregate on thistles to molt, we tested their preference and survival on spiny and complex plants, using fake plant models. We found that both traits are preferred, and protect the insects during this critical transition.
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Eiseman, C.S.; Feldman, T.S.; LoPresti, E.F. & M.W. Palmer. 2017. First North American records of Porphyrosela minuta Clarke (Lepidoptera: Gracillariidae), with notes on its native congener, P. desmodiella (Clemens). Proceedings of the Entomological Society of Washington. 119: 18-23
A leaf miner of clover, originally from South America, has been recently found in various parts of the United States. This paper presents these records and how to distinguish this recent introduction from a native relative.
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LoPresti, EF & K Toll. 2017. The three criteria for resistance by carrion provisioning; insect entrapment and predator enrichment on Mimulus bolanderi. Ecological Entomology, 42: 230-234.
An ephemeral, fire-following sticky monkeyflower (Diplacus [Mimulus] bolanderi.) seems to get protection from bodyguarding predators that feed on entrapped insects. We discuss the natural history of this plant species, the fact that this indirect defense is very facultative, as well as ways to test this potential indirect defensive strategy.
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2016
LoPresti, EF and Karban, R. 2016. Chewing sandpaper: grit, plant apparency and plant defense in sand-entrapping plants. Ecology. doi: 10.1890/15-1696 (natural history supplement here)
-> press: here
-> public radio segment here
Many sticky plants in sandy areas incidentally entrap sand. While this has been hypothesized as a defense against chewing herbivores several times since William Beal first proposed it in 1878, the idea had not been tested. In manipulative experiments on Abronia latifolia and Navarettia mellita, we found that sand is an effective defense against chewing herbivory, and that this crusty covering is not acting as camouflage, but rather as a direct defense.
LoPresti, EF and MG Weber. 2016. Breaking barriers in evolutionary biology: a pioneering woman in science and her early theory of plant chemical macroevolution. American Naturalist. 188: 2-4
Marge and I summarized and contextualized a really cool paper by Helen de Abbott about how plant chemistry evolves; the first written of this topic at all. While the specifics she detailed were mostly incorrect (as she was working off a massively flawed phylogeny), her ideas of chemical evolution were a century ahead of her time!
This charismatic large beetle has been lost in almost all of its former range. Here we summarized decades of reintroduction work on Nantucket Island including movement of marked individuals, breeding success, overwintering success and more. While this reintroduction has been largely unsuccessful, we found methods that might work in this and other future ABB reintroduction projects.
A great diversity of plants have chemical defenses on their surfaces, secreted there by a multitude of specialized tissues. These chemicals are not usually considered a class of their own. However, because they are in a different location than most chemical defenses, their modes of activity and interactions with other organisms and the environment fundamentally differ from internal defenses (at least, that's what I try to convince you of in this paper!).
Given that most ecologists do lots of incidental natural history, we advocate that people include data and observation in a supplement as to give future scientists information on the system. ​
2015
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LoPresti, EF; Pearse, IS & Charles, GK. 2015. The siren song of a sticky plant. Columbines provision mutualist arthropods by attracting and killing passerby insects. Ecology doi: 10.1890/15-0342.1 (natural history supplement here)
-> a really nice write-up on this project by Elizabeth Preston here.
A sticky columbine is attractive to small flying insects, which become entrapped on its surfaces. These dead insects provision predatory bugs and spiders, which reduced herbivory on the plant in a manipulative experiment.
Gidmark, NJ; Taylor, C; LoPresti, EF & Brainerd, E. 2015. Functional morphology of durophagy in Black Carp, Mylopharygodon piceus. Journal of Morphology. doi: 10.1002/jmor.20430
A description of the morphology of this specialized mollusk-eating fish native to Asia. The extreme bite force generated by this fish was demonstrated in Gidmark (2014) and this paper summarizes the musculature and bone structure of this cool fish.
​LoPresti, EF; Warren, AW; Stichter, SB & Eastwood, R. 2015. A review of the historical occurrence of Hesperia attalus in New England. Journal of Research on the Lepidoptera. 48: 9-12
The dotted skipper is a rare and in some states endangered butterfly of coastal plains. Here we reanalyze the records of this species, as the most recent, and perhaps most reliable, record in the northeast was a misidentification with a more common species. ​​
Specialized structures on chenopod stems and leaves have been long recognized as important in osmoregulation. However, they are also important in resistance to herbivory in a great many species.
LoPresti, EF & Angulo F. 2014. New bird distribution records for Lambayeque, Peru: Nomonyx dominicus (Linneaus 1766) (Aves: Anatidae) and Incaspiza pulchra (Sclater, 1886) (Aves: Emberizidae). Checklist 10: 618-620 doi:10.15560/10.3.618
Fernando and I detail records of two interesting bird populations in northwestern Peru which greatly extended their known ranges.
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2013
We tested at what gape size a molluskivorous carp generated its maximum bite force (and thus, what size hard-shelled prey it was able to eat). We found, as hypothesized, that it had higher bite force at intermediate gapes.
LoPresti, EF & Morse, DH. 2013. Costly leaf shelters protect moth pupae from parasitoids. Arthropod-plant Interactions. 7:445–453 doi: 10.1007/s11829-013-9261-4
Fern moth caterpillars roll the ends of ferns into little shelters where they live, feed, and pupate. We showed that these shelters have a cost (in time investment), yet effectively protect the pupae from a parasitoid wasp.
While working in Chile, I found the farthest south nest of a Chilean Mockingbird yet reported. Here we summarize the sightings near the (current) southern extent of their expanding range (paper in Spanish).
Stager, M; Lopresti, EF; Angulo F; Ardia DR; Caraces-Apaza D; Cooper CB; Molina J; Taylor N & Winkler DW. 2012. Reproductive biology of a narrowly endemic Tachycineta swallow in dry, seasonal forest in coastal Peru. Ornitologia Neotropical. 23:1 95-112
We summarize the life history of a little-studied, yet very interesting, Peruvian endemic swallow. Can it carry a coconut? Read to find out.
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*graduate student coauthor; †undergraduate/post baccalaureate coauthor; ‡amateur naturalist (nonacademic)