Sticky Plant Research Articles

The sticky hemiparasitic plant Parentucellia viscosa catches hostplant seeds that may provision its descendants

In addition to physiological functions, sticky plant trichomes perform a variety of anti-herbivory functions, such as deterring invertebrate and mammalian herbivores, and attracting the natural predators of stuck arthropods by providing them with immobilized prey. However, since the adaptive value of sticky glands has only been studied in a small fraction of trichrome-bearing plant species, other functions of these structures may yet be discovered. Several hemiparasitic plants, which obtain nutrients by both photosynthesis and from the roots of other plants, bear dense glandular trichomes on their aboveground parts. Field observations of the alien hemiparasitic plant Parentucellia viscosa were conducted in central Japan. The plants colonized a sparsely vegetated riverbank and gradually increased in number over time. The glandular trichomes on the plants not only entrapped small insects, but also grass seeds. It is thus possible that various sticky hemiparasitic plants, including P. viscosa, may intercept and capture the dispersed seeds of other plants, ensuring that their own seeds germinate in the same vicinity as those of the dispersing hostplant seeds in the following season. In so doing, P. viscosa may provision future juvenile plants with potential hosts. This scenario may be restricted to the early colonizing phase on plantless areas of disturbed soil. The seed-intercepting function of the glandular trichomes may act in conjunction with direct and indirect anti-herbivore defenses, and lower the dispersal of seeds of wind-borne plants in the vicinity beyond the reach of this hemiparasite.

Proboscidea and Dicyphini: An example of spontaneous mutualism by a population of predatory bugs inhabiting a sticky plant

A population of the mirid-bug Dicyphus errans (Miridae) a species occurring in Europe, colonized a group of Devil’s Claw (Proboscidea louisianica subsp. fragrans (Martyniaceae)) native to the USA and cultivated in a garden in Germany. More than 20 individuals of these predatory bugs have been found living and moving freely on these sticky plants, feeding on stuck victims, while garden ants (Lasius spp. (Hymenoptera)) trying to place aphids for “sugar farming” became captured together with their “productive livestock”, as do small flies and bees. The observations on this spontaneous mutualism between the American Devil’s Claw and a small mosquito-like European mirid-bug has been recorded on video (Hartmeyer 2022). This constitutes an additional example for the adaptation of these ubiquitous predatory bugs to feed on the prey of sticky plants that would usually capture small-sized insects. The American Frank Obregon (2017), who found native mirid-bugs on his cultivated Roridula (Roridulaceae) in California, called the phenomenon assisted carnivory, which fits quite nicely. Proboscidea as well as Roridula do not produce digestive enzymes, so they cannot benefit directly from their diverse captured prey. But as soon as predatory bugs colonize the plants and feed on the sticking prey, their droppings provide a suitable fertilizer to be absorbed by the stomata of the leaf. A perfect mutualism. In addition, some historic facts on bug-plant interaction are provided.

Living on a sticky trap: natural history and morphology of Bactrodes assassin bugs (Insecta: Hemiptera: Reduviidae: Bactrodinae)

ABSTRACT Plants with glandular trichomes have been shown to attract specialist, mutualistic predatory insects. Despite recent advances in understanding the plant component in this association, few sticky plant specialist insects are well documented and their adaptations to the sticky plant environment are understudied. We here describe and illustrate, for the first time, aspects of the natural history and morphology of a small clade of predatory hemipteran insects, the Bactrodinae (Reduviidae). Our study suggests that these insects are exclusively associated with plant species with glandular trichomes. The relationship is not specific as one species of Bactrodes Stål may be associated with multiple species, genera or even families of plants. We document a unique clamp-like structure formed by one of the pretarsal claws and opposing tarsal spine-like setae that enables Bactrodinae to grasp trichomes and walk on leaves densely covered with trichomes. We further present observations of Bactrodes species scavenging on insects entrapped on leaves. Bactrodinae also oviposit on their host plants, and females engage in behaviours that we interpret as maternal egg guarding, a life history strategy that is rare in predatory true bugs. We speculate that instead of or in addition to decreasing egg predation or egg parasitism, female egg guarding may be a response to the limited availability of sticky plants and a strategy against cannibalism.

Arthropod carrion influences plant choice, oviposition, and cannibalism by a specialist predator on a sticky plant

1. Dead arthropods, entrapped by trichomes on plant surfaces, are an underappreciated form of plant‐provided food. Specialist predatory arthropods able to manoeuvre on plants covered in trichomes facultatively scavenge on the alternative food resource, increasing their abundance and reducing plant damage by herbivores.2. This protective mutualism dependent on arthropod carrion has been demonstrated in several plant species, but the mechanisms driving the increase in predator abundance have not been identified. Through a series of greenhouse and laboratory experiments, the effect of arthropod carrion on predator behaviour was assessed.3. The predatorJalysus wickhamipreferredNicotiana tabacumplants augmented with arthropod carrion, spending significantly more time and laying more eggs on those plants than plants without arthropod carrion.4. Under lowJ. wickhamidensities, arthropod carrion did not reduce egg cannibalism by adults. Under high densities, egg cannibalism byJ. wickhamiadults was reduced in the presence of arthropod carrion, but cannibalism by fifth instars was not.5. Arthropod carrion may be utilised by a wide range of predatory arthropods that facultatively scavenge, and this research demonstrates its potential for influencing arthropod–plant and arthropod–arthropod interactions.

Induction of the sticky plant defense syndrome in wild tobacco.

Many plants engage in protective mutualisms, offering resources such as extrafloral nectar and shelters to predatory arthropods in exchange for protection against herbivores. Recent work indicates that sticky plants catch small insects and provide this carrion to predators who defend the plants against herbivores. In this study, we investigated whether wild tobacco, Nicotiana attenuata, fits this sticky plant defense syndrome that has been described for other sticky plants. We developed a bioassay for stickiness involving the number of flies that adhered to flowers, the stickiest tissues. In surveys conducted over three field seasons at four sites, we found that the number of carrion that adhered to a plant was positively correlated with the number of predators that we observed foraging over its surfaces. The number of predators was positively correlated with the number of seed capsules that the plant produced, a measure of lifetime female reproductive success. Structural equationmodeling indicated strong support for the causal path linking carrion numbers to predator numbers to capsule production. We investigated whether stickiness was an inducible trait and examined two potential cues. We found that experimental clipping of rosette leaves induced greater stickiness, although clipping of neighboring sagebrush leaves did not. Damage to leaf tissue is likely to be a more reliable predictor of risk than is damage to a neighboring plant. The sticky plant defense syndrome is a widespread protective mutualism; its strength and ecological relevance can adjust as risk of herbivory changes.

Aspectos químicos y morfo-funcionales de la interacción entre un chinche neotropical de resina y una planta pegajosa

Rubus adenotrichos es una planta de mora andina que contiene tricomas glandulares los cuales secretan un exudado pegajoso. El chinche de las resinas Heniartes stali se encuentra con frecuencia en esta planta recogiendo el exudado con sus patas delanteras para mejorar su capacidad en la captura de las presas. En este trabajo empleamos microscopia de luz y microscopia electronica de barrido para describir la morfologia de los tricomas. Los constituyentes quimicos del exudado fueron estudiados mediante tecnicas histoquimicas, de cromatografia de gases y espectrometria de masas. Tambien combinamos observaciones del comportamiento del insecto en la recoleccion y almacenamiento del exudado con el analisis de la morfologia de sus patas, empleando microscopia de luz y microscopia electronica de barrido para identificar las posibles adaptaciones morfo-funcionales desarrolladas para la manipulacion de estas secreciones adhesivas. Los tricomas glandulares exhibieron un tallo largo multicelular y una cabeza glandular en forma de caliz con celulas alineadas radialmente. El fluido resinoso estaba compuesto principalmente por terpenos y compuestos fenolicos, los cuales parecen contribuir con sus propiedades adhesivas. La presencia de estructuras tipo pincel en las puntas de las tibias de las patas delanteras sugieren un caracter adaptativo para recoger el exudado de los tricomas. Tambien describimos un area en las patas traseras profusamente cubierta de pelos, que funcionaban como estructuras de almacenamiento de la resina. En la cuticula de estas observamos abundantes aberturas similares a poros y sugerimos que a traves de ellos se secretan sustancias que impiden el endurecimiento de la resina almacenada. Estos hallazgos aportan informacion sobre caracteristicas morfologicas y quimicas de un novedoso modelo de interaccion insecto-planta en el neotropico.

The siren song of a sticky plant: Columbines provision mutualist arthropods by attracting and killing passerby insects.

Many plants provide predatory arthropods with food or shelter. Glandular trichomes entrap insects and may provision predators with insect carrion, though it has not been clear whether this putative benefit functions with natural amounts of carrion, whether plants actively attract insect "tourists," and how common this provisioning system is. We tested the hypothesis that a sticky columbine (Aquilegia eximia: Ranunculaceae) attracts passerby arthropods (a siren song leading them to their demise); that these entrapped arthropods increased predators on the plant; and that these predators reduced damage to the plant. Sticky traps baited with columbine peduncles entrapped more arthropod carrion than unbaited control traps. Predator abundance correlated positively with carrion abundance observationally, and experimental removal of carrion reduced predator numbers. Experimental removal of carrion also increased damage to reproductive structures, likely due to reductions in predator numbers. This indirect defense may be common; we compiled a list of insect-trapping sticky plants that includes over 110 genera in 49 families, suggesting a widespread convergence of this trait, even in non-carnivorous plants. The ubiquity of this trait combined with these experiments suggest that carrion entrapment should be viewed as a common and active process mediated by the plant for indirect defense.

Molecular phylogeny of Harpactorinae and Bactrodinae uncovers complex evolution of sticky trap predation in assassin bugs (Heteroptera: Reduviidae).

Sticky trap predation, the use of adhesive substances to trap and capture prey, is an intriguing yet poorly studied predatory strategy. Unique among known sticky trap predators, assassin bugs (Reduviidae) have evolved both exogenous and endogenous sticky trap predatory mechanisms: some trap their prey with sticky plant resins, some scavenge insects entrapped by sticky plant trichomes and others self-produce sticky secretions. The evolution of these different strategies in assassin bugs is poorly understood due to the lack of comprehensive phylogenies. We reconstruct a phylogeny of Reduviidae (141 taxa; >5000bp) focusing on the Harpactorinae and Bactrodinae that engage in sticky trap predation. Ancestral state reconstruction, and temporal and geographical divergence analyses show that sticky trap predation techniques in assassin bugs evolved at least seven times independently since the late Cretaceous: use of sticky plant trichomes evolved as many as four times, resin-use twice independently and once as a transition from trichome use, and 'self-stickiness' once. Exogenous and endogenous sticky traps first appeared in the Neotropics, with the two exogenous mechanisms (resin and trichome use) subsequently evolving independently in the Old World. This study illustrates, for the first time, the complex evolutionary pattern of sticky trap predation within assassin bugs.

Search for potential vectors of ‘Candidatus Liberibacter solanacearum’: population dynamics in host crops

‘Candidatus Liberibacter solanacearum’ has recently been reported to be associated with vegetative disorders and economic losses in carrot and celery crops in Spain. The bacterium is a carrot seedborne pathogen and it is transmitted by psyllid vector species. From 2011 to 2014 seasonal and occasional surveys in carrot, celery and potato plots were performed. The sticky plant method was used to monitor the arthropods that visited the plants. The collected arthropods were classified into Aphididae and Cicadellidae, and the superfamily Psylloidea was identified to the species level. The superfamily Psylloidea represented 35.45% of the total arthropods captured on celery in Villena and 99.1% on carrot in Tenerife (Canary Islands). The maximum flight of psyllid species was in summer, both in mainland Spain and the Canary Islands, reaching a peak of 570 specimens in August in Villena and 6,063 in July in Tenerife. The main identified psyllid species were as follows: Bactericera trigonica Hodkinson, B. tremblayi Wagner and B. nigricornis Förster. B. trigonica represented more than 99% of the psyllids captured in the Canary Islands and 75% and 38% in 2011 and 2012 in Villena, respectively. In addition, Trioza urticae Linnaeus, Bactericera sp., Ctenarytaina sp., Cacopsylla sp., Trioza sp. and Psylla sp. were captured. ‘Ca. L. solanacearum’ targets were detected by squash real-time PCR in 19.5% of the psyllids belonging to the different Bactericera species. This paper reports at least three new psyllid species that carry the bacterium and can be considered as potential vectors.

Mirid (Hemiptera: Heteroptera) Specialists of Sticky Plants: Adaptations, Interactions, and Ecological Implications

Sticky plants-those having glandular trichomes (hairs) that produce adhesive, viscous exudates-can impede the movement of, and entrap, generalist insects. Disparate arthropod groups have adapted to these widespread and taxonomically diverse plants, yet their interactions with glandular hosts rarely are incorporated into broad ecological theory. Ecologists and entomologists might be unaware of even well-documented examples of insects that are sticky-plant specialists. The hemipteran family Miridae (more specifically, the omnivorous Dicyphini: Dicyphina) is the best-known group of arthropods that specializes on sticky plants. In the first synthesis of relationships with glandular plants for any insect family, we review mirid interactions with sticky hosts, including their adaptations (behavioral, morphological, and physiological) and mutualisms with carnivorous plants, and the ecological and agricultural implications of mirid-sticky plant systems. We propose that mirid research applies generally to tritrophic interactions on trichome-defended plants, enhances an understanding of insect-plant interactions, and provides information useful in managing crop pests.

Generalist and sticky plant specialist predators suppress herbivores on a sticky plant

Glandular trichomes are conventionally viewed as a type of direct defense against herbivores that carry indirect costs associated with the exclusion of numerous predators. We tested the hypothesis that predators are ineffective on sticky plants using a predator that is adapted to sticky plants, the harpactorine assassin bug Pselliopus spinicollis Champion, and a common surrogate generalist predator in analogous studies, the coccinellid Hippodamia convergens Guerin. We tested their top–down effects on herbivores using sticky and non-sticky races of common madia plants (Asteraceae: Madia elegans) and their native herbivores, a noctuid moth (Noctuiidae: Heliothodes diminutiva Hodges) and an aphid (Aphididae: Uroleucon madia Swain). We report that both predators were effective at reducing herbivore abundances on sticky and non-sticky plants, with greater efficacy on sticky plants.

Sticky plant traps insects to enhance indirect defence

Plant-provided foods for predatory arthropods such as extrafloral nectar and protein bodies provide indirect plant defence by attracting natural enemies of herbivores, enhancing top-down control. Recently, ecologists have also recognised the importance of carrion as a food source for predators. Sticky plants are widespread and often entrap and kill small insects, which we hypothesised would increase predator densities and potentially affect indirect defence. We manipulated the abundance of this entrapped insect carrion on tarweed (Asteraceae: Madia elegans) plants under natural field conditions, and found that carrion augmentation increased the abundance of a suite of predators, decreased herbivory and increased plant fitness. We suggest that entrapped insect carrion may function broadly as a plant-provided food for predators on sticky plants.

Sticky plant captures prey for symbiotic bug: is this digestive mutualism?

Many plants capture and kill insects but, until relatively recently, only carnivorous plants with digestive enzymes were known to gain directly from the nutrients of those insects. Recent studies show that some carnivorous plants lack digestive enzymes and have evolved digestive mutualisms with symbiotic insects that digest their prey for them. Rhododendron macrosepalum, a plant with sticky leaves that captures insects, has an association with symbiotic Mirid bugs that consume the insects captured. Here, we determine what the nature of the relationship is between Mirid and plant. We find that R.macrosepalum has no digestive enzymes of its own but that it does not seem to have the ability to absorb hemipteran faeces through its leaf cuticle. Naturally occurring levels of (15) N and (14) N were used to determine that R.macrosepalum gains no nitrogen through its association with the Mirid bugs and that it obtains all of its nitrogen from the soil. The Mirids, on the other hand, seem to obtain nitrogen from insects captured by the plant, as well as from plant tissues. The relationship between plant and Mirid is not a digestive mutualism but more likely an antagonistic relationship. This study adds to our understanding of how digestive mutualisms evolve and shows that insect capture alone, or in combination with a symbiotic insect relationship does not necessarily make a plant 'carnivorous'.

Chemical Signatures of Fossilized Resins and Recent Plant Exudates

Amber is one of the few gemstones based on an organic structure. Found over most of the world, it is the fossil form of sticky plant exudates called resins. Investigation of amber by modern analytical techniques provides structural information and insight into the identity of the ancient plants that produced the source resin. Mass spectrometric analysis of materials separated by gas chromatography has identified specific compounds that are the basis of a reliable classification of the different types of amber. NMR spectroscopy of bulk, solid amber provides a complementary classification. NMR spectroscopy also can be used to characterize modern resins as well as other types of plant exudates such as gums, gum resins, and kinos, which strongly resemble resins in appearance but have very different molecular constitutions.

An insect trap as habitat: cohesion-failure mechanism prevents adhesion ofPameridea roridulaebugs to the sticky surface of the plantRoridula gorgonias

The glandular trichomes of the plant Roridula gorgonias release an extremely adhesive, visco-elastic, resinous secretion that traps a variety of insects, including those having a considerable body size. However, the specialized mutualistic mirid bug Pameridea roridulae lives and walks on this sticky plant surface without being trapped. We have sought to reveal the mechanism underlying the apparent non-sticky nature of the cuticle of this bug. In this study, we have visualized intact plant and insect surfaces using cryo-scanning electron microscopy and measured the adhesive properties of the plant secretion on different surfaces. We present a combination of structural and experimental results that suggest that a thick and cohesively weak film of an outermost, epicuticular greasy secretion acts as a ;sloughing-off' layer, preventing the formation of contacts between the sticky plant secretion and the solid insect cuticle. In a comparative study of fresh cuticle fractures of flies representing a typical prey of R. gorgonias, a thin, fragmentary layer of epicuticular grease was revealed. These results indicate that, when trapping prey, the plant adhesive might form proper contact with solid islands of the insect cuticle that are free of epicuticular grease.

A New Model of Coal Seam Formation vis-a-vis Banded Structure and Distribution of Minerals in Coal Seams

In a new model of coal seam formation, advocating the allochthonous process, it has been suggested that the precursor of vitrain was deposited as chemical sediment in a dissolved state derived principally from cellulose segregated from wood tissues. Under acidic conditions, this sediment precipitated as humic acid and continued to float over the aqueous medium. Due to seasonal desiccation of the basin, the floated humic layer, free from contamination of argillaceous impurities, gradually descended and superimposed over the earlier-formed lithotypes. The precursors of durainous lithotypes, in contrast, composed principally of lignin-enriched residual plant cell walls, sticky hydrogen-rich plant ingredients, and agrillaceous dirts, were deposited in the basin as clastic sediments. With a fresh influxof chemical and clastic sediments, the horizontal deposition of basic infrastructures of lithotypes covering an extensive area was repeated, thereby developing the vertical height of the coal seam depicting alternate bands with characteristic affinity to argillaceous impurities.

Gamma-ray induced meiotic chromosome stickiness in tomato

In gamma-ray treated populations of tomato, one of the plants showed stickiness of chromosomes at meiosis. At diakinesis, some of the bivalents tended to fall apart as univalents, and at about the same time or a little later, the bivalents and/or univalents congregated into groups. At metaphase I, the number of such groups varied from 1 to 14 and the groups were of various sizes; the masses of chromatin in which the individuality of chromosomes seemed to be completely lost were spherical, oval or irregular in outline and freely dispersed in the cytoplasm. Some of the masses were so small that they might possibly represent fragments of chromosomes. As the stage passed to anaphase I, the masses dissolved into individual chromosomes, even though stickiness was still persistent but less intense. Laggards in varying numbers were also found. At completion of meiosis, in some proportion of telophase II cells, persistent laggards were found. Pollen fertility and seed set were low. The selfed M2 progeny of the sticky plant contained a few yellow seedlings which died at the cotyledon stage. Cytological examination of meiosis of some of the individuals of this progeny revealed stickiness again in a majority of plants. Sticky as well as normal plants in M2 were selfed and the M3 generation raised. In progenies of both kinds, yellow lethals were found in proportions that gave a good fit with three green to one yellow seedlings in many cases. The occurrence of a sticky plant in M1 and many such plants in M2 was assumed to be due to a dominant mutation induced by gamma irradiation. This, besides causing sticky meiosis, also produced recessive yellow lethal mutations.