Beneficial Effects of Flower-Dwelling Predators on Their Host Plant (original) (raw)

Anti‐Herbivore Protection by Mutualistic Spiders and the Role of Plant Glandular Trichomes

Ecology, 2008

Although specific associations between spiders and particular types of plants have been reported for several taxonomic groups, their consequences for spiders and plants are still poorly understood. The most common South American lynx spiders, Peucetia flava and P. rubrolineata, live strictly associated with various plant species that have glandular trichomes. To understand more about these spider-plant relationships, we investigated the influence of the spiders on the fitness of a neotropical glandular shrub (Trichogoniopsis adenantha) and on the arthropod community structure on the plant. We also tested whether glandular hairs provided any benefit to the spiders. Spiders reduced the abundance of several species and guilds of herbivores on the leaves and inflorescences. Consequently, damage to the leaves, capitula, ovaries, corollas, and stigmas caused by leaf-mining and chewing insects, as well as endophagous insects, were strongly reduced in the presence of Peucetia spp. Although the spiders fed on flower visitors, their negative influence on ovary fertilization was only marginally nonsignificant (P ¼ 0.065). Spiders on plants of Trichogoniopsis adenantha that fed on common fruit flies that had died before adhering to the glandular trichomes did not lose body mass. However, those living on plants without stalked glandular trichomes (Melissa officinalis) did not feed on dead flies and lost 13-20% of their biomass. These results indicate that Peucetia spiders are effective plant bodyguards and that when there is limited live prey they may feed on insect carcasses adhered to glandular trichomes. Since several spider species of the genus Peucetia live strictly associated with glandular trichome-bearing plants in neotropical, Neartic, Paleartic, and Afrotropical regions, this type of facultative mutualism involving Peucetia and glandular plants may be common worldwide.

The role of spider hunting mode on the strength of spider-plant mutualisms

Oecologia, 2018

The strength and outcome of mutualistic interactions can be highly dependent on the combination of traits of the species involved. Distinct foraging strategies (e.g., hunting mode) of mutualistic predators may cause predator-prey interactions to vary, potentially affecting the strength of trophic cascades. We evaluate the causes of variation in the strength of spider-plant mutualisms by focusing on contrasting hunting modes of two spiders: an actively hunting lynx spider (Peucetia sp.) and a sit-and-wait crab spider (Misumenops argenteus). We manipulated spider species composition by assigning each plant to one of the following treatments: (1) no spiders; (2) sit-and-wait spiders only; (3) actively hunting spiders only; (4) actively hunting + sit-and-wait spiders. We then examined the independent and interactive effects of spider species on floral herbivory and fitness of the glandular trichome-bearing plant, Trichogoniopsis adenantha (Asteraceae). Both spider species increased plan...

Trait-mediated effects on flowers: artificial spiders deceive pollinators and decrease plant fitness

Ecology, 2008

Although predators can affect foraging behaviors of floral visitors, rarely is it known if these top-down effects of predators may cascade to plant fitness through traitmediated interactions. In this study we manipulated artificial crab spiders on flowers of Rubus rosifolius to test the effects of predation risk on flower-visiting insects and strength of traitmediated indirect effects to plant fitness. In addition, we tested which predator traits (e.g., forelimbs, abdomen) are recognized and avoided by pollinators. Total visitation rate was higher for control flowers than for flowers with an artificial crab spider. In addition, flowers with a sphere (simulating a spider abdomen) were more frequently visited than those with forelimbs or the entire spider model. Furthermore, the presence of artificial spiders decreased individual seed set by 42% and fruit biomass by 50%. Our findings indicate that pollinators, mostly bees, recognize and avoid flowers with predation risk; forelimbs seem to be the predator trait recognized and avoided by hymenopterans. Additionally, predator avoidance by pollinators resulted in pollen limitation, thereby affecting some components of plant fitness (fruit biomass and seed number). Because most pollinator species that recognized predation risk visited many other plant species, trait-mediated indirect effects of spiders cascading down to plant fitness may be a common phenomenon in the Atlantic rainforest ecosystem.

Impact of flower-dwelling crab spiders on plant-pollinator mutualisms

Basic and Applied Ecology, 2010

Indirect effects in interactions occur when a species influences a third species by modifying the behaviour of a second one. It has been suggested that indirect effects of crab spiders (Thomisidae) on pollinator behaviour can cascade down the food web and negatively affect plant fitness. However, it is poorly understood how different pollinator groups react to crab spiders and, thus, when a reduction in plant fitness is likely to occur. Using continuous video surveillance, we recorded the behaviour of pollinators on two flower species and the pollinators' responses to three crab spider treatments: inflorescences (1) with a pinned dried spider, (2) with a spider model made of paper, and (3) without spiders (control). We found that pollinators avoided inflorescences with dried spiders only on one plant species (Anthemis tinctoria). Pollinators showed no significant avoidance of paper spiders. Honeybees and bumblebees did not react to dried spiders, but solitary bees and syrphid flies showed a strong avoidance. Finally, we found no evidence that inflorescences with dried spiders suffered from a decrease in fitness in terms of a reduced seed set. We hypothesise that top-down effects of predators on plants via pollinators depend on the degree of specialisation of pollinators and their tendency to avoid spiders. (R. Brechbühl). den Kontrollblüten festgestellt werden. Wir stellen die Hypothese auf, dass ''top-down''-Effekte auf Pflanzen durch Prädation auf Bestäuber vom Ausmass der Spezialisierung der einzelnen Bestäubergruppen und deren Tendenz Spinnen zu meiden, abhängen dürften.

Indirect effect of spiders on herbivory of insects: A review

Journal of entomology and zoology studies, 2017

Herbivory can be very overpricing as it causes great losses in agricultural industry. Entomologists are concerning for replacement of synthetic chemicals with natural methods of controlling pests to avoid environmental hazards. Spiders are considered as a natural enemy of a wide range of insect pests. The chemical cues as pheromones and spider’s silk on plants may also cause a fear among herbivorous insects; hence they avoid the plants that bear spiders or their cues. Which cause prolonged starvation in herbivorous and ultimately leads to death. In this way, presence of spiders alters the foraging behavior of insect pests. This predatory phenomenon is the combination of induced migration and consumption. The objective of current review is to explore factors, mechanisms and responses of spider toward herbivory of insects. So that introduction, augmentation or conservation of spiders in agro-ecosystem can be adopted to keep natural check on herbivory of economically important insect p...

Risk of spider predation alters food web structure and reduces local herbivory in the field

Oecologia, 2015

Predators can indirectly enhance plant performance via herbivore suppression, with both prey consumption and changes in prey traits (e.g. changes in foraging behaviour) contributing to the reduction in herbivory. We performed a field experiment to determine the extent of such non-consumptive effects which consisted of repeatedly placing spiders (Pisaura mirabilis) on enclosed plants (Urtica dioica) for cue deposition. Control plants were enclosed in the same way but without spiders. After cue deposition, the enclosures were removed to allow arthropods to colonize the plants and feed on them. Arthropods were removed from the plants before the subsequent spider deposition or control enclosure. During six cycles of enclosure, we quantified leaf damage on the plants. After a seventh cycle, the colonizing arthropods were sampled to determine community composition in relation to the presence/absence of spider cues. We found that the presence of chemotactile spider cues reduced leaf damage...

Evidence for competition between carnivorous plants and spiders

… of the Royal …, 2010

Several studies have demonstrated that competition between disparate taxa can be important in determining community structure, yet surprisingly, to our knowledge, no quantitative studies have been conducted on competition between carnivorous plants and animals. To examine potential competition between these taxa, we studied dietary and microhabitat overlap between pink sundews (Drosera capillaris) and wolf spiders (Lycosidae) in the field, and conducted a laboratory experiment examining the effects of wolf spiders on sundew fitness. In the field, we found that sundews and spiders had a high dietary overlap with each other and with the available arthropod prey. Associations between sundews and spiders depended on spatial scale: both sundews and spiders were found more frequently in quadrats with more abundant prey, but within quadrats, spiders constructed larger webs and located them further away from sundews as the total sundew trapping area increased, presumably to reduce competition. Spiders also constructed larger webs when fewer prey were available. In the laboratory, our experiment revealed that spiders can significantly reduce sundew fitness. Our findings suggest that members of the plant and animal kingdoms can and do compete.

Predator and floral traits change pollinator behaviour, with consequences for plant fitness

1. Flower-dwelling predators may interfere in plant-pollinator interactions through changes in pollinator behaviour, leading to a reduction in pollination services. Although the context-dependency of tri-trophic interactions is often acknowledged, the relative contribution of predator, pollinator and flower traits in shaping pollinator behaviour has been rarely studied simultaneously.