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

Abstract

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.

Temporal variation in extrafloral nectar secretion in different ontogenic stages of the fruits ofAlibertia verrucosaS. Moore (Rubiaceae) in a Neotropical savanna

“…The main and bestknown defense mechanism against herbivory is direct defense, in which the plants have secondary compounds in several structures that make the herbivores' ability to exploit these plants more difficult (Coley & Kursar 1996;Cortesero et al 2000). However, plants also have indirect defenses by the third trophic level, particularly predator insect and parasitic wasps and flies (parasitoids), which are known to protect plants against herbivory (Rico-Gray & Oliveira 2007;Romero et al 2008). This indirect and biotic defense is usually induced, where the plant releases volatile and/or nutritive substances that attract predators and herbivore parasitoids (Kessler & Baldwin 2001;Sabelis et al 2001;Heil 2008).…”

Comparative Functional Genomic Analysis ofSolanumGlandular Trichome Types

“…These structures perform important biological functions, such as discouraging herbivory, attracting pollinators, and maintaining a boundary layer (Nihoul, 1993;Van Dam and Hare, 1998;Kennedy, 2003;Moyano et al, 2003;Simmons and Gurr, 2005;Liu et al, 2006;Horgan et al, 2007;Gonzalez et al, 2008;Romero et al, 2008;Nonomura et al, 2009;Kang et al, 2010). Many of these functions are the result of the specialized nature of glandular trichomes (glands) as sites for the synthesis and storage of biologically active specialized metabolites (Alonso et al, 1992;Antonious, 2001;Iijima et al, 2004;Siebert, 2004;Deschamps et al, 2006;Nagel et al, 2008;Wang et al, 2008;Biswas et al, 2009;Sallaud et al, 2009).…”

Might Heterostyly Underlie Spider Occurrence on Inflorescences? A Case Study ofPalicourea rigida(Rubiaceae), a Common Shrub from Brazilian Cerrado

“…The presence of spiders on inflorescences may easily affect the plant reproductive success. Spiders can prey on phytophagous harmful to the floral structures and consequently reduce their abundance, a fact that lead to an increase in plant reproductive success [3]. Indeed, several studies have demonstrated that spiders may play an effective role in biological pest control [2,38].…”

“…They frequently use plants as substrate to forage and represent one of the main predators that control phytophagous arthropods in natural and agricultural systems [2,3]. Furthermore, spiders also represent a key-assemblage to plants, since they play a potentially critical role over the dynamics of local trophic networks [4,5].…”

“…Since some flowers could be more or less attractive to spiders establishment and, therefore, present a more or less diverse spider assemblage, it would be possible that this differential spider distribution leads to variations of phytophagous impact on floral structures or seeds and, consequently, in reproductive success. For instance, [3] it was experimentally demonstrated that the spiders on or at least near inflorescences can influence herbivory rate, as well as visits by pollinators, which, by the way, leads to straight consequences for the plant adaptive value.…”