Entrapped carrion increases indirect plant resistance and intra‐guild predation on a sticky tarweed

Abstract

Many plants employ indirect defenses against herbivores; often plants provide a shelter or nutritional resource to predators, increasing predator abundance, and lessening herbivory to the plant. Often, predators on the same plant represent different life stages and different species. In these situations intraguild predation (IGP) may occur and may decrease the efficacy of that defense. Recently, several sticky plants have been found to increase indirect defense by provisioning predatory insects with entrapped insects (hereafter: carrion). We conducted observational studies and feeding trials with herbivores and predators on two sticky, insect‐entrapping asters, Hemizonia congesta and Madia elegans, to construct food webs for these species and determine the prevalence of IGP in these carrion‐provisioning systems. In both systems, intraguild predation was the most common interaction observed. To determine whether IGP was driven by resource abundance, whether it reduced efficacy of this indirect defense and whether stickiness or predator attraction was induced by damage, we performed field manipulations on H. congesta. Carrion supplementation led to an increase in predator abundance and IGP. IGP was asymmetric within the predator guild: assassin bugs and spiders preyed on small stilt bugs but not vice versa. Despite increased IGP, carrion provisions decreased the abundance of the two most common herbivores (a weevil and a mealybug). Overall seed set was driven by plant size, but number of seeds produced per fruit significantly increased with increasing carrion, likely because of the reduction in the density of a seed‐feeding weevil. Observationally and experimentally, we found that carrion‐mediated indirect defense of tarweeds led to much intraguild predation, though predators effectively reduced herbivore abundance despite the increase in IGP.

Induction of the sticky plant defense syndrome in wild tobacco

“…Carrion‐removal and ‐addition experiments involving another tarweed species produced similar results; plants with more carrion had fewer herbivores, more predators, and produced more seeds per fruit (LoPresti et al. ). Sticky columbine plants have also been found to attract insects that are nearby (LoPresti et al.…”

“…, Krimmel and Pearse , LoPresti et al. , , Wheeler and Krimmel ). This sticky plant defense syndrome is likely to be more effective in arid and Mediterranean environments where the adhesive materials do not wash off plant surfaces during rainstorms (LoPresti ).…”

“…Specialized guilds of true bugs exploit sticky plants of many diverse plant species (Krimmel and Pearse , LoPresti et al. , , Wheeler and Krimmel ). These specialized bugs thrive on sticky plants by avoiding contact with the adhesive exudates.…”

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

“…Scavenging on vertebrate carrion by arthropod decomposers (Benbow et al ., ) and conspecifics by social arthropods (Sun & Zhou, ) is well studied, but facultative scavenging by arthropods on arthropod carrion has been neglected. Facultative scavenging by a diverse group of arthropods has been reported (Lavigne & Pfadt, ; Wheeler, ; Coelho & Hoagland, ; Pierce, ; Foltan et al ., ; Vetter, ) but few studies have assessed the effects of scavenging on individuals and communities (Wilson & Wolkovich, ; Peng et al ., ; LoPresti, ; LoPresti et al ., ; Nelson et al ., ). Our study indicates that scavenging by predators can reduce cannibalism, probably via satiation on arthropod carrion, potentially increasing their abundance.…”

Antiherbivore protection and plant selection by the lynx spider Peucetia flava (Araneae: Oxyopidae) in the Brazilian Cerrado

“…We found that the presence of P. flava is positively related to the carrion abundance as well as showed by other studies focused on several predators on glandular trichome‐bearing plants (LoPresti et al ., , ). Since the scavenging behavior has been recorded for lynx spiders (Romero et al ., ; and herein), it is possible they take into account the carrion abundance before choosing their host plants.…”