Systemically-induced response of cabbage plants against a specialist herbivore, Pieris brassicae

Abstract

Plant responses to herbivory might directly affect the herbivore (''direct'' defences) or might benefit the plant by promoting the effectiveness of natural antagonists of the herbivores (''indirect'' defences). Brussels sprouts attacked by Pieris brassicae larvae release volatiles that attract a natural antagonist of the herbivores, the parasitoid Cotesia glomerata, to the damaged plant. In a previous study, we observed that feeding by caterpillars on the lower leaves of the plant triggers the systemic release of volatiles detectable by the parasitoids from upper leaves of the same plant.The role of these systemically induced volatiles as indirect defence and the dynamics of their emission were investigated in wind-tunnel dual choice tests with C. glomerata. The systemically induced emission of volatiles varied depending on leaf age and on plant age. Systemic induction affected parasitoid effectiveness, as induced plants could be more easily located by parasitoids than non-induced ones.The role of the systemic induction as a direct defence was investigated through behavioural and feeding tests with P. brassicae. In dual choice assays, 1st instar larvae preferred to feed and fed more on systemically induced than on non-induced leaves. In single choice assays, the leaf area consumed by caterpillars was larger on systemically induced leaves than on non-induced control leaves. However, caterpillars fed on systemically induced leaves attained the same weight as those feeding on non-induced controls. In addition, P. brassicae pupae whose larvae were fed on systemically induced leaves had longer developmental times than those of larvae fed on non-induced leaves. Adult oviposition behavior was not influenced by systemic induction.We conclude that systemically induced responses in cabbage might reduce P. brassicae fitness both directly, by affecting their development and feeding behavior and indirectly by making caterpillars and pupae more vulnerable to attack by carnivores. The occurrence of a possible relationship between direct and indirect defence is discussed.

Defence mechanisms of Brassicaceae: implications for plant-insect interactions and potential for integrated pest management. A review

“…This particular kind of defence is important with regard to innate resistance, in case the defence is metabolically expensive, and when the attack is unpredictable but frequent (Haukioja, 1999). Plant responses that affect herbivore arthropods directly through systemic production of toxic metabolites are named direct defences, whereas responses that result in the attraction of natural enemies of the herbivores are designated as indirect defences (Dicke, 1999;Mattiacci et al, 2001). The term indirect defence, that is generally used when plants attract, nourish or house other organisms to reduce pressure from their enemies, has been referred to in the literature only in the last 20 years (Dicke and Sabelis, 1989; see review by Heil, 2008).…”

“…P. rapae and P. brassicae are also the hosts for the egg parasitoid Trichogramma evanescens Westwood in cabbage (Noldus and Van Lenteren, 1985a, b). Cotesia plutellae Kurdjumov is a dominant solitary koinobiont, larval endoparasitoid of P. xylostella, and generally regarded as being highly specific to P. xylostella (Talekar and Shelton, 1993;Agelopoulos and Keller, 1994a-c;Geervliet et al, 1994Geervliet et al, , 1998Mattiacci et al, 1994Mattiacci et al, , 2001Harvey et al, 2003;Fatouros et al, 2005b). Diadegma semiclausum Hellén is a specialised parasitoid of P. xylostella (Bruinsma et al, 2009).…”

Volatiles from wasabi inhibit entomopathogenic fungi: implications for tritrophic interactions and biological control

“…The diamondback moth, Plutella xylostella L., has an enzyme, sulfatase, which desulfates the glucosinolates to metabolites that are not substrates for myrosinase and so do not produce AITC (Ratzka et al 2002). In addition, these crucifer specialists use volatile AITC as an attractant to detect host plants Li et al 2000;Rask et al 2000), and their parasitoids also use the compound as a cue to detect their herbivore hosts (Geervliet et al 1994(Geervliet et al , 1996Rask et al 2000;Mattiacci (Kumagai et al 1994;Oliver et al 1999); some of these other isothiocyanates have fungicidal activity against entomopathogenic fungi (Inyang et al 1999) and the plant pathogens H. solani and V. dahlia (Oliver et al 1999). In our study, other compounds in addition to AITC were detected in the volatiles from macerated wasabi leaves (data not shown) and it is possible that these compounds may also have negative effects on conidial germination of B. bassiana s.l.…”

Evolutionary community ecology of plant‐associated arthropods in terrestrial ecosystems

“…Herbivory by P. versicolora triggers the production of phenolic compounds in willows (Fields and Orians 2006). In general, the patterns of herbivoreinduced plant responses often depend on the leaf age (Karban and Baldwin 1997;Mattiacci et al 2001;Anderson and Agrell 2005). Thus, we predict that genetic variation in the leaf beetle preference may influence plant-mediated indirect effects on other herbivores on willows.…”