Isolation, Identification, and Synthesis of Miriamides, New Hostmarkers from Eggs of Pieris brassicae

Abstract

The large white butterfly, Pieris brassicae L., a herbivorous pest of crucifers, produces egg-associated chemical markers that inhibit its oviposition. The identification of the marker compounds is reported herein. Separation by means of reversed-phase hplc demonstrated the presence of three active substances, which were identified as tra»j-2- [3-(3,4,5- and trans-2-[3-(3,4dihydraxyphenylpropenoyl)amino]-3,5-dihydroxybenzoic acid [31, using mass and nmr spectroscopy and chemical synthesis. This group of compounds has not been reported from the animal kingdom before. The same compounds are produced by two related Pieris species. This is the first report of taxon-specific compounds affecting butterfly oviposition behavior. The availability, stability, and inhibitory action on colonization of cabbage plants by butterflies make application of these compounds in the protection of cabbage crops feasible and comparable with other environmentally safe crop protection strategies.Females of several herbivorous insect species are known to deposit a marking substance on or near the eggs (1-3). This substance signals to conspecific females (and also to herself if she happens to visit the same site again) that the site is already occupied. This phenomenon constitutes an important element in foraging strategies of herbivorous insects, because it prompts an even distribution of eggs over the available food resources, results in reduction of intraspecific competition, and improves resource exploitation. Because of their important ecological function these host-marking pheromones (HMPs), formerly often labeled as oviposition-deterring pheromones (ODPs), attract much attention. Egg-associated substances also affect related herbivorous species and natural enemies of the herbivores (4-7). Oviposition deterring activity has also been found in feces from larvae (8-10). A more detailed analysis of the ecological role of an HMP requires its chemical identification. Thus far, only a few attempts to identify eggassociated HMPs have been successful (11-13), with a notable example concerning the cherry fruit fly, Rhagoletis cerasi (11).Within the Lepidoptera, several potential uses of HMPs have been reported (14,15). The large white butterfly, Pieris brassicae L., a specialized herbivore of cabbage (Brassica oleráceo) and other cruciferous plants, has been studied in detail (14,16,17). Oviposition by P. brassicae is inhibited when a potential host plant carries conspecific eggs or is sprayed in a methanolic egg wash (14,16). Inhibition of oviposition is especially pronounced when females have a choice between HMP-treated plants and control plants, or when dispersal activity can be manifested (18). Based on a two-choice bioassay, the inhibition of oviposition by egg-associated compounds was quantified (17). Herein the identification and synthesis of HMPs isolated from eggs of P. brassicae is presented. RESULTS AND DISCUSSIONEggs ofP. brassicae, freshly laid on cabbage leaves, Brassica olerácea L. var. gemmifera

Chemical nature and persistence of the oviposition deterring pheromone in the tracks of the larvae of the two spot ladybird, Adalia bipunctata (Coleoptera: Coccinellidae)

“…In the case of the cabbage seed weevil, C. assimilis, the oviposition deterring pheromone is also mainly made up of alkanes (Mudd et al 1997). Most of the reports on the chemical identification of oviposition deterring pheromones relate to insect herbivores (e.g., Schoonhoven 1990; Blaakmeer et al 1994;Gabel & Thiery 1996) and few to parasitoids (e.g., Millar & Hare 1993). This is the first time that the chemical nature of the oviposition deterring pheromone of an insect predator has been investigated.…”

Behavioral Manipulation Methods for Insect Pest-Management

“…Trials with the synthetic pheromone have given similar reductions in fruit infestation (5). The recent identification and synthesis of host-marking pheromones from the eggs of butterflies in the genus Pieris (23) and the relative stability of these compounds present a similar opportunity for using oviposition deterrents to protect cabbage crops from these pests (135).…”

The Plant's Response towards Insect Egg Deposition

“…Egg depositions of Pieris brussicue on cabbage leaves (Brussicu oleruceu) induces the plant to produce oviposition deterrents which reduce the number of subsequent egg depositions of this butterfly at that site (Blaakmeer et al, 1994a). From these egg washes, the socalled miriamides, which are three novel avenanthramide alkaloids, have been identified as active oviposition deterrents (Blaakmeer et al, 1994b). However, this effect has been attributed to oviposition deterrents associated with the eggs, since methanolic and watery egg rinsing applied to cabbage leaves also reduced the number of egg depositions (Rothschild and Schoonhoven, 1977).…”