Emission of Alarm Pheromone in Aphids: a Non-Contagious Phenomenon
ABSTRACT In response to attack by natural enemies, most aphid species release an alarm pheromone that causes nearby conspecifics to cease feeding and disperse. The primary component of the alarm pheromone of most species studied is (E)-beta-farnesene. We recently demonstrated that the production and accumulation of (E)-beta-farnesene during development by juvenile aphids is stimulated by exposure to odor cues, most likely by (E)-beta-farnesene emitted by other colony members. Here, we tested whether the release of (E)-beta-farnesene can be triggered by exposure to the alarm pheromone of other individuals, thereby amplifying the signal. Such contagious emission might be adaptive under some conditions because the amount of (E)-beta-farnesene released by a single aphid may not be sufficient to alert an appropriate number of individuals of the colony to the presence of a potential threat. By using a push-pull headspace collection system, we quantified (E)-beta-farnesene released from Acyrthosiphon pisum aphids exposed to conspecific alarm signals. Typical avoidance behavior was observed following exposure to (E)-beta-farnesene (i.e., aphids ceased feeding and dropped from host-plant); however, no increase in alarm pheromone amount was detected, suggesting that contagious release of (E)-beta-farnesene does not occur.
Full-textDOI: · Available from: Francois Verheggen, Sep 25, 2015
- SourceAvailable from: John F Tooker
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- "When other aphids detect this cue, they remove their stylets from the host plant and fall, jump, or walk away to escape potential danger (Edwards et al., 1973; Montgomery and Nault, 1977; Roitberg and Myers, 1978; Wohlers, 1981; Braendle and Weisser, 2001). Aphids that sense alarm pheromone do not appear to release additional pheromone (Hatano et al., 2008; Verheggen et al., 2008b). Alarm pheromones are emitted by nearly all aphid species, and the sesquiterpene E-b-farnesene (Ebf), the most common component, has been found in more than 40 aphid species (Xiangyu et al., 2002). "
ABSTRACT: Extensive use of pesticides to control insect pests can have negative effects on the environment, natural enemies and food safety. The aphid alarm pheromone, E-β-farnesene (Eβf), appears to hold strong potential for controlling a wide variety of aphid pests. To understand the control potential of Eβf, we used field experiments in a factorial design to test its influence and that of the insecticide imidacloprid on populations of aphids Lipaphis erysimi (Kaltenbach) and Myzus persicae (Sulzer) on Chinese cabbage, Brassica rapa pekinensis (Brassicales: Brassicaceae). Our results showed imidacloprid treatment alone can significantly decrease aphid populations, and that combining insecticide with Eβf further reduced numbers of apterous aphids at distances of 5 m from pheromone emitters in two years of our experiments. Our results demonstrate that imidacloprid can be effective in reducing the abundance of aphids in Chinese cabbage fields, but the degree of control can be even stronger in the presence of Eβf.Crop Protection 05/2012; DOI:10.1016/j.cropro.2012.01.003 · 1.49 Impact Factor
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- "However, Kunert et al. (2005) reported that A. pisum react more strongly to the frequency of pheromone releases than to the amount of pheromone released during each signaling event. This observation is consistent with the results of two later studies, which found that aphids do not propagate or amplify the alarm signal by emitting additional EBF in response to perception of the alarm pheromone (Hatano et al., 2008a; Verheggen et al., 2008b). Thus, the frequency, rather than the intensity of alarm pheromone emission events, may determine the scale of the response induced. "
ABSTRACT: Aphids are important agricultural and forest pests that exhibit complex behaviors elicited by pheromonal signals. The aphid alarm pheromone--of which (E)-β-farnesene is the key (or only) component in most species--plays important roles in mediating interactions among individuals as well as multitrophic interactions among plants, aphids, and aphid natural enemies. Though many important questions remain to be answered, a large body of research has addressed various aspects of the biology, physiology, and ecology of aphid alarm pheromones. Here we review recent advances in our understanding of (a) the identity and composition of aphid alarm signals; (b) their biosynthesis and production; (c) their effects on conspecifics; (d) their role as cues for other insect species; and (e) their potential application for the management of pest organisms.Insect biochemistry and molecular biology 12/2011; 42(3):155-63. DOI:10.1016/j.ibmb.2011.11.008 · 3.45 Impact Factor
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- "In our olfactometric bioassays, both E. connexa and T. striatula were attracted to infested plants of V. faba when a foliar aphidophagous beetle (i.e., H. variegata or E. connexa) was present (Figure 2A and C). When disturbed by natural enemies, aphids release an alarm pheromone through their cornicles, which is perceived by their conspecifics nearby and as a result, they cease feeding and disperse by dropping to other plants or to the ground (Verheggen et al., 2008). As a consequence, and taking into account that all treatments with carabids as stimulus sources (which did not physically disturb the aphids) and those with only predators (with or without the plant) did not elicit attraction, we suggest that chemical attraction in E. connexa and T. striatula (and therefore, intraguild interactions between them) could be explained by an attraction to volatiles released in response to disturbing and predation on aphids, and particularly to the aphid alarm pheromone emitted in presence of a natural enemy on the plant. "
ABSTRACT: Based on their effect on prey populations, predators can interact synergistically, additively, or antago-nistically. Predator attraction by semiochemicals in response to herbivory is well documented; how-ever, the possibility of semiochemicals mediating synergistic interactions has not been explored. Eriopis connexa (Germar) and Hippodamia variegata (Goeze) (both Coleoptera: Coccinellidae) inter-act synergistically with carabid species in Central Chile, a phenomenon in which semiochemicals may be involved. Moreover, olfactory behaviour in these coccinellids is unknown. Olfactometries contrasting non-infested vs. infested plants with Acyrthosiphon pisum Harris (Hemiptera: Aphididae) were performed to study olfactory prey-searching in E. connexa, H. variegata, and Trirammatus stria-tula (Fabricius) (Coleoptera: Carabidae). To evaluate whether semiochemicals can mediate synergis-tic predatory interactions, four experiments were established: olfactometries contrasting (1) infested plants with and without a predator, (2) uninfested plants with and without a predator; (3) predator vs. air, and (4) plants with previous physical activity of a predator vs. clean plants (nine combinations of predator species, according to whether they corresponded to the stimulus or focal individual). Hippodamia variegata and T. striatula were attracted to infested plants when contrasted with non-infested plants. Infested plants with a conspecific and H. variegata elicited attraction in E. connexa, whereas T. striatula preferred infested plants with E. connexa or H. variegata. Treatments with only predators (with or without the plant) did not elicit responses, except in E. connexa which was repelled by conspecifics and H. variegata, perhaps indicating an antagonistic interaction between them; plants with previous physical activity of predators did not elicit responses. These results corroborated the importance of semiochemicals produced by herbivory in the prey-searching behaviour of aphido-phagous predators. In addition, presence of predators on the foliage may favour emission of aphid alarm pheromones, which could attract E. connexa and T. striatula. Volatiles can intervene in syner-gistic interactions between carabids and coccinellids; this should be replicable in other systems where predator-facilitation between aphidophagous predators is observed.Entomologia Experimentalis et Applicata 10/2010; 137(1). DOI:10.1111/j.1570-7458.2010.01034.x · 1.62 Impact Factor