Role of (E)-β-farnesene in systematic aphid prey location by Episyrphus balteatus larvae (Diptera: Syrphidae)

Abstract

Abstract. The foraging behaviour of beneficials such as aphidophagous predators depend largely on volatile compounds emitted by potential preys. Even if polyphagous predatory species are considered, all the potential preys are not systematically localised and accepted. In this work, chemical cues from different aphids and plants, each alone or in association, were studied to elucidate their role in prey location. Using a four-arm olfactometer, attraction of combinations of three aphid (Megoura viciae, Acyrthosiphon pisum and Aphis fabae) and one plant (Vicia faba) species for Episyrphus balteatus larvae was observed. Predatory hoverfly larvae were attracted by all tested stimuli in the presence of aphids, whatever the species. Whole or crushed aphids and also aphids on bean plant parts were attractive to syrphid larvae, but the host plant alone did not present any infochemical role for E. balteatus. Identification and quantification of the volatile releases from aphid and plant species, alone or in association, were performed using SPME and GC-MS methods. Aphid alarm pheromone, (E)--farnesene, was found in the volatile pattern of each aphid and was tested for its role as an effective kairomone for the hoverfly.

Aphid honeydew: An arrestant and a contact kairomone for Episyrphus balteatus (Diptera: Syrphidae) larvae and adults

“…Almohamad et al, 2007Almohamad et al, , 2009). Infochemical cues emitted from aphids are also known to increase the foraging efficiency of predatory hoverfly larvae (bargen et al, 1998;Francis et al, 2005). Chandler (1969) reported that aphidophagous hoverfly larvae start moving directly until their first tactile contact with aphids.…”

“…These observations are consistent with the findings of bargen et al (1998) who suggested that the prey location of E. balteatus larvae may be guided by the aphid-born volatiles when searching for prey. There is evidence that E. balteatus larvae respond to olfactory volatile chemicals associated with different aphid species, (Acyrthosiphon pisum, Megoura viciae and Aphis fabae: Francis et al, 2005). theory suggests that the intensified search (random, non directional search) in a small area helps the insect predator to find sufficient food if the prey is distributed in clusters (Murdie, 1972).…”

Tomato-aphid-hoverfly: a tritrophic interaction incompatible for pest management

“…Broad beans, V. faba, have been largely used in the study of the oviposition behavior of hoverflies, demonstrating its suitability for this aphidophagous predator within pest management strategies (e.g. Vanhaelen et al 2001;Francis et al 2005b;Verheggen et al 2008). Potatoes have also been presented as suitable host plants for hoverfly female oviposition (e.g.…”

Review An overview of odorant-binding protein functions in insect peripheral olfactory reception

“…For example, the aphid alarm pheromone (E)-β-farnesene (EβF) is secreted by at least 16 aphid species (Francis et al, 2005a) but to which the Brevicoryne brassicae does not show their aposematism. Therefore, it has been suggested that EβF role is to distinguish conspecifics from host plant rather than as an alarm signal by B. brassicae (Francis et al, 2005b). As a huge and diverse group, insects have been estimated to have 4-5 million species (Novotny et al, 2002) and occupy numerous different habitats.…”