TY - JOUR
T1 - Modulation of Aphid Alarm Pheromone Emission of Pea Aphid Prey by Predators
AU - Joachim, Christoph
AU - Hatano, Eduardo
AU - David, Anja
AU - Kunert, Maritta
AU - Linse, Cornelia
AU - Weisser, Wolfgang W.
N1 - Funding Information:
Acknowledgments The authors thank Katz Biotech Services for supplying C. carnea and C. septempunctata free of charge. We thank Wilhelm Boland for permission to use the zNose™ of the MPI for Chemical Ecology. This work was supported by the Deutsche Forschungsgemeinschaft (WE 3081/2-3).
PY - 2013/6
Y1 - 2013/6
N2 - Recent studies on animal alarm signaling have shown that alarm calls generally are not uniform, but may vary depending on the type and intensity of threat. While alarm call variability has been studied intensively in birds and mammals, little is known about such variation in insects. We investigated variability in alarm signaling in aphids, group-living insect herbivores. Under attack, aphids release droplets containing a volatile alarm pheromone, (E)-β-farnesene (EBF), that induces specific escape behavior in conspecifics. We used a handheld gas chromatograph (zNose™), which allows real-time volatile analysis, to measure EBF emission by pea aphids, Acyrthosiphon pisum, under attack from different predators, lacewing or ladybird larvae. We demonstrate that aphid alarm signaling is affected by the predator species attacking. Ladybirds generally elicited smaller EBF emission peaks and consumed aphids more quickly, resulting in lower total EBF emission compared to lacewing attacks. In 52 % of the replicates with lacewings and 23 % with ladybirds, no EBF was detectable in the headspace, although aphids secreted cornicle droplets after attack. We, therefore, examined EBF amounts contained in these droplets and the aphid body. While all aphid bodies always contained EBF, many secreted droplets did not. Our experiments show that alarm signaling in insects can be variable, and both the attacker as well as the attacked may affect alarm signal variation. While underlying mechanisms of such variation in aphid-predator interactions need to be investigated in more detail, we argue that at least part of this variation may be adaptive for the predator and the aphid.
AB - Recent studies on animal alarm signaling have shown that alarm calls generally are not uniform, but may vary depending on the type and intensity of threat. While alarm call variability has been studied intensively in birds and mammals, little is known about such variation in insects. We investigated variability in alarm signaling in aphids, group-living insect herbivores. Under attack, aphids release droplets containing a volatile alarm pheromone, (E)-β-farnesene (EBF), that induces specific escape behavior in conspecifics. We used a handheld gas chromatograph (zNose™), which allows real-time volatile analysis, to measure EBF emission by pea aphids, Acyrthosiphon pisum, under attack from different predators, lacewing or ladybird larvae. We demonstrate that aphid alarm signaling is affected by the predator species attacking. Ladybirds generally elicited smaller EBF emission peaks and consumed aphids more quickly, resulting in lower total EBF emission compared to lacewing attacks. In 52 % of the replicates with lacewings and 23 % with ladybirds, no EBF was detectable in the headspace, although aphids secreted cornicle droplets after attack. We, therefore, examined EBF amounts contained in these droplets and the aphid body. While all aphid bodies always contained EBF, many secreted droplets did not. Our experiments show that alarm signaling in insects can be variable, and both the attacker as well as the attacked may affect alarm signal variation. While underlying mechanisms of such variation in aphid-predator interactions need to be investigated in more detail, we argue that at least part of this variation may be adaptive for the predator and the aphid.
KW - (E)-β-farnesene
KW - Acyrthosiphon pisum
KW - Alarm signal variation
KW - Aphididae
KW - Homoptera
KW - zNose
UR - http://www.scopus.com/inward/record.url?scp=84878616401&partnerID=8YFLogxK
U2 - 10.1007/s10886-013-0288-x
DO - 10.1007/s10886-013-0288-x
M3 - Article
C2 - 23686467
AN - SCOPUS:84878616401
SN - 0098-0331
VL - 39
SP - 773
EP - 782
JO - Journal of Chemical Ecology
JF - Journal of Chemical Ecology
IS - 6
ER -