Collective defense of Aphis nerii and Uroleucon hypochoeridis (Homoptera, Aphididae) against natural enemies.
The prevalent way aphids accomplish colony defense against natural enemies is a mutualistic relationship with ants or the occurrence of a specialised soldier caste typical for eusocial aphids, or even both. Despite a group-living life style of those aphid species lacking these defense lines, communal defense against natural predators has not yet been observed there. Individuals of Aphis nerii (Oleander aphid) and Uroleucon hypochoeridis, an aphid species feeding on Hypochoeris radicata (hairy cat's ear), show a behavioral response to visual stimulation in the form of spinning or twitching, which is often accompanied by coordinated kicks executed with hind legs. Interestingly, this behaviour is highly synchronized among members of a colony and repetitive visual stimulation caused strong habituation. Observations of natural aphid colonies revealed that a collective twitching and kicking response (CTKR) was frequently evoked during oviposition attempts of the parasitoid wasp Aphidius colemani and during attacks of aphidophagous larvae. CTKR effectively interrupted oviposition attempts of this parasitoid wasp and even repelled this parasitoid from colonies after evoking consecutive CTKRs. In contrast, solitary feeding A. nerii individuals were not able to successfully repel this parasitoid wasp. In addition, CTKR was also evoked through gentle substrate vibrations. Laser vibrometry of the substrate revealed twitching-associated vibrations that form a train of sharp acceleration peaks in the course of a CTKR. This suggests that visual signals in combination with twitching-related substrate vibrations may play an important role in synchronising defense among members of a colony. In both aphid species collective defense in encounters with different natural enemies was executed in a stereotypical way and was similar to CTKR evoked through visual stimulation. This cooperative defense behavior provides an example of a surprising sociality that can be found in some aphid species that are not expected to be social at all.
Hartbauer
Manfred
M
Behavioural Ecology Group, Department of Zoology, Karl-Franzens University Graz, Graz, Austria. manfred.hartbauer@uni-graz.at
D000819:Animal Communication; D000818:Animals; D001000:Ants; D001042:Aphids / Q000502:physiology*; D001522:Behavior, Animal; D004924:Escape Reaction; D010775:Photic Stimulation; D013559:Symbiosis; D014863:Wasps
J Insect Physiol. 1970 Jun;16(6):1141-5
5469742
J Exp Biol. 2005 Apr;208(Pt 8):1481-8
15802672
Biol Rev Camb Philos Soc. 1996 Feb;71(1):27-79
8603120
Science. 1976 Jun 25;192(4246):1349-51
1273595
Anim Behav. 1998 Mar;55(3):761-5
9514674
Proc Biol Sci. 2007 Apr 22;274(1613):1087-92
17284408
Annu Rev Entomol. 2003;48:29-50
12414736
Oecologia. 1991 Oct;88(2):197-203
28312132
J Theor Biol. 1964 Jul;7(1):17-52
5875340
Proc Natl Acad Sci U S A. 2001 Oct 9;98(21):12068-71
11562469
J Theor Biol. 1971 May;31(2):295-311
5104951
Proc Biol Sci. 2005 May 22;272(1567):1023-9
16024360
Proc Biol Sci. 2000 Sep 22;267(1455):1863-8
11052537
J Acoust Soc Am. 2000 Nov;108(5 Pt 1):2412-8
11108381