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Zoological Lett

Title:		Linoleic acid as corpse recognition signal in a social aphid
Author(s):		Shibao H; Kutsukake M; Matsuyama S; Fukatsu T;
Address:		"Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, 305-8572, Japan. Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 305-8566, Japan. Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, 305-8572, Japan. t-fukatsu@aist.go.jp. Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 305-8566, Japan. t-fukatsu@aist.go.jp. Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Tokyo, 113-0033, Japan. t-fukatsu@aist.go.jp"
Journal Title:		Zoological Lett
Year:		2022
Volume:		20220106
Issue:		1
Page Number:		2 -
DOI:		10.1186/s40851-021-00184-w
ISSN/ISBN:		2056-306X (Print) 2056-306X (Electronic) 2056-306X (Linking)
Abstract:		"Social insect colonies constantly produce dead insects, which cause sanitary problems and potentially foster deadly pathogens and parasites. Hence, many social insects have evolved a variety of hygienic behaviors to remove cadavers from the colonies. To that end, they have to discriminate dead insects from live ones, where chemical cues should play important roles. In ants, bees and termites, such corpse recognition signals, also referred to as 'death pheromones' or 'necromones', have been identified as fatty acids, specifically oleic acid and/or linoleic acid. Meanwhile, there has been no such report on social aphids. Here we attempted to identify the 'death pheromone' of a gall-forming social aphid with second instar soldiers, Tuberaphis styraci, by making use of an artificial diet rearing system developed for this species. On the artificial diet plates, soldiers exhibited the typical cleaning behavior, pushing colony wastes with their heads continuously, against dead aphids but not against live aphids. GC-MS and GC-FID analyses revealed a remarkable increase of linoleic acid on the body surface of the dead aphids in comparison with the live aphids. When glass beads coated with either linoleic acid or body surface extract of the dead aphids were placed on the artificial diet plates, soldiers exhibited the cleaning behavior against the glass beads. A series of behavioral assays showed that (i) soldiers exhibit the cleaning behavior more frequently than non-soldiers, (ii) young soldiers perform the cleaning behavior more frequently than old soldiers, and (iii) the higher the concentration of linoleic acid is, the more active cleaning behavior is induced. Analysis of the lipids extracted from the aphids revealed that linoleic acid is mainly derived from phospholipids that constitute the cell membranes. In conclusion, we identified linoleic acid as the corpse recognition factor of the social aphid T. styraci. The commonality of the death pheromones across the divergent social insect groups (Hymenoptera, Blattodea and Hemiptera) highlights that these unsaturated fatty acids are generally produced by enzymatic autolysis of cell membranes after death and therefore amenable to utilization as a reliable signal of dead insects"
Keywords:		Cleaning behavior Corpse recognition signal Death pheromone Fatty acid Insect gall Linoleic acid Social aphid Soldier caste Tuberaphis styraci;
Notes:		"PubMed-not-MEDLINEShibao, Harunobu Kutsukake, Mayako Matsuyama, Shigeru Fukatsu, Takema eng 18K06373/japan society for the promotion of science/ England 2022/01/08 Zoological Lett. 2022 Jan 6; 8(1):2. doi: 10.1186/s40851-021-00184-w"