Individual and social components of wood ant response to conifer sawfly defence (Hymenoptera: Formicidae, Diprionidae)

• Published in: Animal behaviour 1996-10, Vol.52 (4), p.801-811
• Main Authors: CODELLA, JR, SYLVIO G., RAFFA, KENNETH F.
• Format: Article
• Language: English
• Subjects: Animal ethology; Biological and medical sciences; Diprionidae; Formica obscuripes; Formicidae; Fundamental and applied biological sciences. Psychology; Protozoa. Invertebrata; Psychology. Psychoanalysis. Psychiatry
• ISSN: 0003-3472; 1095-8282
• DOI: 10.1006/anbe.1996.0225

Although wood ants frequently encounter defended prey, there has been little study of how anti-predator traits affect worker behaviour patterns. Interactions between western thatching ants, Formica obscuripesForel, and chemically defended conifer sawfly larvae were observed in a laboratory setting. Individual ant responses to sawflies were strongly affected by prey defence status and predator approach behaviour. Solitary workers that initially examined (antennated, mandibulated) sawflies were more likely to abandon larvae than were workers that attacked immediately. Ants were more likely to persist in prey encounters when sawflies were experimentally depleted of chemical defence. Attacking workers attracted recruits more rapidly than did ants that examined prey. Prey discovery resulted in a decline in honey water attendance at food stations as additional workers engaged in prey retrieval, but did not affect overall foraging rate. Survival of fully defended larvae was significantly greater than that of depleted prey. Sawfly defences appear most effective in the early stages of encounters with ants. A generalist diet and the opportunistic nature of prey exploitation have probably precluded the evolution of refined wood ant responses to sawfly defences.