Reduction in the foraging activity of the leaf-cutting ant Atta sexdens caused by the phorid Neodohrniphora sp

• Published in: Entomologia experimentalis et applicata Vol. 89; no. 3; pp. 305 - 311
• Main Authors: Bragança, Marcos Antonio L., Tonhasca Jr, Athayde, Della Lucia, Terezinha M.C.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Science Ltd 01.12.1998; Blackwell
• Subjects: Animal ethology; Atta sexdens; Biological and medical sciences; Formicidae; Fundamental and applied biological sciences. Psychology; leaf-cutting ants; Neodohrniphora; parasitism; Phoridae; Protozoa. Invertebrata; Psychology. Psychoanalysis. Psychiatry; Laboratory study; Formicidae; Feeding behavior; Insecta; Antiparasite behavior; Defensive behavior; Parasite; Atta sexdens; Social insect; Formicoidea; Foraging behavior; Feeding; Arthropoda; Parasitism; Hymenoptera; Invertebrata; Phoridae; Diptera; Aculeata; Worker insect; Interspecific relation
• ISSN: 0013-8703; 1570-7458
• DOI: 10.1046/j.1570-7458.1998.00413.x

Females of the parasitic phorid Neodohrniphora sp. were collected in the field and released singly inside an observation chamber placed between a laboratory colony of Atta sexdens (L.) and its foraging arena. The number and speed of loaded and unloaded ants returning to the nest, the weight of foragers and their loads, the number of leaf fragments abandoned by ants, and the number of small workers ‘hitchhiking’ on leaf fragments were measured before phorids were released, while they were in the observation chamber, and after they were removed. Relatively few ants were attacked by Neodohrniphora sp., but the presence of flies prompted outbound ants to return to the nest and caused a significant reduction on the number and mass of foragers. Additionally, the weight of leaf fragments transported by ants was reduced and the number of abandoned fragments increased in response to Neodohrniphora sp. Presence of the parasitoid caused no significant changes in the number of hitchhiking ants. The regular ants' traffic was resumed after phorids were removed, but foraging activity remained below normal for up to three hours. In the field A. sexdens forages mostly at night, but colonies undergo periods of diurnal foraging during which ants are subject to parasitism from several species of phorid flies. Considering that daytime foraging may be necessary for nutritional or metabolical needs, phorids may have a significant impact on their hosts by altering their foraging behavior regardless of the numerical values of parasitism.