Diet and foraging activity in Myrmicaria opaciventris (Hymenoptera : Formicidae : Myrmicinae)

In order to know the ecological impact of Myrmicaria opaciventris, a myrmic ine ant known for its large polydomous colonies mostly installed in anthrop ized areas, we studied the diet and the rhythm of activity of this species. Workers gather numerous vegetal (sap, young twigs and buds, honeydew from attended Homopterans) and animal (whole prey, scavenged remains) products. Among solid products, insect prey are the most frequent (40 to 50% of captu red prey). Thanks to an efficacious recruiting behavior, workers are able t o react quickly to any insect proliferation and can scavenge human refuse. Also, hunting workers are able to rob prey from hunting columns of driver a nts without being attacked by them. The worker rate of effectiveness (ratio between the number of successful workers returning to the nest with a prey , a piece of prey or gaster distended and the total number of workers which returned to the nest) is greater than 40%. The rhythm of activity for predation varied according to the season. It was diurnal during the dry season and extended all along the nychthemeral cycl e during the rainy season, but sugary substances were gathered all along th e year. M. opaciventris directly attack young tissues of economically important pla nts while indirect pest activity was noted when the workers attended Hemipt erans known as vectors of plant diseases. The case of the delphacid Peregri nus maidis observed on maize was especially striking. As a consequence, alt hough workers of M. opaciventris were able to attack a large amount of prey insects, including termites and defoliator caterpillars such as Achea cato caloides (Lepidoptera, Noctuidae) which are known as major pest insects in African tropical zones, this ant species can not be recommended as a biolog ical control agent.