Abstract

PEROTTO, María C; BUFFA, Liliana M  and  DELFINO, Miguel A. Attendance effects of Camponotus rufipes (Fabricius) (Hymenoptera, Formicidae) on aggregations of Enchenopa sericea Walk. (Hemiptera, Membracidae). Ecol. austral [online]. 2002, vol.12, n.2, pp.91-97. ISSN 1667-782X.

Enchenopa sericea Walk. (Membracidae), a gregarious, sap-feeding treehopper, is tended by the ant Camponotus rufipes (Fabricius) (Formicidae) on Caesalpinea gilliesii (Wall. et Hook.) Dietr. (Fabaceae) shrubs in La Quebrada, Río Ceballos, province of Córdoba. We investigated the effects of ant-attendance on eggs, nymphs and adults of the membracid. Local populations of the membracid and their associated ants were counted nondestructively at weekly intervals during 21 weeks from October 1997 to March 1998. Seventy-four ant-present aggregations (control) and 25 ant-excluded aggregations (unattended) were studied. The results of field censuses revealed a positive correlation between ants and membracids. Attendance greatly increases the mean number of surviving nymphs, reaching them higher numbers in ant-present aggregations than in ant-excluded aggregations. The mean number of females and males, and the sexual ratio, were greater when attended by the ants than where ants were excluded. Eggs were not attractive to Camponotus rufipes and no correlation was found with them. Enchenopa sericea females apparently remain longer with the egg masses in the absence of ants to attract them to the future group of nymphs, and this behaviour is interpreted as a form of parental care. Proportionally, ants attended adults in larger numbers than nymphs, suggesting that ant attendance can be related to the quantity of honeydew available.

Keywords : Enchenopa sericea; Membracidae; Camponotus rufipes; Formicidae; Interactions.

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