Studies on the Association of the AntOecophylla longinoda(Latr.) (Formicidae) with the Scale InsectSaissetia zanzibarensisWilliams (Coccidae)

Abstract

A close association exists between the ant Oecophylla longinoda (Latr.) and the scale insect Saissetia zanzibarensis Williams.Several factors cause the scale to be rare in the absence of the ant. Contamination by honey-dew and sooty moulds prevents increase of the S. zanzibarensis population above a relatively low level, while, in addition, insect parasites and probably predators virtually exterminate the scale. A fungal parasite may destroy honey-dew-contaminated S. zanzibarensis under humid conditions.The attendant O. longinoda prevents contamination of the scale by honeydew. It gives absolute protection from Coccinellid predators and, although parasitism by Coccophagus spp. and predation by Eublemma spp. is not prevented, the mortality of S. zanzibarensis which they cause is thought to be of little significance.O. longinoda workers benefit S. zanzibarensis in other ways. They remove débris from the scale clusters; they transport the nymphs and establish them at suitable feeding sites. The effect of these benefits is most marked when the ant population is high relative to that of the scale.The silken shelters built by O. longinoda over S. zanzibarensis clusters protect the ant during adverse weather and may only incidentally benefit the scales.S. zanzibarensis and other honey-dew-producing Homoptera are the major food source for O. longinoda. Other sources are sufficient to maintain only relatively low populations of the ant.