1987] 
Letourneau & Choe — Wasps and ants 
89 
behavioral plasticity may be adaptive under conditions of variable 
tender quality. It may also play an important role in mediating 
competitive interactions within mutualistic systems. 
Summary 
A web of multispecies interactions involving a planthopper, 
Aetalion reticulatum, and a membracid, Aconophora ferruginea, 
and their hymenopteran attendants were studied in Costa Rica. A 
wasp, Parachartergus fraternus, tended both species of Homoptera 
diurnally and prevented other Hymenoptera from obtaining honey- 
dew. Camponotus abdominalis, a major nocturnal attendant, also 
showed a similar degree of “ownership” behavior. Other ant species, 
however, appeared to be opportunistic. Although associations were 
highly stochastic with regard to partnership, A. reticulatum showed 
a clear preference for P. fraternus over ant attendants. It provided 
significantly more honeydew to P. fraternus and in the presence of 
P. fraternus it behaved antagonistically toward any ants. The litera- 
ture on associations of Homoptera with wasps and bees is also 
reviewed. 
Acknowledgments 
We thank the Servicio de Parques Nacionales of Costa Rica and 
the Organization for Tropical Studies (OTS) for making our study 
in Parque Nacional de Corcovado possible. We are grateful to R. R. 
Snelling for identifying the Hymenoptera and to T. K. Wood for 
identifying the Homoptera. P. H. Adler, C. B. Bristow, J. Carpen- 
ter, B. Holldobler, S. Koptur, D. L. Perlman, and E. O. Wilson have 
provided important suggestions for improving earlier drafts. JCC 
was supported by the Richmond Fund of Harvard University. 
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