COMMUNITY AND ECOSYSTEM ECOLOGY Host Use and Resource Sharing by Fruit/Seed-Infesting Insects on Schoepfia schreberi (Olacaceae)

The interactions between the fruit ßy Anastrepha spatulata Stone (Diptera: Tephritidae) and two species of moths, the gelechiid Coleotechnites sp. and an unidentiÞed tortricid species, were examined on their effects on seed production in terms of their exploitation within fruits of Schoepfia schreberi J.F. Gmel (Santalales: Olacaceae). The studywas carried out in three experimental sites during 3 yr. Under conditions of abundant fruit, A. spatulata was the dominant exploiter at the population level, as shown by its ability to infest the largest number of fruits of the three herbivores and substantially displace its moth competitors. In a separate experiment, when resource-partitioning specieswereexcluded,A. spatulata infested twice asmany fruits as the twomoth species (44.3%).Field observations examined the ability of A. spatulata to locate suitable fruits. We found that, the variation in fruit characters inßuenced fruit suitability in relation to its size (4.1261 0.0272mm[mean SE]) and weight (0.0618 0.0005 mg [mean SE]). Uninfested fruits produce viable seed but the interaction of all species (exploiting for the fruits) led to limited seed formation.