Relative abundance of Ceratitis capitata and Anastrepha fraterculus (Diptera: Tephritidae) in diverse host species and localities of Argentina.

Abstract

Two fruit fly species (Diptera: Tephritidae) of economic importance occur in Argentina, the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) and the South American fruit fly, Anastrepha fraterculus (Wiedemann). Their geographical distributions overlap in large areas of Argentina, but C. capitata extends to temperate regions, while A. fraterculus is restricted to tropical and subtropical climates. In regions where C. capitata and A. fraterculus coexist, we compared the relative abundances of both fruit fly species in 26 different fruit species sampled from 62 localities of Argentina. A relative abundance index (RAI) was calculated for each host in each locality using the number of emerged adults of each species. RAI was calculated as the abundance of C. capitata relative to the combined abundance of A. fraterculus and C. capitata. In general, some taxonomic families of fruit species were more prone to show high (Rutaceae and Rosaceae) or low (Myrtaceae) RAI values, and also native plants showed lower RAI values than introduced plants. RAI showed a high variation among host species in different localities, suggesting a differential use of these hosts by the two flies. There were localities where A. fraterculus was not found in spite of suitable climate and the presence of hosts. Some host species showed little variation in RAI among localities, usually favoring C. capitata, while others (e.g., peach, grapefruit, and guava) showed high variation, suggesting that these fruit species were suitable for both fruit flies but more favorable to one or the other, according to particular ecological characteristics of each locality.