Larval competition between Anastrepha fraterculus (Wiedemann) and Ceratitis capitata (Wiedemann) in different natural host.

LIENDO, MARÍA CLARA; DEVESCOVI, FRANCISCO; FABIÁN MILLA; BACHMANN, GUILLERMO; JURI, MARIANELA; BOUVET, JUAN PEDRO; CLADERA, JORGE LUIS; VERA, M. TERESA; SEGURA, DIEGO F

Congreso; 9th Meeting of the Tephritid Workers of the Western Hemisphere (9TWWH); 2016

SENASA

Anastrepha fraterculus and Ceratitis capitata coexist in Argentina and widely share their host range. Previous studies on competitive interactions between them analyzed their abundance in different host species and geographic locations, but did not assesed the actual level of larval competition between them in natural conditions. Here, we study the levels of larval competition between these two species in three primary host species: guava, plum and peach. To this end, fruits of the three host species were sampled in an area of coexistence. Fruits were kept in individual containers and the pupae recovered were weighted and placed individually until adult emergence. For each fruit and host species we measured pupal weight of each fly species and their absolute (number of pupae/kg of fruit) and relative (number of pupae of C. capitata/total number of pupae) abundance. For both fly species and in the three hosts, the pupal weight decreased as the absolute density increased. In C. capitata the pupal weight decreased when the relative density increased, suggesting that C. capitata larvae suffer more sharing the resource with conspecific larvae, particularly in peach. For A fraterculus the pupal weight decreased as the relative density of the competitor species increased, showing a negative effect when sharing the fruit with heterospecific. Our results suggest that larval competition is strongly affected by the density of larvae in the fruit, and in some cases by the proportion of larvae of each species. In guava, A. fraterculus were heavier evidencing a competitive advantage when it shares a native fruit with C. capitata; whereas C. capitata obtained a competitive advantage in an exotic host, such as peach. This separation of fruit species may support the coexistence of two species in nature.