Summary In Tucumán (northwestern Argentina) during 2013 and 2014, Anastrepha fraterculus (Wiedemann) (Diptera: Tephritidae) and Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) were found infesting organically grown blackberries in the humid piedmont region (Monte Grande, Famaillá). In 2016, only A. fraterculus was found infesting organically grown blackberries and raspberries in the temperate semiarid region (Tafí del Valle), where studies conducted in prior years showed coexistence of both fruit fly species with prevalence of C. capitata over A. fraterculus, but in other fruit species. In this study, we found that A. fraterculus had a remarkable preference for raspberries over blackberries. These are the first records of fruit fly occurrence in Rubus (Rosales: Rosaceae) in northwestern Argentina and expand the range of host species for fruit flies in the region. Fruit fly infestation levels in blackberries in the humid region were very low, whereas fruit fly infestation in the semiarid region was r... Sumario En Tucumán (noroeste de Argentina,) durante 2013 y 2014 se encontraron Anastrepha fraterculus (Wiedemann) (Diptera: Tephritidae) y Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) infestando zarzamoras orgánicas en la región del pedemonte húmedo (Monte Grande, Famaillá). En 2016, sólo se encontró A. fraterculus infestando zarzamoras y frambuesas orgánicas en la región templada semiárida (Tafí del Valle), donde estudios realizados en años anteriores mostraron la coexistencia de ambas especies de mosca de la fruta con prevalencia de C. capitata sobre A. fraterculus, pero en otras especies frutales. Cabe señalar que en este estudio, encontramos que A. fraterculus tenía una notable preferencia por las frambuesas sobre las moras. Estos son los primeros registros de ocurrencia de moscas de la fruta en Rubus (Rosales: Rosaceae) en el noroeste de Argentina y amplían el rango de especies hospedantes para las moscas de la fruta en la región. Los niveles de infestación en moras en la región húmeda fuero...

Understanding the mechanisms associated with the coexistence of competing parasitoid species is critical in approaching any biological control strategy against the globally invasive pest spotted-wing drosophila (=SWD), Drosophila suzukii (Matsumura). This study assessed the coexistence of two resident pupal parasitoids, Trichopria anastrephae Lima and Pachycrepoideus vindemiae Rondani, in SWD-infested fruit, in disturbed wild vegetation areas of Tucumán, northwestern Argentina, based on niche segregation. Drosophilid puparia were collected between December/2016 and April/2017 from three different pupation microhabitats in fallen feral peach and guava. These microhabitats were “inside flesh (mesocarp)”, “outside flesh”, but associated with the fruit, and “soil”, i.e., puparia buried close to fruit. Saprophytic drosophilid puparia (=SD) belonging to the Drosophila melanogaster group and SWD were found in all tested microhabitats. SD predominated in both inside and outside flesh, whereas SWD in soil. Both parasitoids attacked SWD puparia. However, T. anastrephae emerged mainly from SD puparia primarily in the inside flesh, whereas P. vindemiae mostly foraged SWD puparia in less competitive microhabitats, such as in the soil or outside the flesh. Divergence in host choice and spatial patterns of same-resource preferences between both parasitoids may mediate their coexistence in non-crop environments. Given this scenario, both parasitoids have potential as SWD biocontrol agents.