Parasitoids of Anastrepha fraterculus (Wiedemann) and Ceratitis capitata (Wiedemann) infesting wild guava (Psidium guajava L.) and peach (Prunus persica (L.) Batsch) fruits in the southernmost extension of the Bolivian Yungas forest, in the Province of Tarija, were surveyed in Dec (early summer), Feb (mid summer) and Mar (late summer) 1999 and 2000. The abundance patterns and diversity of fruit fly larval-pupal parasitoid species were similar to previously published data for the southern and northern Yungas forests of Argentina. A total of 1,600 guavas and 800 peaches, weighing 57.713 kg and 24.544 kg, respectively, were collected yielding 13,080 tephritid puparia, 78.4% of which were A. fraterculus and 21.6% Ceratitis capitata (Wiedemann). We reared 712 larval-pupal parasitoids of the following species: Doryctobracon areolatus (Szepligeti), D. brasiliensis (Szepligeti), D. crawfordi (Viereck), Opius bellus Gahan, Utetes anastrephae (Viereck) (all Braconidae, Opiinae), Aganaspis pelleranoi (Brethes) Odontosema anastrephae Borgmeier, and Lopheucoila anastrephae (Rohwer) (all Figitidae, Eucoilinae). Utetes anastrephae, O. anastrephae, and L. anastrephae are new fruit fly parasitoid reports for Bolivia, as well as O. anastrephae in the South American Yungas forest. A thorough sampling of other C. capitata and Anastrepha host plants, mostly native fruit species, will be necessary in the Yungas forest of Bolivia before further conclusions on abundance and composition of all fruit fly parasitoids can be reached.

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.

In the laboratory, the effect of host fruit species Citrus paradisi, C. aurantium, Prunus persica, and Psidium guajava on A. fraterculus parasitism by Diachasmimorpha longicaudata was studied. The number of ovipositor-probing events and the probing-time were documented to evaluate the role of fruit chemistry, and epicarp and mesocarp thickness, respectively. The relationship between the parasitization rate and fruit size in particular plant species was analyzed by applying a simple regression. Results showed that guava and peach yielded significantly more parasitoids than both Citrus spp. Probably, the parasitization rate of D. longicaudata on A. fraterculus would be influenced in part by chemical and physical factors from fruit species.