Prevalence and potential distribution of Anastrepha spp. (Diptera: Tephritidae) in native populations of cherimoya in southern Ecuador

The cherimoya ( Annona cherimola Mill.) is a subtropical fruit tree of the Annonaceae family, valued for its excellent organoleptic properties and economic potential. Native to the Andean region, specifically from southern Ecuador and Northern Peru, its production faces significant agronomic challenges, including pest infestations. Given these challenges, this study aimed to assess the prevalence and potential distribution of Anastrepha spp. (Diptera: Tephritidae) associated with cherimoya populations in southern Ecuador. Physiologically ripe cherimoya fruits were collected from March to June 2023 across eight cantons of Loja province, southern Ecuador (Calvas, Celica, Espíndola, Gonzanamá, Loja, Paltas, Quilanga, and Saraguro). Sampling covered different altitudinal ranges, and fruits were obtained from trees exhibiting variation in exocarp morphology (e.g. smooth and mammillate types). After collection fruits were incubated under controlled conditions for fly emergence and taxonomic identification using stereomicroscopes and identification keys. Species distribution modeling was conducted using the biomod2 package in R, which integrates multiple modeling algorithms to generate ensemble predictions of habitat suitability. A total of 609 flies emerged from 343 fruits, all belonging to the Anastrepha genus, with Anastrepha fraterculus Wiedemann (96 %) being the dominant species. Anastrepha distincta Greene also was collected in lower amounts. Prevalence varied among cantons (second-level administrative divisions), with Calvas and Gonzanamá showing the highest populations of A. fraterculus , while Celica and Saraguro had minimal or no presence. The results show that in both species, the observed sex ratio did not significantly deviate from 1:1. Statistical analysis showed a significant relationship between exocarp type and intensity, with higher intensity in impressa and lissa types. Altitude also influenced infestation, with greater numbers observed between 1,500 and 1,800 m a.s.l.. The prevalence of fruit flies in southern Ecuador was significantly influenced by slope orientation, warmest quarter (bio18), isothermality (bio03), and temperature seasonality (bio04). These findings provide a baseline for understanding Anastrepha diversity and distribution in native cherimoya populations of southern Ecuador, supporting the development of targeted pest management strategies.