The use of stable isotope as tracers of Anastrepha fraterculus (Wiedemann, 1830) (Diptera: Tephritidae)

• Autor(a) principal: Botteon, Victor Wilson
• Data de Publicação: 2018
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Biblioteca Digital de Teses e Dissertações da USP
• Texto Completo: https://www.teses.usp.br/teses/disponiveis/64/64134/tde-14072021-100741/
• topic: Artificial diet; Dieta artificial; Fator de discriminação isotópica; Isotopic turnover; Sterile Insect Technique; Taxa de turnover; Técnica do Inseto Estéril; Trophic discrimination factor

Aiming to suppress the South American fruit fly, Anastrepha fraterculus (Diptera: Tephritidae), an Area-Wide Integrated Pest Management (AW-IPM) program that integrates the Sterile Insect Technique (SIT) will be implemented on apple growing areas in Southern Brazil. An accurate distinction between the sterile-released flies and the wild fertile flies is essential, since false detections could trigger unnecessary and costly control actions over the surveyed area. In this context, the use of Stable Isotopes Analysis (SIA) emerges as a potential tool for discriminating the origin of the insects. The present study demonstrated whether it is possible to adequately identify laboratory-reared A. fraterculus flies, besides evaluating the influence of attractive and preservative substances on flies\' isotopic composition over time. This study also assessed for the first time the trophic discrimination factor (TDF) and the turnover rate of A. fraterculus after diet switching, once the lack of these species-and element-specific laboratory-derived parameters could limit the SIA application in understanding the ecological patterns of this fruit fly. The ?13C and ?15N signals of the larval and adult diets, laboratory-flies, wild flies captured in Southern Brazil (Vacaria), attractive and preservative substances and the flies immersed in the substances were performed by CF-IRMS at CENA/USP. The isotopic compositions from males and females, either from laboratory and wild flies, did not differ significantly. The A. fraterculus flies reared on larval diets presented different ?13C values compared to wild flies and those reared on fruits (C3-based diets). The values of ?15N were not conclusive for flies differentiation, and traceability could not depend solely on ?15N values. In relation to the capture and preservation methods tested (CeraTrapTM, grape juice and absolute ethanol), it was observed that, depending on the substance, at least one of the isotopic values can suffer alteration compared to the controls. Despite the fact that isotopic compositions of the laboratory-flies could be affected by attractive and preservative substances and by the time that the flies remained immersed in the trap, it was still possible to distinguish flies reared on artificial diet from wild flies. After the diet switching experiment, the ?13C signals of flies began to change, reflecting their recent diet as a result of metabolic turnover, expressed in half-life (t1/2). All treatments showed significant difference in ?13C values over time. The ?15N showed values fewer conclusive when compared to the ?13C values, because the variation of the diet sources was based on the stable isotopes of carbon. Despite of these results, after 15 days of diet shift, the isotopic compositions of laboratory-flies in all treatments were statistically different from the isotopic composition of wild flies. The C4-based diets in the larval and adult stages can be considered suitable tracers of A. fraterculus in an SIT program