Antimicrobial Feeding of Parental Adults Reduces Offspring Tolerance to Chemical Stress in the Mediterranean Fruit Fly Ceratitis capitata

ABSTRACT Fruits constitute chemically complex environments in which frugivorous insects must cope against plant defensive compounds such as secondary metabolites. In this context, gut microbiota may play a key role in expanding the host's detoxification capacity. However, the role of parental microbiota in shaping offspring tolerance to these compounds, as well as the magnitude of its intergenerational effects, remains poorly explored. In this study, we evaluated the effect of parental microbial status on the performance of Ceratitis capitata offspring under chemical stress during larval development. Dysbiosis was induced in the parental generation through antimicrobial delivery, and offspring were reared on two diets: a control diet and a diet supplemented with juglone (0.5 mg/g), a phenolic compound with high redox activity found in Juglans australis . Developmental traits (pupal recovery and adult emergence) and survival (adult longevity) were assessed. Results showed that both parental antimicrobial treatment and exposure to juglone significantly affected performance during the egg–pupa transition, indicating that early larval development represents a critical stage under chemical stress. In contrast, no clear effects were observed on the pupa–adult transition, and emergence rates remained high across treatments. Conversely, the effects of chemical stress became more evident, significantly reducing adult longevity, particularly in offspring derived from aposymbiotic parents. Overall, these findings indicate that parental microbiota contributes to tolerance against plant defensive compounds throughout development and adult life, potentially facilitating exploitation of hosts with diverse phytochemical profiles.