Excessive sugar mediating gut microbiota decrease body size and longevity of Bactrocera dorsalis

The oriental fruit fly (Bactrocera dorsalis) is a global invasive pest that inflicts damage on numerous fruits and vegetables. Given its ability to adapt to various host plants, it is crucial to examine the influence of nutritional composition on the life-history flexibility of B. dorsalis. This study aimed to examine the impact of different sucrose levels on the life-history traits of B. dorsalis and plasticity of their gut microbiota, shedding light on host adaptation. The results indicated that a low-sucrose diet (3%) led to a significant increase in the body size of B. dorsalis, whereas a high-sucrose diet (22%) resulted in a notable decrease in body size. Moreover, a low-sucrose diet led to a larger ovaries and longer lifespans of adult flies compared to those in the control group. Additionally, the consumption of a high-sucrose diet caused substantial alterations in the intestinal microbiota of B. dorsalis when compared to the control group. Notably, 26 and 17 species of gut microbe were found to be enriched in the low-sucrose and high-sucrose diets, respectively. These findings suggest that specific intestinal microbes might contribute to enhancing the adaptability of B. dorsalis. By elucidating the effects of sucrose concentration on the life history, this study deepens our understanding of the adaptive mechanisms underlying insect-microbiome holobiont. It provides a foundation for further exploration into the adaptive mechanisms of B. dorsalis and its microbiome, emphasizing the significance of sucrose concentration in shaping insect life history.