Abstract
Bactrocera cucurbitae (Coquillett) and Bactrocera tau (Walker) (Diptera: Tephritidae) are two invasive pests that pose a great threat to melon and fruit crops in tropical and subtropical regions. Previous studies have indicated that there may be a competitive relationship between these two pests because they have similar morphologies and a tendency to damage the same range of hosts. However, no studies have yet confirmed this competitive relationship, which is crucial for predicting the tephritid community structure and population dynamics, as well as for designing management strategies for these pests. In this study, we combined field investigations, literature reviews, and host preference tests to analyze the species association, niche width, and overlap of the two fruit flies to confirm their competitive relationship. We found that B. cucurbitae was more abundant in the wild than B. tau, and there was a negative correlation between them regardless of habitat types. The niche widths of B. cucurbitae and B. tau were 7.50 and 7.42, respectively, and the niche overlap was 0.87 when we analyzed the data from the selected literature. Similarly, the niche widths were 4.95 and 4.44, with a niche overlap of 0.95 when we analyzed data from host preference tests. These results indicate that the two fruit flies co-occur and have a competitive relationship due to their similar niche widths and high niche overlap. The findings offer insights into predicting the field population dynamics and structures of these pests, important for pest monitoring and management.