Oviposition Competition Between Zeugodacus cucurbitae and Bactrocera dorsalis Adults in Five Hosts

The <i>Zeugodacus cucurbitae</i> and <i>Bactrocera dorsalis</i> are economically significant pests that share similar habitats and host plants, leading to intense interspecific competition. To elucidate their competitive interactions, this study investigated the oviposition competition behavior of mixed laboratory populations on five common host plants: pumpkin (<i>Cucurbita moschata</i>), cucumber (<i>Cucumis sativus</i>), winter melon (<i>Benincasa hispida</i>), bitter melon (<i>Momordica charantia</i>) and guava (<i>Psidium guajava</i>). The results exhibited that among the five hosts tested, <i>B. dorsalis</i> exhibited a significant competitive advantage in oviposition on pumpkin and bitter melon, with its fecundity greater than that of <i>Z. cucurbitae</i> across all ratios. Conversely, <i>Z. cucurbitae</i> showed a clear preference for cucumber. Except at the extreme ratio of 16:4, where <i>B. dorsalis</i> laid slightly more eggs than that of <i>Z. cucurbitae</i>, <i>Z. cucurbitae</i> laid more eggs at all ratios. The results can provide a reference for further investigation on the oviposition selectivity and interspecific competition between the adults of <i>Z. cucurbitae</i> and <i>B. dorsalis</i>.