The Bactrocera dorsalis caspase-1 gene is expressed throughout development and required for female fertility

The oriental fruit fly Bactrocera dorsalis is one of the most destructive pests of fruits and vegetables. The sterile insect technique (SIT) is an effective and environmentally friendly approach to the control of tephritid fruit flies. The pro-apoptotic gene head involution defective (hid) has been used as an effective lethal effector in SIT. It initiates an interaction cascade including activation of caspase-like proteases. However, the biological role of caspase activity in tephritid fruit flies has yet to be explored.

In this study, the B. dorsalis caspase-1 gene (Bdcp-1) was cloned and characterized. Sequence comparison showed that Bdcp-1 protein shared highly homology with Drosophila effector caspases Drice and Dcp-1. It is predicted to contain a short pro-domain because two proteolytic cleavage sites (Asp¹⁶ and Asp²²³ ) are present. Expression patterns indicated that Bdcp-1 is highly transcribed in embryos and expression was upregulated during metamorphosis and upon ultraviolet irradiation. RNA interference showed that Bdcp-1 is essential for ovarian development and female fertility. For example, knockdown of Bdcp-1 caused transcriptional downregulation of expression of the yolk protein-1 gene (Bdyp-1) and delayed ovarian development. The percentage of spawning females and female fecundity were significantly reduced.

This study illustrates the function of the Bdcp-1 gene and provides an attractive method to develop a biological way to control the oriental fruit fly through the control of caspases. © 2020 Society of Chemical Industry.