Characterization of diuretic hormones and their receptors in spotted-wing drosophila

Insect diuresis is one of the major physiological response that excretes excessive fluid and facilitate the ostomic homeostasis in the body. Diuresis is initiated by diuretic hormones (DHs) which is called as a neuropeptides (NPs) produced in the central nervous system (CNS), binding their corresponding receptors in excretory organs. In this study, we identified and characterized the two DHs and DH-receptors (DH-Rs) in spotted-wing Drosophila (SWD) Drosophila suzukii (Diptera: Drosophilidae), an invasive insect originated from Southeast Asia and cause detrimental economic loss in the small fruits industry unlike other dipterians.

In Drosophila, there are two DH peptides, DH31, and DH44, which are consisted of 31 or 44 amino acids. We ran quantitative PCR (qPCR) to characterize DH31 and corresponding DH31-Rs to measure the relative expression in D. suzukii digestive tissues and lifestages. In addition we identified DH31-Rs variants (DH31-Ra and DH31-Rb), conducted cAMP Glo assay and FLIPR calcium 6 assay with DH-Rs gene transfected sf9 cells with DH31 and checked the receptor activation activities, measuring cAMP and calcium ions through luminescence and fluorescence respectively. We also conducted in vivo bioassay, injected DHs into female SWD adults and observed fluid excretion from the fly. Based on the results, DH31 showed the dose-dependent manner in facilitating diuresis for the fly.