Peptidergic control of reproduction and development in dipteran insects (Drosophila spp. and the mosquitoes, Aedes aegypti and Anopheles gambiae)

Peptides and biogenic amines are important regulators of muscle activity in reproductive tissues, and therefore can play important roles in the reproductive success of insects. The role of neuropeptides was investigated in regulating contractions of the male accessory gland (MAG) and the ejaculatory duct (ED). The FlyAtlas tissue expression database indicated that DMS, dromyosuppressin (DMS) pro-hormone, is highly expressed in the MAGs of D. melanogaster. However, DMS, could not be found using HPLC and mass spectrometry, but was detected by immunohistochemistry which revealed extensive staining of neuronal processes on the surface of MAGs and ED of Drosophila melanogaster, D. yakuba, D. erecta, D. virilis, D. simulans, and the pest species D. suzukii. The GAL4-UAS expression system revealed DMS neuronal fibres descending from the abdominal ganglion onto the surface of the MAG, ED, and seminal vesicles. A pair of rectal cells and a single cell, that we have called the ejaculatory duct cell because of its projections to the ED, also contain DMS. The rectal and ED cells were isolated and subjected to MALDI-TOF mass spectrometry. Molecular ions of several neuropeptides were detected, and the identity of DMS and sNPF4-11 were confirmed by fragmentation sequencing. Both DMS and sNPF 4-11 reduced the frequency of contractions of the MAG and ED, suggesting that these peptides are involved in regulating ejaculation of seminal fluid and spermatozoa. Furthermore, the finding of DMS-R1 and DMSR2 expression in the epitracheal cells suggested that both receptors might be involved in adult ecdysis. The silencing of DMS expression using nSyb-GAL4/UASdicr2>DMS-RNAi (108760), shows abnormal abdomen phenotype and mortality at day 5 post-emergence. Inhibitors of neuropeptide metabolism were shown to be larvicidal when fed to two species of mosquitoes (Anopheles gambiae and Aedes aegypti) identifying an enzyme target for the development of novel control chemicals.