Vol.:(0123456789) 1 3 Amino Acids (2017) 49:1679–1690 DOI 10.1007/s00726-017-2461-y ORIGINAL ARTICLE The African froghopper Ptyelus flavescens (suborder: Cicadomorpha) contains two novel and one known peptides of the adipokinetic hormone (AKH) family: structure, function and comparison with aphid AKH (suborder: Sternorrhyncha) Gerd Gäde 1  · Petr Šimek 2  · Heather G. Marco 1   Received: 14 May 2017 / Accepted: 29 June 2017 / Published online: 14 July 2017 © Springer-Verlag GmbH Austria 2017 (LC–ESI–MS) including tandem MS 2 spectra obtained by collision-induced dissociation. High resolution MS was employed to distinguish between Gln and Lys residues in the peptides. Three AKHs are discovered in the raintree bug: an octapeptide (Peram-CAH-I: pEVNFSPNW amide) previously known from cockroaches, and two novel deca- peptides (Ptyf-AKH-I: pEINFSTGWGQ amide and Ptyf- AKH-II: pEINFSTAWGQ amide). The novel peptides were synthesized and the sequence assignments were unequivo- cally confrmed by co-elution of synthetic peptides and the natural equivalent and by identical MS data of the two forms. A conspecifc bioassay in the froghopper describe the endogenous peptide Ptyf-AKH-I as hypertrehalosemic. In heterologous bioassays the two novel AKHs induce an increase of circulating carbohydrates in cockroaches: Ptyf- AKH-I is much more active than Ptyf-AKH-II. Moreover, if the Ile 2 in Ptyf-AKH-II is replaced with a Leu 2 residue, biological activity is further diminished. The current data show that the raintree AKH decapeptides difer by four amino acids from the aphid AKH (Acypi-AKH: pEVNFT- PTWGQ amide). Therefore, it may be permissible to use the aphid AKH ligand–receptor pair to develop a “green” insecticide to target aphid metabolism. Keywords “Green” insecticide · Receptor–ligand interaction · Insects · Hemiptera · Spittlebugs · Froghoppers · Aphids · Adipokinetic hormone family · Mass spectrometry · Sequence elucidation · Biological assays Introduction The Nobel Prize in Chemistry for the year 2012 was awarded to two scientists, Lefkowitz and Kobilka, for their Abstract The rationale of “green pesticides” in food security is to use information about endogenous hor- mones of pest insects to make peptide mimetics that will act against the pest insects to alter their behaviour or physi- ology, while taking care not to harm benefcial insects or other organisms in the food chain. Such “green” insec- ticides are designed thus, on the basis of neuropeptide ligand–receptor interaction and it is of paramount interest to have fnally a mimetic at hand that is harmful only to pest insects. For this concept to work, one has to identify the ligands in pest and benefcial insects. In this study we investigate adipokinetic hormones (AKHs) from a hemip- teran source. The most harmful hemipterans on an eco- nomic scale are aphids (Hemiptera: Sternorrhyncha: Aphi- doidea) of which the AKH is known. Here we identify the AKH complement of a member of a related suborder, the raintree bug or froghopper Ptyelus flavescens (Hemip- tera: Cicadomorpha: Cercopoidea). Identifcation and sequence elucidation of the adipokinetic peptides of this species was achieved by a heterospecifc and conspecifc trehalose-mobilizing bioassay, and by liquid chromatog- raphy coupled to positive electrospray mass spectrometry Handling Editor: M. S. Palma. Electronic supplementary material The online version of this article (doi:10.1007/s00726-017-2461-y) contains supplementary material, which is available to authorized users. * Gerd Gäde gerd.gade@uct.ac.za 1 Department of Biological Sciences, University of Cape Town, Private Bag, Rondebosch 7700, South Africa 2 Biology Centre, Czech Academy of Sciences, 37005 České Budějovice, Czech Republic