|Nachman, Ronald - Ron|
Submitted to: Journal of Insect Physiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/24/2003
Publication Date: 3/1/2004
Citation: Zdarek, J., Verleyen, P., Maresh, M., Doleckova, L., Nachman, R.J. 2004. Comparison of the effects of pyrokinins and related peptides identified from arthropods on pupariation behavior in flesh fly (Sarcophaga bullata) larvae (Diptera: Sarcophagidae). Journal of Insect Physiology. 50:233-239. Interpretive Summary: Because of problems with the development of resistance to conventional pesticides, there is a critical need for new concepts and alternative approaches in controlling insect pests. The basic premise of this research is that neuropeptides (short chains of amino acids) serve as potent internal messengers in insects to regulate vital functions such as the transformation of immature flies to adults. New, selective control measures may be developed by designing metabolically stable mimics of these neuropeptides that actively inhibit or over-stimulate functions regulated by them, resulting in disruption of the internal environment of the insect. We report on an evaluation of the effects of several sub-families of insect neuropeptides that are related by structure on the development of immature flies. The results delineate the minimum portion (core) of the neuropeptides, and a specific structural feature within that core region, required to elicit the transformation of the immature forms of adult flies. A deeper understanding of structural requirements for neuropeptide action in insects will aid in the design of neuropeptide mimics capable of interfering with the development of pest flies. The work brings us one step closer to the development of practical neuropeptide-like substances that will be effective in controlling pest insects in an environmentally friendly fashion.
Technical Abstract: Peptides from the pyrokinin/PBAN family and some structurally related compounds identified in various arthropods were tested for acceleration of puparial contraction in fleshfly larvae. Modifications of behavioral patterns of pupariation were further studied for the active compounds using a behavioral analysis based on the recording of changes in tension of the cuticle. Nine peptides belonging to the pyrokinin/PBAN family (Lem-PK, Pea-PK-5, Lom-PK II, Hez-PBAN, Bom-DH-1), identified in five different insect species, two pyrokinin peptides derived from the genome of Drosophila melanogaster (capa-3, and hugin), and two pyrokinins identified from the white shrimp, Penaeus yannamei, were very active in the pupariation assay, with threshold doses within the range of 0.1 to 5.0 pmol per larva. High activity was also detected for a related peptide ETH1 from Drosophila. All of these peptides share a C-terminal PRLamide, which is essential and sufficient for the activity. Interestingly, two other structurally related peptides from Drosophila ' ETH2 and capa-1 ' which feature conservative changes (Ile and Val, respectively) at the C-terminal Leu position were inactive within the physiological range of concentrations. It is clear that the receptor mediating the acceleration of puparial contraction behavior is sensitive to the introduction of greater steric bulk at the C-terminal Leu position. The peptides that accelerated pupariation showed very similar patterns of muscular and cuticular activity.