Dessication, thermal stress and associated mortality in Drosophila fruit flies induced by neuropeptide analogue treatment

Authors: ALFORD, LUCY - University Of Glasgow; MARLEY, RICHARD - University Of Glasgow; DORNAN, ANTHONY - University Of Glasgow; DOW, JULIAN - University Of Glasgow; Nachman, Ronald; DAVIES, SHIREEN - University Of Glasgow

Submitted to: Journal of Pest Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/21/2019
Publication Date: 6/15/2019
Citation: Alford, L., Marley, R., Dornan, A., Dow, J., Nachman, R.J., Davies, S. 2019. Dessication, thermal stress and associated mortality in Drosophila fruit flies induced by neuropeptide analogue treatment. Journal of Pest Science. 92(3):1123-1137. https://link.springer.com/article/10.1007/s10340-019-01100-0.

Interpretive Summary: Insect pests have developed resistance to several conventional pesticides, and new approaches are needed for pest management. Although neuropeptides (short chains of amino acids) serve as potent messengers in insects to regulate vital functions, the neuropeptides hold little promise as either pest control agents or beneficial agents because they can be degraded in the target pest and/or beneficial insect. New, selective control agents may be developed by designing mimics of these neuropeptides that resist degradation and either inhibit or over-stimulate critical neuropeptide-regulated life functions. This work reports that mimics of the CAP2b neuropeptide class that block the action of the native neuropeptide hormones can increase the tolerance to desiccation that leads to significantly longer lifespans selectively in one of two species of Drosophila fruit flies; while reducing tolerance to desiccation stress and lifespan in pest aphids. This concept may be of interest if applied to the selective increase in the robustness of beneficial insects such as the honeybee. They also demonstrate that neuropeptide mimics can act in a selective manner, affecting a pest species of Drosophila while having no effect on a non-pest species of the same genus. These results could provide the basis for the development of practical neuropeptide-like substances that may either effectively aid beneficial insects or selectively control pest insects in an environmentally friendly fashion.

Technical Abstract: Drosophila suzukii is a serious pest of soft fruit worldwide. With the global over-dependence on broad-spectrum pesticide application, a strong imperative exists for more effective, environmentally-friendly and targeted methods of control. One promising avenue involves employing synthetic neuropeptide analogues as insecticidal agents to selectively reduce target pest fitness. Neuropeptides, central to the regulation of physiological and behavioural processes, play a vital role in cold and desiccation survival. Building upon this, the current study investigated the effects of biostable kinin, CAP2b and pyrokinin (PK) analogues (the latter of which have previously displayed cross-talk with the capa receptor), on desiccation, starvation and cold stress tolerance of the pest, D. suzukii, and the closely related non-pest, D. melanogaster. Results demonstrated analogues of the PRXamide superfamily (CAP2b and PK derived) significantly impacted the survival of the target insect when under conditions of desiccation stress. However, these peptides enhanced desiccation stress survival in relation to controls, suggesting that they may act as antagonists of the capa signalling pathway in the Malpighian tubules. Of particular note was the ability of analogues 1895 (2Abf-Suc-FGPRLa) and 1902 (2Abf-Suc-FKPRLa) to impact D. suzukii but not D. melanogaster. A focus on native Drosophila CAP2b / PK and kinin sequences in analogue development may yield pure agonists with diuretic action that may reduce desiccation stress survival in the pest flies. In highlighting the PRXamide neuropeptide superfamily more generally, and the structures of promising analogues more specifically, this research will feed the evolution of next generation analogues and drive forward the development of neuropeptidomimetic-based agents.