|GUI, SHUN-HUA - GHENT UNIVERSITY|
|TANING, CLAUVIS NJI - GHENT UNIVERSITY|
|DE SCHUTTER, KRISTOF - GHENT UNIVERSITY|
|YANG, QUN - GHENT UNIVERSITY|
|CHEN, PENGYU - GHENT UNIVERSITY|
|SMAGGHE, GUY - GHENT UNIVERSITY|
Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/2020
Publication Date: 9/10/2020
Publication URL: https://handle.nal.usda.gov/10113/7105662
Citation: Gui, S., Taning, C.T., De Schutter, K., Yang, Q., Chen, P., Nachman, R.J., Smagghe, G. 2020. Assessment of insecticidal effects and selectivity of CAPA-PK peptide analogues against the peach-potato aphid and four beneficial insects following topical exposure. Pest Management Science. 76:3451-3458. https://doi.org/10.1002/ps.5971.
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 hormone messengers in insects to regulate vital functions. Nevertheless, neuropeptides in and of themselves hold little promise as pest control agents because of susceptibility to being degraded in the target pest and inability to penetrate the outer shell of insects. New, selective control measures may be developed by designing stable mimics of these neuropeptide hormones that interact with the active site within the target pest in such a way as to either inhibit or over-stimulate critical neuropeptide-regulated life functions. This work discusses the insecticidal potential of two stable mimics of the ‘CAPA’ neuropeptide class, regulators of critical life processes such as water balance, digestion, desiccation stress tolerance, and development. One of the ARS-developed mimics applied topically resulted in 33% mortality of the peach-potato aphid, while the other mimic led to 17% mortality. However, when topically applied together, the two can function cooperatively to elicit 47% mortality in the aphid and reduce total lifetime production of offspring by 24%. In addition, the two mimics do not induce any harmful effects in a bee pollinator as well as natural enemies of insect pests. This study lays the groundwork for a new cooperative strategy to design and develop practical neuropeptide-like substances that can function as environmentally friendly and effective agents for the control of pest aphid populations without harming beneficial insects such as pollinators and natural enemies.
Technical Abstract: BACKGROUND: Insect capability neuropeptides (CAPAs) play a critical role in modulating different physiologies and behaviour in insects. In a previous proof of concept study, the CAPA analogues 1895 (2Abf-Suc-FGPRLamide) and 2129 (2Abf-Suc-ATPRIamide) were reported to reduce aphid fitness when administered by injection. In the current study, the insecticidal efficacy of 1895 and 2129 on the peach potato aphid Myzus persicae was analysed by topical application, simulating a spray application scenario in the field. Additionally, the selectivity of the tested analogues was evaluated against several beneficial insects [natural enemies (Adalia bipunctata, Chrysoperla carnea and Nasonia vitripennis) and a pollinator (Bombus terrestris)]. RESULTS: Applying 0.09 pmoles of 1895 and 2129 topically to aphids, resulted in 33% and 17% mortality within 3-4 days, respectively. However, when a combination of the two analogues was administered, an increase in mortality to 47% within 3-4 days was observed. Additionally, aphids treated with 1895 showed a reduction in total lifetime reproduction (GRR) of 30% and a mild reduction following treatment with 2129 (16%). Applying a mixture of the two analogues resulted in a GRR of 24%. Of interest from a biosafety perspective is that by using the same delivery method and dose, no significant effects on survival and weight increase/food intake was observed for the representative natural enemies and the pollinator. CONCLUSION: This study highlights the potential of exploiting the CAPA analogues, 1895 and 2129, as aphicides. Additionally, these CAPA analogues were quite selective as they showed no effects when applied on four representative beneficial insects.