|BRANDL, MICHAEL - Georg August University|
|SCHUMANN, MARIO - Georg August University|
|VIDAL, STEFAN - Georg August University|
Submitted to: Journal of Insect Behavior
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/27/2016
Publication Date: 7/5/2016
Citation: Brandl, M., Schumann, M., French, B.W., Vidal, S. 2016. Screening of botanical extracts for repellence against western corn rootworm larvae. Journal of Insect Behavior. 29:395-414. doi:10.1007/s10905-016-9571-3.
Interpretive Summary: History has shown that the ability of western corn rootworm (WCR) to consistently overcome management practices requires us to continuously develop and implement new control strategies. Plants often produce chemicals that deter insect feeding and deploying these chemicals can work in concert with biological control agents to reduce insect pest populations and consequently plant damage. Several plant derived compounds, including garlic, capsicum, cape aloe, neem and turmeric were studied for their ability to repel WCR larvae around corn roots, their primary source of food. Of all of the compounds, WCR larvae avoided garlic and turmeric treated soil the most. WCR larvae also avoided Turmeric treated soil up to 5 cm from its application in the root system, resulting in an increase of larval actively moving through the soil thereby reducing larval feeding damage. Turmeric can serve as a repellent compound for WCR larvae and might further be exploited for WCR management by working together with an insecticide or a biological control agent.
Technical Abstract: The ability of Western corn rootworm (WCR) to develop resistance to various management practices enforces the development of new control options. Repellent substances can act as efficacy enhancing agents in WCR control with biological control agents. The present study investigated the potential repellence of garlic, capsicum, cape aloe, neem and turmeric derived compounds against WCR larvae in a no-choice bioassays. Garlic and turmeric were evaluated as the most promising substances as WCR larvae avoided garlic and turmeric treated soil. Turmeric was further evaluated in a rhizotron set up to quantify larval distribution and behavioural changes over time. WCR larvae avoided Turmeric treated soil up to 5 cm from its application in the root system, resulting in an increased dispersal and the formation of multiple clusters in the rhizotron. The proportion of larvae actively moving in the soil subsequently increased, whereas larval feeding significantly decreased. The spatial and behavioural alterations in the soil lead to the conclusion that Turmeric is a repellent compound for WCR larvae. Turmeric repellence might further be exploited for WCR management through a synergy with an insecticidal substance or microbial antagonists.