A biologically-active pest deterrent: what is the mode-of-action and how does this affect pest behaviour?

The application of chemical pesticides to protect crops is standard practice worldwide, however, the detrimental repercussions of excessive use on human health and environmental degradation are becoming more evident. Integrated pest management strategies, providing non-chemical alternatives to pest control, have been prioritized by stakeholders in the United Kingdom and overseas. Grazers Ltd has set out to produce an environmentally sustainable feeding deterring product, which can be applied in a similar fashion as chemical pesticides, but without the harmful side effects. The Grazers Ltd G3 product has a simple formulation, with calcium chloride acting as the active component. Before the product can be registered and utilized commercially in agriculture, the mode-of-action which alters the feeding behaviour of pests must be determined. Laboratory bioassays were performed to determine the insecticidal and antifeedant properties of the product on Spodoptera littoralis, when presented with treated semi-artificial wheatgerm-based diet cubes, Triticum aestivum leaves, and Brassica napus ssp. Pabularia leaves. Additionally, the ability of the Ca2+ ion from the active component to penetrate through the adaxial leaf surface was also tested. The product was analysed as a complete formulation (‘Old’), with a new source of calcium chloride (‘New’), and when broken down into each individual component. The complete formulations exhibited a deterrent effect when applied to plants but not diet, indicating a plant-mediated effect in a two-choice setting. The ‘Old’ formulation appeared to alter oviposition behaviour significantly while the ‘New’ formulation did not. Furthermore, the individual components did not show significant antifeedant abilities. Despite a lack of research into calcium chloride as a feeding or oviposition deterrent, these findings suggest that the calcium chloride-based product exhibits a plant-mediated deterring effect on the phytophagous pest.

Name dc:type.qualificationname

masters

Level dc:type.qualificationlevel

masters

Grantor dc:publisher.institution

Lancaster University

Year dc:date.issued

2019

Authors dc:creator

• Mansfield, Faye
• Roberts, Mike
• Wilson, Kenneth