Volcanic glass, a new active for the control of tobacco thrips, Frankliniella fusca

Frankliniella fusca (Hinds) (Thysanoptera: Thripidae) is an early-season pest of economically important crops. It is a competent vector of tomato spotted wilt virus, which causes substantial yield loss in infected crops. Control strategies for this pest are increasingly challenged by resistance to commonly used insecticides, e.g., neonicotinoids and organophosphates, alongside growing regulatory concerns of these chemical classes. These challenges underscore the urgency for alternative modes of action to control this pest. With a growing interest in non-chemical approaches, our group is studying applications in the material sciences for insect pest control.
We have discovered and are studying the use of a mechanical insecticide made from volcanic rock (VR) as a residual spray for mosquito, filth fly, and tick control. The VR can be applied in water using conventional spray equipment. We hypothesize that this new active can also translate to the control of plant pests. When we exposed adult Frankliniella fusca to VR-treated filter paper at a dose of 5 g/m2, the time to 50% mortality at 27°C and 35% relative humidity was 120 min. This application rate was used before as an indoor residual wall spray in Africa for 80% mosquito control for six months, while synthetic chemical insecticides failed in two months or less. Dose-response studies will be presented under different environmental conditions to evaluate the proof of concept and efficacy of VR in a first possible agricultural use. Scanning electron microscopy data of treated thrips will be presented to assess the mode of action of VR.