Evaluation of menadione and menadiol toxicity in various food sources on German cockroaches

German cockroaches (Blattella germanica L.) are a globally distributed urban pest. Application of gel baits is a valuable tool for controlling B. germanica, and efficacy varies based on the active ingredients and food sources that act as phagostimulants. B. germanica developed resistance to numerous insecticides used for their control, indicating the need for alternative active ingredients. Menadione and menadiol are synthetic analogs of vitamin K, used in pet feeds, and medicine, and are structurally similar to naphthoquinones. Menadione has been shown to have insecticidal properties, is somewhat unpalatable to insects, and has not been tested on B. germanica. Therefore, this study aims to evaluate the toxicity of menadione and menadiol as reduced-risk insecticides to control B. germanica when mixed with different phagostimulants. This goal was achieved with two objectives: 1) Conduct dose-response experiments with B. germanica by feeding them menadione or menadiol in different foods and 2) Evaluate the influence of different food types on menadione and menadiol efficacy and consumption. Bioassays revealed that both menadione and menadiol are toxic to German cockroaches. However, menadione was more toxic than menadiol. Within the J-wax strain, vitamin K efficacy varied by food source, with rodent chow, and carbohydrates having greater mortalities than sugary compounds. However, mortality differed by food source between the J-wax laboratory and Baton Rouge field strain, where fructose caused greater mortality in the field strain due to greater consumption. These findings indicate that menadione could be used as a reduced-risk alternative insecticide for German cockroach control.