Toxicity and repellency of 2-undecanone against German cockroaches (Blattella germanica)

Formulations of 2-Undecanone (Methyl-Nonyl-Ketone, C₁₁H₂₂O) are currently being sold as insect repellents under the trade name BioUD. This novel repellent has been shown to be comparable to DEET in its activity against mosquitoes. In the research presented here I tested different formulations of BioUD and Soy-Methyl-Ester (SME) for its repellency and toxicity against German cockroaches. For the repellency experiments, polypropylene cup walls were covered with Fluon®, and half of the bottom was treated with BioUD. Cockroach (late-instars) positions were recorded between 5-120 min. For a hydrateable suspension containing 1% 2-Undecanone 100% repellency was achieved after 120 min, while a 1% suspension of BioUD in ethanol reached 100% repellency after 90 min. For the toxicity experiments, the whole bottom was treated with a formulation. All formulations showed insecticidal activities against adult cockroaches, with pure 2-Undecanone being the most active (LC50 for 120 min=0.04 µL/cm²), followed by BioUD5 and BioUD4 (5% 2-Undecanone and 4% 2-Undecanone, hydrateable, respectively; LC50 for both formulations=0.42), and SME (LC50=0.55). In the third experiment, ten µL of either BioUD10 (10% 2-Undecanone), 2-Undecanone, or several household insecticides available in stores were applied onto pronota and wings of adult cockroaches. The time until all appendages ceased to move varied strongly so that no significant statistical differences could be found. For BioUD10, the average time was 14 min 23 sec, for 2-Undecanone 7 min 48 sec, and for Raid® 11 min 39 sec. For other insecticides, appendages did not cease moving even after several hours.