Coconut fatty acids repel southwestern United States urban pest arthropods

The southwestern U.S. contains a variety of urban pest arthropods that cause many problems, whether they be nuisance pests or are/potentially could be medically significant pests. Chosen model pests in urban environments for this study include the nuisance Turkestan cockroach, Blatta lateralis, the kissing bug, Triatoma rubida, and the potentially life-threatening Arizona Bark Scorpion, Centruroides sculpturatus. These pest arthropods are overwhelmingly controlled via insecticide sprays which are becoming ever more restricted and may be causing increased resistance in arthropods. Alternatives to insecticides are often lacking, especially for scorpions. Botanical compounds derived from coconuts containing fatty acids have been shown to repel a variety of insects, often performing better than proven repellents such as java citronella oil and DEET. Using two-choice tests and/or video tracking software to demonstrate and characterize behavioral responses of the three arthropods to fresh mixtures of coconut fatty acids and their constituents such as capric, lauric, or caprylic acid and their methyl esters. In the choice tests, most of the test materials exhibited high repellent activity to all the chosen model arthropods at an efficacy rate of over 90%. Tracking of T. rubida and B. lateralis showed that these insects tended to avoid zones treated with various fatty acids. Further evaluations demonstrated that the repellency activity of residues of coconut fatty acids remained high for at least seven days. Coconut-derived compounds are promising tools to be incorporated into management programs of economically and medically important urban pests in the southwestern United States.