Essential Oils as an Alternative to Conventional Pesticides for Managing Brown Recluse Spiders, Loxosceles reclusa, (Araneae: Sicariidae)

ABSTRACT: There are several species of spiders in the midwestern United States that cohabit with humans, but probably the most concerning is the brown recluse spider, Loxosceles reclusa, (Araneae: Sicariidae) because of the potential for a venomous bite. Thus, managing the brown recluse spider is a continuous endeavor. Essential oils (EOs), i.e. specific plant extracts, have often been used to control or deter other arthropods and pests. In this study, several EOs were selected to test their effectiveness as alternatives to synthetic pesticides for L. reclusa control. Spiders were exposed to EOs by direct contact or as a fumigant (inhalation) treatment for 24 h, and mortality was recorded. Physical contact with the oils resulted in the greatest mortality, with wintergreen, peppermint and lavender to a lesser extent, showing potential for L. reclusa control. Mortality attributed to lemon, lemongrass or wild orange was too low to provide effective reduction of L. reclusa populations. Fumigants (inhalation) caused less mortality than contact treatments, never resulting in more than 20%. Two EOs, wintergreen and peppermint, demonstrated effective toxicity to L. reclusa and may have potential as alternatives to synthetic pesticides for this pest, warranting further investigation.