Aerosolized essential oils and individual natural product compounds as brown treesnake repellents

Abstract

Chemical irritants useful as repellents for brown treesnakes (Boiga irregularis) were identi®ed. Exposure to various compounds produced a range of intensities for locomotory behavior in snakes. Essential oils comprised of 10 g liter À1 solutions of cedarwood, cinnamon, sage, juniper berry, lavender and rosemary each were potent snake irritants. Brown treesnakes exposed to a 2-s burst of aerosol of these oils exhibited prolonged, violent undirected locomotory behavior. In contrast, exposure to a 10 g liter À1 concentration of ginger oil aerosol caused snakes to locomote, but in a deliberate, directed manner. We also tested speci®c compounds, all derivative of food and¯avor ingredients. 10 g liter À1 solutions delivered as aerosols of m-anisaldehyde, trans-anethole, cineole, cinnamaldehyde, citral, ethyl phenylacetate, eugenol, geranyl acetate or methyl salicylate all acted as potent irritants for brown treesnakes. The individual ingredients were classi®ed using cluster analysis into groups that promoted different levels of response by snakes. This study is the ®rst to systematically investigate the irritant potential of natural products for snakes. These data will be useful in the development of practical pest management tools for snakes.

Calcium responses of chicken trigeminal ganglion neurons to methyl anthranilate and capsaicin

“…Brown treesnakes (Boiga irregularis) were behaviorally insensitive to ocular application of 1% oleoresin of Capsicum (estimated 100·p.p.m. CAP; Clark and Shivik, 2002). All of these taxa, including birds, share a common trait of insensitivity to CAP.…”

Effectiveness and persistence of cinnamic aldehyde as an antifeedant on rats under storage conditions

“…Cinnamic aldehyde is reported to repel dogs and other canids (Mason, 1998). It also acted as an irritant for brown tree snake (Clark and Shivik, 2002). Antignawing activity of cinnamic aldehyde is also reported against mice (Lee et al, 1999).…”

Chemical repellents appear non-useful for eliciting exit of brown tree snakes from cargo

“…Furthermore, not all cargo leaving Guam receives canine inspection prior to export ; therefore, having a quick, cheap, and reliable method to treat previously uninspected Guam-derived cargo in recipient ports would provide those jurisdictions additional protection. To meet these goals, chemical fumigants have long been suggested as a potential solution to elicit exit of brown tree snakes from cargo refuges (Brown Tree Snake Control Committee 1996; Clark & Shivik 2002;, and they continue to receive interest at meetings of the Brown Tree Snake Working Group, but they have remained untested. Such technology would require minimal training for effective application, and some chemicals À in particular, essential oils and their constituent active ingredients À have been found to elicit strong aversive responses when sprayed directly onto brown tree snakes (Clark & Shivik 2002).…”

“…To meet these goals, chemical fumigants have long been suggested as a potential solution to elicit exit of brown tree snakes from cargo refuges (Brown Tree Snake Control Committee 1996; Clark & Shivik 2002;, and they continue to receive interest at meetings of the Brown Tree Snake Working Group, but they have remained untested. Such technology would require minimal training for effective application, and some chemicals À in particular, essential oils and their constituent active ingredients À have been found to elicit strong aversive responses when sprayed directly onto brown tree snakes (Clark & Shivik 2002). These chemicals in particular have long been thought to hold promise as a management tool.…”

“…Despite early results suggesting that essential oils might find use as effective snake repellents (Clark & Shivik 2002), several potential limitations must be overcome for chemical fumigation to be an effective means of impelling snakes to exit cargo. First, any such chemical must be able to penetrate and attain a high enough concentration in all potential cargo refuges to drive out snakes.…”