Toxicity of Seven Monoterpenoids to Tracheal Mites (Acari: Tarsonemidae) and Their Honey Bee (Hymenoptera: Apidae) Hosts When Applied as Fumigants

Abstract

Laboratory bioassays were conducted to characterize the acute toxicity of 7 monoterpenoids to tracheal mites, Acarapis woodi (Rennie), and their honey bee, Apis mellifera L., hosts. Citral, thymol, carvacrol, a-terpineol, pulegone, d-limonene, and menthol were applied as fumigants to mite-infested honey bees. Thymol and menthol were the most toxic compounds to honey bees, and a-terpineol was the least toxic. Menthol, citral, thymol, and carvacrol were more toxic to tracheal mites than to honey bees. Pulegone, d-limonene, and a-terpineol were more toxic to honey bees than to tracheal mites. Menthol was 18.9 times more toxic to tracheal mites than to honey bees at the LC so concentrations; however, as the concentration increased, bee mortality increased more rapidly than mite mortality, and menthol was only 5.7 times more toxic at the LCgo concentrations. Probit regressions for bee and mite mortality were parallel for citral and thymol. Citral and thymol were 2.9 (2.5-3.3) and 2.0 (1.0-3.6) times more toxic to tracheal mites, respectively, at all concentrations estimated.

Standard methods for toxicology research inApis mellifera

“…For example, if bees are exposed to different pyrethroid pesticides which share the same mode of action, then the observed toxicity is a sum of the doses of the different pyrethroid pesticides (e.g. tau-fluvalinate and bifenthrin, Ellis and Baxendale, 1997). Differential potencies between different agents with similar modes of action may need to be taken into account (Robertson et al, 2007).…”

Assessing in Vitro Acaricidal Effect and Joint Action of a Binary Mixture Between Essential Oil Compounds (Thymol, Phellandrene, Eucalyptol, Cinnamaldehyde, Myrcene, Carvacrol) Over Ectoparasitic Mite Varroa Destructor (Acari: Varroidae)

“…Although the experience has shown remarkable in vitro toxicity against Varroa mites, further studies should be conducted in the field to assess possible effects on brood, queen mortality and possible interference in beneficial microflora within the internal environment of the colony, since monoterpenoids such as Thymol may not be safe for honey bee colonies. These compounds play a role as broad spectrum pesticides (Isman, 2006) and in previous studies, Thymol and menthol had been found to be among the most toxic of all terpenoids tested when applied to honey bees as a fumigant (Ellis & Baxendale, 1997). Despite being naturally derived, Thymol treatment can induce brood removal (Marchetti, Barbattini & D'Agaru, 1984;Floris et al, 2004) and result in increased queen mortality in field conditions (Whittington et al, 2000).…”

Plant Essential Oils Used Against Some Bee Diseases

“…Menthol was found to be about 19 times more toxic to mites than to bees. Menthol can be used in the control of these mites and is commercially available (Ellis and Baxendale, 1997). Calderone and Spivak, (1995) studied thymol, eucalyptus oil, and menthol and camphor mixture.…”

“…They are important for plant defense as possessing antimicrobial, antiparasitic, antiviral, antifungal properties (Hyldgaard et al, 2012). Some plant essential oils or components have a broad spectrum of activity against pathogenic bacteria and fungi (Kotan et al, 2008); tick infestation (Coskun et al, 2008); human lice and house dust mite (Williamson et al, 2007); insect vector (Chaiyasit et al, 2006); honey bee mites (Calderone et al, 1997;Ellis and Baxendale, 1997). Also, essential oils obtained by steam distillation of plant leaves and leaves of some aromatic plants (especially in Myrtaceae and Lamiaceae families, but also other plant families) are used to protect traditionally stored grain and legumes, and to repel flying insects in the house (Isman, 2000).…”