|Vander Meer, Robert - Bob|
Submitted to: Journal of Insect Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/29/2006
Publication Date: 2/1/2007
Citation: Barron, A.B., Maleszka, J., Vander Meer, R.K., Robinson, G.E., Maleszka, R. 2007. Comparing injection, feeding and topical application methods for treatment of honey bees with octopamine. Journal of Insect Physiology. 53(2):187-194. Interpretive Summary: Biogenic amines play an important role in insect behavior by controlling the sensitivity of those insects to compounds, such as pheromones that are extremely important in maintaining the social structure of insects such as ants and honey bees. Being able to manipulate and measure the amount of biogenic amine in a sample is critical to understanding how these compounds function. Several methods have been used to apply biogenic amines or their agonist to insects, in order to determine their function; however, there has not been a comparative study to evaluate which method is most efficacious. Scientists at the Center for Medical, Agricultural and Veterinary Entomology, USDA, ARS, Gainesville, Florida USA, the Research School of Biological Sciences, Australian National University, Canberra, Australia, and the Department of Entomology, University of Illinois at Urbana-Champaign, Urbana, IL, investigated existing methods of biogenic amine manipulation and found that topical application of the biogenic amine, octopamine, dissolved in dimethylformamide (dMF) to the thorax was as effective as thoracic injections of the biogenic amine in delivering the compound to the brain. Our findings demonstrate the value of thoracic topical treatment with compounds dissolved in dMF, as an effective non-invasive method for systemic biogenic amine treatments.
Technical Abstract: Entomologists have used a range of techniques to treat insects with neuroactive compounds, but like vertebrates, insects possess a blood-brain barrier and it is not clear how different treatment methods compare in delivering a compound to the brain. Here we used five different techniques to treat honey bees with 3H-octopamine and analyzed how the distribution of the 3H radiolabel through different tissues of the bee differed between the five treatment methods and changed over time. All treatment methods, even injection of the median ocellus, resulted in recovery of 3H from all parts of the honey bee. Injection through the median ocellus was the most effective method for delivering 3H to the brain. Topical application of 3H-octopamine dissolved in dimethylformamide (dMF) to the thorax was as effective as thoracic injections of 3H-octopamine in delivering 3H to the brain, but topical applications to the abdomen were less so. Most of the 3H applied topically remained associated with the cuticle and the tissues of the body segment to which it had been applied. For all treatment methods 3H was rapidly lost from the brain and head capsule and accumulated in the abdomen suggesting the behavioral effects of a single treatment may be transient. Our findings demonstrate the value of thoracic topical treatment with compounds dissolved in dMF as an effective non-invasive method for systemic pharmacological treatments.