<abstract xmlns="http://www.w3.org/1999/xhtml"> Dichlorvos is an insecticide used in slow-release plastic strips for controlling chalcid wasp parasites, such as Pteromalus venustus Walker, in incubators used to raise alfalfa leafcutting bees (Megachile rotundata F.). Beekeepers need a practical method to detect dichlorvos in air and verify that it has dissipated to levels acceptable for worker re-entry and for the bees to emerge. We evaluated three methods for analysis of the dichlorvos concentration in air. Vapor sampling tubes using a manually operated pump or diffusion collection had insufficient sensitivity in the concentration range of interest. Air samples collected using battery powered pumps were analyzed by liquid chromatography/tandem mass spectrometry (LC/MS/MS), which was accurate and sensitive, but too costly and slow for practical use. Finally, a convenient bioassay for detecting dichlorvos in air was developed using leafcutting bees and verified by comparison with the results obtained by LC/MS/MS for a series of dose levels. The bioassay is simple enough to be done by the beekeeper on-site, is inexpensive, and gives results within 1 h. The LC50 for dichlorvos vapor in air after 1 h of exposure was 273.2 μg/m3 by the probit regression method or 277.3 μg/m3 by the logit regression method.</abstract>

Dichlorvos is an insecticide used in slow-release plastic strips for controlling chalcid wasp parasites, such as Pteromalus venustus Walker, in incubators used to raise alfalfa leafcutting bees (Megachile rotundata F.). Beekeepers need a practical method to detect dichlorvos in air and verify that it has dissipated to levels acceptable for worker re-entry and for the bees to emerge. We evaluated three methods for analysis of the dichlorvos concentration in air. Vapor sampling tubes using a manually operated pump or diffusion collection had insufficient sensitivity in the concentration range of interest. Air samples collected using battery powered pumps were analyzed by liquid chromatography/tandem mass spectrometry (LC/MS/MS), which was accurate and sensitive, but too costly and slow for practical use. Finally, a convenient bioassay for detecting dichlorvos in air was developed using leafcutting bees and verified by comparison with the results obtained by LC/MS/MS for a series of dose levels. The bioassay is simple enough to be done by the beekeeper on-site, is inexpensive, and gives results within 1 h. The LC50 for dichlorvos vapor in air after 1 h of exposure was 273.2 μg/m3 by the probit regression method or 277.3 μg/m3 by the logit regression method.

Bioassay for Detection of Dichlorvos Insecticide in Air in Alfalfa Leafcutting Bee (Megachile Rotundata F.) Incubators

University of Guelph, Guelph, Ontario, Canada

Abacus Consulting Services Ltd., Campbellville, Ontario, Canada

Journal of Apicultural Science

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Dichlorvos is an insecticide used in slow-release plastic strips for controlling chalcid wasp parasites, such as Pteromalus venustus Walker, in incubators used...

Bioassay for Detection of Dichlorvos Insecticide in Air in Alfalfa Leafcutting Bee (Megachile Rotundata F.) Incubators

Published Online: Dec 11, 2014

Page range: 41 - 47

Received: Feb 13, 2014

Accepted: Nov 03, 2014

DOI: https://doi.org/10.2478/jas-2014-0021

Keywords
bioassay, dichlorvos, LC50, Megachile rotundata, Pteromalus venustus

© by John R. Purdy

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Bioassay for Detection of Dichlorvos Insecticide in Air in Alfalfa Leafcutting Bee (Megachile Rotundata F.) Incubators

Published Online: Dec 11, 2014

Page range: 41 - 47

Received: Feb 13, 2014

Accepted: Nov 03, 2014

DOI: https://doi.org/10.2478/jas-2014-0021

Keywordsbioassay, dichlorvos, LC50, Megachile rotundata, Pteromalus venustus

© by John R. Purdy

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

Keywords
bioassay, dichlorvos, LC50, Megachile rotundata, Pteromalus venustus