Use of a parasitic wasp as a biosensor

Authors: Olson, Dawn; RAINS, GLEN - University Of Georgia

Submitted to: Biosensors and Bioelectronics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/29/2014
Publication Date: 5/8/2014
Citation: Olson, D.M., Rains, G. 2014. Use of a parasitic wasp as a biosensor. Biosensors. 4:150-160. DOI: 10.3390/bios4020150.

Interpretive Summary: Utilizing classical associative learning techniques with sucrose as reward, we found that M. croceipes learns individual concentrations of methyl benzoate, and they generalize this learning to the training and lower concentrations. Their sensitivity to methyl benzoate is very low at an estimated 3 ppt, which is 1000 times lower than the threshold of detection of methyl benzoate for canines. The wasps are also able to detect methyl benzoate when covered completely by green tea, but were not able to detect methyl benzoate when covered completely by coffee grounds. Habituation to the tea and coffee odors prior to testing improves their responses, resulting in effective detection of methyl benzoate covered by the coffee grounds. With the aid of the portable container, the wasp hound, the wasps appear to have a high potential to be effective on-site biosensors for the detection of cocaine.

Technical Abstract: Screening cargo for illicit substances is still in need of high-throughput inspection systems that can rapidly screen and accurately identify suspicious cargo. Here we investigate the ability of a parasitic wasp, Microplitis croceipes to detect and respond to methyl benzoate, the volatile component of cocaine, by examining their response to training concentrations, their sensitivity to at low concentrations, and their ability to detect methyl benzoate when two concealment substances (green tea and ground coffee) are added to the testing arena. Utilizing classical associative learning techniques with sucrose as reward, we found that M. croceipes learns individual concentrations of methyl benzoate, and they generalize this learning to the training and lower concentrations. Their sensitivity to methyl benzoate is very low at an estimated 3 ppt. They are also able to detect methyl benzoate when covered completely by green tea, but were not able to detect methyl benzoate when covered completely by coffee grounds. Habituation to the tea and coffee odors prior to testing improves their responses, resulting in effective detection of methyl benzoate covered by the coffee grounds. With the aid of the portable container called ‘the wasp hound’, the wasps appear to have a high potential to be effective on-site biosensors for the detection of cocaine.