Determination of pesticide residues by LCMS/MS and GC-MS/MS spectrometry using the modified QuEChERS extraction method in mass mortalities observed honey bees and honey

The increase in mass mortalities of bee observed in almost every region of the world in recent years and the investigation of the causes of these deaths are among the most remarkable issues. As a result of studies on increasing bee deaths, it shows that these deaths may be caused by pesticide exposure in bees. As a result of the risk assessments of pesticides with high toxicity in bees, the necessity of prohibiting the use of some of them in the world has arisen. Colony losses due to mass bee deaths in our country as well as in the world can cause serious damage both in terms of ecosystem and economy. For this reason, it has a great importance to present risk assessments by performing pesticide residue analyzes in colonies where mass mortalities are observed. With this thesis, it is aimed to carry out method validation studies for the first time in Turkey to detect pesticide residues in bees by modifying the QuEChERS extraction method, which is a universal method in pesticide analysis, although there are some examples that using for also bee analysis in the world. Thus, it is aimed to use this method in multiple residue method analyzes on bees. Also, method validation studies were carried out for the analysis of multiple residue method in honey, and it was aimed to detect pesticide residues in honey. For these purposes, mass bee deaths in the Marmara, Aegean and Mediterranean regions, where there are intensive agricultural practices and have more than half of Turkey's honey production, were followed and collected honeybees and honey samples from their hives. In addition, if there is no mass death, dead bees' sample also were collected from the front of the hive in the designated locations to check the usability of method. First of all, different modifications were tried based on the QuEChERS method for bee analysis, and the method that met the best method performance criteria was selected and the validation of this method was carried out. Bee and honey samples extracted with the validated modified QuEChERS method were analyzed with LC-MS/MS and GC-MS/MS devices for a total of 600 pesticide active substances. In 2020 and 2021 total of 42 bee and 56 honey samples were analyzed. At least one pesticide active ingredient was detected in 29 of the analyzed bee samples, and, with values varying between 0.002 and 3.66 mg/kg. 56 different pesticide active ingredients were detected in these samples. At least one pesticide active ingredient was detected in 22 of the analyzed honey samples. In these samples, 16 different active substances were found with values varying between 0.002 and 0.052 mg/kg. Hazard coefficients (HQ-Hazard Quotient) were calculated in order to see pesticide exposure in bees and it was determined that the HQ scores of 29 positive bee samples 34% were HQ<50, 7%, HQ>50 and 59% were HQ>1000. Pesticide exposure shows itself in 66% of positive samples when the risks are compared according to the parameter HQ>50, that is, the relevant pesticide load. While the HQ scores of the detected pesticides vary between 0 and 1.016.667, the HQ scores of the samples vary between 0.02 and 1.016.670. All detected pesticides that alone put the samples under a elevated pesticide load due to the HQ score above 1000 were insecticides. It is possible to obtain fast and reliable results of quantitative analysis of multiple residues in bees without discrimination in pesticide groups with the modified QuEChERS method, which has been validated as a result of this study. It is recommended that this modified QuEChERS method be used in pesticide residue analysis in bees, with its outstanding features such as completing the analyzes in less than two hours after the homogenization process, being able to work easily with the infrastructure available in all control laboratories, low analysis costs, and being easy and reliable. In addition, it is recommended that the risk assessment calculations made in response to pesticide exposure presented in this study should be used as a guide for interpreting pesticide exposure after residue analysis in bees in our country.