Metabolic pathway of pesticides within honeybee colonies
1 Edmund Mach Foundation - Centre for Technology Transfer, via E: Mach,1 38010 San Michele all’Adige (TN) – Italy
2 Dipartimento di Scienze Agrarie e Ambientali - Università di Udine, via delle Scienze 206, 33100 Udine
3 Dipartimento di Agraria – Laboratorio di Entomologia E. Tremblay – Università degli studi di Napoli Federico II, via Università, 100, 80055 Portici (Napoli) Italy
4CREA honeybee and silkwarm unit - Via di Saliceto, 80 40128 BOLOGNA, Italy
5 Faculty of Science and Technology, Free University of Bozen-Bolzano, Bolzano 39100, Italy
The application of pesticides has increased massively in the last decades and their use in agricultural cropping systems is often discussed as a factor influencing bee health. Research has demonstrated that the agrochemicals can seriously affect honeybees' health and behavior. This highlights the need of multi-residue analytical methods with high analytic sensitivity in order to detect the lowest levels of contaminants in various matrices within honeybee colonies. The requirement of low LODs is related to bee the toxicity of several products showing an oral and contact LD50 in the ng/g scale. Neonicotinoids are regarded as widespread threats for honeybee colonies’ vitality and survival all over the world, even at sublethal doses. Therefore, we aimed at assessing the possible contamination pathway of beehives focusing our attention on Imidacloprid, studying its concentration in bees and bee products, such as pollen, honey, wax and royal jelly, which were collected from bee colonies exposed to pesticides in the field.
Colonies were placed in apple orchards in an area where Imidacloprid is widely used, and samples were collected during Spring and Summer. Pesticides residues were analyzed by HPLC-DAD and UHPLC-MS/MS. Adult bee samples showed a low contamination, with a concentration below 0.5 ng/bee. Among the different bee products, bee bread samples (collected in the combs) and pollen loads (collected with pollen traps) generally showed the highest concentration of pesticides. In all the other bee product samples, such as honey, wax and royal jelly, low levels of pesticides and in particular of imidacloprid were detected.
Pollen does not directly intoxicate foraging bees since it is carried on their external body surface. Therefore, contaminated pollen entering the beehives may represent a major route of contamination