ORIGINAL ABSTRACT

Stingless bee cerumen is a mixture of wax and plant resins. Foragers of stingless bees are exposed to various chemical contaminants during their plant visits and collection activities. These contaminants have the potential to be transferred into the nest. This study aimed to elucidate the existence of chemical contaminants in Ecuadorian cerumen. To this end, the following aims were established: (i) to determine and quantify glyphosate (GLY), aminomethylphosphonic acid (AMPA), some other pesticides, metals and metalloids in cerumen and (ii) to establish possible risks associated with the presence of these chemical contaminants to the health of stingless bees and humans. The quantification of chemical contaminants was conducted using gas chromatography (GC), liquid chromatography (LC), and ion chromatography (IC) coupled to mass spectrometry (MS). Glyphosate (0.02-0.2 mg/kg) and AMPA (0.028 mg/kg) were detected in four of the pooled samples (n = 14) from the northern and southern highland regions. Other pesticide traces were not detected in any cerumen samples. Metals (Cd, Cr, Pb, Ni, Sn) and metalloids (As, Sb, Se) were found in all samples, including highlands and the lower Amazon. The potential risks of exposure to glyphosate and AMPA for stingless bees and humans appear to be minimal (except for the specific conditions given for Tetragonisca angustula) and safe, respectively. It seems that cerumen may serve as an effective biomonitoring matrix for assessing the environmental health of stingless bee nests. Establishing guidelines and regulations for the safe use and handling of products derived from the stingless bee consumption is therefore imperative.