**3. Results**

Table 1 presents a summary of the pesticides detected in the samples analyzed within 5 years of monitoring. Tables 2 and 3 summarize the main findings by survey year for honeybees and other matrices, respectively. Figure 1 shows the location of the positive and negative samples for each officially reported honeybee mortality event.


**Table 1.** Active ingredients detected in the samples analyzed in the five years of monitoring.


**Table 1.** *Cont*.

a A, acaricide; B, bactericide; F, fungicide; H, herbicide; I, insecticide; N, nematicide PGR, plant growth regulator. b beeswax, beebread, soil, leaves and maize seeds.


**Table 2.** Pesticides detected in the samples of honeybees analyzed in the five years of monitoring.


**Table 3.** Pesticides detected in other matrices analyzed in the five years of monitoring.

In total, 63 different active ingredients were found in honeybee samples, with concentrations ranging from 0.1 to 134,665 ng/bee, and 51 different active ingredients in the other analyzed matrices (beeswax, bee bread, honey and vegetable matrices), ranging from 0.01 to 359.5 mg/kg. Most investigated samples were positive for at least one active ingredient (53%) and contaminated by more than one residue: 53% of the samples were contaminated by at least two different residues, 32% by at least three, while as many as nine active ingredients were detected in one extreme case, coming from Udine province (North-Eastern Italy).

Insecticides were the most frequently detected active substances (49.2%) in honeybees (Tables 1 and 2), the most prevalent being the acaricide tau-fluvalinate (38.2%). Pyrethroid permethrin, the second most frequently found active substance, had a prevalence of 13.3%. Chlorpyrifos was the third most commonly determined pesticide (12.9%).

Globally, most of the other matrices analyzed (67%) were positive for at least one active ingredient (Table 3). Again, the acaricide tau-fluvalinate was the most commonly found active ingredient, with a prevalence of 53.4%, followed by the insecticide methiocarb with a prevalence of 13.6% (also considering the metabolite methiocarb sulfoxide), and the synergist piperonyl butoxide (11.0%).
