In the last years, the honeybee population is facing growing threats such as expansion 4 of pathogens, the incorrect use of phytosanitary products and environmental 5 contaminants, loss or fragmentation of habitat, invasive species and climate change. In 6 Spain, the citrus cultivation in integrated pest management (IPM) attempts the most 7 available use of strategies for the control of pests populations by means of taking 8 actions that prevent problems, remove levels of damage and use of chemical control 9 only when and where is necessary. The purpose of this work is to develop a simple 10 analytical method that permits to evaluate the pesticide residue levels in honeybees 11 and corbicular pollen when honeybees are exposed to plant protection products (PPPs) 12 used in integrated management fields of citrus orchards. The proposed method is 13 based in an ultrasound assisted extraction procedure followed by a dispersive solid 14 phase extraction (d-SPE) clean-up with alumina and LC-MS/MS determination. The 15 method was validated in samples of honeybee and corbicular pollen for the 10 16 pesticides mostly used in citrus orchards with IPM. This procedure was compared with 17 QuEChERS methodologies for these matrices. The developed method was applied to 18 the determination of these pesticides in both matrices in a two -year study in citrus 19 orchards. 20
Ground-cover vegetation attracts and harbors beneficial insects to the agrosystem, playing an important role in conservation biological control. Integrated pest management (IPM) program guidelines recommend the implantation of sowed or resident wild covers in perennial crops. Given the high-quality fruit requirements, even in IPM programs, insecticides can be required in citrus crops. This study presents, over a year, the levels of neonicotinoids (thiamethoxam and imidacloprid) in not-target ground-cover wildflowers growing spontaneously in citrus orchards after foliar treatment of citrus trees. The presence and persistence of these neonicotinoids in different wildflower species were studied. Concentrations of thiamethoxam and imidacloprid in whole wildflowers ranged from < method quantification limit (MQL) to 52.9 ng g−1 and from < MQL to 98.6 ng g−1, respectively. Thiamethoxam was more frequently detected than imidacloprid. Thiamethoxam and imidacloprid were detected up to 336 and 230 days after treatment, respectively. The highest detection frequencies (100%) and highest thiamethoxam and imidacloprid mean concentrations (26.0 ± 7.3 ng g−1 and 11.0 ± 10.6 ng g−1, respectively) occurred in wildflowers collected 9 days after the treatments. Since application, a clear decrease in the concentration of both compounds and differences in the accumulation depending on wildflower species were observed. Cross contamination was detected, indicating a transport from adjacent treated plots. Maintaining a cover crop in citrus orchards may lead to detrimental effects on non-target arthropods if these neonicotinoid compounds are used for pest control since they can entail a chronic exposure during at least 230 days for imidacloprid and 336 days for thiamethoxam.
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