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Dung odours are composed of a large number of different volatile organic compounds (VOCs). Dung beetles are attracted to dung by olfactory cues, and their selection depends on the odorous VOCs emitted from this resource. The possible effects of ivermectin (IVM) on the chemical composition of dung volatile emissions and how this could modify its attraction to dung beetles have been debated for years.In this work, we analysed the possible effects of IVM on the VOCs emitted by cattle dung and the attraction of the dung beetle Ateuchetus cicatricosus Lucas, using behavioural bioassays.The results of the study showed that the chemical analyses of the dung volatile emissions from untreated cattle, treated cattle with IVM (200 μg/kg b.w.; collected at 7 and 14 days post‐administration) and dung spiked with IVM (100 and 500 μg/kg) were not significantly different. We detected a total of 44 VOCs among the treatments. The olfactometer bioassays showed no significant difference in the rates of attraction between different treatments.This study suggests that cattle dung does not experiment with a direct modification of the volatile compounds emitted, either via the digestive tract of cattle or by direct addition with IVM, ruling out the possible influence of any transformation product from the anthelmintic that could be present. In addition, a change in the microbiota of the digestive tract in cattle as a result of the mode of action of the drug is not supported. Further possible indirect effects are discussed. [ABSTRACT FROM AUTHOR]

1. Greenhouse gas (GHG) emissions from livestock contribute significantly to global warming, and a reduction of this source of emissions is crucial in achieving the goal of mitigating global warming. 2. CO2 and CH4 emissions from dung pats were analysed by means of a mesocosm experiment in a Mediterranean ecosystem. The experiment consisted of a total of 30 mesocosms distributed across three treatments: a well‐preserved, undisturbed dung beetle assemblage associated with organic livestock; a dung beetle assemblage that was impoverished as a result of the long‐term use of veterinary medical products; and a control treatment without dung beetles. 3. Corrections related to insect respiration allow researchers to provide more precise measurements of CO2 emissions from dung, especially in the initial and final phases of dung exposure, when the percentage of CO2 emitted by dung beetles can become greater than the emissions from the dung pats themselves. 4. The effects of dung beetles on CO2 and CH4 emissions are much more accentuated in warm‐temperate conditions than in northern temperate areas previously studied. Mediterranean assemblages remove and spread dung faster and more effectively than do northern dung beetle assemblages characterised by a lower functional richness and beetle abundance and biomass. 5. From a livestock management viewpoint, mesocosms representing areas with impoverished dung beetle assemblages, due to the long‐term use of veterinary medical products, such as ivermectin, emitted 1.6‐ and 2.8‐fold higher total CO2 and CH4, respectively, than mesocosms mimicking sites with untreated livestock. [ABSTRACT FROM AUTHOR]

A new analytical method based on solvent extraction, followed by continuous solid-phase extraction (SPE) clean-up using a polymeric sorbent, was demonstrated to be applicable for the detection of ivermectin in complex biological matrices of dung beetles (hemolymph, excreta or dry tissues) using liquid chromatography combined with positive electrospray ionization tandem mass spectrometry (LC/ESI+–MS/MS). Using a signal-to-noise ratio of 3:1, the limit of detection (LOD) in the insect matrices at trace levels was 0.01 ng g–1 and the limit of quantification (LOQ) was 0.1 ng g–1. The proposed method was successfully used to quantitatively determine the levels of ivermectin in the analysis of small samples in in vivo and post mortem samples, demonstrating the usefulness for quantitative analyses that are focused on future pharmacokinetic and bioavailability studies in insects and the establishment of a new protocol to study the impact of ivermectin on non-target arthropods such as dung beetles and other insects that are related with the “dung community”. Because satisfactory precision and accuracy values were obtained in both in vivo matrices, we suggest that the method can be consistently used for quantitative determinations that are focused on future pharmacokinetic and bioavailability studies in insects. Furthermore, this new analytical method was successfully applied to biological samples of dead dung beetles from the field suggesting that the method can be used to establish a new routine analysis of ivermectin residues in insect carcasses that is applied to complement typical mortality tests. [ABSTRACT FROM AUTHOR]