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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]

The beetle Omorgus suberosus (F.) is a facultative predator of eggs of the olive ridley turtle Lepidochelys olivacea (Eschscholtz). Laboratory and field investigations were conducted in order to characterize volatile attractants of O. suberosus and to explore the potential for application of these volatiles in a selective mass trapping method. Headspace sorptive extraction (HSSE) coupled to thermo-desorption gas chromatography–mass spectrometry (TD-GC-MS) analysis of the volatile constituents from beetles or turtle nests revealed 24 potential compounds. However, electroantennographic (EAG) measurements revealed antennal sensitivity only to indole, linoleic acid, trimethylamine, dimethyl sulphide, dimethyl disulphide and ammonia. Behavioural tests showed that these compounds are highly attractive to O. suberosus. Field trapping experiments revealed that indole and ammonia were more attractive than the other volatile compounds and showed similar attractiveness to that produced by conventional baits (chicken feathers). The use of a combined bait of indole and NH3 would therefore be the most effective trap design. The data presented are the first to demonstrate effective massive capture of O. suberosus using an attractant-based trapping method. These findings have potential for the development of an efficient mass trapping method for control of this beetle as part of efforts towards conservation of L. olivacea at La Escobilla in Oaxaca, Mexico. [ABSTRACT FROM AUTHOR]