Evaluation of the attraction, lethal and sublethal effects of the faeces of ivermectin‐treated cattle on the dung beetle Digitonthophagus gazella (Coleoptera: Scarabaeidae)

Abstract

The attraction of the Digitonthophagus gazella dung beetle to the excreta of cattle treated with ivermectin (IVM) at 1% under controlled and field conditions (Phase 1) as well as the lethal (mortality) and sublethal effects (fecundity, emergence, and dung removal) of the excreta of bovines treated with IVM-1% and IVM-3.15% were evaluated (Phase 2). In Phase 1, an olfactometer was used to evaluate the attraction/repellency in the laboratory and fieldcontrolled conditions using faeces of cattle recovered on 5, 14, 21 and 28 days posttreatment (DPT) from animals treated with IVM-1% (0.2 mg/kg) and untreated animals. Under field conditions, pitfall traps baited with faeces from animals treated with IVM-1% (5 DPT), and untreated animals were used to evaluate the attraction/repellency for D. gazella. In all three experiments, the faeces of treated cattle did not affect (P > 0.05) the attraction/repellency of D. gazella towards IVM-1% (P > 0.05). In Phase 2, six cattle were used:(1) three treated with subcutaneous IVM-1% 0.2 mg/kg and (2) three treated with subcutaneous IVM-3.15% (0.63 mg/kg). The collection of faeces was at À1 (control), 5, 14, 21 and 28 DPT. Each bioassay consisted of a terrarium with a pair of sexually mature beetles, where they received 50 g of faeces for 10 days with 15 replicates per group. The bioassays consisted of nine groups: control, IVM-1% at 5, 14, 21 and 28 DPT and IVM-3.15% at 5, 14, 21 and 28 DPT. There were no lethal effects on adults of D. gazella when exposed to faeces treated with IVM-1% and IVM-3.15%; however, faeces collected at 5 DPT from cattle treated with IVM-1% and IVM-3.15% showed a significant reduction in the average number of brood masses produced and in the average number of imagoes emerged (P < 0.05). There were no differences in faeces removal between treatments. In conclusion, D. gazella does not discriminate between faeces of cattle treated with IVM and untreated, and there were no lethal effects seen; however, fertility was significantly reduced at 5 DPT.

Sexually transmitted mutualist nematodes shape host growth across dung beetle species

“…While effectively deworming the treated individual, remnants of these drugs (and other antibiotics) can persist in and be excreted in the feces, which exposes the dung insect community to pharmaceutical residues. Such ivermectin residues can have drastic lethal and sublethal effects on various species of dung beetles and dung flies (Conforti et al., 2018 ; Pérez‐Cogollo et al., 2015 ; Rodríguez‐Vivas et al., 2020 ; van Koppenhagen et al., 2020 ). The presence of mutualist nematodes suggests that some of the sublethal effects of ivermectin exposure on dung beetle growth and adult size may be indirectly caused by the loss of symbiotic nematodes.…”

Principales Contribuciones Científicas De La FMVZ-Uady Al Conocimiento De La Ecología De Los Escarabajos Estercoleros Y El Efecto Adverso De Las Lactonas Macrocíclicas Sobre Sus Poblaciones

“…Numerosos estudios han demostrado que las heces de bovinos tratados con estas LM (principalmente la IVM) tienen efectos letales (mortalidad) y subletales (disminución reproductiva e interferencia en el desarrollo postembrionario) sobre diferentes especies de EE (Pérez-Cogollo et al, 2018, Rodríguez-Vivas et al, 2020a, lo que ha puesto de manifiesto en el ámbito de la conservación de los recursos naturales y la producción de alimentos, la necesidad de abordar el estudio de esta problemática. En este contexto, la Facultad de Medicina Veterinaria y Zootecnia de la Universidad Autónoma de Yucatán (FMVZ-UADY) tiene entre sus principales metas promover la generación de investigación en el manejo sustentable de los recursos naturales, la producción agropecuaria y la salud animal de Latinoamérica (www.ccba.uady.mx).…”