Onthophagus landolti and Canthon indigaceus chevrolati (Coleoptera: Scarabaeinae) are attracted to the feces of ivermectin-treated cattle in the Mexican tropics / Onthophagus landolti y Canthon indigaceus chevrolati (Coleoptera: Scarabaeinae) son atraídos por las heces de ganado tratado con ivermectina en el trópico mexicano

Abstract Ivermectin (IVM) is widely used for parasite control in livestock in the tropics. Residual IVM in feces conserves its insecticide activity for weeks and can harm dung beetle (DB) species. Attraction to the feces of IVM-treated cattle was tested using the DB species Onthophagus landolti (Harold) and Canthon indigaceus chevrolati (Harold) as models. Experiments were done under controlled laboratory conditions, semi-controlled field conditions and uncontrolled field conditions. Olfactometers were used in the controlled and semi-controlled trials. The control treatment was baited IVM-free feces, and the experimental treatments were the feces of cattle treated with 1 % IVM (subcutaneous administration; single, 0.2 mg/kg bw dosage) and collected at 5, 14, 21 and 28 days post-treatment. The uncontrolled field trial involved pitfall traps baited with IVM-free feces or feces from IVM-treated cattle collected five days post-treatment. Under controlled and semi-controlled conditions, the feces of IVM-treated cattle (at 5, 14, 21 or 28 days post-treatment) attracted more O. landolti and C. i. chevrolati individuals than IVM-free feces (P < 0.05). The same response occurred under uncontrolled conditions. This clear attraction for IVM-containing cattle feces by the studied DB species highlights that incorrect IVM use may pose a risk to DB communities in cattle production systems.(AU)

Resumen La ivermectina (IVM) es ampliamente utilizada para el control de parásitos en el ganado en los trópicos. La IVM residual en las heces conserva su actividad insecticida durante semanas y puede dañar diversas especies de escarabajos estercoleros. La atracción a las heces del ganado tratado con IVM se probó usando a las especies Onthophagus landolti (Harold) y Canthon indigaceus chevrolati (Harold) como modelos de estudio. Los experimentos se realizaron bajo condiciones de laboratorio controladas, condiciones de campo semicontroladas y condiciones de campo no controladas. Se utilizaron olfatómetros en los ensayos controlados y semicontrolados. El tratamiento de control consistió en heces exentas de IVM, y los tratamientos experimentales fueron heces de ganado tratado con IVM al 1 % (administración subcutánea, dosis única, 0.2 mg / kg pv) las cuales se recogieron a los 5, 14, 21 y 28 días después del tratamiento al ganado. El ensayo de campo no controlado incluyó trampas de caída libre o pitfall cebadas con heces libres de IVM y con heces de ganado tratado con IVM recogido cinco días después del tratamiento. En condiciones controladas y semicontroladas, las heces del ganado tratado con IVM (a los 5, 14, 21 y 28 días después del tratamiento) atrajeron más individuos O. landolti yC. i. chevrolati que las heces sin IVM (P < 0.05). La misma respuesta ocurrió bajo condiciones no controladas. Esta clara atracción a las heces de ganado que contienen IVM por las especies estudiadas pone de relieve que el uso incorrecto de IVM puede plantear un riesgo para las comunidades de escarabajos estercoleros en los sistemas de producción ganadera.(AU)

Rhipicephalus (Boophilus) microplus resistant to acaricides and ivermectin in cattle farms of Mexico / Rhipicephalus (Boophilus) microplus resistentes aos acaricidas e ivermectina nas fazendas de gado do México

Ticks and the diseases they transmit cause great economic losses to livestock in tropical countries. Non-chemical control alternatives include the use of resistant cattle breeds, biological control and vaccines. However, the most widely used method is the application of different chemical classes of acaricides and macrocyclic lactones. Populations of the cattle tick, Rhipicephalus (Boophilus) microplus, resistant to organophosphates (OP), synthetic pyrethroids (SP), amitraz and fipronil have been reported in Mexico. Macrocyclic lactones are the most sold antiparasitic drug in the Mexican veterinary market. Ivermectin-resistant populations of R. (B.) microplus have been reported in Brazil, Uruguay and especially in Mexico (Veracruz and Yucatan). Although ivermectin resistance levels in R. (B.) microplus from Mexico were generally low in most cases, some field populations of R. (B.) microplus exhibited high levels of ivermectin resistance. The CHPAT population showed a resistance ratio of 10.23 and 79.6 at lethal concentration of 50% and 99%, respectively. Many field populations of R. (B.) microplus are resistant to multiple classes of antiparasitic drugs, including organophosphates (chlorpyrifos, coumaphos and diazinon), pyrethroids (flumethrin, deltamethrin and cypermethrin), amitraz and ivermectin. This paper reports the current status of the resistance of R. (B.) microplus to acaricides, especially ivermectin, in Mexican cattle.

Carrapatos e as doenças por eles transmitidas causam grandes perdas econômicas ao gado dos países tropicais. Alternativas não-químicas incluem o uso de raças de gado que sejam resistentes, controle biológico e vacinas. No entanto, o método mais utilizado é a aplicação de diferentes classes químicas de acaricidas e lactonas macrocíclicas. Populações de piolhos de gado, Rhipicephalus (Boophilus) microplus, resistentes aos organofosfatos (OP), piretoides sintéticos (SP), amitraz e fipronil, foram descritas no México. Lactonas macrocíclicas são as drogas antiparasitárias mais vendidas no mercado veterinário mexicano. Populações de R. (B.) microplus resistentes à irvemectina foram relatadas no Brasil, Uruguai e especialmente no México (Veracruz e Yucatan). Embora os níveis de resistência à ivermectina no R. (B.) microplus do México tenha sido relativamente baixa, na maioria dos casos, algumas populações campestres de R. (B.) microplus mostraram altos níveis de resistência à ivermectina. A população CHPAT mostrou uma razão de resistência de 10,23 e 79,6 na concentração letal de 50% e 99%, respectivamente. Muitas populações campestres de R. (B.) microplus são resistentes a múltiplas classes de drogas antiparasitárias, incluindo organofosfatos (clorpirifós, coumafos e diazinon), piretoides (flumetrina, deltametrina e cipermetrina), amitraz e ivermectina. Este artigo relata o estado atual de resistência do R. (B.) microplus aos acaricidas, especialmente ivermectina, no gado mexicano.