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Open AccessCommunication

First Report of Cattle Tick Rhipicephalus (Boophilus) annulatus in Egypt Resistant to Ivermectin

1
School of Life Science and Engineering, Foshan University, Foshan 528231, China
2
Faculty of Science, Kafrelsheikh University, Kafr el-Sheikh 33516, Egypt
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Department of Parasitology, Faculty of Veterinary Medicine, Beni-Suef University, Beni-Suef 62515, Egypt
4
Department of Parasitology, Faculty of Veterinary Medicine, Cairo University, Cairo 11865, Egypt
*
Authors to whom correspondence should be addressed.
Insects 2019, 10(11), 404; https://doi.org/10.3390/insects10110404
Received: 21 May 2019 / Revised: 17 August 2019 / Accepted: 6 September 2019 / Published: 15 November 2019
Tick control is mainly dependent on the application of acaricides, but resistance has developed to almost all classes of acaricides, including macrolactones. Therefore, we aimed to investigate ivermectin resistance among tick populations in middle Egypt. The larval immersion test was conducted using a commercial formulation of ivermectin (1%). Different concentrations of the immersion solution (0.0000625% (625 × 10−7%), 0.000125% (125 × 10−6%), 0.0005% (5 × 10−4%), 0.001% (1 × 10−3%), 0.0025% (2.5 × 10−3%), 0.005% (5 × 10−3), and 0.01% (1 × 10−2%)) were prepared by diluting a commercial ivermectin (1%) with distilled water containing 1% (v/v) ethanol and 2% (v/v) TritonX-100. Field populations of Rhipicephalus annulatus were collected from five different localities in Beni-Suef province, Egypt. Adult engorged female ticks were collected and assessed for oviposition and egg fertility. Eggs were collected, and hatched larvae were then used in the experiment. Application of acaricides was conducted on 10-day-old larvae. There was a significant difference in the LC50 (50% lethal concentration) among the examined localities on the log dose-response plot, where, the LC50 of tick populations from two localities (Emin elaros and Aldiabia) was higher than the other localities (Alhalabia, Alkom, and Beshnna). Besides, tick populations from Emin elaros and Aldiabia showed higher LC90 values with lower slope values compared to those from Alhalabia, Alkom, and Beshnna. According to these values (LC50, LC90, and slope values), as well as a history of acaricide failure to ticks in these areas, R. annulatus developed resistance to ivermectin. This study documents the first report of field populations of R. annulatus resistant to ivermectin in Egypt. View Full-Text
Keywords: Rhipicephalus annulatus; larval immersion test; ivermectin; resistance Rhipicephalus annulatus; larval immersion test; ivermectin; resistance
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MDPI and ACS Style

El-Ashram, S.; Aboelhadid, S.M.; Kamel, A.A.; Mahrous, L.N.; Fahmy, M.M. First Report of Cattle Tick Rhipicephalus (Boophilus) annulatus in Egypt Resistant to Ivermectin. Insects 2019, 10, 404.

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