The development of acaricide resistance in ticks infesting cattle is a major problem in the livestock industry in tropical and subtropical regions worldwide. To determine the current global trends and prevalence of acaricide resistance development (ARD) in tick populations of cattle, a systematic review and meta-analysis with an emphasis on Rhipicephalus (Boophilus) microplus was conducted. Data searches from five English electronic databases yielded 88 journal articles published between 1992 and 2020. In total, 218 in-vitro bioassays were used to investigate 3939 tick populations of cattle; of these, the 57.6% that exhibited ARD were largely limited to South America (Brazil), Central America (Mexico), and Asia (India). A total of 3391 of these tick populations were R. (B.) microplus, of which 2013 exhibited ARD. Random effects meta-analyses indicated that the exhibition of ARD was higher in R. (B.) microplus (66.2%) than in other tick species. Global prevalence estimates of ARD in R. (B.) microplus vary as a function of geography, detection methods, and acaricide compounds. In general, high heterogeneity was noted among the studies. However, homogeneity was observed among studies from India, suggesting the establishment of acaricide resistance in Indian R. (B.) microplus populations. Current tick control interventions are urgently required to limit the evolution and implications of resistance development.
Field studies were conducted during the 2008 -2009 cropping season to determine the minimal insecticide application which can reduce cowpea yield losses on the field due to insect pest infestations in the Transkei region of South Africa. Treatments consisted of five cowpea varieties and four regimes of insecticide spray which were laid out with a split-plot experimental design with four replications. Observations were taken on the incidence of major insect pests, cowpea pod and seed damage by insects as well as growth and yield parameters of the cowpea varieties. Results showed that spray regimes had significant effects on insect population counts, pod and seed damage and consequently on cowpea yield parameters. Application of insecticide once each at flower budding and early podding significantly reduced pod borers and pod-sucking bugs infestations by 44 and 56%, respectively, compared to the untreated control. Application of insecticide, once at flower budding, early podding and pod filling significantly reduced pod and seed damage, resulting in substantial increase in number of pods, pod weight and seed weight per plant, and also number of seeds per pod of cowpea compared to the untreated control. This study provides information on the incidence of major insect pests of cowpea as well as the minimum insecticide control intervention necessary for effectively reducing cowpea yield losses on the field. Two insecticide spray regimes (once at flowering and podding) significantly reduced insect population and damage of cowpea.
Chemical acaricides are widely used to control ticks and tick borne pathogens on cattle. However, prolonged and indiscriminate use of these chemicals inevitably leads to selection of resistant ticks. In-vitro bioassays (adult and larval immersion tests) were conducted to assess amitraz and del-tamethrin resistance in Rhipicephalus (Boophilus) microplus populations from communal farms of the King Sabata Dalindyebo municipality of South Africa. Data generated on percentage inhibi-tion of oviposition (% IO) revealed that all the tick populations assessed showed resistance (% IO≤ 95%) to at least one of the acaricides. All six tick populations assessed for efficacy (% IO≥ 95% at the DD) with deltamethrin were resistant (% IO≤ 95%) and only one of six tick populations as-sessed for efficacy with amitraz was susceptible. Based on resistance ratios, the adult immersion test detected amitraz and deltamethrin resistance in three and five of the six tick populations re-spectively. With the larval immersion test, deltamethrin and amitraz resistance (Larval mortality < 90 % at the DD) was detected in all four, and three of four R. (B.) microplus populations assessed respectively. This data is critical for the design of an effective and sustainable tick control strategy on the communal farms.
Chemical acaricides are widely used to control ticks and tick-borne pathogens in cattle. However, prolonged and indiscriminate use of these chemicals inevitably leads to the selection of resistant ticks. In-vitro bioassays (adult and larval immersion tests) were conducted to assess amitraz and deltamethrin resistance in Rhipicephalus (Boophilus) microplus populations from communal farms of the King Sabata Dalindyebo municipality of South Africa. Data generated on percentage inhibition of oviposition (%IO) revealed that all the tick populations assessed showed resistance (%IO ≤ 95%) to at least one of the acaricides. All six tick populations assessed for efficacy (%IO ≥ 95%) at the DD) with deltamethrin were resistant (%IO ≤ 95%) and only one of the six tick populations assessed for efficacy with amitraz was susceptible. Based on the resistance ratios (RR), the adult immersion test detected amitraz and deltamethrin resistance in three (RR ranging from 2.30 to 3.21) and five (RR ranging from 4.10 to 14.59) of the six tick populations, respectively. With the larval immersion test, deltamethrin and amitraz resistance (larval mortality < 90% at the DD) was detected in all four and three of four R. (B.) microplus populations assessed, respectively. These data are critical for the design of an effective and sustainable tick control strategy on the communal farms.
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