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Edinburg, TX, United States

Thomas D.B.,Cattle Fever Tick Research Laboratory
Southwestern Entomologist | Year: 2012

Vacuum devices were compared for sampling the abundance of psyllids. One vacuum device was an AC rechargeable, handheld, cordless model, while a second was a handheld, DC model powered through a cord connected to a 12-volt vehicle battery. Each of the devices had a mesh cylinder (substituted for a dust bag) in which the insects were captured. The third device was a reversed leaf blower with a two-cycle gasoline engine, with the insects captured in a standard-sized aerial insect net. Each device had advantages and disadvantages over the others depending on the collecting situation. However, the gas-powered device captured the most psyllids. The handheld models provided ease in handling compared to the bulkier (and noisier) leaf blower. The DC-powered sampler was tethered to its power source, in this case, a vehicle that could access trees in a commercial grove, whereas, the AC cordless device may be more suitable for dooryard situations. The disadvantage of the cordless device was that its operating time of approximately 10 minutes was sufficient for sampling psyllids on only two trees before it had to be recharged for 16 hours. Because of greater air flow, the gas device captured greater numbers than did either of the smaller electrical devices. The sampling procedure consisted of vacuuming a target tree for 5 minutes. The mean numbers of psyllids captured per tree with the AC, DC, and leaf blower devices were respectively: 17.4 (n = 44), 33.0 (n = 72), and 96.8 (n = 47). All mean differences were statistically significant. To test the efficiency of the leaf blower, some trees were immediately re-sampled. The proportion of psyllids in the first sample compared to the resample was approximately 3:1.

Miller R.J.,Cattle Fever Tick Research Laboratory | White W.H.,Eli Lilly and Company | Davey R.B.,Cattle Fever Tick Research Laboratory | George J.E.,U.S. Department of Agriculture | Leon A.P.D.,U.S. Department of Agriculture
Journal of Medical Entomology | Year: 2011

Various acaricide-resistant strains of Rhipicephalus (Boophilus) microplus, representative of the major resistance mechanisms found in Mexico and Brazil, were exposed to spinosad using the Food and Agriculture Organization of the United Nations larval packet test and adult immersion test (AIT). Larvae of all strains tested were found to be susceptible to spinosad. Conversely, spinosad did not show toxic activity toward engorged females used in the AIT. In vitro tests against larvae, nymphs, and adults of acaricide-susceptible Amblyomma americanum and Dermacentor variabilis revealed differences in activity that were dependent on tick species and parasitic life stage. Spinosad seemed to be a viable alternative to current acaricides available for tick control in the species tested. The larval packet test should be used for future monitoring of resistance, as the AIT did not provide useful information with this chemical. The potential benefit for the use of spinosad in integrated pest management or eradication programs is discussed.

Davey R.B.,Cattle Fever Tick Research Laboratory | Pound J.M.,Knipling Bushland United States Livestock Insects Research Laboratory | Klavons J.A.,Knipling Bushland United States Livestock Insects Research Laboratory | Lohmeyer K.H.,Knipling Bushland United States Livestock Insects Research Laboratory | And 3 more authors.
Journal of Medical Entomology | Year: 2011

The therapeutic and persistent efficacy of a single subcutaneous injection of a long-acting formulation of moxidectin at a concentration of 1 mg/kg body weight was determined against Rhipicephalus (Boophilus) microplus (Canestrini), along with the concentration-time blood sera profile in treated cattle. The therapeutic efficacy against ticks of all parasitic stages on cattle at the time of treatment was >99.9%, and the mean tick number, index of fecundity, engorgement weight, and egg mass weight of ticks recovered from treated animals were all significantly lower than ticks from untreated animals. The index of fecundity, engorgement weight of females, and egg mass weight of ticks recovered from treated animals infested at weekly (7-d) intervals between 14 and 63 d posttreatment were significantly lower than for ticks on untreated animals, whereas the number of ticks per animal recovered from treated cattle remained lower than that of untreated cattle for up to 49 d posttreatment. The percentage control remained >99% at weekly intervals between 14 and 49 d posttreatment, which is the minimum level of efficacy considered acceptable for use in the United States Cattle Fever Tick Eradication Program. The serum concentration of moxidectin in treated cattle increased to 25.6 ppb (parts per billion) within 1 d after treatment, and peaked at 47.3 ppb at 8 d posttreatment. Moxidectin sera levels remained above the estimated 100% threshold level for elimination of feeding ticks (5-8 ppb) for 44-53 d after treatment. The label claim of 50 d of prevention against reinfestation for the long-acting moxidectin formulation used in the study was supported by the efficacy and sera concentration data obtained. Based on these results, cattle could be treated at 63-d intervals with minimal risk of viable ticks detaching from treated animals. This treatment interval would be 4.5-fold longer than the presently required treatment interval of 14 d, thus leading to ≈ 75% reduction in gathering and handling costs of cattle incurred by producers. © 2011 Entomological Society of America.

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