Heartland Virus in Lone Star Ticks, Alabama, USA

We detected Heartland virus (HRTV) in lone star nymphs collected in 2018 in northern Alabama, USA. Real-time reverse transcription PCR selective for the small segment of the HRTV genome and confirmatory sequencing of positive samples showed high identity with HRTV strains sequenced from Tennessee and Missouri.

Early Season Applications of Bifenthrin Suppress Host-seeking Ixodes scapularis and Amblyomma americanum (Acari: Ixodidae) Nymphs

We assessed the efficacy of bifenthrin to suppress Ixodes scapularis Say and Amblyomma americanum (L.) nymphs when applied prior to the initiation of spring host-seeking activity versus when nymphs were already active. Treatment and control plots were sampled for host-seeking ticks every week from mid-April through June, and single occasion bifenthrin applications were done in different sets of treatment plots on 15 April, 29 April, 13 May, and 27 May. Ixodes scapularis nymphs and A. americanum nymphs and adults were effectively suppressed after each application, with at or near 100% suppression of all ticks being observed for up to 8-wk postapplication. Irrespective of the bifenthrin application date, the level of suppression of I. scapularis nymphs never declined below 70% during the study period. However, with the exception of the last application, the suppression of A. americanum nymphs decreased dramatically to below 25% by the conclusion of the trial. The results of this study demonstrated that preseason applications of bifenthrin can mitigate acarological risk of exposure to ticks throughout much of their spring peak activity period.

Effects of Silica-Based CimeXa and Drione Dusts Against Lone Star Tick (Ixodida: Ixodidae) on Cattle

Ixodid ticks vector pathogens of humans, livestock, and wildlife, and occur in tropical and temperate regions worldwide. We used the lone star tick, Amblyomma americanum (L.) (Ixodida: Ixodidae), as a model for other ixodid species, including the southern cattle fever tick, Rhipicephalus (Boophilus) microplus (Canestrini) (Ixodida: Ixodidae). We assessed the lethality of CimeXa, an inert silica-based desiccant dust, and Drione, a silica-based desiccant dust with pyrethrin and piperonyl butoxide (PBO), against A. americanum larvae and nymphs on calves. CimeXa was highly lethal to larvae released onto shaved calf skin 72-96 h previously, and moderately toxic to nymphs. It did not affect immature life stages treated after they began feeding because desiccation was offset by ingestion of blood. Being inert, CimeXa can protect cattle from infestation before feeding occurs for a potentially indefinite period of time. Drione killed immatures within 24 h when released on treated skin and when applied to feeding ixodids because of the pyrethrin and PBO (PBO will also reduce resistance to pyrethrin if it develops). When CimeXa was applied to calves with the hair intact, ≈90% and ≈70% of A. americanum larvae and nymphs, respectively, were killed within 24 h and Drione killed 100% of each life stage. Drione also prevented and drastically reduced egg production and hatching. While CimeXa protects against infestation by immatures, Drione will also control ticks that are feeding. When pyrethrin and PBO in Drione eventually degrade, the silica aerogel carrier can continue to protect against infestation indefinitely.