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ARS Home » Plains Area » Kerrville, Texas » Knipling-Bushland U.S. Livestock Insects Research Laboratory » Livestock Arthropod Pest Research Unit » Research » Publications at this Location » Publication #411465
Research Project: Management of Ticks of Veterinary Importance

Location: Livestock Arthropod Pest Research Unit

Title: Lack of host-associated differentiation in Ixodes scapularis using population genetics

Author
item Tietjen, Mackenzie
item ESTEVE-GASENT, MARIA - Texas A&M University
item CASTRO-ARELLANO, IVAN - Texas State University
item Li, Andrew
item MEDINA, RAUL - Texas A&M University

Submitted to: Entomologia Experimentalis et Applicata
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/18/2024
Publication Date: N/A
Citation: N/A

Interpretive Summary: The blacklegged tick is the main vector of Lyme disease in the US. Because it feeds on multiple different hosts, separate populations of this tick associated with host species could exist. If there are host associated populations, then tick control efforts need to target these populations separately for the best results. Host-associated differentiation was tested for blacklegged ticks from six different hosts. It was determined that host-associated differentiation is not occurring on these six host species. This informs control efforts because targeted control methods are not necessary.

Technical Abstract: Ixodes scapularis (Say) (Acari: Ixodidae) is the main vector of Lyme disease in the US. It is a generalist vector feeding on a wide variety of vertebrate hosts that differ in their ability to maintain the Lyme disease bacterium. Several generalist parasites exhibit host-associated differentiation (HAD), a process that results in genetically distinct populations associated with different host species. Knowing whether I. scapularis exhibits HAD, is important to better understand the disease ecology of Lyme disease. To test for HAD in I. scapularis, ticks were collected directly from six different hosts and whole-genome resequencing was completed. HAD was not found in I. scapularis on six of its host species (i.e., cotton mice (Peromyscus gossypinus), opossum (Didelphis virginiana), raccoon (Procyon lotor), gray fox (Urocyon cinereoargenteus), wild boar or feral hog (Sus scrofa), and white-tailed deer (Odocoileus virginianus). As expected, geographic genetic population structure was detected between northern and southern tick populations. The presence of HAD in I. scapularis associated with lizard or rodent hosts could not be ruled out. The results of this study contrast with findings from another host generalist, Dermacentor variabilis (Say) (Acari: Ixodidae), that does exhibit HAD in their large and rodent hosts. Our results suggest that these two tick species differ in their propensity to HAD. One explanation could be that I. scapularis can mate off-host, maintaining panmixia, while D. variabilis mate only on the host. The lack of HAD in I. scapularis should be confirmed by sampling ticks from lizard and rodent hosts. If confirmed across the most common I. scapularis hosts in both the southern and northern populations, this will inform control efforts and justify the use of area-wide tick control strategies.