Tick Talk December 2024

Groundbreaking Genetic Research Could Revolutionize Tick Control

A collaboration between the Texas A&M Department of Entomology and the USDA has uncovered a promising avenue for controlling disease-spreading ticks. Jason Tidwell, a USDA microbiologist and Texas A&M graduate student, identified genetic markers for sex determination in the cattle fever tick (Rhipicephalus microplus). This discovery could lead to innovative pest control strategies, such as genetic manipulation to disrupt reproduction, which has already shown success with other pests like mosquitoes.

The study supports the USDA’s Cattle Fever Tick Eradication Program, which aims to prevent these ticks from reestablishing in current control methods despite facing challenges of pesticide resistance, through genetic solutions. Experts believe this breakthrough could pave the way for controlling other disease-carrying ticks, such as those that spread Lyme disease.

Winter Ticks, Climate Change, and their effect on Moose Populations

Warmer, shorter winters allow winter ticks to thrive, as late falls give larvae more time to find hosts and early springs improve egg-laying conditions. Climate change, particularly shorter winters and later snow, is lengthening the winter tick season in the Northeast, worsening infestations on moose. Warmer falls give winter ticks more time to find hosts before snow or freezing conditions disrupt their activity. Winter ticks do not spread disease but pose a severe threat to Maine's iconic moose by compromising their health and survival, highlighting the interconnected challenges of wildlife management and climate change.

Maine has the largest moose population in the lower 48 states, supported by abundant habitat and effective wildlife management. While the population is stable in its core range, climate change has worsened the proliferation of winter tick, threatening moose health and reproduction. Winter ticks attach by the thousands and feed on a single moose throughout all life stages; larvae, nymph, and adult.

Winter ticks attach to moose in massive numbers—each moose hosts an average of 47,000 ticks, leading to emaciation, hair loss, and often death. Moose calves are especially vulnerable, with many dying from anemia and extreme weight loss caused by tick feeding. Calves experience over 50% mortality in some areas. Winter tick infestations reduce moose fertility. Healthy populations once had 20–30% twin births, but this has dwindled to nearly none. Younger females are no longer ovulating due to poor health. Adult moose survival is high, but tick infestations reduce reproduction and force them to expend critical energy on excessive grooming instead of feeding and staying warm.

In the 1970s, extensive forest regeneration in New England created ideal moose habitats, leading to a surge in the moose population. This abundance of hosts now exacerbates winter tick infestations. Deer, which groom themselves effectively, are less affected than moose, which cannot easily remove ticks.

Suggestions like introducing guinea fowl, using pesticides, or directly treating moose with anti-tick medications pose significant challenges and risks. Controlled moose hunting is being studied as a potential way to reduce the population density and disrupt the tick's life cycle. Maine’s Department of Inland Fisheries and Wildlife has studied winter tick impacts since 2014 and is testing whether reducing moose density in a small area (6% of the core range) can break the tick cycle. Their long-term goal is a healthier moose population with higher reproduction rates and fewer parasites.

Shrews Spreading Lyme Disease in Martha's Vineyard

New research from Tufts University has revealed that shrews, not just white-footed mice, are a significant contributor to the spread of Lyme disease on Martha's Vineyard. This discovery challenges decades of research and has implications for Lyme disease management strategies.

Analysis of ticks collected from 2019-2023 found that shrews were the largest host for ticks carrying Borrelia burgdorferi, Lyme disease bacteria. Infected ticks were twice as likely to have fed on shrews as on mice. Researchers used a groundbreaking method to identify the blood meal sources of nymph ticks, marking a major advance in tick-borne disease research.

Current interventions, like bait boxes and tick tubes, which target mice, may not work on shrews due to their different behavior and biology. While mice remain significant Lyme disease contributors, shrews appear to play a leading role across much of the Vineyard and could influence similar findings elsewhere. Despite the complexities, tick bite prevention remains crucial. Experts recommend wearing permethrin-treated clothing and conducting regular tick checks to reduce Lyme disease risk.

MilTICK Study Shows Effectiveness of Permethrin-Treated Clothing

A recent study of over 22,000 ticks submitted to the U.S. military’s MilTICK program highlights the effectiveness of permethrin-treated clothing in reducing the risk of tick-borne diseases. Researchers found that individuals wearing treated uniforms had significantly fewer engorged ticks, which are more likely to transmit disease, than those without treated clothing.

The most commonly submitted ticks were lone star ticks, American dog ticks, and black-legged ticks. Permethrin-treated clothing reduced the number of engorged ticks by more than half compared to untreated clothing. Permethrin effectiveness declines after repeated washings, highlighting the need for reapplication or uniform replacement. While permethrin-treated clothing offers valuable protection, the study emphasizes that it should be part of a broader strategy, including regular tick checks, repellents, and awareness of tick risks in outdoor environments.

Invasive Plants and Tick Control: New Research Underway

Scientists in Vermont and Maine are investigating how managing invasive plants like Japanese barberry, bush honeysuckle, and common buckthorn might reduce black-legged tick populations and the risk of tick-borne illnesses. These invasive species often create ideal environments for ticks by maintaining optimal humidity levels and providing dense cover for mice, a primary tick host.

With a $1.8 million National Science Foundation grant, researchers will collect data over the next five years from public and private lands in Vermont and Maine. Their goal is to develop and share effective land management practices with property owners to curb tick habitats. Although removing invasive plants won't eliminate ticks entirely, the project seeks practical solutions that reduce disease risks while addressing the widespread dislike of both ticks and invasive species.