R — C Lice Treatment Kit Uses, Side Effects — Warnings

R & C Lice Treatment Kit

Generic Name: piperonyl butoxide and pyrethrins topical (pye PER oh nil bue TOX ide and pye REE thrins TOP i kal)
Brand Name: A-200 Lice Treatment, Good Sense Lice Killing Shampoo, Step 1, Leader Lice Solution, Pronto Lice Kill System, R & C Lice Treatment Kit, Rid Pediculicide, Tegrin-LT Lice Treatment Kit, Triple X Pediculicide

Medically reviewed by Drugs.com on Sep 4, 2019 – Written by Cerner Multum

What is R & C Lice Treatment Kit?

Piperonyl butoxide is a chemical that stops the breakdown of pyrethrins, an insecticide chemical.

R & C Lice Treatment Kit (for the skin) is a combination medicine used to treat lice.

R & C Lice Treatment Kit may also be used for purposes not listed in this medication guide.

Important Information

Follow all directions on your medicine label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.

Before taking this medicine

You should not use R & C Lice Treatment Kit if you are allergic to it, or if you have an allergy to chrysanthemums or ragweed.

FDA pregnancy category C. It is not known whether R & C Lice Treatment Kit will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medication.

It is not known whether this medicine passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breast-feeding a baby.

How should I use R & C Lice Treatment Kit?

Follow all directions on your prescription label. Do not use this medicine in larger or smaller amounts or for longer than recommended.

Lice infestations are highly contagious. All household members may need to be treated for lice. Lice can be spread from person to person by sharing a hairbrush, a comb, hats, or headbands. It can also be spread through head-to-head contact.

Apply the shampoo to dry hair. Shake well before use. Apply to all areas of the scalp, including behind the ears and neck. Treat hair from the roots to the ends and leave the shampoo in the hair for no longer than 10 minutes, then rinse thoroughly with warm water. The shampoo should be used again in 7 to 10 days to kill any newly hatched lice.

Keep your eyes tightly closed while using this medicine in your hair. You may use a washcloth or towel to protect your eyes while applying the medication to your head. Do not apply to your eyebrows or eyelashes. Call your doctor if these areas become infected with lice.

You will need to remove any eggs (nits) from the hair shafts with a special comb. Some lice products come provided with a nit comb. If you do not have such a comb, ask your pharmacist where you can get one. Nits may not be removed effectively with a regular fine-tooth comb.

Use this medication for the full prescribed length of time. Your symptoms may improve before the lice infestation is completely cleared. Call your doctor if your condition does not improve, or if your symptoms get worse while using this medication.

To prevent reinfection with lice, wash all clothing, hats, bed linens, stuffed toys, hair brushes, and combs in hot water with a strong cleanser to remove any mites or eggs. You may need to use a special lice control spray to treat furniture, mattresses, sports helmets, headphones, and other non-washable items. Ask your doctor or pharmacist about disinfecting your home.

Store the medicine at room temperature away from moisture and heat.

What happens if I miss a dose?

Use the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not use extra medicine to make up the missed dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while using R & C Lice Treatment Kit?

Avoid using other medications or skin products on the areas you treat with R & C Lice Treatment Kit, unless your doctor tells you to.

Avoid getting this medication in your eyes, nose, mouth, or vagina. If this does happen, rinse with water. Do not use R & C Lice Treatment Kit on sunburned, windburned, dry, chapped, irritated, or broken skin.

Avoid close contact with others until the infection has been cured. Also avoid sharing hair combs, hair accessories, hats, clothing, bed linens, pillows, and other items of personal use.

R & C Lice Treatment Kit side effects

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.

Stop using piperonyl butoxide and pyrethrins and call your doctor at once if you have severe stinging, burning, itching, swelling, or irritation where the medication is applied.

Common side effects may include:

mild itching, burning, or stinging;

numbness or tingly feeling.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

See also:

What other drugs will affect R & C Lice Treatment Kit?

It is not likely that other drugs you take orally or inject will have an effect on topically applied piperonyl butoxide and pyrethrins. But many drugs can interact with each other. Tell each of your health care providers about all medicines you use, including prescription and over-the-counter medicines, vitamins, and herbal products.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Copyright 1996-2018 Cerner Multum, Inc. Version: 3.02.

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The best nit and head lice treatments for 2020

Put us to the test

Our Test Labs compare features and prices on a range of products. Try Which? to unlock our reviews. You’ll instantly be able to compare our test scores, so you can make sure you don’t get stuck with a Don’t Buy.

Do cheap nit and head lice treatments work? Are nit combs or lotions most effective? Discover the best head lice treatments for 2019 as voted by parents.

We surveyed thousands of parents to find the best nit and head lice treatment.

Discover whether you should go for medicated lotions, such as Hedrin, Lyclear or Full Marks, nit combs or herbal treatments.

Our research also found out whether it’s best to try one of these popular nit and head lice treatments, or a combination of them.

In February 2019, we surveyed 2,180 UK parents of children aged under twelve who had treated head lice, asking them which treatment they deemed best.

Which? members can log in, now to reveal the results.

If you’re not a Which? member, you can unlock all the results of our research, plus a step-by-step guide to treating head lice, with a trial to Which?.

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Lice Treatment Liquid

GENERIC NAME(S): Permethrin

OTHER NAME(S): Lice Treatment (Permethrin) Liquid

This medication is used to treat head lice, tiny insects that infest and irritate your scalp. Permethrin is also used to help avoid infestation in people who have close contact with someone who has head lice. It belongs to a class of drugs known as pyrethrins. Permethrin works by paralyzing and killing lice and their eggs (nits).

How to use Lice Treatment Liquid

Apply this medication as soon as possible after it is prescribed. When treating head lice, apply this medication to the hair and scalp only. First wash hair with your regular shampoo, but do not use conditioner. Thoroughly rinse the shampoo out with water, and towel-dry hair. Shake this medication well before using. Cover your eyes with a towel while applying this medication. Completely cover the hair and scalp with the medicine (especially behind the ears and on the hairline at the neck). Avoid getting permethrin in your nose, ears, mouth, vagina, or eyes. If the medicine gets in any of these areas, flush with plenty of water. Do not use more medication than prescribed. Leave the medication on your hair for 10 minutes or as directed by your doctor, then rinse with warm water. Towel-dry your hair and comb out any tangles. A single permethrin treatment can help prevent lice from coming back for 14 days. If eyebrows or eyelashes are infested, do not apply this medication to those areas without first consulting your doctor.

Head lice lay small white eggs (nits) at the base of hair close to the scalp, especially on the hairline at the back of the neck and behind the ears. After treatment with this medication, the infected person should be checked by another person for lice and nits using a magnifying glass and bright light. To remove nits, use the special comb provided, and follow the instructions on the package. After combing, re-check the entire head every day for nits you might have missed. Remove any nits by combing, by hand using a disposable glove, or by cutting them out. If live lice are seen 7 days or more after treatment, a second treatment with permethrin or another drug may be needed.

Inform your doctor if your condition persists or worsens.

Related Links

Side Effects

Scalp irritation, including itching, swelling, or redness may occur with head lice and temporarily worsen after treatment with permethrin. Mild burning, stinging, tingling, or numbness may also occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.

In Canada — Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Related Links

Precautions

Before using permethrin, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

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Before using this medication, tell your doctor or pharmacist your medical history, especially of: skin infections, asthma.

Constant or forceful scratching of the skin/scalp may lead to a bacterial skin infection. Tell your doctor right away if you develop worsening redness or pus.

Tell your doctor if you are pregnant before using this medication.

It is unknown if this drug passes into breast milk but is unlikely to harm a nursing infant. Consult your doctor before breast-feeding.

www.webmd.com

3 New Head Lice Drugs Could Change How Lice Are Treated

Head lice: A most unwelcome invasion

No one wants to talk about head lice. Even though, for those under 12, head lice is now more common than all other communicable diseases (other than the common cold) put together.

Yet there’s still a good deal of shame attached to admitting that your home and family are infested with lice.

There’s also a deep well of frustration and sense of futility — ask anyone who’s tried to get rid of lice, and they’ll tell you the effort made them feel like a complete failure.

Why? Because the lice treatments that crowd drugstore shelves only work on bugs that aren’t pesticide-resistant — which at this point appears to be less than 50 percent of them. Yet somehow no one tells you that, while you shampoo and shampoo away. So this month’s news of a new lice treatment product will be welcomed by many.

Ivermectin

Sanofi’s new lice-killer Sklice

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According to the New England Journal of Medicine, a new topical cream of 0.5% ivermectin killed 95 percent of head lice, and is toxic to lice eggs, or nits, as well. Reports Journal Watch Dermatology, «one ten-minute application was very effective.»

Topical ivermectin is being marketed by Sanofi Pasteur as Sklice, available by prescription only. It was developed by Topaz Pharmaceuticals, which the pharmaceutical giant purchased in February, 2012.

Here are the data from the maker-sponsored trials: On day 2, 95 percent of those treated were louse-free; on day 8, 85 percent were clear, and on day 15 it was still 74 percent. That may not sound entirely convincing, but compared with what’s currently available it’s a major improvement.

Most appealing, the study was based on a one-time 10-minute application with no nit combing. Tell that to anyone battling lice and they’ll be waiting outside the doctor’s office when the doors open tomorrow. Add a second dose a week later, or some vigilant nit removal, and it should be possible to get to 100 percent efficacy.

Sklice could be a huge seller for Sanofi; the FDA reports there are 6 to 12 million cases of head lice infestation in the U.S. each year. (It’s hard to know for sure because lice is under-reported; it’s not exactly a subject most people bandy about.) The typical consumer treats lice at home and doesn’t necessarily consult a doctor. But knowing that more effective prescription remedies are available would prompt anyone I know to make the call.

Ivermectin taken orally has been used for many years to treat scabies, roundworms, and threadworms, and recently desperate patients have been asking doctors to prescribe it off-label for head lice. Two years ago a smaller, open-label study published in the journal Pediatrics and Adolescent Medicine found oral ivermectin was 100 percent effective against lice with one or two doses. So it’s possible that the FDA will eventually approve oral ivermectin for lice as well.

The Competition: Natroba and Ulesfia

After decades of inaction on the lice front, the past three years have seen pediatricians inundated with information about new prescription-only lice products. Here are the other two lice products that the FDA has approved in the past three years.

1. Spinosad topical suspension 9% (brand name Natroba) is a topical organic pesticide that became available in 2011, brought to market by tiny upstart ParaPro of Indiana. Interestingly, spinosad is the same pesticide used in Comfortis, familiar to dog owners as a flea medication. Natroba also contains benzyl alcohol in addition to spinosad, so it has the advantage of being a dual-action medication. In clinical trials, Natroba was 85 percent effective 14 days after a one-dose treatment without nit combing. The biggest limitation for Natroba is that it hasn’t been proven safe for children under the age of four.

2. Benzyl alcohol 5% lotion (brand name Ulesfia): Another topical cream, which hit the market in 2009, Ulesfia is made by Japanese pharmaceutical company Shionog. It works by coating lice and suffocating them, which means it’s not a pesticide, making it less toxic. In fact, it’s considered safe for babies six months and older. Ulesfia only kills live bugs, not nits, so you have to reapply a week later and hope that timing is right to kill hatched lice.

Clearly, a battle is just beginning in the prescription lice treatment arena. Pediatricians will decide which product to recommend based not just on research, but on cost, insurance coverage availability, and eventually on anecdotal reports from patients. They’ll hear about what worked, what didn’t, and what inconveniences and challenges families encountered during treatment and that will influence prescription preferences as much as anything the FDA says.

What hopefully will change the fastest, though, is the misdirection and misinformation that leaves consumers spending hundreds of dollars on ineffective products, children missing days of school, and families spending hundreds of tearful hours in nit combing using combs with teeth that are too far apart to actually remove nits.

And for college students, who are encountering lice in dorms, a lice treatment that doesn’t require hours of nit-picking (which is hard to do on yourself) will be very welcome.

Follow me on Twitter, @MelanieHaiken or find me on Facebook

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Vectra 3D

Vectra 3D

— Vectra 3D ® for dogs and puppies 2.5 to 20 lbs, over 7 weeks of age

— Vectra 3D ® for dogs and puppies 21 to 55 lbs, over 7 weeks of age

— Vectra 3D ® for dogs 56 to 95 lbs

— Vectra 3D ® for dogs over 95 lbs

AVAILABLE FROM LICENSED VETERINARIANS ONLY

— 6-way protection, repels and kills fleas, ticks, mosquitoes, lice, biting and sand flies, and mites (excluding mange mites)

— Repels and kills Brown Dog ticks, American Dog ticks, Deer ticks, and Gulf Coast ticks and Lone Star ticks for one month

— Begins reducing flea feeding in 5 minutes; starts to kill fleas within 2 hours

— Kills all stages of the flea life cycle

— Repels and kills ticks that may cause Lyme disease, Rocky Mountain spotted fever, babesiosis, ehrlichiosis, bartonellosis, hepatozoonosis and anaplasmosis

— Kills biting flies that may transmit fly strike

— Convenient topical treatment that allows application down to skin

— Continues to kill and repel fleas and ticks after shampooing

Vectra 3D spreads over the dog’s body to provide full body protection against fleas, ticks and mosquitoes.

Active Ingredients

DO NOT USE ON CATS

KEEP OUT OF REACH OF CHILDREN

Warning

FOR ADDITIONAL INFORMATION, PLEASE CONTACT US AT 1-800-999-0297 or [email protected]

READ ENTIRE LABEL BEFORE EACH USE

USE ONLY ON DOGS OR PUPPIES OVER 7 WEEKS OLD

Precautionary Statements

HAZARDS TO HUMANS AND DOMESTIC ANIMALS

For external use on dogs only. Do not use this product on cats.

Warning

Do not use this product on debilitated, aged, medicated, pregnant or nursing dogs, or dogs known to be sensitive to pesticide products without first consulting a veterinarian.

Sensitivity, such as slight transitory redness, erythema or pruritus at the site of application, may occur after using ANY pesticide product for dogs. If signs of sensitivity occur, bathe your dog with mild soap or shampoo and rinse with large amounts of water. If signs of individual dog sensitivity occur and persist, contact your veterinarian. Have the product container or label with you when calling your veterinarian for advice.

DO NOT USE ON CATS. Due to their unique physiology and inability to metabolize certain compounds, this product must not be used on cats. If applied to a cat, or ingested by a cat that actively grooms a recently treated dog, this product may have serious harmful effects. If this occurs, contact your veterinarian immediately.

First Aid

Hold eye open and rinse slowly and gently with water for 15-20 minutes. Remove contact lenses, if present, after the first 5 minutes, then continue rinsing. Call a poison control center or doctor for treatment advice.

Call a poison control center or doctor for treatment advice. Do not induce vomiting unless told to do so by a poison control center or doctor. Have person sip a glass of water if able to swallow. Do not give anything by mouth to an unconscious person.

Take off contaminated clothing. Rinse skin immediately with plenty of water for 15-20 minutes. If skin appears irritated after rinsing call a poison control center, or doctor, or 1-800-999-0297 or after 6 pm EST call 1-888-426-4435 immediately for treatment advice.

Have the product container or label with you when calling a poison control center or doctor or going for treatment. You may contact 1-800-999-0297 weekdays between 9 am and 6 pm EST or 1-888-426-4435 for emergency medical treatment information.

Directions For Use

It is a violation of Federal law to use this product in a manner inconsistent with its labeling. [Precaución al consumidor: si usted no lee ingles, no use este producto hasta que la etiqueta le haya sido explicada ampliamente. (To the User: If you cannot speak English, do not use this product until the label has been fully explained to you.)]

1. USE ONLY ON DOGS. DO NOT USE ON CATS OR OTHER ANIMALS.

2. Remove applicator from package.

3. The dog should be standing or in a comfortable position for easy application.

4. Holding the applicator tube upright, place thumb and index finger around the applicator tip under the large disk. With other hand, grasp the stem of applicator tip above smaller disk. Press down firmly on small disk until both disks meet, piercing the seal. See illustration.

5. Using the applicator tip part the hair at the base of the tail and begin applying the product onto the skin in a continuous line from the base of the tail along the center of the back all the way up to the shoulder blades, as shown in the diagram, squeezing the applicator tube until its empty.

Do not get the product in the dog’s eyes or mouth. Avoid superficial application to the dog’s hair.

6. Discard empty applicator tube as outlined in Storage and Disposal.

7. Repeat every month or as recommended by your veterinarian. Do not apply in less than 30 days.

8. For optimum treatment, control and prevention of adult and immature fleas, ticks, mosquitoes, lice, biting and sand flies and mites (excluding mange mites) year-round treatment is recommended.

Storage And Disposal

Do not contaminate water, food or feed by storage and disposal. Storage: Store in a cool, dry place. Protect from freezing. Disposal: If empty, do not reuse the container. Place in trash or offer for recycling if available. If partially filled, call your local solid waste agency for disposal instructions. Never place unused products down any indoor or outdoor drain.

Limited Warranty And Limitation Of Damages

Seller warrants that the material conforms to the chemical parameters of the US EPA registration and the label. To the extent consistent with applicable law seller makes no warranty, express or implied, other than indicated on the label. Buyer and user assume all risk of use and handling of this material when such use and handling are contrary to the label instructions. To the extent consistent with applicable law any damages arising from a breach of this warranty shall be limited to direct damages and shall not include consequential commercial damages such as loss of profit or values.

Volume varies with size of animal for which package is intended and number of applicators per package. Product may be packaged in 1, 3, 6 or 36 applicators per package. Total volume will correspond to number of applicators.

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EPA Reg. No. 83399-6

EPA Est. No. 68669-NC-1

Made in the USA by Ceva Animal Health, LLC, 301 Rt. 17 N, Rutherford, NJ 07070

Ceva Animal Health, LLC will provide new product or your money back.

For additional information please contact us at 1-800-999-0297 or [email protected]

©2011 Ceva Animal Health, LLC V3D-409-11 6/11

Toll-Free: 1-800-999-0297
Toll-Free Fax: 877-777-5138
Website: www.ceva.us
Every effort has been made to ensure the accuracy of the Vectra 3D information published above. However, it remains the responsibility of the readers to familiarize themselves with the product information contained on the US product label or package insert.

Copyright © 2020 Animalytix LLC. Updated: 2020-04-01

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Host defense triggers rapid adaptive radiation in experimentally evolving parasites

School of Biological Sciences, University of Utah, Salt Lake City, Utah, 84112

These authors contributed equally to this work.

School of Biological Sciences, University of Utah, Salt Lake City, Utah, 84112

These authors contributed equally to this work.

School of Biological Sciences, University of Utah, Salt Lake City, Utah, 84112

Illinois Natural History Survey, Prairie Research Institute, University of Illinois at Urbana‐Champaign, Champaign, Illinois, 61820

School of Biological Sciences, University of Utah, Salt Lake City, Utah, 84112

School of Biological Sciences, University of Utah, Salt Lake City, Utah, 84112

School of Biological Sciences, University of Utah, Salt Lake City, Utah, 84112

These authors contributed equally to this work.

School of Biological Sciences, University of Utah, Salt Lake City, Utah, 84112

These authors contributed equally to this work.

School of Biological Sciences, University of Utah, Salt Lake City, Utah, 84112

Illinois Natural History Survey, Prairie Research Institute, University of Illinois at Urbana‐Champaign, Champaign, Illinois, 61820

School of Biological Sciences, University of Utah, Salt Lake City, Utah, 84112

School of Biological Sciences, University of Utah, Salt Lake City, Utah, 84112

Abstract

Adaptive radiation occurs when the members of a single lineage evolve different adaptive forms in response to selection imposed by competitors or predators. Iconic examples include Darwin’s finches, Caribbean anoles, and Hawaiian silverswords, all of which live on islands. Although adaptive radiation is thought to be an important generator of biodiversity, most studies concern groups that have already diversified. Here, we take the opposite approach. We experimentally triggered diversification in the descendants of a single population of host‐specific parasites confined to different host “islands.” We show rapid adaptive divergence of experimentally evolving feather lice in response to preening, which is a bird’s main defense against ectoparasites. We demonstrate that host defense exerts strong phenotypic selection for crypsis in lice transferred to different colored rock pigeons (Columba livia). During four years of experimental evolution (∼60 generations), the lice evolved heritable differences in color. Strikingly, the observed color differences spanned the range of phenotypes found among congeneric lice adapted to other species of birds. To our knowledge, this is the first real‐time demonstration that microevolution is fast enough to simulate millions of years of macroevolutionary change. Our results further indicate that host‐mediated selection triggers rapid divergence in the adaptive radiation of parasites, which are among the most diverse organisms on Earth.

Impact Summary

Understanding species diversification is a central theme in biology. Studies of plants and animals from island archipelagos show that different forms evolve in response to divergent natural selection. Such adaptive radiations are also likely to occur among parasites, which live on “host islands.” Here, we take an experimental evolution approach to better understand how adaptive evolution governs diversification from microevolutionary to macroevolutionary scales. We show that anti‐parasite behavior of birds drives rapid and divergent evolution of cryptic coloration in host specific feather lice. Differences we observed in microevolutionary time reflect differences among species of lice parasitizing different species of birds. Our results imply that host defense should be included with competition and predation as major mechanisms driving species divergence.

Adaptive radiation is a major source of organismal diversity (Simpson 1953 ; Schluter 2000 ; Nosil and Crespi 2006 ; Meyer and Kassen 2007 ; Losos 2010 ). Ironically, however, the role of this process in parasite diversification remains unclear, despite the fact that parasitism is one of the most common lifestyles on the planet (Price 1980 ; de Meeus and Renaud 2002 ; Poulin 2014 ; Wiens et al. 2015 ; Jezkova and Wiens 2017 ). Parasites may adapt and radiate among host species, just as free‐living species adapt, and radiate among islands within archipelagos. Host species are analogous to islands that limit dispersal and gene flow between parasite populations and species. Nevertheless, as in the case of physical islands, the barriers created by host islands are not absolute because even host‐specific parasites occasionally switch host lineages over macroevolutionary time (Ehrlich and Raven 1964 ; Ziętara and Lumme 2002 ; Fordyce 2010 ; Giraud et al. 2010 ; Johnson et al. 2011 ; Hardy and Otto 2014 ; Clayton et al. 2015 ; Nylin et al. 2017 ). Host switching can lead to patterns consistent with adaptive radiation in phytophagous insects (Fordyce 2010 ; Hardy and Otto 2014 ; Forbes et al. 2017 ), fungal plant pathogens (Giraud et al. 2010 ), helminth worms (Ziętara and Lumme 2002 ), avian brood parasites (Sorenson et al. 2003 ), and ectoparasitic arthropods (Johnson et al. 2011 ; Clayton et al. 2015 ). Host‐mediated selection also appears to drive the adaptive divergence of parasites exposed to varying defensive regimes on different host islands (Ehrlich and Raven 1964 ; Price 1980 ; Loker 2012 ; Wiens et al. 2015 ). However, this hypothesis has not been tested experimentally because it is difficult to isolate and manipulate components of host defense. We conducted such a test using an unusually tractable host‐parasite system consisting of rock pigeons (Columba livia) and their feather lice (Insecta: Phthiraptera: Ischnocera).

Feather lice are host‐specific parasites of birds that feed on the downy regions of feathers, causing energetic stress that leads to a reduction in host fitness through reduced survival and mating success (Clayton et al. 2015 ). Feather lice depend on feathers for efficient locomotion. Thus, transmission between host individuals usually requires direct contact, such as that between parent birds and their offspring in the nest. However, feather lice can also disperse by hitchhiking phoretically on parasitic flies that are less host‐specific than lice (Harbison and Clayton 2011 ). As a consequence, lice periodically end up on novel host species (Clayton et al. 2015 ). Birds combat lice by removing them with their beaks during regular bouts of preening. Lice are thought to escape from preening through background matching crypsis because light colored bird species have light colored lice, whereas dark colored species have dark colored lice (Bush et al. 2010 ) (Fig. 1A and B). Although these observations suggest that preening is the selective agent responsible for the evolution of cryptic coloration in feather lice, this hypothesis has never been tested experimentally.

Materials and Methods

STUDY SYSTEM

One of the challenges of experimental work with host‐specific parasites is that, by definition, they are difficult to culture in sufficient numbers on novel host species. We circumvented this problem by working with rock pigeons (Columba livia), a single host species that harbors extensive intraspecific diversity in color as a result of artificial selection (Shapiro and Domyan 2013 ). Rock pigeons with contrasting plumage colors were used as stepping stones to simulate environments that lice dispersing between different species of pigeons would encounter in nature. All animal procedures were approved by the IACUC of the University of Utah.

ELIMINATION OF “BACKGROUND” LICE

Before using pigeons in experiments, all “background” lice were eradicated by housing the birds in low humidity conditions ( 2008 ). During experiments, the relative humidity in animal rooms was increased to 35–60%, which provides sufficient humidity for feather lice to extract the moisture they need from the air while living on birds (Nelson and Murray 1971 ).

IMPAIRED PREENING

Preening was impaired using harmless poultry bits, which are C‐shaped pieces of plastic inserted between the upper and lower mandibles of a bird’s beak (Fig. 2F). Bits spring shut in the nostrils to prevent dislodging, but without damaging the tissue. They create a 1–3 mm gap that prevents the forceps‐like action of the bill required for efficient preening (Clayton et al. 2005 ). Bits have no apparent side effects and they do not impair the ability of birds to feed (Clayton and Tompkins 1995 ).

PREENING‐MEDIATED SELECTION EXPERIMENT

Painting lice: We manipulated the color of lice by covering the dorsal surface of live, adult C. columbae with enamel paint (Floquil TM Railroad Enamel, Vernon Hills, IL). Painting is a reliable method that has been used successfully with other species of lice, even under field conditions (Zohdy et al. 2012 ). First, we tested whether the paint affects survival of C. columbae, as follows: live adult C. columbae were removed from infested pigeons and placed in a petri dish next to a small piece of dry ice to keep them anesthetized with CO2 during the painting process. We divided 75 lice into three treatments: 25 lice painted white, 25 lice painted black, and 25 unpainted control lice. Paint was applied to the dorsal surface of each louse with a very fine brush. Lice in the control treatment were handled and brushed, but without applying paint. We did not paint the legs of lice, as this might interfere with mobility. Painted lice were placed on feathers from gray feral pigeons in 50 mL glass tubes in a Percival © incubator set at optimal conditions for lice: 33˚C and 75% relative humidity on a 12‐hour light/dark photoperiod (Bush and Clayton 2006 ). We compared the survival of lice among the three treatments under a dissecting scope (Olympus® SZ‐CTV stereoscope) on six occasions over a 20‐day period (days: 1, 3, 5, 7, 11, and 20). Over this period of time, there was no significant difference in the survival of lice painted white, painted black, or unpainted controls (Kaplan–Meier survival, Wilcoxon χ 2 = 2.2, df = 2, P = 0.34).

Experimental infestation with painted lice: 16 pigeons (eight white, eight black; Fig. 2A and B) were randomly divided (within each color treatment) into two preening treatments: half could preen normally, and the other half had their preening impaired with bits (see above). Pigeons in this experiment were housed individually in 30 × 30 × 56 cm wire mesh cages in our animal facility. Cages were separated by plastic partitions to prevent any contact between the feathers of birds in adjacent cages, which might allow transmission of lice between pigeons. Birds were maintained on a 12‐hour light/dark photoperiod and provided ad libitum grain, grit, and water.

Each bird received 30 cryptic lice and 30 conspicuous lice (Fig. 2C and D). The survival of lice was assessed 48 hours after the pigeons were experimentally infested. To do this, all pigeons were sacrificed and their lice removed by “body washing” (Clayton and Drown 2001 ). Each louse was inspected under a dissecting scope and the number of white and black lice recovered from each bird was recorded.

EXPERIMENTAL EVOLUTION

To test whether preening selects for divergence in the color of lice, we infested different colored pigeons with normal, unpainted C. columbae. Prior to experimental infestation, recipient pigeons were cleared of lice by housing them in low humidity conditions (as described above). Next, we transferred 2400 lice from wild caught feral rock pigeons to 96 captive rock pigeons (25 lice per bird): 32 white pigeons, 32 black pigeons, and 32 “gray” pigeons (controls; see Fig. 1B). Within each color, half the birds, chosen at random, were allowed to preen normally (Fig. 2E), whereas the other half were given bits to impair their preening (Fig. 2F). At this time (Time 0), we also randomly sampled hundreds of lice from the source population on wild caught gray feral pigeons and their luminosity was scored (as described below).

Pigeons were housed in groups of four in 1.8 × 1.5 × 1.0 m aviaries. In summary, the 96 pigeons used in this experiment were housed in 24 aviaries, each containing four birds of the same color and preening treatment (two males and two females per aviary).

See also:  WHO, Control strategies

During the experiment, all pigeons were maintained on a 12‐hour light/dark photoperiod and provided ad libitum grain, grit, and water. When a bird died during the course of the experiment (a rare occurrence), the lice from the dead bird were transferred to a new parasite‐free pigeon of the same color and sex within 24 hours. Columbicola columbae lice can survive for days on a dead bird, but cannot leave the dead bird’s feathers under their own power, so few lice were lost.

The experiment ran for four years. Given that C. columbae has a mean generation time of 24.4 days (Harbison et al. 2008 ), this is about 60 generations. Every six months, random samples of lice were removed from pigeons and digitally photographed. Lice were removed by anesthetizing them with CO2 (Moyer et al. 2002 ). After exposure to CO2 the feathers of each bird were ruffled over a collection tray. Lice not selected randomly for photography were returned to the bird unharmed. The remaining lice were photographed by placing each louse dorsal side up on a glass slide fitted with a Kodak® Q‐13 white color standard. The lice were immobilized by placing a 22 × 22 mm micro cover slip (VWR®) directly on their body. Digital photographs were taken at high resolution (uncompressed TIFF 2560 × 1920 pixels) using a DP25 digital camera on an Olympus® SZ‐CTV stereoscope linked to a computer running CellSens® image acquisition and analysis software. All of the photos were scored digitally (Villafuerte and Negro 1998 ; Stevens et al. 2007 ). For each image, the metathorax was selected and luminosity calculated using the open source imaging software ImageJ 1.3. To correct for slight differences in luminosity due to variation in ambient lighting, we also recorded the luminosity of the color standard immediately adjacent to each louse. We determined how much the photograph of the color standard differed from pure white (luminosity = 255), then added this correction factor to the luminosity score (Bush et al. 2010 ). Although the digital camera is optimized for human vision, pigeons and humans have similar achromatic spectral sensitivities (Brown and Wald 1964 ; Bowmaker et al. 1997 ).

PLUMAGE COLORATION

We also used digital photography to quantify the plumage luminosity of 23 dead pigeons representing the three colors in the evolution experiment (eight black pigeons, five white pigeons, and 10 gray pigeons). The dorsal and ventral surface of each bird was photographed next to a Kodak® Q‐13 white color standard. High‐resolution (5184 × 3456 pixels) digital photos were taken using a Canon® EOS Rebel® SL1 digital camera. We then highlighted the plumage in each image with the “Quick Selection Tool” in Adobe® Photoshop® CC 2015, and determined the luminosity of the highlighted area. To correct for slight differences in luminosity due to variation in ambient lighting, we also recorded the luminosity of the color standard immediately adjacent to the bird. We determined how much the photograph of the color standard differed from pure white (luminosity = 255), then added this correction factor to the luminosity score for the plumage (Bush et al. 2010 ). We used the mean plumage luminosity of the dorsal and ventral surfaces of each pigeon in analyses.

COMMON GARDEN EXPERIMENT

The goal of this experiment was to test for heritability of preening‐mediated changes in the color of lice. We therefore used lice only from the 12 aviaries containing birds with normal preening. Lice of each sex were randomly sampled from each aviary using CO2. We marked the lice by clipping setae along the right side of the abdomen and thorax with scissors designed for retinal surgery. Setal clipping is a reliable method that has been used successfully with other species of lice, including under field conditions (Durden 1983 ). Removal of setae does not influence survival, and the setae do not grow back. After clipping, lice from each aviary were placed on a single gray pigeon with impaired preening. The 12 “common garden” pigeons were isolated in 12 wire mesh cages (30 × 30 × 56 cm). After a period of 48 days, all lice were removed from each of the 12 pigeons using CO2 (as described above). At 48 days, most F1 offspring had developed to the adult stage, and could be distinguished from members of the parental cohort, which had clipped setae. In contrast, F2 lice had not yet developed to the adult stage. Thus, using this design, we were able to compare adults of the parental and F1 cohorts of lice on each common garden bird. F1 lice were removed from each bird and digitally photographed and their luminosity scored (as described above). The luminosity of the F1 cohort from each common garden pigeon (n = 4–29 lice per bird for a total of 170 lice) was then compared to the luminosity of the parental cohort (n = 11–48 lice per aviary, for a total of 303 lice).

Results and Discussion

We measured the selective effect of preening on the color of pigeon lice (Columbicola columbae) by comparing the survival of experimentally manipulated lice placed on different colored rock pigeons (see Materials and Methods). Live lice were painted black or white and distributed evenly among eight black and eight white pigeons (Fig. 2A–D). Half of the birds could preen normally, whereas the other half had their preening ability impaired with harmless bits that prevent complete closure of the beak (Fig. 2E and F). After 48 hours, all birds had their lice removed by body washing (Clayton and Drown 2001 ). Birds with normal preening had significantly more cryptic lice than conspicuous lice at the end of the experiment (Fig. 2G). Conspicuous lice were 40% more likely be removed by preening, revealing intense selection for cryptic coloration. In contrast, there was no significant difference in the number of cryptic and conspicuous lice on pigeons with impaired preening (Fig. 2G).

This direct demonstration of preening‐mediated selection for crypsis implies that preening leads to the diversification of parasite color among different colored hosts. Because feather lice are permanent parasites that pass their entire life cycle on the body of the host, they can be evolved experimentally under natural conditions on captive birds. Therefore, to test for adaptive divergence in response to host preening, we conducted a four‐year experiment (ca. 60 louse generations) using C. columbae isolated on captive rock pigeons of different colors (see Materials and Methods). We transferred lice from wild caught gray feral rock pigeons (Fig. 1B) to white, black, or gray (control) rock pigeons that could either preen normally, or were impaired with bits.

At six‐month intervals, random samples of lice were removed from each pigeon and digitally photographed under identical lighting conditions against a color standard (Villafuerte and Negro 1998 ). The photographs were used to quantify the luminosity (brightness) of individual lice on a gray‐scale from pixel values of 0 (pure black) to 255 (pure white) (Stevens et al. 2007 ). We used luminosity—the achromatic component of color—because feather lice vary mainly from light to dark (Bush et al. 2010 ). We also quantified variation in background coloration by measuring the luminosity of plumage on the white, black, and gray pigeons.

Over the course of the four‐year experiment, the luminosity of lice on white and black birds changed relative to the luminosity of lice on control gray birds. The relative luminosity of lice on white birds increased dramatically, while the luminosity of lice on black birds decreased, but more slowly (Fig. 3A; Appendix Tables A1 and A3). In contrast, lice on white and black birds with impaired preening showed no significant change in luminosity, relative to lice on control grey birds, even after 60 generations (Fig. 3B; Tables A2 and A4). Thus, merely living and feeding on different colored feathers, in the absence of preening, had no effect on the color of the lice. Changes in the luminosity of lice on preening birds were proportional to differences in background luminosity, that is the luminosity of host plumage. The luminosity difference between gray and white plumage was fivefold greater than that between gray and black plumage (Fig. 3C). Thus, lice on white birds presumably experienced more intense selection for background matching than lice on black birds. Differences in selection intensity may therefore have contributed to the greater change in the color of lice on white birds than on black birds.

Over the course of the experiment, birds with impaired preening had more lice (mean ± SE: 394.5 ± 15.6) than normally preening birds (19.1 ± 2.4) (ANOVA, F = 1211.3, df = 1, 95, P 2007 , Smith et al. 2011 ). Thus, our study demonstrates rapid adaptive diversification in descendants of a single population living under natural conditions. Our results suggest that the differences in color among wild species of lice may have evolved quickly.

In summary, we show that preening selects for cryptic coloration, and causes the rapid divergence of heritable phenotypes on different host backgrounds. Thus, even small populations harbor sufficient genetic variation for rapid adaptation to novel hosts within several parasite generations. This process is integral to the successful establishment of parasite populations after rare episodes of dispersal to the “wrong” host species, the precursor to host switching. Adaptive radiation catalyzed by host switching is thought to be a central mechanism of diversification among parasites, which represent a substantial fraction of the earth’s biodiversity (Price 1980 ; de Meeus and Renaud 2002 ; Poulin 2014 ; Forbes et al. 2017 ). Our results imply that other modes of host defense, such as immunological resistance, or secondary chemical compounds, may trigger rapid divergence in endoparasites, phytophagous insects, and other hyper‐diverse groups. Host defense should be included with competition and predation as one of the principal mechanisms driving divergence in adaptive radiations.

ACKNOWLEDGMENTS

We thank F. Adler, A. Beach, J. Baldwin‐Brown, W. C. Brown, H. Campbell, K. Caseii, J. Endler, M. Evans, D. Feener, D. Kim, L. Mulvey, N. Phadnis, E. Poole, M. Reed, J. Ruff, J. Seger, N. Vickers, V. Zafferese, and E. Waight for discussion and other assistance. We thank R. Lenski and an anonymous reviewer for comments that helped to improve the manuscript. All procedures followed guidelines of the Institutional Animal Care and Use Committee of the University of Utah. This work was supported by National Science Foundation DEB‐0107947 and DEB‐1342600.

AUTHOR CONTRIBUTIONS

S.E.B., S.M.V., K.P.J., M.D.S., and D.H.C. designed the experiments. S.E.B., S.M.V., and J.C.A. collected the experimental data. S.E.B. and D.H.C. collected field specimens. S.E.B., S.M.V., and D.H.C. analyzed the data. S.E.B., K.P.J., M.D.S., and D.H.C. obtained funding for the work. S.E.B., S.M.V., K.P.J., M.D.S., and D.H.C. contributed to writing of the manuscript. S.E.B., S.M.V., and J.C.A. took photographs. S.E.B., S.M.V., and D.H.C. prepared figures.

DATA ARCHIVING

Key data generated and analyzed during this study are available in Dryad (https://doi.org/10.5061/dryad.43vh49k).

Table A1. Linear mixed model (LMM) summary comparing the luminosity of lice on pigeons with normal preening.

Table A2. Linear mixed model (LMM) summary comparing the luminosity of lice on pigeons with impaired preening.

Table A3. Mean luminosity of lice from white, grey, and black pigeons with normal preening over the course of the four‐year experiment.

Table A4. Mean luminosity of lice from black, white, and grey pigeons with impaired preening over the course the four‐year experiment.

Table A5. Repeated‐measures ANOVAs with Huynh‐Feldt Epsilon sphericity correction testing the effect of host color on the number of lice per bird over the 48mo experiment.

Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

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