February 2 2016 by Ray Sahelian, M.D.
Mosquitoes exhibit blood-sucking preferences, and are able to choose victims that would be more appropriate for them. Female mosquitoes -- male mosquitoes do not bite people -- need human blood to develop fertile eggs. One in 10 people are highly attractive to mosquitoes and this makes it particularly relevant to individuals who are traveling to parts of the world that have mosquito related illnesses, such as dengue fever or malaria.
Natural Mosquito repellents
Soybean oil-based repellent is able to protect from mosquito bites for about 2 to 3 hours. Other oils -- citronella, cedar, peppermint, lemongrass, and geranium -- provide short-lived protection. Oil-of-eucalyptus products, however, may offer longer-lasting protection. Pine oil could also be an effective mosquito repellant (see studies bottom of page).
In addition to repelling ticks, numerous studies have shown Buzz Away Extreme's mosquito repelling effectiveness under varying conditions. In one USDA study comparing eleven products, the formula earned a top rating by repelling three common species of mosquito for a mean average of 7.2 hours. In a field study conducted by Canada's University of Guelph, this formula proved to be 92% effective after 3 hours. A low percentage DEET-based formula was only 79% effective 3 hours after application. Buzz Away repellent is made from soy bean oil and other natural plant oils.
Complement Ther Med. 2014. Efficacy and safety of topical Trikatu preparation in, relieving mosquito bite reactions: A randomized controlled trial. Trikatu is composed of dried fruits of Piper nigrum L and Piper retrofractum Vahl, and dried rhizomes of Zingiber officinale R. Although this preparation has been used to relieve pruritis, pain, and inflammation for a long time, there is no clinical evidence to confirm its efficacy and safety. Therefore, we performed a double-blind, within person-randomized controlled study of 30 healthy volunteers to determine efficacy and safety of topical Trikatu on mosquito bite reactions. All subjects were bitten by Aedes aegypti laboratory mosquitoes on their forearms and they were randomly assigned arms to apply either Trikatu or reference product on the mosquito bite papule. The main outcome was the difference of papule size reduction at 30min, measured by a caliper, between the Trikatu and reference arms. Pruritis, redness, pain, and patient satisfaction were assessed at 15, 30, 60, 180, and 360min as secondary outcomes. There were no significant differences between treatment and reference arms on any outcome at any time of measurement. Trikatu did not show additional effects for relieving mosquito bite reaction as compared with the reference product containing camphor, menthol, and eucalyptus. For further study, it is very important to consider a proper selection of subjects, comparator product, and concentration of extract when Trikatu preparation is investigated.
Who Mosquitoes Like
Genetics account for about 85% of our susceptibility to mosquito bites. There are certain elements of our body chemistry that, when found in excess on the skin's surface, make mosquitoes swarm closer. People with high concentrations of steroids or cholesterol on their skin surface attract mosquitoes. That doesn't necessarily mean that mosquitoes prey on people with higher overall levels of cholesterol. These people simply may be more efficient at processing cholesterol, the byproducts of which remain on the skin's surface.
Mosquitoes also target people who produce excess amounts of certain acids, such as uric acid,. These substances can trigger the mosquitoes' olfactory sensations.
Mosquitoes can smell their dinner from an impressive distance of up to 50 meters. This doesn't bode well for people who emit large quantities of carbon dioxide. Any type of carbon dioxide is attractive, even over a long distance. Larger people tend to give off more carbon dioxide, which is why mosquitoes typically prefer munching on adults to small children. Pregnant women are also at increased risk, as they produce a greater-than-normal amount of exhaled carbon dioxide. Movement and heat also attract mosquitoes.
So if you want to avoid an onslaught of mosquito bites at your next outdoor gathering, stake out a chaise lounge rather than being active. Mosquitoes sense movement and head toward you. When you pant from exertion, the smell of carbon dioxide from your heavy breathing draws them closer. So does the lactic acid pouring from your sweat glands.
Even if your body chemistry doesn't attract mosquitoes,
where you're located might.
Some of the worst mosquito populations exist along coastal areas. And being several miles inland does not guarantee your safety from the pests. They'll fly 40 miles for a meal.
While any water source is potential breeding grounds
for mosquitoes, they much prefer stagnant water.
Can you find respite high in the mountains? Don't count on it. Although they're generally not active below 55 degrees Fahrenheit, mosquitoes have been sighted in the Himalayan Mountains,
How about cold climates in places such as Alaska? You're safe for most of the year. But, mosquitoes flock there for a brief, three-week period between July and August. "The Arctic National Refuge is one big bog, making the mosquito population there second only to that in the Florida Everglades.
With a long track record -- mosquitoes have been around for 170 million years -- and more than 175 known species in the U.S..
Chemical-Based Mosquito Repellents
Several varieties of mosquito repellents are sold. The majority of available mosquito repellents derive their effectiveness from chemicals.
Protecting the public from mosquitoes since 1957, DEET continues to be the chemical of choice used in repellents. In 2005, the CDC began recommending alternatives to DEET for repelling mosquitoes. DEET has been in use for over 40 years and has a remarkable safety record. Only few hospitalizations have been reported, mainly due to gross overuse.
Picaridin, which is new to the U.S., has been used worldwide since
1998. It has proven to be as effective as DEET but is more pleasant to use
because it has a light, clean feel and is virtually odorless. Picaridin is safe
for children older than 2 months. This substance is marketed as Cutter Advanced.
Field trials comparing commercially available repellent formulations containing picaridin (1-piperidinecarboxylate acid, 2-(2-hydroxyethyl)-1-methylpropylester) and deet (N,N-diethyl-3-methylbenzamide) against mosquitoes in Northern Territory, Australia, were conducted. Three repellents were compared: Autan Repel containing 9.3% picaridin, RID containing 10% deet, and Bushman Ultra containing 80% deet in a gel. The predominant mosquito species collected were Culex annulirostris Skuse (63%), Ochlerotatus normanensis (Taylor) (19%), and Anopheles meraukensis Venhuis (8%). Autan Repel provided >95% protection against all mosquitoes for 2 h, RID for 7 h, and Bushman for >8 h. Against Cx. annulirostris, Autan Repel provided >95% protection for 5 h, RID for 7 h, and Bushman for >8 h. The study showed that both deet formulations provided significantly better protection against mosquitoes than picaridin (Autan Repel). All 3 repellents provided good protection against Cx. annulirostris, an important vector of arboviruses in Australia.
Oil of lemon eucalyptus is available under the Repel brand name. Oil of Lemon offers protection similar to low concentrations of DEET. Lemon eucalyptus is safe for children older than 3 years.
The chemical IR3535, better known as Avon's Skin-So-Soft, has also been marketed as a repellent in the U.S. in recent years. The efficacy of the repellent IR3535 was tested and compared with DEET using two laboratory colonies of phlebotomine sand flies, Phlebotomus mascittii and Phlebotomus duboscqi. P. duboscqi, originating from Senegal, is a proven vector of Leishmania major. IR3535 and DEET were tested at an effective concentration of 10% in ethanol on two (one male, one female) human volunteers. The mean protection time against P. duboscqi was 5.9h for both repellents, against P. mascittii 10 and 8h for IR3535 and DEET, respectively.
Rats exposed to liquid mosquito repellent (LMR) containing allethrin (3% w/w) 8-hrs/ day for a period of ninety days did not produce any signs of toxicity or death.
Paraguay- Cotton shirts soaked in lemon-scented citronella oil have been
launched by Pombero brand. Citronella oil comes from a perfumed grass and acts
as an insect repellent. Insect repellent apparel sold in the United States is
coated in permethrin, a manmade derivative of the chrysanthemum plant. But in
Paraguay, the shirts are a novelty. Government scientists are interested in
finding out whether they could provide extra protection from ailments like
malaria or dengue, an infectious disease transmitted by mosquitos.
Mosquito traps work by emitting substances that biting mosquitoes find attractive -- such as carbon dioxide, heat, moisture, and other mosquito-friendly byproducts. They attract, then trap or kill female mosquitoes.
Yosef Schlein and Gunter Muller of Jerusalem's Hebrew University report they eliminated virtually the entire mosquito population of a southern Israeli oasis by spraying a sugar solution mixed with "Spinosad" insecticide on acacia trees. The mosquitoes are more attracted to the acacia than other plant life. Acacias are common in Africa, where malaria has been on the rise due to environmental changes, drug resistance and mosquito resistance to conventional insecticides.
During August-September 2005, the New Hampshire Department of Health and Human Services reported seven cases of human eastern equine encephalitis virus (EEEV) disease, the first laboratory-confirmed, locally acquired cases of human EEEV disease reported from New Hampshire in 41 years of national surveillance. Also during August--September 2005, the Massachusetts Department of Public Health reported four cases of human EEEV disease, five times the annual average of 0.8 cases reported from Massachusetts during the preceding 10 years. Four of the 11 patients from New Hampshire and Massachusetts died. EEEV is transmitted in marshes and swamps in an enzootic bird- mosquito -bird cycle primarily by the mosquito Culiseta melanura. Bridge mosquito vectors (e.g., Coquillettidia perturbans, Aedes vexans, or Aedes sollicitans) transmit EEEV to humans and other mammals.
Mosquito and Malaria
Migration of the protozoan parasite Plasmodium through the mosquito is a complex and delicate process, the outcome of which determines the success of malaria transmission. The mosquito is not simply the vector of Plasmodium but, in terms of the life cycle, its definitive host: there, the parasite undergoes its sexual development, which results in colonization of the mosquito salivary glands. Two of the parasite's developmental stages in the mosquito, the ookinete and the sporozoite, are invasive and depend on gliding motility to access, penetrate and traverse their host cells.
The Anopheles annularis group of mosquitoes is widely distributed in Southeast Asia and may be locally important as malaria vectors.
Eau to Man
Scientists have isolated chemicals in the odor of people who don't get bitten and hope to use them to improve controls to prevent the spread of insect-borne diseases such as malaria, dengue and yellow fever in developing countries. Professor John Pickett of Rothamsted Research, a charitable scientific trust in England and researchers from Aberdeen University in Scotland used a technique known as gas chromatography-electroantennography to identify which components of the odour mosquitoes can detect. They are currently comparing their impact to insect repellents approved by the World Health Organisation (WHO). So far results have been promising, according to the researchers. In addition to mosquitoes, they are also looking at tics and other disease-carrying insects. They hope to develop a formula that will be marketed by 2009.
Natural Mosquito Repellent
Parasitol Res. 2014. Evaluation of the repellent effects of Nepeta parnassica extract, essential oil, and its major nepetalactone metabolite against mosquitoes.
Trop Biomed. 2013. The antimosquito properties of extracts from flowering plants in South Africa. Extracts of selected flowering plants, which are considered eco-friendly, are used for the treatment of numerous ailments and vector control worldwide. This has resulted in approximately 25 per cent of currently used drugs being derived from herbal sources. The aqueous and methanolic extracts of twelve plant species, Psidium guajava (pink fruit), Psidium guajava (white fruit), Psidium cattleianum var. cattleianum, Psidium guineense and Psidium X durbanensis, Achyranthes aspera, Alternanthera sessilis, Guilleminea densa, Capparis tomentosa, Leonotis leonurus, Dichrostachys cinerea and Carpobrotus dimidiatus, were tested for insecticidal activity, including larvicidal, adulticidal and repellent activities against the adult female mosquito, Anopheles arabiensis. The extracts of P. guajava (white fruit), C. tomentosa, L. leonurus,D. cinerea, and C. dimidiatus exerted a pronounced inhibitory effect on adult insects, while those of P. guajava (pink fruit), P. X durbanensis, P. cattleianum var. cattleianum, P. guineense, A. aspera, A. sessilis, and G. densa were ineffective and failed to satisfy the criteria set by the World Health Organization. In the tests for repellency against An. arabiensis, all the tested aqueous and methanolic plant extracts except those of A. sessilis repelled 80-100% of mosquitoes. The most effective mosquito repellents were the methanol and aqueous extracts of P. guajava (pink fruit), P. X durbanensis, P. cattleianum var. cattleianum, P. guineense, G. densa,L. leonurus and D. cinerea, which are potential sources of cost effective mosquito repellents to be utilized in malarial endemic areas.
mosquito repellent activities of Pine (Pinus longifolia, family: Pinaceae) oil.
J Vector Borne Dis. 2005. Malaria Research Centre (ICMR), 20-Madhuban, Delhi, India
Various plant-based products are safe and biodegradable alternatives to synthetic chemicals for use against mosquitoes. Oil of Pinus longifolia is traditionally used for protection against mosquitoes in some rural areas but there is no documented report of its use against mosquitoes. The present study was undertaken to scientifically evaluate the activity of Pine oil against mosquitoes. The oil was procured from the market and its contents were chemically analysed. Larvicidal activity of oil was tested in laboratory bioassays, while repellent action was studied during whole night bait collections in field by direct application on the skin and after its impregnation on mats. Results showed varying degree of larvicidal activity of Pine oil against mosquitoes with LC50 values ranging between 82 and 112 ppm. The Pine oil had strong repellent action against mosquitoes as it provided 100% protection against Anopheles culicifacies for 11 h and 97% protection against Culex quinquefasciatus for nine hours respectively. Electrically heated mats prepared from Pine oil provided, 94 and 88% protection against An. culicifacies and Cx. quinquefasciatus for 10 and seven hours respectively. Pine oil is effective against mosquito larvae at very higher doses which are not of any practical utility. However, Pine oil showed strong repellent action against An. culicifacies (malaria vector) and Cx. quinquefasciatus (pest mosquito). Thus its use could be popularised as mosquito repellent.
evaluation of New Mountain Sandalwood Mosquito Sticks and New Mountain
Sandalwood Botanical Repellent against mosquitoes in North Queensland,
J Am Mosq Control Assoc. 2006. Ritchie SA, Williams CR, Montgomery BL.
Dr. Edward Koch Foundation, PO Box 2964, Cairns, Queensland 4870, Australia.
The mosquito repellent efficacy of New Mountain Sandalwood Mosquito Sticks (containing 0.5% w/w essential oils) and New Mountain Sandalwood Botanical Repellent (containing soybean and geranium oils) was assessed. Tests were conducted in the field with 4 volunteers in a wooded area near Cairns, North Queensland, Australia. Predominant biting species were Verrallina funerea and Ve. lineata. A pair of burning Mosquito Sticks immediately upwind of the subject (acting as an area repellent) provided a 73.1% mean reduction in mosquito landing and probing over the 3-h test period. The Botanical Repellent and a DEET-based control were both 100% effective in preventing mosquito probing for 3 h. These data are consistent with other studies of area repellents in that such products provide significant protection from mosquito bites, albeit inferior to the protection provided by topically applied repellents.
properties of celery, Apium graveolens, compared with commercial repellents,
against mosquitoes under laboratory and field conditions.
Trop Med Int Health. 2005. Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand.
In our search for new bioactive products against mosquito vectors, we reported the slightly larvicidal and adulticidal potency, but remarkable repellency of Apium graveolens both in laboratory and field conditions. Repellency of the ethanolic preparation of hexane-extracted A. graveolens was, therefore, investigated and compared with those of 15 commercial mosquito repellents including the most widely used, DEET. Hexane-extracted A. graveolens showed a significant degree of repellency in a dose-dependent manner with vanillin added. Ethanolic A. graveolens formulations (10-25% with and without vanillin) provided 2-5 h protection against female Aedes aegypti. Repellency that derived from the most effective repellent, 25% of hexane-extracted A. graveolens with the addition of 5% vanillin, was comparable to the value obtained from 25% of DEET with 5% vanillin added. Moreover, commercial repellents, except formulations of DEET, showed lower repellency than that of A. graveolens extract. When applied on human skin under field conditions, the hexane-extracted A. graveolens plus 5% vanillin showed a strong repellent action against a wide range of mosquito species belonging to various genera. It had a protective effect against Aedes gardnerii, Aedes lineatopennis, Anopheles barbirostris, Armigeres subalbatus, Culex tritaeniorhynchus, Culex gelidus, Culex vishnui group and Mansonia uniformis. The hexane-extracted A. graveolens did not cause a burning sensation or dermal irritation when applied to human skin. No adverse effects were observed on the skin or other parts of the human volunteers' body during 6 months of the study period or in the following 3 months, after which time observations ceased. Therefore, A. graveolens can be a potential candidate for use in the development of commercial repellents that may be an alternative to conventional synthetic chemicals, particularly in community vector control applications.
In addition to repelling ticks, numerous studies have shown Buzz Away Extreme's mosquito repelling effectiveness under varying conditions. In one USDA study comparing eleven products, the formula earned a top rating by repelling three common species of mosquito for a mean average of 7.2 hours. In a field study conducted by Canada's University of Guelph, this formula proved to be 92% effective after 3 hours. A low percentage DEET-based formula was only 79% effective 3 hours after application.
Garli-Eze Insect Repellent for Livestock- Press release
2006 - San Clemente-based StableKare, an equestrian well-being specialty manufacturer has launched its new all-natural-ingredient, garlic-based insect repellant. The nutritional supplement, marketed under the brand name Garli-Eze is claimed by the manufacturer for the prevention of biting from irritating and disease carrying flies, mosquitoes and other insects. Garlic has long been used as an ancient remedy for a variety of ailments and has been extensively investigated both scientifically and clinically for its antibiotic and anti-hyperlipidemic activities and has been used in the past as a natural insect repellant for horses and other livestock. During the 1940s scientists isolated the active ingredient in garlic that is responsible for these benefits. This compound is called allicin. Until recently, allicin was not commercially investigated because of its inherent instability, foul smell and inability to be absorbed into the bloodstream without its natural garlic clove. Typically, once garlic is crushed, the measurable allicin compounds begin to degrade immediately. Garli-Eze claims to have stabilized and standardized the allicin content and buffered the garlic granules so it can be delivered into the digestive tract with no noticeable degradation to the active ingredient. Garli-Eze is available in 1-pound re-sealable foil pouches, which typically provides a 90-day supply for an average size horse. "As horse owners ourselves, we know what a hassle it is to store and handle big 5-pound drums of supplements. About StableKare: Founded in 2005, StableKare Brands, a division of DogEquine, LLC, is dedicated to manufacturing and marketing safe and effective companion animal supplements and food components that are scientifically formulated, using only natural ingredients.
How DEET works
The bug repellent DEET was thought to make mosquitoes unable to smell the sweet aroma of human sweat that alerts them that a meal of blood is nearby. DEET was first produced by government scientists in 1946 after the jungle warfare of World War II hammered home the need to prevent mosquito and other insect bites. It has been available to the public since 1957. DEET is the world's most widely-used topical agent against mosquitoes and other blood-eating insects.
New research suggests DEET, the widely used mosquito repellent, does not block the insects' sense of smell but simply stinks to them, U.S. Researchers managed to record the signals from individual neurons in the antennae, which mosquitoes use to smell, and determined that they were not blocked by DEET but stimulated in a way that suggested the odor was simply unpleasant. DEET, the common name for N,N-diethyl-3-methylbenzamide, is the most common active ingredient in insect repellents. The U.S. Centers for Disease Control and Prevention and other health groups recommend DEET as the best way to avoid the bites of mosquitoes, ticks and other disease-carrying insects. DEET was developed by scientists at the U.S. Department of Agriculture and patented by the U.S. Army in 1946.