Insect Spraying Pros and Cons

Published in Poisons Beware

For several years, the local councils of Jelsa, Stari Grad and Hvar have routinely sprayed the streets against mosquitoes, flies and other 'flying pests'. Is this a good thing?

Due warnings?

Bees, of course, are not among the targeted victims. When the spraying is due, beekeepers are routinely warned to close their hives. Over the years, I have found that very few beekeepers hear the warning, many don't heed it even if they do. Some have even told me that the spraying is "not very harmful" to bees.

The poisons used are said to be harmless to warm-blooded creatures. However, people with breathing problems are advised to stay inside and shut all windows and doors. Not much help to tourists staying in the campsites, nor to anyone on a night out when the spraying (known as 'fogging') starts at 22:00, finishing at 06:00 the next morning. When the spray-van passes up the road, it does not stop its poison-spreading to ask people if they are vulnerable to chest problems! As I experienced first-hand in 2012, to my dismay.

Although the sprayings take place during the summer season, they are only announced in Croatian. English-language websites, such as Total Hvar, are able to transmit them if they wish - if they happen to get the news in time. But at times the warning has been issued late. On occasion the spraying has happened earlier than the night advertised. In the past, notice was given in some local Council websites (notably Stari Grad's) and the local press. This year, there have been two sprayings to date just over a month apart - in late June and early August - with very little public notification.

Which poisons?

The names of the poisons used for the spraying are never publicly announced. Ekocijan, which covers Hvar, states on its website that its insecticides are "imported, environmentally friendly, biodegradable and harmless to warm-blooded creatures." But it stops short of naming them. After some research, I found that the Croatian Beekeepers' Association revealed in 2012 that on Hvar two pyrethroids, Cypermethrin and Permethrin, were being used in combination as the basis for the poisoning. In 2014, a product called Permex 22E was used, a combination of Permethrin with another pyrethroid, Tetramethrin.

According to the American Environmental Protection Agency (EPA), Pyrethroids are "synthetic chemical insecticides". They should not be confused with Pyrethrins, which are botanical insecticides derived from the pyrethrum flower, a type of chrysanthemum called buhać in Croatian. The chemical structure of Pyrethroids is based on that of Pyrethrins, but there are significant differences in the way the two insecticides are formulated as preparations for use.

Pyrethroid effects

Pyrethroid insecticides act on the target's nervous system, causing paralysis and death. Apart from killing mosquitoes, Cypermethrin is highly toxic to bees, water insects and fish, less so to birds. In humans, Cypermethrin poisoning can cause numbness, burning, loss of bladder control, vomiting, loss of co-ordination, coma, seizures, and death. It is also classified in the United States as a possible cause of cancer. Permethrin comes in different formulations, some more toxic than others. It is highly toxic to bees, aquatic life, fish and other wildlife. It is also toxic to cats. Its possible effects on humans are considered less dramatic than those of Cypermethrin, but it can affect the immune and endocrine systems. The EPA rates it as possibly carcinogenic. In view of their damaging effects on aquatic life, pyrethroids should not be applied near water sources - which are of course the breeding grounds for mosquitoes. Permethrin is not supposed to be sprayed where animals might forage. The EPA re-registration document for Tetramethrin (2010) classified the poison as a possible human carcinogen, and identified it as highly toxic to bees and aquatic organisms including fish and aquatic invertebrates. It can cause dizziness, breathing difficulties, coughing, eye irritation, gastrointestinal upset, blisters and skin rashes. The EPA document stated that: "Tetramethrin is used by individual homeowners or industrial / commercial property owners, in individual, isolated areas, and in small amounts as opposed to wide scale uses (i.e., for agriculture or mosquito abatement by public authorities)." For this reason, they did not test the effect of Tetramethrin on drinking water. Tetramethrin is not supposed to be used on or near foodstuffs.

Croatia and insect control

Croatia's Law for Protecting the Population Against Infectious Diseases (Zakon o zaštiti pučanstva od zaraznih bolesti) holds that controlling harmful insect populations through mechanical, physical, biological or chemical means is a general measure for preventing and controlling infectious diseases (Article 10). In practice, the most frequently used method is spraying with chemical poisons, as happens on Hvar. Local Councils are responsible for organizing the spraying, although apparentty some have failed to do so because of lack of funds. Earlier this year, the Croatian Parliament debated bringing in fines for authorities who did not undertake anti-insect measures.

Why anti-insect measures?

The Croatian Association for Disinfection and Control of Insects and Vermin (Hrvatska udruga za dezinfekciju, dezinksekciju i deratizaciju - HUDD), which collaborates with the Croatian Public Health Authority, has issued a leaflet for the public outlining measures of control by individuals as well as professional organizations. The leaflet describes the sins of the mosquitoes: "they can spread infectious diseases; their bites cause significant skin problems; they are a nuisance in relation to normal human activities; and when there are a lot of mosquitoes, they collectively cause dissatisfaction among citizens and tourists" - this last 'mosquito crime' is given special emphasis with bold enlarged type.

There is no doubt that mosquitoes can cause serious diseases. Historically, tropical countries were those worst affected, but there has been a steady spread around other countries, and in recent years mosquito-borne diseases have been surfacing in Europe. Despite the fact that thousands of people are bitten every day by mosquitoes and other insects in Europe, there has been no epidemic of these diseases. In Croatia, there were four cases of West Nile Virus in horses between 2001 and 2002, and two cases of Dengue fever in humans confirmed in 2010. There was a large outbreak of Dengue fever on the Portuguese island of Madeira at the end of 2012, totalling over 2,000 cases, without any reported deaths. The World Health Organization (WHO) estimates that there are about 500,000 cases of severe Dengue infection worldwide each year, of which about 2.5% (12,500) die, whereas tobacco causes about 6 million premature deaths each year, including more than 600,000 due to second-hand smoke.

Does anti-insect spraying work?

In early 2014, it was reported that the authorities in Osijek in northeastern Croatia were complaining that their efforts at controlling mosquitoes through spraying were undermined by invasions from neighbouring areas which were not using insect control measures. The Croatian government allocated 5 million kunas (654,000 euros, £518,000) to Osijek for the war against mosquitoes, with a further 4.5 million kunas (588,000 euros, £466,000) due from the city budget. These are very large sums in terms of the Croatian economy. Presumably similar incentives will be given to neighbouring regions to carry out anti-insect measures.

On Hvar, anti-mosquito spraying has been carried out at least twice annually for some years. In that time, the mosquito infestations have become noticeably worse. As I write, a few days after the latest spraying, tiger mosquitoes are gliding around in a little silent horde, at intervals feasting on the exposed parts of my arms and legs. During the evening and overnight, the tiger mosquitoes' noisy buzzing cousins take over. Most people on Hvar agree that the immedtiate effect of the spraying is to make the mosquitoes angry and more ferocious, but there's no evidence of the numbers reducing, quite the contrary.

The principle of fighting a war to kill off all the 'enemies' is faulty in every context. Our civilization has arguably been more successful in driving towards extinction species which in fact we want to preserve than in exterminating perceived threats to our wellbeing, whether bacteria, terrorists - or insects. There is a strong body of opinion against spraying poisons to control mosquitoes.   For instance, writing for the Environmental Association of Nova Scotia (EHANS), Canadian Rebecca Watson outlined the reasons why spraying is not the solution to potential diseases like West Nile Fever. It is said that insect control spraying can be relatively successful in the short term, if it is properly planned, targeted and timed. But even then, the use of poisons invariably leads to resistance in the target species, as happened when DDT was used in large quantities against malarial mosquitoes in the 1940s and 50s. Poisons also cause collateral damage, often reducing the target insects' natural predators, not to mention essential insects such as bees. 

Non-chemical methods of insect control

While spraying is widely used, there is debate over the best way to control disease-carrying mosquitoes. Methods other than chemical spraying are being developed. These include genetic control, which consists either of suppressing mosquito populations by introducing genetically modified mosquitoes with a lethal gene so that when they mate with wild mosquitoes they do not produce young, or of replacing the wild populations with GM mosquitoes which are less potent disease carriers. This method has been effective in reducing carrier mosquito populations, but there are question marks over its safety if the GE mosquitoes infect human blood.

Biological control consists of using natural predators to prevent mosquito populations from multiplying, such as mosquitofish (Gambusia affinis) and frogs. A variation is the Sterile Insect Technique (SIT), in which male mosquitoes sterilized by irradiation are released into the wild to mate with females. This reduces the targeted mosquito population as any offspring produced cannot survive to adulthood. One of the most promising alternatives to straightforward chemical methods of controlling mosquitoes is said to be the use of the bacterium Bacillus thuringiensis (Bt). However, even this has been found to have unwanted effects, possibly reducing biodeversity and affecting reproduction in birds.

Positive thinking

It is very easy to panic about the possibility of 'deadly diseases' smiting human populations. Outbreaks and epidemics are frightening events. Preventing diseases is complex. A lot depends on the conditions in which people live: worldwide, good health depends on clean water, a healthy environment, a safe food supply and pure air, to name but a few. Lifestyle habits also play their part in strengthening or undermining the human immune system, which is key to avoiding disease or being able to recover if an illness is contracted. Mortal enemies to good health are smoking, excess alcohol, over-eating unhealthy foods, under-eating and insufficient exercise.

There are practical measures which individuals can take to reduce the risks and nuisance from mosquitoes. Using citronella candles or electronic 'bug-zappers' can keep the numbers in your immediate vicinity down. Mosquito nets over windows can help prevent them from entering your environment. Bites can be soothed by plant-based creams such as Arnica. I mentioned that I am being bitten as I write: when I was young, I suffered strong reactions to mosquito bites, but in later years this ceased, for a number of reasons. One of my preventive measures is to take a vitamin B complex supplement, having read that it would help the problem. For me, it works. Dealing with life's challenges is individual, and every reasoning person should be free to choose his or her own way. 

Some, probably many of us want to avoid contact with poisons as far as possible in our lives. At present, on Hvar and elsewhere in Croatia, that freedom of choice has been removed. It's time to scrutinize the use of poisons in the environment and to understand how dangerous they are for the health of present and future generations. Non-toxic methods of dealing with potentially harmful creatures must be used in place of the chemical poisons which cause mass destruction of vital natural resources.

URGENT ACTION IS NEEDED!

© Vivian Grisogono 2014, updated 2016, 2017

POSTSCRIPT: The tragic case of Bobi, the dog who didn't need to die, has highlighted that in 2017, three years on from when this article was first written, the practice of large-scale insecticide spraying or 'fogging' on Hvar has gone from bad to worse. Four toxic chemicals in a lethal cocktail, sprayed round the streets with minimum warning: how can anyone justify that?

Comment with a useful link from the USA:
"Saw your article. Agree wholeheartedly. 
Indiscriminate spraying like Ekocijan does has been discontinued virtually everywhere in the civilized world.
Here for example is a paper from the US CDC http://wwwnc.cdc.gov/eid/article/7/1/70-0017_article
But I guess someone is making a nice living and does not feel the need for change..." Zdravko Podolski, August 7th 2014
 
Tips: Citronella oil, a natural insect repellent, and more
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