What Is The Difference Between An Insecticide And An Insecticidal Soap?
The difference between insecticide and insecticidal soap is its action on insects. Insecticides try to kill insects by poisoning or by disrupting transmissions between synapses, meanwhile, insecticidal soap works by breaking down the cellular structure of the insects.
Insecticidal soap is a relatively simple product that works on contact and acts on the physiology of insects to kill them. It is generally harmless to mammals, birds, non-target insects, and the environment. It can be insufficient to control bad infestations.
Insecticides are poisons, often acting on the neurological systems of target insects. They are effective but can be unintentionally harmful to non-target insects, birds, and mammals, to human beings and to the environment.
What Is An Insecticide?
An insecticide is a substance that kills insects. Insecticides may also kill other non-insect pests such as snails and slugs. They are generally used to kill insect pests which are in some way threatening to human activities, very often insects that are damaging a food crop.
According to the US EPA’s most recent figures, in 2012, the world market for insecticides was worth just over $16 billion, up from $12.4 billion in 2008 (source). Some 50% of this figure is accounted for by use in homes and gardens.
How Do Insecticides Work?
An insecticide kills the target pest when the pest eats it or comes into contact with it, depending on the category of insecticide and the pest involved. Insecticides also cover ovicides and larvicides, which kill insect eggs and larvae respectively. A familiar example of this is the insecticides that pet owners use to kill fleas on their dogs and cats.
Some insecticides are designed to be carried by an adult insect back to the nest, where juveniles and other adults come into contact with it, causing the whole nest to die.
Insecticides may kill on contact, or they may kill slowly as the poison is absorbed into the insect’s system, by breathing it in or eating it.
The main categories of insecticidal chemicals include:
- Organochlorides – these work on contact and damage the insect’s nervous system.
- Carbamates and Organophosphates – these also work on contact and damage the nervous system of the insect
- Pyrethroids – mimic the way the natural insecticide pyrethrum works, and these are often found in household insecticides such as fly spray
- Neonicotinoids – derivatives from nicotine, these work very fast on contact
- Ryanoids – mimics a naturally occurring substance, and blocks the transmission of calcium in the skeleton and muscles
Here are some useful tips for applying insecticides:
What Is An Insecticidal Soap?
Insecticidal soap works differently from a regular insecticide. Insecticidal soap has been used for hundreds of years, and although it isn’t known precisely how it works, it is thought to damage an insect’s cellular structure. It is used for controlling pests that are predating plants, very often greenfly and other aphids. Insecticidal soap is sprayed on to an affected crop and kills on contact.
Insecticidal soaps are made from potassium salts of fatty acids. These will affect the insects, but not the plants that are hosting the insects. Soaps may not feature the word “soap” on the label, instead, you might find the words “potassium laurate” or “sodium salts of fatty acids”.
Possible mechanisms for the damage to the target insects could be:
- Soap enters the trachea of the insect and damages membranes
- Soap may dissolve the insect’s wax coating leading to death by dehydration
- Soap may be disruptive of the insect’s hormones
- Soap may interfere with the insect’s ability to breath
- Soap may have a generally negative effect on the insect’s metabolism
It can be seen that most of these possible reasons for the effectiveness of insecticidal soap involve a physical effect on the insect, rather than a poisoning as such.
Insecticidal soaps are most effective on soft-bodied small insects such as thrips, mites, greenfly, whitefly, blackfly, mealybugs and scale insects. They can be somewhat effective against larger insects such as caterpillars. Beneficial predator insects such as ladybugs and wasps are not usually affected by insecticidal soaps, and this makes them useful especially in confined spaces such as greenhouses, where predator insects are encouraged.
Interestingly, insecticidal soap has also been found to be effective against powdery mildew and can be used to remove moss and algae.
Did you know you can prepare your own insecticidal soap at home? Check out the video below:
How To Use Insecticidal Soap
Insecticidal soap is usually used at a 2% concentration with water – soft rather than hard water is best. If you have hard water in your area, you could collect rainwater to use for your insecticidal soap mixture.
Because it works on contact alone, you must make very sure that plants are thoroughly soaked with the soap. Pay particular attention to the undersides of leaves and the nodes between stalk and leaves, where insect pests like to hang out. It’s a good idea to also spray the soil, as pests can spend their day in and on the soil, coming out at night. The best time to spray is at the end of the day.
Some plants are adversely affected by insecticidal soap sprays, so it is usually best to test the spray on just one plant or part of a plant before going ahead with a full-scale application. An application a few times a week is advisable.
Is Insecticide Safe?
Insecticides are poisons and should be regarded as unsafe. Having said that, if used correctly, their benefit might outweigh the harm they do.
Harm from insecticides comes into the following general categories:
- Damage to non – target insects, for example, ladybugs and bees
- Damage to birds which may eat poisoned insects or poison granules
- Damage to mammals which may come into contact with poison granules
Organochlorine poisons such as DDT, when absorbed by predatory birds, results in the shells of their eggs being too thin to survive. This led to the ban of such insecticides throughout most of the world
Unintended transfer of insecticides by means of runoff and percolation can mean that poisons reach wildlife, such as fish and insect life in rivers, resulting in unintended deaths
The decline and in some cases, the collapse of bird populations. The shortage of food insects or the eating of poisoned insects has played its part in the large scale collapse of some bird populations. (The bird population of North America has decreased by 29%, or three billion birds, over the past fifty years.)
Damage to bee populations has also resulted, leading to a lack of sufficient pollinators for food crops, and consequent unintended impacts on food production.
Dangers To Humans From Insecticides
Insecticide residues can be found in many foods that we eat. Some of the biggest culprits are fruits that are eaten un-peeled, such as strawberries and peaches.
Farmers who have routinely used pesticides for many years have been shown to be vulnerable to a variety of illnesses.
The effects of insecticide poisons on humans using insecticides can include immediate effects such as rashes. blisters, burning and stinging of the eyes, nose, mouth, and throat, problems breathing, dizziness, feelings of nausea, cold and flu-like symptoms and more.
Long term effects include cancers such as leukemia, birth defects, liver damage, lung damage, kidney problems and more. These effects may not make themselves evident for years after use.
When To Use An Insecticide, And When To Use An Insecticidal Soap
For a minor infestation of soft-shelled insects, then it is probably a good plan to start out by using insecticidal soap. Because soap has little or no toxicity for mammals, then it is the only solution for an insect issue that arises at or very near the day of harvest. Insecticidal soap is permitted for use under these circumstances, unlike insecticides, which have a quarantine period before food sprayed with them can be consumed.
Insecticidal soap is permitted under most organic regimes. It’s safe for use where there are children, birds or domestic animals, so it may well be the first choice for the home gardener or smallholder.
Insecticides, if applied correctly, are very effective. However, they may kill creatures that are not targeted, such as beneficial insects, birds, mammals, and even human beings. For example, slug pellets are eaten by slugs and snails, which are then in turn eaten by birds such as song thrushes. The poison contained in the mollusk is concentrated in the body of the bird, which may subsequently die.
Pesticide effects on crops
Humans who eat crops treated with insecticides are consuming a small quantity of insecticide with their food. Although it is unclear how damaging this is to human health, on the precautionary principle, it seems best to avoid ingesting pesticides, especially for the young, the elderly, and those with impaired health.
For this reason, insecticides should only be used when a crop is at risk of significant damage. They should always be used strictly according to the directions on the product, and if they are used on food crops, withdrawal periods should be strictly observed to avoid damage to human health.
If an insecticide approved for an organic regime, for example, pyrethrum would be effective, this should be the first choice to ensure maximum safety. (It should be noted that even chemicals such as pyrethrum are not entirely harmless)
Conclusion
Consumers are voting with their money and turning more and more to insecticide-free food. The US market in 2018 for organic fruit and vegetables, in other words, fruit and vegetables produced without the use of pesticides, except for those allowed in an organic regime, was $17.4 million. The overall organic food market is worth $48 million and is expected to grow exponentially in future years.