Commercial contact insecticides have at least two names, a chemical name, which is the scientific name and describes the chemical in the spray (e.g. pirimiphos-methyl), and a trade or brand name (e.g. Actellic, Syngenta) given to it by the chemical company. The same chemical, made by different companies will, therefore, have different names (one company may also use different names for the same chemical in different countries, or when presented as different formulations).
Organophosphorous insecticides
Most of the many organophosphorous insecticides that have been developed are of high or moderately high mammalian toxicity. Very few low or moderately low mammalian toxicity are suitable for use in food stores.
Pirimiphos-methyl (trade name Actellic, Syngenta)
Available as dusting powder, emulsifiable concentrate and ULV (ultra low volume) liquid, alone or in combination with permethrin (trade name Actellic Super, Syngenta) or with deltamethrin (trade name Sofagrain, Aventis CropScience). Pirimiphos-methyl is a fast-acting broad-spectrum insecticide with both contact and vapour action. It gives relatively long-lasting control of insect pests on inert surfaces such as wood, sacking and masonry in temperate conditions, and retains its activity when applied to stored agricultural commodities. Pirimiphos-methyl is useful against immature stages within the individual grains, and appears to be effective against many malathion-resistant strains. It can be used effectively against many beetles, especially Sitophilus and Tribolium spp., moths and mites, although it is not particularly effective against R. dominica and P. truncatus. The latter two species are more easily killed by synthetic pyrethroids such as permethrin or fenvalerate. To kill a broad range of pests, especially pest complexes where there are both Sitophilus spp. and P. truncatus, a mixture of actellic and a synthetic pyrethroid is used.
Chlorpyrifos-methyl (trade name Reldan, Dow)
Available as emulsifiable concentrate, ULV liquid and fogging concentrate.
Chlorpyrifos-methyl is a broad-spectrum insecticide of relatively low mammalian toxicity and moderate persistence with contact, stomach and respiratory action.
Chlorpyrifos-methyl has a very similar spectrum of activity to pirimiphos-methyl, and controls a wide spectrum of storage pests including beetles, weevils, moths, mites,
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and also several species with malathion resistance, although it is not effective against resistant strains of some bostrichid beetles.
Fenitrothion (trade names Folithion, Bayer; Sumithion, Sumitomo; Accothion, BASF) Available as emulsifiable concentrate, wettable powder, granules, dusting powder, ULV liquid and aerosol. Fenitrothion is a broad-spectrum insecticide used worldwide against pests of field crops, public health, forestry and storage. Fenitrothion has been widely used for grain protection in a number of countries for at least 20 years.
It is effective against most stored grain pests, although it is not fully effective against R. dominica. Fenitrothion is sometimes combined with pyrethrum or synthetic pyrethroids, for example, with fenvalerate.
Dichlorvos (trade names Nuvan, Syngenta; Vapona, BASF)
Available as emulsifiable concentrate, aerosol, granules, hot fogging concentrate, cold fogging concentrate, impregnated strips and oil-miscible liquid. Dichlorvos was introduced as an insecticide in the mid 1950s and has been widely used against stored-product, household, public health and field crop pests. It is an insecticide and acaricide (kills mites) with vapour, contact and stomach action, giving rapid knockdown. Dichlorvos is characterized by its high vapour pressure and its high insecticidal activity in the vapour phase. Dichlorvos can be applied as a space treatment in non-ventilated stores using a mist sprayer. The sprayer may be controlled by a time clock so that the treatment can be applied automatically to coincide with the time of maximum insect activity, usually early evening. Use of an automated timed application avoids the hazard of exposure to dichlorvos by operators and warehouse staff. It is useful for disinfesting grain brought into storage with live insects. Dichlorvos is very active against a wide spectrum of stored product pests, including larval stages within the grain and against moths. It has a short residual stability, particularly at higher temperatures and high moisture levels.
Malathion (trade names Cythion, BASF; MLT, Sumitomo; Agrothion, Syngenta) Available as emulsifiable concentrate, wettable powder, dusting powder, ULV liquid and aerosol. Malathion has been widely used in many countries for over 30 years. It has been employed against a broad spectrum of pests in agricultural, forestry, public health and food storage situations. Although it is possibly one of weakest of all the organophosphorous insecticides against stored-product pests, it has been responsible for saving enormous quantities of grain and other stored products from destruction. Malathion is still important in many parts of the world despite the development of strains of some pest species that are resistant. In the tropics it has now been largely superseded by pirimiphos-methyl (Actellic).
Pest management of insects
Carbamates
Carbaryl (trade name Sevin, Aventis CropScience)
Available as wettable powder, dusting powder, bait, suspension concentrate, granules and oil-miscible flowable concentrate. Carbaryl is an insecticide with contact and stomach action and has been used to control moths, beetles and other insect pests on more than 120 different crops. Although carbaryl is not particularly effective against the full spectrum of stored-product pests, it gives good control of R. dominica and thus can be used in conjunction with approved organophosphorous insecticides. Carbaryl is cheap, readily available and has a low acute and chronic mammalian toxicity.
Bendiocarb (trade names Ficam, Aventis CropScience; Garvox, Aventis CropScience)
Available as granules, wettable powder, suspension concentrate, dusting powder, ULV liquid, aerosol and seed treatment. Bendiocarb is a contact and stomach-acting insecticide that has been used against a wide range of insects, including cockroaches, ants and flies in public health, food processing and handling, household, public transport and industrial situations. It is also effective against the major stored-product insects and is sometimes used as a surface treatment, but is not generally accepted for use on grain.
Natural pyrethroids Natural pyrethrum
Pyrethrum is the oily extract from the flower of pyrethrum, Tanacetum cinerariifolium, and refers to the plant, flower or the crude, concentrated or refined extract.
Pyrethrum has been known as a natural pesticide for many generations, having localized usage, and has been used for protecting grain and destroying grain pests for at least 50 years. Pyrethrum has a very low acute oral toxicity allied with a rapid knockdown action against a wide variety of insects. One disadvantage, however, is that insects that are rapidly immobilized by pyrethrum and ‘knocked down’ often recover after several hours, as they have the ability to detoxify the small amount of pyrethrum they receive. To overcome this, synergists such as piperonyl butoxide, or small amounts of other contact insecticides such as synthetic pyrethroids, are added to pyrethrum sprays to enhance their effect and reduce costs. A second potential disadvantage of pyrethrum is that it is not very stable and its insecticidal activity is rapidly lost from treated surfaces, particularly in the presence of direct or indirect sunlight. It is, however, useful for treating an active infestation and, if used in combination with a synergist or organophosphorous insecticide, can provide residual protection in bulk grain. Pyrethrum is effective against the spectrum of stored-product pests including moths and their larvae, although where the control of moths is the major requirement, unsynergized pyrethrum preparations are most cost-effective, for synergists do not improve the effectiveness of pyrethrum against moths.
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Synthetic pyrethroids
Permethrin (trade names Ambush, Syngenta; Talcord, BASF; Eksmin, Sumitomo) Available as emulsifiable concentrate, wettable powder, ULV liquid, aerosol, dusting powder and water-dispersible granules. Also available in combination with pirimiphos-methyl. Permethrin is a stomach and contact insecticide, effective against adults, larvae and eggs of insect pests, including those of field crops, public health, animal house and storage situations. Permethrin is used to control a wide range of stored-product pests, but it is most useful in conjunction with organophosphorous insecticides, as it is relatively weak against non-bostrichid beetle species. The combination of organophosphates and permethrin can be used to control insects that are tolerant or resistant to organophosphates. The efficacy of permethrin can be increased significantly by combining it with the synergist piperonyl butoxide.
Deltamethrin (trade name K-Othrine, Aventis CropScience)
Available as emulsifiable concentrate, wettable powder, ULV liquid, suspension concentrate, granules, dusting powder and fogging concentrate. Also available in combination with pirimiphos-methyl. Deltamethrin is used against pests of agricultural field crops, public health, forestry, animal houses and stored-product situations. Deltamethrin is one of the latest synthetic pyrethroids to be introduced, and is very stable. It is highly potent against the majority of stored product pests, being effective at low doses in the range of 1–2 mg/kg.
Fenvalerate (trade names Sumicidin, Sumitomo; Fenkill, United Phosphorous;
Sumitox, Aventis CropScience)
Available as emulsifiable concentrate, ULV liquid and suspension concentrate.
Fenvalerate is an insecticide and acaricide with contact and stomach action. It controls a wide range of pests on agricultural field crops and in public health situations, including those resistant to organochlorine, organophosphorous and carbamate insecticides. Fenvalerate is registered in many countries in Europe, Asia and the Americas, and also in Australia where it has undergone silo-scale field trials as a stored-grain protectant. Fenvalerate has been shown to be effective at low doses against R. dominica and at higher doses against most other storage pests. It is used in combination with organophosphorous insecticides (e.g. malathion or fenitrothion) and can be synergized with piperonyl butoxide.
Bioresmethrin (trade name Isathrine, Aventis CropScience)
This is available as emulsifiable concentrate, aerosol, ULV liquid and wettable powder. Bioresmethrin was one of the first successful synthetic pyrethroids developed in the 1960s. It is a potent contact insecticide producing rapid knockdown against a wide range of insect pests. It has been used against cockroaches, flies and mosquitoes in household and food premises and also as a grain protectant and disinfectant. Bioresmethrin is synergized by a factor of between two- and ninefold by piperonyl butoxide. It has proved particularly effective against R. dominica, and can
Pest management of insects
be used in combination with organophosphorous insecticides against grain pests, enabling the amount of organophosphorous insecticide applied to be reduced considerably. It is used mainly in Australia.