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Development of Silafluofen-Based Termiticides in Japan and Thailand.

Katsuda Y, Minamite Y, Vongkaluang C - Insects (2011)

Bottom Line: Additional silafluofen product lines include anti-termitic plastic sheets which are laid under buildings.On the other hand, in Thailand, we proceeded with development works of silafluofen-based termiticides from 2005 by starting laboratory efficacy tests and field efficacy tests in Phuket.Both laboratory and field tests showed good efficacy as a soil termiticide, suggesting that the material will perform well for commercial use in high biological hazard environments such as Thailand and can be used in environments close to water where fish toxicity might be a concern with other pyrethroids.

View Article: PubMed Central - PubMed

Affiliation: Dainihon Jochugiku Co., Ltd., 1-11, 1-Chome, Daikoku-cho, Toyonaka, Osaka 561-0827, Japan. y.katsuda@kincho.co.jp.

ABSTRACT
With the advancement from natural pyrethrins to synthetic pyrethroids, their applications have expanded from household insecticides for indoor use against sanitary pests to outdoor use for agriculture, forestry, animal health, termite control, and many other pest situations. However, high fish toxicity and development of pyrethroid resistance in some pests have been cited as common shortcomings of pyrethroids. To overcome these pyrethroid problems such as high fish toxicity, Katsuda and fellow scientists invented silafluofen by introducing a silicone atom into the pyrethroidal chemical structure in 1984. In addition to the high insecticidal activity and low mammalian toxicity, this compound features low fish toxicity, chemical stability under sunlight, in the soil and under alkaline environments. These features make silafluofen unique among pyrethroids. In Japan, silafluofen has been used as an agricultural insecticide for 15 years since 1995 for various plants, especially useful for paddy rice protection because of its low fish toxicity. Over the last 20 years, silafluofen-based termiticides including emulsifiable concentrate (EC) and oil formulations have been widely used in Japan for soil treatment and timber treatments. Additional silafluofen product lines include anti-termitic plastic sheets which are laid under buildings. In this paper, literature on the development of silafluofen and its use in Japan are reviewed. On the other hand, in Thailand, we proceeded with development works of silafluofen-based termiticides from 2005 by starting laboratory efficacy tests and field efficacy tests in Phuket. Both laboratory and field tests showed good efficacy as a soil termiticide, suggesting that the material will perform well for commercial use in high biological hazard environments such as Thailand and can be used in environments close to water where fish toxicity might be a concern with other pyrethroids.

No MeSH data available.


Related in: MedlinePlus

Chemical structure of silafluofen.
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f1-insects-02-00532: Chemical structure of silafluofen.

Mentions: To overcome these environmental problems with pyrethroids, additional structural modifications were made that led to the invention of silafluofen (Figure 1) in 1984 [13-16]. The unique feature of silafluofen includes the introduction of a silicone atom into the pyrethroidal chemical structure. This new and novel compound is quite different in structure from the prototype pyrethrins. It is certain, however, that the idea of sila-substitution in pyrethroids emerged in the course of pyrethroid development. Interestingly, the findings on silafluofen were independently published almost at the same time in Japan (1984 in terms of patent application), Germany (1985) [17] and USA (1986) [18]. The mode of action for silafluofen involves its actions on the neuroaxonal sodium channels: it is still considered to be a pyrethroid [19]. While pyrethroids are considered a contact poison, silafluofen is noticeably different and acts both as contact and stomach poisons. In Japan, fish toxicity is classified into the following three classes based on the LC50 values for carp: A rank (>10 ppm), B rank (0.5–10 ppm), and C rank (<0.5 ppm). Generally, pyrethroids including bifenthrin are considered highly toxic to fish and belong to C rank except for etofenprox and cycloprothrin that both belong to B rank group. In contrast, silafluofen is the only synthetic pyrethroid in A rank, because of its low toxicity to fish. The unique safety of silafluofen is considered a favorable characteristic and makes it highly valued in its use. Unlike other pyrethroids, such as bifenthrin, which are ester compounds and decompose easily under alkaline conditions, silafluofen is chemically stable. The linkage between carbon and silicon atoms stabilizes silafluofen when applied to alkaline soils. For example, a stability test of test compounds with mortar (pH of water-extract: 12.8) revealed that silafluofen gave a remarkably high recovery rate of more than 90% at 50 °C after 4 week storage whereas bifenthrin almost decomposed within one week [16]. In summary, silafluofen superiority over pyrethroids includes its patent insecticidal activity, low mammalian toxicity described below [20], low fish toxicity [20], mode of action that includes both contact and stomach poisons, and chemical stability in the alkaline soil. The latter three characteristics are very different from those of conventional pyrethroids.


Development of Silafluofen-Based Termiticides in Japan and Thailand.

Katsuda Y, Minamite Y, Vongkaluang C - Insects (2011)

Chemical structure of silafluofen.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4553446&req=5

f1-insects-02-00532: Chemical structure of silafluofen.
Mentions: To overcome these environmental problems with pyrethroids, additional structural modifications were made that led to the invention of silafluofen (Figure 1) in 1984 [13-16]. The unique feature of silafluofen includes the introduction of a silicone atom into the pyrethroidal chemical structure. This new and novel compound is quite different in structure from the prototype pyrethrins. It is certain, however, that the idea of sila-substitution in pyrethroids emerged in the course of pyrethroid development. Interestingly, the findings on silafluofen were independently published almost at the same time in Japan (1984 in terms of patent application), Germany (1985) [17] and USA (1986) [18]. The mode of action for silafluofen involves its actions on the neuroaxonal sodium channels: it is still considered to be a pyrethroid [19]. While pyrethroids are considered a contact poison, silafluofen is noticeably different and acts both as contact and stomach poisons. In Japan, fish toxicity is classified into the following three classes based on the LC50 values for carp: A rank (>10 ppm), B rank (0.5–10 ppm), and C rank (<0.5 ppm). Generally, pyrethroids including bifenthrin are considered highly toxic to fish and belong to C rank except for etofenprox and cycloprothrin that both belong to B rank group. In contrast, silafluofen is the only synthetic pyrethroid in A rank, because of its low toxicity to fish. The unique safety of silafluofen is considered a favorable characteristic and makes it highly valued in its use. Unlike other pyrethroids, such as bifenthrin, which are ester compounds and decompose easily under alkaline conditions, silafluofen is chemically stable. The linkage between carbon and silicon atoms stabilizes silafluofen when applied to alkaline soils. For example, a stability test of test compounds with mortar (pH of water-extract: 12.8) revealed that silafluofen gave a remarkably high recovery rate of more than 90% at 50 °C after 4 week storage whereas bifenthrin almost decomposed within one week [16]. In summary, silafluofen superiority over pyrethroids includes its patent insecticidal activity, low mammalian toxicity described below [20], low fish toxicity [20], mode of action that includes both contact and stomach poisons, and chemical stability in the alkaline soil. The latter three characteristics are very different from those of conventional pyrethroids.

Bottom Line: Additional silafluofen product lines include anti-termitic plastic sheets which are laid under buildings.On the other hand, in Thailand, we proceeded with development works of silafluofen-based termiticides from 2005 by starting laboratory efficacy tests and field efficacy tests in Phuket.Both laboratory and field tests showed good efficacy as a soil termiticide, suggesting that the material will perform well for commercial use in high biological hazard environments such as Thailand and can be used in environments close to water where fish toxicity might be a concern with other pyrethroids.

View Article: PubMed Central - PubMed

Affiliation: Dainihon Jochugiku Co., Ltd., 1-11, 1-Chome, Daikoku-cho, Toyonaka, Osaka 561-0827, Japan. y.katsuda@kincho.co.jp.

ABSTRACT
With the advancement from natural pyrethrins to synthetic pyrethroids, their applications have expanded from household insecticides for indoor use against sanitary pests to outdoor use for agriculture, forestry, animal health, termite control, and many other pest situations. However, high fish toxicity and development of pyrethroid resistance in some pests have been cited as common shortcomings of pyrethroids. To overcome these pyrethroid problems such as high fish toxicity, Katsuda and fellow scientists invented silafluofen by introducing a silicone atom into the pyrethroidal chemical structure in 1984. In addition to the high insecticidal activity and low mammalian toxicity, this compound features low fish toxicity, chemical stability under sunlight, in the soil and under alkaline environments. These features make silafluofen unique among pyrethroids. In Japan, silafluofen has been used as an agricultural insecticide for 15 years since 1995 for various plants, especially useful for paddy rice protection because of its low fish toxicity. Over the last 20 years, silafluofen-based termiticides including emulsifiable concentrate (EC) and oil formulations have been widely used in Japan for soil treatment and timber treatments. Additional silafluofen product lines include anti-termitic plastic sheets which are laid under buildings. In this paper, literature on the development of silafluofen and its use in Japan are reviewed. On the other hand, in Thailand, we proceeded with development works of silafluofen-based termiticides from 2005 by starting laboratory efficacy tests and field efficacy tests in Phuket. Both laboratory and field tests showed good efficacy as a soil termiticide, suggesting that the material will perform well for commercial use in high biological hazard environments such as Thailand and can be used in environments close to water where fish toxicity might be a concern with other pyrethroids.

No MeSH data available.


Related in: MedlinePlus