Residual action

Rya.nia., The root and stem of the plant yania speciosa family Flacourtiaceae, native to South America, contain from 0.16—0.2% of iasecticidal components, the most important of which is the alkaloid ryanodine [15662-33-9] C25H250 N (8) (mp 219—220°C). This compound is effective as both a contact and a stomach poison. Ryanodine is soluble ia water, methyl alcohol, and most organic solvents but not ia petroleum oils. It is more stable to the action of air and light than pyrethmm or rotenone and has considerable residual action. Ryania has an oral LD q to the rat of 750 mg/kg. The material has shown considerable promise ia the control of the European com borer and codling moth and is used as a wettable powder of ground stems or as a methanohc extract. Ryanodine uncouples the ATP—ADP actomyosia cycle of striated muscle. 

Synthetic Pyrethroid Insecticides. Elucidation of the chemical stmctures of the naturally occurring pyrethmm esters, their rapid and selective insecticidal action, and their high cost stimulated the search for effective synthetic derivatives (13,17,21). Since the 1940s, stmctural optimisation has produced an array of broad-spectmm insecticides with activity 10- to 20-fold greater than other types of insecticides, and with extended residual action. These synthetic pyrethroids have become one of the most important classes of insecticides with world aimual production estimated at 6000 t (21). 

Tetradifon [116-29-0], 2,4,5,4 -tetrachlorodiphenyl sulfone (141), is a crystalline soHd (mp 148°C). It is soluble in water to 200 mg/L. Tetradifon is stable to the action of acid and alkaUes, light and temperature, and has a very prolonged residual action. It is active against all stages of mites and has an oral... 

The residual toxicity of the pure gamma isomer was found to be equivalent to that of ordinary commercial benzene hexachloride. Commercial usage has shown that the residual action is effective for a longer time with dust or wettable powder spray applications than with emulsive solvent-type formulations. The over-all residual life of the chemical is on the order of 4 to 8 days as compared to 14 to 21 days for DDT. This is, of course, adequate residual life for good insect control in most cases and the shorter... 

Aldrin, like chlordan, exhibits residual effectiveness under field conditions for somewhat less than 3 weeks. Even when aldrin is applied at the uneconomical and unnecessary rate of 5 pounds per acre, leafy material so treated exhibits only slight insect toxicity after 3 weeks. Aldrin, therefore, falls into that class of materials which exhibit pronounced initial toxicity but relatively short residual action. 

Residual action moderate mobility and ready availability to roots and soil-borne organisms lo - lo 0.5 - 20... 

Residual action on plant surfaces. Many crop protection agents exert their effects by residual action following application to plant surfaces. In addition to photochemical stability. 

None of the other chemicals tested in the second series showed more promise than DDT, although some of the data were rather fragmentary. Certainly, none of the materials would be expected to have the residual action of DDT, which, from the settling of the larger fog particles, produced a sufficient deposit of DDT on horizontal, face-up surfaces, to have a residual effect for several weeks... 

Residual action to avoid nonregular or jagged disinfections (advantage compared to not persistent effect of UV disinfection systems)... 

Propargite is an acaricide with residual action, powders and emulsifiable concentrates. 

The residual action can be studied by spraying a range of surfaces and storing some samples for future exposures. The application should be made in a manner which is considered practical. 

Lotions and mists for the control and rcpellency of ear mites of dogs/puppies. cals/kittens, and rabbits are frequently formulated with PBO. A typical formulation will contain 0.15% pyrethrins synergized at a I 10 ratio with PBO-Since synergized pyrethrins are not cholinesterase inhibitors, they may be used in conjunction with flea and tick dips, collars and oral medications- Products based on pyreth ram and PBO offer veterinarians safe, effective residual action without (he inclusion of toxic additives and without restrictions on repeat applications or concomitant treatments with other insecticides or anthelmintics (MacDonald and Miller, 1986). 

Residual action against fleas for up to 8 days can be obtained with a formulation containing 0.15% pyrethrins and 0,70% PBO in a dual-synergist, microencapsulated system. 

It has a long residual action. Spraying with its aqueous solution protects plants for 18-26 days against sucking insects. 

Azinphos-methyl and phosmet are typical contact insecticides with high stability and thus with a long residual action, whereas methidathion, readily absorbed by the leaf tissues, is an insecticide possessing systemic properties. The oral lDjq of... 

Contrary to most phosphoric acid esters with acaricidal action, neither of the two compounds has systemic properties. Both have a long residual action. The oral ld jg of carbophention for rats is 28-100 mg/kg, and that of phenkapton 200-260 mg/kg. 

The adsorption process also proceeds in organic soils, but the situation is more complicated and not completely clear. Bipyridylium herbicides are strongly adsorbed and thus deactivated by organic soil. However, in peat soils, for example, adsorption is often slow or incomplete, so that residual action must be reckoned with (OToole, 1965). 

Because of its basicity methazole is strongly adsorbed in the soil, thus remaining in the upper layer of a few centimetres. Methazole is slowly degraded in the soil its residual action must therefore be taken into consideration. 

In some cases it is found that the action of defoaming agents may depend on the concentration of the surfactant present. If the surfactant concentration is below the cmc, the defoamer will usually be most effective if it spreads as a lens on the surface rather than as a monolayer film. Above the cmc, however, where the defoamer may be solubilized, the micelles may act as a reservoir for extended defoaming action by adsorption as a surface monolayer. If the solubilization limit is exceeded, initial defoaming effect may be due to the lens spreading mechanism with residual action deriving from solubilized material. 

Sevin is a effective insecticide for the Mexican bean larva and adults, bean aphids, armyworms, German roaches, rice weevil. Eastern caterpillars, milkweed bug and Colorado potato beetle. Sevin is a particularly effective insecticide, possessing a combination of desirable properties. Its broad spectrum of activity, its long residual action, and its effectiveness against insects which are resistant to many common types of Insects and its low mammalian toxicity combine to make it one of the most outstanding insecticides ever developed. 

Some have shorter residual action or protection times. Costs may be higher than synthetic compounds. Supplies of natural products can be subjected to interruption due to crop failures. 

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