Pyrethroid insecticides, bifenthrin

Two synthetic pyrethroid insecticides, bifenthrin and permethrin (3-phenoxybenzyl (lR5)-cis-fra s-3-(2,2-dichlorovinyl)-2,2-dimcthylcyclopropane-carboxylate), are the major runoff constituents considered in our monitoring and evaluation studies. Bifenthrin has a solubility of <1 ppb, and a Koc of240,000 ml g. Permedirin has a solubility of 6 ppb in water, and a Ka- of 100,000 ml g (5). The stroi adsorption on soil suggests that a large fiaction of the pesticide is associated wifii die suspended solids in nursery runoff. This determines that the downstream distribution of these pesticides is closely related to distribution of sediments, and that practices aiming to remove suspended solids from runoff will also be effective in reducing the level of these pesticides. 

The insecticidal activity and structure-activity relationships of novel pyrethroids prepared by reacting methyl phenyl substituted pyrazole methanols with dichloro chrysanthemic acid chloride are reported. These pyrethroids are active on tobacco budworm, fall armyworm, southern corn rootworm, and aster leafhopper, generally in the concentration range of 1000-250 ppm. Although less active than the pyrethroid standard bifenthrin, the overall structure-activity of these pyrazole pyrethroids with regard to substitution patterns is similar to that previously observed with bifenthrin analogs. 

Seven pyrethroid insecticides (allethrin, cypermethrin, tetramethrin, bifenthrin, permethrin, fenpropathrin, fenvaleiate) extracted from surface water samples were... 

J-M Hougard, S Duchon, M Zaim, and P Guillet. Bifenthrin A useful pyrethroid insecticide for treatment of mosquito nets. J. Med. Entomol. 39 526-533, 2002. 

This chemical is used for the control of cone worms, seed bugs, seed worms, and other insects and mites. The USEPA has classified bifenthrin as toxicity class II, meaning it is moderately toxic.4,5 Bifenthrin is a member of the pyrethroid chemical class. It is an insecticide and acaricide that affects the central nervous system (CNS) and causes paralysis in insects.6,7 It is highly toxic to fish and aquatic organisms. 

Yu and Nguyen (1996) showed that selection of a strain of diamondback moth (Plu-tella xylostella) with permethrin for 21 generations resulted in over 600-fold resistance to permethrin in this strain. The resistant strain was also cross-resistant to all pyrethroids tested, including bifenthrin, fenvalerate, esfenvalerate, A.-cyhalothrin, fluvalinate, and tral-omethrin. However, it remained susceptible to organophosphate, carbamate, cyclodiene, neonicotinoid, avermectin, and microbial insecticides tested. Biochemical studies indicated that pyrethroid resistance observed in this strain was most likely due to decreased target site sensitivity. 

Pyrethrins and Pyrethroids Absorption Eluman toxicity Exposure symptoms Pesticide uses Exemplars Inhalation, ingestion Low human toxicities by themselves Irritating to mouth, nose, throat Insecticides and acaricides Pyrethrin, dimethrin, fenvalerate, permethrin, bifenthrin... 

CF3CCl2-substituted alcohols in good yields. In this case, when insitu-geaeiaied zinc alkoxides are subsequently treated with AC2O and zinc dust at 50°C, trifluoromethylated alkenes can be obtained in good yields (Scheme 26.33). This practical one-pot synthesis can be applied for the preparation of highly potent insecticides, so-called synthetic pyrethroids, such as bifenthrin and others. ... 

---