Permethrin resistance

Yoon KS,GaoJ-R, Taplin D, etal. Permethrin-resistant human head lice, Pediculus capitis, and their treatment. Arch Dermatol 2003 139 994-1000. 

Hydrolases. Hydrolytic mechanisms are also important in insecticide resistance, despite the apparent low activities in resistant insects when compared to mammalian enzymes (Table III). Some strains of resistant mosquitoes (22), Tribolium beetles (24), and Indianmeal moth (22) have specific resistance for malathion and similar carboxylester insecticides. This is due to increased catalytic hydrolysis, possibly through production of a more efficient enzyme (25.26). Californian tobacco budworms with low level permethrin resistance exhibited twice the normal activity of trans-permethrin carboxylester hydrolase (27). 

Toloza, A. C., Lucia, A., Zerba, E., Masuh, H., Picollo, M. I. 2010. Eucalyptus essential oil toxicity against permethrin-resistant Pediculus humanus capitis (Phthiraptera Pediculidae). Parasitol. Res. 106(2) 409-414. 

Insecticide-susceptible strains of body louse from Israel (IS-BL) and head lice from Panama (PA-HL) and Ecuador (EC-HL) have been previously described 10,14). Another permethrin-susceptible strain of head louse was collected from Seoul, Korea (KR-HL). Permethrin-resistant strains of head louse were obtained from Western Massachusetts (MA-HL), Plantation, Florida (FL-HL), Homestead, FL (SF-HL), San Bernardino County, California (SC-HL) and four locations in Texas (TCC-HL, TMF-HL, TMS-HL and TSA-HL). A petmeduin- and malathion-resistant strain (BR-HL) of head louse was provided by G. Coles (University of Bristol). 

Molecular analysis ofkdr in permethrin-resistant head lice. 

DEET-treated net jackets also provide good protection, but an additional appHcation of 10—25% solutions of repellent to the unprotected face is necessary for maximum protection. Clothing treated with permethrin [52645-53-1] (9) does not provide the protection expected against these insects. Because sandfly behavior and resistance to quick knockdown are responsible for the numbers of bites recorded, maximum protection from bites thus requires appHcation of DEET or another suitable repellent to the exposed skin when wearing permethrin-treated clothing (35). 

Johnson, SJ USDA To determine the resistance by soybean looper insects to methyl parathion and permethrin. 

These synthetic pyrethroids mimic natural counterparts, of which the most important is pyrethrin 1 (10.265). Unfortunately, the natural products lack the photochemical and hydrolytic stability necessary for use as wool insect-resist agents. The synthetic products have the required stability, yet retain the low mammalian toxicity and low environmental retention of the natural products. Permethrin, however, is toxic to aquatic life and is therefore subject to increasingly severe discharge limits. There is some evidence that permethrin is less effective against larvae of a certain beetle. This can be compensated for by using a combination of permethrin with the hexahydropyrimidine derivative 10.264. Some possible alternative pyrethroids have been mentioned [517] as development products (10.266-10.269). 

The R/S ratios for permethrin and phenothrin in Table 3 are 204 and 283, respectively. The Hiroyama strain showed high cross-resistance to permethrin and phenothrin, whereas the R/S ratio for natural pyrethrins was only 7. Moreover, the R/S ratio for racemic allethrin was 97, indicating the slow development of resistance compared with permethrin and phenothrin. These results agree well with the findings of Sawicki et al. [49], who reported that pyrethroids with the cyclopentenolone ring showed only a slight resistance at the International Congress of Pesticide Chemistry in Ottawa in 1986. 

It is noteworthy that the Obihiro strain of M. domestica showed markedly high cross-resistance to photostable pyrethroids such as permethrin and phenothrin having a benzyl group in the alcohol moiety, with their R/S ratios being 281 and 301, respectively. 

In the example of M. domestica shown in Table 3, the development of resistance to permethrin (21) and phenothrin (16) was 204 and 283 times, respectively, but the resistance to natural pyrethrins was only 7 times and that to d-allethrin was very low, 33 times. Moreover, the development of resistance to natural pyrethrins and prallethrin (ETOC ) was found to be low in A. aegypti as described previously. 

So far, no serious resistance against pyrethroids has been recorded in vectors or pest populations, although there is an indication that it may be developing in some species. At present, 14 anopheline malaria vector species have developed resistance to organochlorine insecticides, eight to organophosphorus compounds and three to carbamates, and three species have reduced susceptibility to permethrin. 

Figure 10.1 Probit regression lines for permethrin against susceptible (S) and resistant (R) diamondback moths and their F, progeny. (From Yu, S.J., /. Econ. Entomol, 86, 680, 1993. With permission.)...

Cross-resistance refers to a situation in which a strain that becomes resistant to one insecticide automatically develops resistance to other insecticides to which it has not been exposed. For example, selection of a strain of Spodoptera littoralis with fenvalerate resulted in a 33-fold increase in tolerance to fenvalerate. The resistant strain also showed resistance to other pyrethroids (11- to 36-fold) and DDT (lower than for the pyrethroids). Exposure of Cidex qninquefasciatus to fenitrothion resulted in the development of resistance to the carbamate insecticide propoxur. Similarly, selection of a housefly strain with permethrin resulted in a 600-fold increase in resistance to permethrin. The resistant strain also showed resistance to methomyl, DDT, dichlorvos, and naled (Hassall, 1990). 

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. 

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