Resistance pyrethroid insecticides

Sawicki, R.M. 1985. Resistance to pyrethroid insecticides in arthropods. Pages 143-192 in D.H. Hutson and T.R. Roberts (eds.). Progress in Pesticide Biochemistry and Toxicology. Vol. 5. Insecticides. John Wiley, New York. 

Resistance to insecticides has drawn global attention since the Korean War in 1950 when the mass use of organic synthetic insecticides, such as DDT and BHC, against agricultural pests and sanitary pests became common. Organophosphorus compounds and carbamates were used thereafter, but invited problems of safety concerns and insect resistance. Synthetic pyrethroids were watched with keen interest as alternatives and have become used widely not only for sanitary pests but also agricultural pests. The development of resistance to synthetic pyrethroids is also not a rare phenomenon and has spread all over the world. 

The mechanisms of resistance fall into two main categories. Many insects produce an increased level of detoxifying enzymes, such as esterases, that modify the insecticides to inactive metabolites very rapidly. Such a system is seen in aphids that are resistant to OP insecticides. In other cases it is the target site that is modified such that the insecticide (the enzyme inhibitor) no longer binds to the target and is, therefore, ineffective. This has recently been shown to occur in some aphids that are resistant to OP insecticides but the classical example is knockdown resistance (kdr) and super-kdr to pyrethroid insecticides shown by many insects but particularly house flies Musca domes tied). This resistance is thought to result from a modification of... 

Resistance genes can be dominant, recessive, incompletely dominant, or incompletely recessive. Resistance to carbamates and organophosphates is usually dominant or incompletely dominant. Resistance to DDT, Bt, and spinosyns is usually recessive. Resistance to dieldrin is usually incompletely dominant. Resistance to pyrethroids is usually incompletely recessive. As shown in Figure 10.1 and 10.2, diamondback moth resistance to per-methrin was inherited as an incompletely recessive, autosomal factor, whereas resistance to methomyl was inherited as an incompletely dominant, autosomal factor. In cases of monofactorial inheritance of resistance to insecticides, the degree of dominance (D) in the progeny can be calculated, as described by Stone (1968), as follows ... 

Carboxylesterases are involved in resistance to ester-containing insecticides such as organophosphate, carbamate, and pyrethroid insecticides. Resistance to organophosphate insecticides caused by enhanced carboxylesterase activity has been demonstrated in numerous insects and mites, including the mosquito (Cidex tarsalis, Culex pipiens, and... 

Soderlund, D.M. and Knipple, D.C., The molecular biology of knockdown resistance to pyrethroid insecticides, Insect Biochem. Molec. Biol., 33,563, 2003. 

Because of the intimate involvement of sodium channels in pyrethroid insecticide resistance (see below), partial cDNA clones of para-orthologs were isolated from other in-... 

U.S. states to combat the bollworms fliat have acquired resistant against the broad-range pyrethroid insecticides. In all states, the amount of active ingredient and the number of pesticide applications have subsequently decreased (Table 1). 

Piperonyl hu 10Aide (PBO) is primarily used as a synergist in combination with natural pyrethrins or pyrethroids in space spray, residual and admixture products for the control of insect pests in or around domestic and commercial premises, especially food preparation areas. The suitability of PBO for (his purpose has been proven over many decades of study and widespread practical use. The main attributes oflhe compound which have ensured this long-las ting utilization in urban pest control procedures are summarized below. The beneficial effect that PBO has on insects showing resistance to insecticides is referred to in Chapters 12, 13 and 19 of this volume. 

A case in point is the unraveling of resistance to methyl parathion in the tobacco budworm, Heliothis virescens, which is a major pest of cotton as well as tobacco. In South Carolina, there is very severe, stable resistance. Although pyrethroid insecticides are very effective and there is no resistance to them in South Carolina at this time, it would be very useful to understand the genetic basis of methyl parathion resistance in case resistance to pyrethroids should arise in the future or spread eastward from Texas where it has been detected. Recent investigations with this pest will be described to illustrate certain mechanisms. 

Soon thereafter, it was determined that field populations of OP-resistant tobacco budworms in the USA had varying levels of cross-resistance to the pyrethroid insecticides, which became available for commercial use during the late 1970 s (8-13). 

Houseflies on Danish farms have become resistant to almost every new insecticide introduced for their control since the 1950 s (M.). In the mid 1970 s, scientists showed that resistance to DDT and the new pyrethroid insecticides is due to a common resistance factor (the kdr and super-kdr genes), and they predicted that rapid resistance development to the more persistent SP compounds would rapidly evolve in the field. In 1978-79, surveys for SP resistance indicated that resistance to long-residual compounds was beginning to develop in the field. Overall, the survey data indicated that resistance would soon be widespread. Several steps were immediately taken to evaluate the resistance potential of... 

A final example of where little progress has been made in achieving resistance management is with the pear psylla in parts of Europe (Table 1). As noted earlier, in areas where both pre-bloom and summer applications of pyrethroid insecticides have been used unilaterally, resistance to the SP has developed widely. 

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