Development Of Pyrethroid Resistant Strains And Fitness Cost Of Deltamethrin Resistance In The House Fly, Musca Domestica

The M.domestica.is one of the most important disease vectors and distributes all over the world,which affect our environment and health.Due to the wide use of insecticides,resistance of many insects increased quickly.In China,M.domestica is always the target of insects' control, but resistance of M domestic is found in many locations.The resistance to insecticides decreases the efficacy of insectides,thus,attract extensive concerns.Knowledge of occurrence, development and level of resistance of M.domestica is very significant to establish reasonable control strategies.In this thesis,we reported our results of resistance evolution of four strains of house flies after selection using pyerthroids.We also demonstrated the inheritance mode of resistance..In addition,we evaluated the fitness cost ofpyrethroid resistance in this pest.1.Selection of house fly swains resistant to deltamethrin and permethrinAfter selection of 9 generations of selection,resistance to deltamethrin of the selected BJD strain changed from 2203-fold to 7241-fold.The realized heritability of deltamethrin resistance during seleceion was slow,indicating resistance development potential of deltamethrin low,(h~2=0.007).After 8 generation of selection,resistance to of ratio to permethrin of the selcetded ISO strain increased to 3421-fold.The realized heritability of permethrin resistance during seleceion was slow(h~2=0.012).The resistance to deltamethrin of the selected TZ-D strain increased to 138-fold after 15 genertations.And heritability of deltamethrin resistance of TZ-D strain is low(h~2=0.016).After 15 generations of selection,resistance to permethrin of the selected TZ-2C1 strain is from 5-fold to730-fold.The realized heritability of permethrin resistance during seleceion was high,indicating resistance development potential of deltamethrin quick(h~2=0.040).2.Genetics and relative fitness of deltamethrin resistance in Musca domestica.The dominance degrees(D)of the F1 progenies from the reciprocal crosses(RR♀×SS♂,RR♂×SS♀)were 0.574,0.536,respectively,and the major gene(s)involved is incompletely dominant.The resistance in fly house(Musca domestica.)appears to be controlled by autosomal gene(s).The fitness cost of fly house,associated with deltamethrin resistance,were evaluated in terms of developmental and reproductive performance by constructing life tables of resistant strain(RR)and susceptible strain(SS)house flies under laboratory conditions.The results showed that there was no significant difference in egg-to-adult developmental duration and the adult longevity of susceptible and deltamethrin- resistant house flies,but the hatchability, pupation rate,pupa body weight,emergence rate and sex ratio were significantly different between the two phenotypes.The relative fitness determined by population growth tendency index(Ⅰ)in the RR strain was 0.36 relative to the SS strain,indicating that fitness cost was associated with pyrethroid resistance in house flies.