| Plutella xylostella L.is a pest of vegetable cruciferae of world, overlapping generations Serious.For a long time,it was mainly depend on chemical control, leading to different degree of resistance to various insecticide. At present research on resistance of one insecticide about monitoring and mechanism of resistance,but few research report on resistance on two insecticide,especially on prongenys of two resistant stranins.Using selection of deltamethtin-resistant strain(R1) and dimpehypo-resistant strain (R2) in Plutella xylostella as parents, test toxicity and enzyme activity on two resistant strains and their prongenys were tested. Susceptibility of pulutella xylostella to deltamethtin and dimpehypo and acticty of CarE and AchE were also analysed.Providing theory of bases for integrated control for different resistant strains on Plutella xylostella in the field production with of insecticide resistance. The results showed:1. Two populations of progenys of reciprocal hybridzations were insentitive to deltamethtin and dimpehypo; there was no signnficant difference between the progeny Fi and parents; two populations of progenys of reciprocal hybridzations had a significant rising trend in the successive generations. Average of four times of suscetility to insecticide in measurement of orthogonal populationF1 are:62.2145μg·larva-1, 65.5131μg·larva-1. Average of four times of suscetility to insecticide in measurement of reciprocal cross populationF1 were:75.2106μg·larva-1,59.8872μg·larva-1. Susceptibility to insecticides in deltamethtin-resistant strains and dimpehypo-resistant strains was close. Average of four times of suscetility to deltamethtin in measurement of R1 was: 70.7838μg·larva-1 and average of four times of suscetility to dimpehypo in measurement of R2 was:74.5678μg·larva-1.2. Two populations of progenys of reciprocal hybridzations had a significant rising trend in the successive generations. Suscetility to deltamethtin in measurement of Orthogonal population in turn were as followings: 65.5133μg·larva-1>33.6273μg·larva-1>19.5μg·larva-1. Suscetility to dimpehypo in measurement of Orthogonal population in turn were as followings: 62.2145μg·larva-1>46.99μg·larva-1>20.46μg·larva-1.Suscetility to deltamethtin in measurement of reciprocal cross population in turn were as followings: 59.8872μg·larva-1>46.3789μg·larva-1>15.6562μg·larva-1.Suscetility to dimpehypo in measurement of reciprocal cross population in turn are as followings: 75.2106μg·larva-1>37.8085μg·larva-1>24.5823μg·larva-1.3. CarE activity of larvae in deltamethtin-resistant strain, dimpehypo-resistant strain and their progenys:Continuous three generations of activity of CarE was close. Activities of CarE of orthogonal population were as followings:1.0245 mM/30min/larva,'1.0276 mM/30min/larva,1.3506mM/30min/larva and no significant difference. Activities of CarE of reciprocal cross population were as followings:1.0650 mM/30min/larva,1.0694 mM/30min/larva,1.2661 mM/30min/larva and no significant difference too. There was no obvious difference in significant of suscetility to activities of CarE in two populations of progenys of reciprocal hybridzations. Activities of CarE in two populations of progenys of reciprocal hybridzations were slightly higher than R1 which was 1.4865mM/30min/larva, the difference was significant;but were close to R2 which was 1.0743mM/30min/larva, the difference was no significant. Activities of CarE of susceptible strain which was 0.8833 mM/30min/larva was lower than actities of CarE in two populations of progenys of reciprocal hybridzations, the difference was no significant.4.AchE activity of larvae in deltamethtin-resistant strain, dimpehypo-resistant strain and their progenys:Continuous three generations of activity of AchE was similar. Activity of AchE in measurement of orthogonal population was as followings: 0.8008mM/30min/larva,0.5153 mM/30min/larva,0.6648 mM/30min/larva and no significant difference. Activity of AchE in measurement of reciprocal cross population asfollowings:0.5501mM/30min/larva,0.3366mM/30min/larva,0.4083mM/30min/larva and no significant difference too. There was no obvious difference in significant of suscetility to actities of AchE in two populations of progenys of reciprocal hybridzations. Compared with two populations of progenys of reciprocal hybridzations:orthogonal populationF1 which is 0.8008 mM/30min/larva was slightly higher but reciprocal crossF2 which was 0.3366mM/30min/larva population was slightly lower, the difference was no significant. Activities of AchE in two populations of progenys of reciprocal hybridzations was slightly lower than R1 which was 0.1409mM/30min/larva, the difference was significant;but was close to R2 which was 1.0743mM/30min/larva, the difference was no significant. Activities of AchE of susceptible strain which was 0.8833mM/30min/larva was close to activities of AchE in two populations of progenys of reciprocal hybridzations, the difference was no significant. Activities of CarE of susceptible strain close to activities of CarE in two populations of progenys of reciprocal hybridzations.5. There was no significant difference in CarE activities and AchE activities between two populations of progenys of reciprocal hybridzations. Activities of CarE in two populations of progenys of reciprocal hybridzations is slightly higher than Ri. Activities of AchE in two populations of progenys of reciprocal hybridzations is slightly lower than R1.6. Two populations of progenys of reciprocal hybridzations were insentitive to deltamethtin and dimpehypo and had a significant decreasing trend in LD50 of the successive generations. Results of enzyme activity assay show that:there was no significant difference in CarE activities and AchE activities between two populations of progenys of reciprocal hybridzations. So that, CarE activities and AchE activities was not important in resistance mechanism.
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