| Secondary metabolites as the plant compounds,play an important role in protecting against insect damage.However,in the long-term co-evolution process,insects can regulate their own growth mechanisms,resist toxic secondary metabolites,and improve their adaptability to host plants.Hyphantria cunea belongs to Lepidoptera,which is a national quarantine pest,and has the characteristics of rapid reproduction and feeding habits.In order to find out the adaptability of H.cunea to different secondary metabolites in host plants.In this study,We observed and measured the effects of different host plant secondary metabolites on the larval growth and development status,nutrition utilization effect and detoxification mechanism of H.cunea by feeding the 4-6 instar larvae with artificial diets containing two doses of tannin(D1,D2),flavonoids(HI,H2),cinnamic acid(R1,R2),salicylin(S1,S2)and-hydroxybenzoic acid(BJ1,BJ2),respectively.This study was to provide ideas and theoretical basis for seeking efficient and environmentally friendly new ways of pest control.The results were as follows:(1)Adaptability of larval growth and development in H.cunea to different plant secondary metabolites.After being fed with diets containing tannins,the body weight,body length,and head capsule width of the American white moth 4th-6th instar larvae were significantly lower than those in the control group(P<0.05),and the larvae died before pupation.After taking flavonoids,cinnamic acid,salicin,and p-hydroxybenzoic acid,the weight,body length,and head capsule width of 4th-6 th instar larvae seemed to be lower than those in the control group in varying degrees,However,no significant differences in the larval survival rates between the control and other treatment groups(P>0.05).Except for R1,the pupal weight was significantly lower than those of the control;In addition,the developmental duration in the flavonoid groups were significantly prolonged,the pupation rate in the salicin S1 group was significantly higher than that in the control group,and the emergence rate of the BJ2-treated group was significantly lower than that in the control group(P<0.05).(2)Adaptability of larval nutritional utilization in H.cunea to different plant secondary metabolites.After being fed with diets containing tannin or flavonoids,the food digestion rate of H.cunea larvae were development-specific,showing that the 4th and 5th instar larvae were lower than those in the control group,and the 6th instar larvae were significantly higher than those in the control group(P<0.05),the food intake,food conversion rate,food utilization rate and relative growth rate were all lower than those of in the control group;among the treatment groups of cinnamic acid,salicin and p-hydroxybenzoic acid,except BJ2,The food intake and food consumption rate were reduced to varying degrees,but the food utilization rate and food conversion rate were not significantly different from those in the control group;and the relative growth rates of the 5th and 6th instar larvae of the salicin and p-hydroxybenzoic acid treatment groups were also somewhat lower than those in the control group,but the cinnamic acid groups were not significantly different from those in the control group.(3)Adaptability of larval detoxification mechanism in H.cunea to different secondary metabolites.Enzyme activity of Cytochrome P450 in all treatment groups revealed a trend of promotion before inhibition,which showed that the 4th age group was higher than the control group,only the D1 group was significantly higher than the control;And the 5th and 6th age groups were lower than the control group,the 6th instar larvae in all high-content groups were significantly lower than control.Acid phosphatase(ACP)and Alkaline phosphatase(AKP)activities,except for the 4th instar larvae of D1,the ACP activity in tannin group was significantly lower than the control(P<0.05),while the AKP in the 4th instar larvae activity was higher than the control,and the 5th and 6th instar of D2 was significantly lower.The ACP activity of flavonoid group,the 5th and 6th instar of H2 was significantly lower than the control(P<0.05),and the AKP activity was not significantly different from the control.In the cinnamic acid group,the activities of ACP and AKP at the 4th instar were higher than the control,and there was no significant difference between the 5th and 6th age with the control.In the salicin and p-hydroxybenzoic acid groups,the ACP activity of S1 at 4th instar was significantly higher than the control,and the ACP activity of BJ1 was significantly higher than BJ2(P<0.05),while the AKP activity of S1 at 6th instar was significantly higher than S2(P<0.05).Total antioxidant capacity(T-aoc)activity,in the tannin and flavonoid groups,only the 5th instar of flavonoids was not significantly different from the control,and other groups were higher than the control;The cinnamic acid,salicin and p-hydroxybenzoic acid treatment groups had stress changes,which were higher than or not significantly different from the control group at the 4th and 6th instar,but significantly lower than the control group at the 5th instar(P<0.05).Acetylcholinesterase(AChE)activity,tannin and flavonoid groups were lower than the control,the 5th instar of R1 was significantly higher than the control,and the 6th instar of BJ2 was significantly lower than the control(P<0.05).To sum up,the growth and development of H.cunea will be affected after feeding on different plant secondary metabolites.However,H.cunea can resist the adverse effects of plant secondary metabolites by using its own antioxidant system and detoxification mechanism or by increasing food consumption rate.H.cunea has different adaptability to different plant secondary metabolites.The order of adaptability to the secondary metabolites was cinnamic acid>salicin>p-hydroxybenzoic acid>flavonoids>tannin. |
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