Feeding Preference Of Hyphantria Cunea(Drury) To Host Plants And Its Metabolic Mechanisms Against The Secondary Metabolites

The Hyphantria cunea(Drury),an invasive polyphagous pest in the forestry,had destroyed more than 636 plants.In order to evaluate the fitness to plants,we studied how plants affected the feeding choice of H.cunea by their nutrients and secondary metabolites.And then we explored the physiological metabolism of H.cunea to analyze how it can adapt to the chemical defense of host plants.The main results of this study were as follows:1.The 4th instar larvae of H.cunea had different feeding choice to host plants,and the order of selection was Fraxinus pennsylvanica(21.7%)and Ailanthus altissima(20.0%)>Morus alba(16.7%)>Ulmus pumila(12.5%)>Malus micromalus(9.2%),Salix babylonica(8.3%)and Lonicera maackii(8.3%)>Populus nigra(3.3%).The H.cunea had the highest approximate digestibility(AD)(0.97±0.01%),the lowest efficiency of conversation of ingested food(ECI)(0.005±0.01%)and efficiency of conversation of digested food(ECD)(0.01±0.01%)on L.maackii.In the oppsite,the larvae consumed S.babylonica with the lowest AD(0.03±0.20%),the highest ECI(0.20±0.02%)and ECD(0.98±1.04%).2.We measured the contents of three kinds of allelochemicals in eight species of host plant leaves.In the leaves of A.altissima,the total phenols(55.85±2.79mg/g)were highest.The contents of tannins(6.08±0.41mg/g)and flavonoids(69.34±2.97mg/g)were highest in M.micromalus.The correlation analysis between the contents of allelochemicals and feeding amounts of H.cunea showed that the contents of flavonoids were negatively correlated with the feeding amount of H.cunea(r=-0.657,P=0.017).However,the contents of total phenols and tannins showed no significant correlation with the consumption of H.cunea.3.The activities of acetylcholine esterase(AchE),glutathione S-transferase(GSTs),carboxylesterase(CarE)and cytochromeP450(P450)in H.cunea larvae fed on different host plants were significantly different(P<0.01).The activities of GSTs(218.34±29.79U/g pro)and AchE(56.59±1.60U/g pro)were highest when the larvae consumed P.nigra.And when the larvae on M.micromalus,the activities of CarE(7.37±0.45U/g pro)and P450(33.94±0.86U/L)were highest.4.The 0.3% flavonoids promoted the consumption and growth of H.cunea,while it was inhibited when the concentration increased.The concentration of tannins which were less than 2.5%had a promote effect on the nutritional indexes of H.cunea and inhibited when the concentration of tannins exceeded 3.0%.The H.cunea consumed 1%-3%total phenols had a lower relative consumption rate and approximate digestibility than control group,which showed that total phenols were inhibited the consumption and digestibility.The 1%-2.5%tannins had a promoting effect on the feeding,utilization and transformation of food of H.cunea larvae,however,the tannins with a conccecntration of more than 3%had a inhibitory effect on the nutritional effects of H.cunea larvae.5.The allelochemicals had significant dose-time effect on detoxification enzymes and AchE of H.cunea.The P450 was induced by allelochemicals among the tested concentrations and treatment time.But the general trend was that low dose and short treatment time could induce the activities of enzymes,and high concentration for long treatment time could make activities of enzymes decreased or fluctuated slightly in stable range.