Effect Of Odontothrips Loti Feeding On The Secondary Metabolites Content In Alfalfa Leaf

In order to indicate the alfalfa physiological mechanism of induced resistance by thripsdamaging, two strains of the alfalfa, the resistant strain to thrips (R-1) and the susceptible strainto thrips (I-1) were chosed in this study, different thrips density (1,3,5,7thrips·branch-1,0thrips·branch-1as a control) were arranged to research the effect of feeding and ovipositionbehavior of thrip adults and growth and development of Odontothrips loti nymph, and measurethe changes of phenols, lignin, total saponin, total flavonoids content.1. The effect of feeding and oviposition behavior of thrip adults and growth anddevelopment of Odontothrips loti nymphAfter feeding with the damaging alfalfa leaves of R-1and I-1in different thrips density to O.loti adults, the ovipositing behavior had no significant difference, but after feeding with thecontrol alfalfa leaves of R-1and I-1, the oviposition of adults in I-1leaves higher than R-1leaves; the feeding area and feeding rate of O. loti nymph in I-1leaves was significant higher inR-1leaves; the developmental duration had no significant difference both leaves of R-1andI-1.Those which could be explained O. loti adults had no significant spawning selection and O.loti nymph had significant feeding selection on both leaves of R-1and I-1. From thedevelopmental duration, alfalfa had no significant resistance to thrips.2. Changes of secondary metabolites content of R-1and I-1alfalfa was induced by thripsdamagingAfter infested by thrips, the polyphenols content in R-1strain higher than I-1strain indifferent thrips density and different damaging period. In low thrips density, polyphenols contentcould be accumulated gradually with the increasing damaging period, but in high thrips density,polyphenols content had no significant difference between R-1leaves and I-1leaves.Tannin content increased in both leaves of R-1and I-1with the increasing thrips density inearly damaging. At the later period, tannin content increased with the increasing thrips density inlow thrips density(5thrips·branch-1), but tannin content decreased in high thrips density(bothhigher than control).Condensed tannin content accumulated gradually in both leaves of R-1and I-1with theincreasing damaging period by thrips, and infested21days, condensed tannin content all increased than control.In different damaging periods, total saponin contents increased with the increasing thripsdensity, and were highest in10thrips·branch-1in both leaves of R-1and I-1. And total saponincontents in R-1strain higher than I-1strain both control and damaged.Total flavonoids contents in R-1control strain higher than I-1control strain, and increasedwith the increasing damaging period by thrips. Total flavonoids contents increased in differentthrips density and different damaging period in both leaves of R-1and I-1, and the totalflavonoids content could be accumulated gradually with the increasing damaging period.After infested by thrips, the lignin content increased significantly compared with the controlin both leaves of R-1and I-1, and were highest in10thrips·branch-1. So,Thrips infestation hadinduced effection to lignin contents of alfalfa.