| In this thesis, resistance and its mechanism of false flax, camelina sativa L., to diamondback moth, Plutella xylostella L., and cabbage aphid, Brevicoryne brassiae, L. were studied. Results are showed as follow:1. Effect of false flax on feeding of larvae and behavior response of adults of diamondback moth were examined with bioassay and Y-olfactometer in laboratory. Compared to cabbage, the 1 st instar larvae, fed on leaves of false flax, got a corrected death rate of 79.2% after 3 days, which indicated that false flax had an obvious antibiosis effect on 1st instar larvae. The 3rd instar larvae, fed on false flax, showed significant lower survival rate, percentage pupation, pupa weight and shorter adult longevity in compared with that fed on cabbage. Diamondback moth larvae preferred leaves of cabbage to false flax in feeding choice test. In no-choice test, the leaves of false flax consumed by diamondback moth larvae were significant fewer than that of cabbage. Otherwise, the test of behavior showed that adults of diamondback moth had a same orientation response to false flax and cabbage. Compared to clean air, adults of diamondback moth preferred to odors coming from the plants of false flax or cabbage, which indicated that the diamondback moth adults had an obvious orientation response to the volatiles of false flax.2. Effect of false flax on feeding of cabbage aphid was studied with bioassay and electrical penetration graph technique (EPG) in laboratory. Cabbage aphids prefer resting and feeding on leaves of cabbage to false flax in feeding choice test. In no-choice test, the number of cabbage aphids resting on cabbage leaves was significant higher than that resting on false flax leaves after 24 hours. During 48 hours to 72 hours, the number of cabbage aphids resting on cabbage leaves was still higher than that resting on false flax, but the difference is not significant, which indicated that cabbage aphids may adapt to the life that rest on false flax. Extended sieve element salivation (El waveform in the electrical graph) is a characteristic activity during early sieve element punctures, particularly in resistance plants. Our record of EPG showed that the times of no-probe of cabbage aphids were not significant different on this two kinds of plants, the duration and frequency of probe of aphids on cabbage were more significant high than those on false flax, but the duration of ingestion in phloem of aphids on cabbage was less than that on false flax. Less time to first probe and to first El and more time to first ingestion in phloem (El>8min) were spent by aphids on cabbage, which indicated that cabbage aphids may adapt to ingest on false flax, though external structure of leaves of false flax maybe hinder the stylet penetration of aphids.3. Studies on morphological resistance to diamondback moth and cabbage aphid of false flax were carried out with scanning electron microscope (SEM) and photomicrography and bioassay in laboratory. On the surface of leaf of false flax, many acute nonglandular trichomes were observed with SEM, and the density of those on adaxial surface was significant higher than that on abaxial surface. The larvae of diamondback moth and cabbage aphids preferred the hairs removed leaves to normal leaves. Compared to leaf of cabbage, the leaf of false flax had a rougher surface with many pleats, a thicker epidermis, and a higher concentration of cellulose. Cuticle was thick on cells of leaf of false flax, but it was not observed on leaf of cabbage. The results showed that false flax maybe has morphological resistance to diamondback moth and cabbage aphid.4. Effects of extract of false flax on diamondback moth and cabbage aphid were treated with serial concentration in laboratory. The extract showed disinfesting and anti-feeding activity to the 1st, 3rd-instar larvae of diamondback moth and cabbage aphids, and had an antixenosis resistance to adults of diamondback moth for oviposition. Fed on cabbage leaves treated by the extract with seria...
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