Striped Flea A Host Selectivity,

This thesis deals with a new method of rearing striped flea beetle (SFB), Phyllotreta striolata. Based on the method, the preference of P. striolata among 5 species of Cruciferous vegetables was studied, the effect of volatiles from host plant, epicuticular wax as well as pubescence on P. striolata host preference was investigated, and the influence of host plant on P. striolata population development was observed.1. Feeding preference was measured simultaneously by the feeding area and by the number of beetles on the plants. The number of on-plant P. striolata was used to indicate that P. striolata preferred B. juncea L. to Raphanus sativus L., B. pekinensis, B. chinensis L., less B. alboglabra Bailey, feeding area of P. striolata used to show that preferred B. juncea L. to B. pekinensis and R. sativus L., B. chinensis L., less B. alboglabra Bailey. Though the result of evaluation had slight difference, the mean numbers of beetles on five hosts were significantly correlated with the amount of feeding area.2. The oviposition preference of P. striolata to five host plants was also researched, which was in accordance with the feeding preference. In a decreasing order, the host plants were B. juncea L., R. sativus L. and B. pekinensis, B. chinensis L., less B. alboglabra Bailey.3. The feeding preference of P. striolata was found to vary with the host plant age. To cotyledons, the preference in decreasing order was B. juncea L., R. sativus L., B. alboglabra Bailey, B. chinensis L. B. pekinensis, but to true leaves that was B. juncea L., B. pekinensis, B. chinensis L., R. sativus L., B. alboglabra Bailey.4. Much more P. striolata attacked the pre-fed B. juncea L. indicated that the pre-fed plants became more attractive. Then the volatiles from B. juncea L. with various treatments were collected from their headspace by solid-phase micro-extraction, and identified by GC-MC. No detectable allyl isothiocyanate was found in the volatiles collected from the damaged hosts, but some unknown new components could be seen and the ratio among the formerly existing components did change, which may be the reason for increasing attractive to P. striolata.5. P. striolata preferred to feed and oviposit on the de-waxed B. alboglabra Bailey. And the feeding pattern also changed from edge-feeding to random-feeding. It suggested that wax affected the feeding behaviour and host preference of P. striolata. But the epicuticular pubescence did not affect the P. striolata feeding preference for both glossy lines and trichime-bearing line of B. pekinensis.6. Based on 6-month rearing of overwinter-generation of P. striolata, the author observed and contrasted the biological characteristics of populations reared on 5 different host plants. The results indicated that host plants had a great effect on the developmental duration of larvae as well as longevity and fecundity of adults. P. striolata reared on B. juncea L. had the shortest average duration of immature stages and average preovipostion period. Also, the female had the largest number of eggs in average. However, the P. striolata reared on B. alboglabra Bailey had the longest duration of immature stages and average preovipostion period. Also, the female had the least number of eggs in average. Moreover, P. striolata reared on R. sativus L. had the highest rate to be female, when they grew up from the larvae to the adults. Those reared on B. juncea L. took the second place. And those reared on B. alboglabra Bailey had the least rate. Furthermore, the female P. striolata reared on R. sativus L. laid eggs in succession overwinter. However, the females reared on the other 4 kinds of vegetables hardly laid eggs when they were over 90-days old. The above data indicated that B. juncea L. and R. sativus L. were the most habit host plants for P. striolata as well as for development of the larvae and fecundity of flea beetles. P. striolata reared on B. alboglabra Bailey was right on the opposition. The above results also indicated that the host plant's adaptability to P. striolata was...