| Bradysia difformis Frey, 1948 is the main liliaceae pests, which has seriously threatened sustainable development of leek, shallot, garlic and Lanzhou lily. The study aimed to find a way to protect liliaceae plants from the damaging of B. difformis. Experimental population life tables on different lily hosts were established through rearing and observation under the artificial climate chamber. Parameters of B. difformis were counted, which involved the developmental stages of larvae, survival rate, adult longevity, average eggs per female spawning, etc. Furtherly calculated the experimental population life parameters like net reproductive rate(R0), the intrinsic rate(rm), mean generation time(T), the population doubling time(t) and the finite rate of increase(λ). Preliminarily screened out the resistant leek cultivars according to the mechanism of plant resistance to insects, and systematicly analyzed the effect of different leek resistance on defense enzymes activities of B. difformis. The main conclusions are as following. 1 Discussed the regular pattern of growth, development and fecundity of B. difformis on four main liliaceous vegetablesGrowth and development of B. difformis can be completed on the leek, shallot, garlic and Lanzhou lily, but there were significant differences between different host plants, especially in its larval developmental stages and survival rates. Host plants, which fit for larval growth and survival rates were also favorable for adult spawning, vice versa. Results of this study confirmed: Larval stage of B. difformis is the key factor affecting its fertility. Thus, take timely control measures in this stage can be cut to avoid the risk of host plants yield losses, which can provide some reference value for insect surveying, forecasting and pests integrated control. The intrinsic rate(rm) and net reproductive rate(R0), which reflected an important indicator of the population potential biomass in certain circumstances, were biological parameters integrated the growth, reproduction and survival changes of insects. From other side, the intrinsic rate reflected a fitness and palatability to hosts.The intrinsic rate of B. difformis on the leek, Lanzhou lily, shallot, garlic bulb and garlic stem were 0.19, 0.09, 0.14, 0.08, 0.10 respectively. Net reproductive rate(R0) were 32.96, 7.39, 23.51, 7.3, 8.01. Therefore, B. difformis had the best adaptability and palatability on the leek, which can be regarded as the susceptible plants among liliaceae. 2 Clarified the population trends of B. difformis on 20 leek cultivarsGrowth, development and reproduction can be completed on different leek cultivars, but the larval developmental stage, adult longevity, fecundity, the intrinsic rate(rm), net reproductive rate(R0) and other biological parameters among 20 leek cultivars showed some differences. Different leek cultivars led to different population trends, female longevity was higher than male on different leek cultivars, and the height of average eggs per female spawning was positively correlated with the length of female longevity. Besides, higher average eggs per female spawning was related to higher survival rates of each instars. Thus, the more typical leek cultivars were ‘Wanyuan Hanzhong Winter leek 1’ and ‘Pingjiu 2’, female longevity was respectively 2.18 d and 2.44 d, and average eggs per female spawning were 56.00 grains and 101.25 grains respectively. The survival rates of eggs, larval, pupa and adult on ‘Wanyuan Hanzhong Winter leek 1’ were respectively 62%, 32%, 25% and 25%, but were 100%, 85%, 82% and 80% on ‘Pingjiu 2’. We counted intrinsic rate of increase(rm), results pointed that the highest was on ‘Pingjiu 2’(0.22) and lowest was on ‘Wanyuan Hanzhong Winter leek 1’(0.07), while rm of other leek cultivars were raged among them. In short, B. difformis had the best adaptability and palatability on the ‘Pingjiu 2’, which caused the heavy demage; while there turned out to be the worst on ‘Wanyuan Hanzhong Winter leek 1’ with lighter damage. Although this study was only under the laboratory by indoor analysis and research, but provide some certain scientific basis for leek production were available. 3 Evaluated 20 leek cultivars B. difformis resistance differenceThere were significant differences of B. difformis damageing 20 leek cultivars.Through scientific analysis of biological parameters as developmental stage, adult longevity and fecundity, survival rats, the intrinsic rate(rm) and net reproductive rate(R0), whereby selected ‘Wanyuan Hanzhong Winter leek 1’ with lighter victim and can be inferred ‘Wanyuan Hanzhong Winter leek 1’ with strong resistance, ‘King of Wanyuan purple root latifolia’ followed, according to parameters of rm and R0. Therefore, choice those two cultivars in the process of planting chives, in theory, can effectively avoid the damage extent. 4 Determined effects of different resistance leek cultivars on the defense enzymes activity of B. difformis20 leek cultivars had different degrees resistant to B. difformis. Study reveled that with the leek resistance weakened, the superoxide dismutase(SOD), peroxidase(POD) and catalase(CAT) were shown to enhance the activity. In other words, the degree of three defense enzymes activity increased with the order: highly resistance of ‘Wanyuan Hanzhong Winter leek 1’ < moderate resistance of ‘Latifolia Malian leek’ < low resistance of ‘Jiyan xiaojiuyuan’ < positive resistance of ‘Pingjiu2’. Thus, strong resistance leek cultivars would make the body of B. difformis produce large amounts of free radicals, but the activity of SOD, POD and CAT wrer seriously damaged that can not maintain homeostasis radicals; while weak resistance leek would make the larval body produce free radicals, and the activity of SOD, POD and CAT were not damaged, that the defense enzyme system was activated, therefore the excess free radicals were cleared. |
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