| As a notorious invasive plant species of worldwide, Solidago canadensis (S. canadensis) has a great influence on production and livelihood of native habitats, because of its features of powerful invasiveness, exclusiveness and hard to be eliminated. To solve the problems caused by this plant’s invasion, a great many scientists and researchers choose it as research object, a large amount of work and study were conducted to learn more about its efficient outspreading mechanism and preventing and controlling strategy. However, the asexual system of S. canadensis led the current use of artificial physical control method to high consumption but low effectiveness, and better effect of chemical control for soil residues, limiting the scope of use. Biological control has its drawbacks such as proving effective slowly, long period and the existence of the secondary invasion, but for the invasion of wide scope and control difficulty weed, if naturally acclimatized or laboratory domestication predator species were existed in invasion area, the bio-control method would have wider application prospect than the physical and chemical prevention, and biological control is more consistent with the evolution of the nature. In the experiment field and field survey, the author found that native insect Argyrogramma albostriata Bremeret Grey(A. albostriata) can feed on a large of S. canadensis, injury severity, and by the following test to study the potential of using the insect to prevent and control of S. canadensis, specific results are as follows:1. Feasibility study(1)Field researchThe feeding phenomena can be easily found in Hefei area but the natural population density is low; meanwhile6predators of the insect and other3host plants were found in the natural condition, and6other can feed on the leaves of S. canadensis in Lepidoptera.(2) Feeding habits:2.1) Host plantsHost range tested with103plant species from51families showed that this insect was oligophagous, only ate Kalimeris indica (K. indica), Conyza canadesis(C. canadesis), Aster subulatus(A. subulatus), Conyza bonariensis(C. bonariensis), Erigeron annuus(E. annuus) and S. canadensis.All are weeds in field, in addition to K. indica the other5are exotic plants.2.2) The location effect of eggingLarvae of the first stadium which were hatched on paper (No-treatment Control Group:NCG) showed preference: C. canadensis>C. bonariensis>E. annuus>(S. canadensis=K. indica)>A. subulatus. Larvae of the first stadium which were hatched on leaves of S. canadensis (Experiment Group:EG) showed preference: C. canadensis>S. canadensis>(C. bonariensis=E. annuus)>K. indica>A. subulatus. The differences were significant. Compared with NCG, the larvae of EG showed more preference of S. canadensis(p<0.05).2.3) feeding habit of larvae feeding by S. canadensisForth stadium larvae feeding with S. canadensis showed preference: S. canadensis>C. canadensis>E. annuus>K. indica>A. subulatus.We paired S. canadensis with C. canadensis, E. bonariensis, E. annuus, K. indica, A. subulatus, A. albostriata showed preference with S. canadensis. The result shows that A. albostriata showed preference with S. canadensis significantly (p<0.05).2.4) Insect Physiological Response on different Host plants①A. albostriata can grew normally on S. canadensis, C. canadensis, K. indica and A. subulatus, however, larvae on E. annuus were inhibited servely and most of them died in13days. Only a few of them can become a pupa. The lifecycle of larvae on S. canadensis were the longest. Pupation rate, eclosion, pupa weight, food conversion efficiency, food utilization rate, approximate digestibility, relative growth rate and relative feeding amount were in the medium level.②Protease activity and amylase activity of larvae on S. canadensis were the lowest (p<0.05).3) Eating mount and reproductive rateThe larvae per insect one life history cycle can feed on the leaf (dry biomass)1.3-1.4g, a keen appetite, a keen appetite, and the number of eggs per female is about 187-405, hatching rate is about97.9%, about30days per lifecycle, each year can produce5-7generations in Hefei, high rate of reproduction.2. Simulated experiment of model based on eating amountMathematical Modeling equation:N0=[S×δ×(0.069h-0.195)]/[(1-γ)×d×A], the model can be used as an instructor for the field experiment. The Mathematical Modeling can give us the mount of larvae for the unit area by caculating the square, the population density and the average height of the invasive weed and the eating amount, the natural death rate of the larvae, thus in the unit time this larvae will cosume all of the leaves which means achieve the goal that prevent the invasive weed from dispersal. |
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