By the time of primary 21st century, water hyacinth had become a serious environmental problem in China. Water hyacinth contributes to the major part of ecological hazards from the invasion of foreign plant species, which is estimated about USD 7 billion a year in values. In the past 10 years, herbicides glyphosate, 2,4-D and paraquat have been used in controlling water hyacinth in China. Although the herbicides provided effective control on the weed in some areas, they could not provide the sustainable inhibition on the weed population, while would lead to pollution of water at various levels. At present, the herbicide application on water hyacinth is forbidden in many areas of China such as Shanghai. In this situation, the asexual reproduction inhibitor, KWH02, was invented for controlling water hyacinth and it provided about 70% of growth inhibition without any risk of dead plant pollution. It has been about 10 years for bio-control of water hyacinth in China. Works focused on mainly the efficacy and safety of the utilization of foreign insects. Researches on microorganism herbicides to control water hyacinth were started and obtained primary achievements in recent years. Although there are different opinion on how to face the water hyacinth problem in China, it is accepted widely that the control methods should be high efficient and safe with low cost. Some practical measures for integrated management of water hyacinth are suggested.
Animals ; China ; Ecology ; Eichhornia ; growth & development ; Female ; Herbicides ; pharmacology ; Male ; Pest Control, Biological ; Rats ; Weevils

The rice water weevil, Lissorhoptrus oryzophilus Kuschel, has two generations in southern Zhejiang, China. To determine oogenesis in first-generation females (summer females) and its relations to temperature, females were collected from a rice field in early and mid-July and reared on young rice plants at 28, 31 and 34 degrees C in the laboratory. Percentage of females having oocytes, number of oocytes of different stages (stage-I, from early previtellogenesis to middle vitellogenesis; stage-II, late vitellogenesis; and mature-oocyte stage), and length of ovarioles were determined every 10 d of feeding. At each temperature, oogenesis took place in over 40% of females after 20~40 d of feeding, but only 0.0~3.3 stage-I, 0.0~0.8 stage-II and 0.0~1.1 mature oocytes were observed at each observation date. Temperature had significant effect on number of stage-I oocytes but not on number of stage-II and mature oocytes in early July females; temperature had no significant effect on number of oocytes of either stage in mid-July females. Conclusively, in southern Zhejiang, summer L. oryzophilus females have great potential to become reproductive on rice, but their oogenesis activity is very low, with the overall procedures little affected by temperature.
Animals ; China ; Female ; Oogenesis ; Oryza ; parasitology ; Seasons ; Temperature ; Weevils ; genetics ; pathogenicity

The rice water weevil (RWW) Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae) is an invasive insect pest of rice Oryza sativa L. in China. Little is known about the interactions of this weevil with indigenous herbivores. In the present study, adult feeding and population density of the weevil, injury level of striped stem borer Chilo suppressalis (Walker) (Lepidoptera: Pyralidae) and pink stem borer Sesamia inferens (Walker) (Lepidoptera: Noctuidae) to rice, as well as growth status of their host plants were surveyed in a rice field located in Southeastern Zhejiang, China, in 2004 with the objective to discover interspecific interactions on the rice. At tillering stage, both adult feeding of the weevil and injury of the stem borers tended to occur on larger tillers (bearing 5 leaves) compared with small tillers (bearing 2~4 leaves), but the insects showed no evident competition with each other. At booting stage, the stem borers caused more withering/dead hearts and the weevil reached a higher density on the plants which had more productive tillers and larger root system; the number of weevils per tiller correlated negatively with the percentage of withering/dead hearts of plants in a hill. These observations indicate that interspecific interactions exist between the rice water weevil and the rice stem borers with negative relations occurring at booting or earlier developmental stages of rice.
Animals ; Coleoptera ; growth & development ; Oryza ; growth & development ; parasitology ; Population Density ; Weevils ; growth & development

OBJECTIVES: We surveyed the awareness and current status of using fumigant carbon disulfide for exterminate Curculio sikkimensis among chestnut farmers in Chungnam Province to suggest directions for health education and public relations. METHODS: We designed questionnaires to evaluate recognition of fumigant carbon disulfide. We conducted a questionnaire survey to assess recognition and recognition level of fumigant carbon disulfide by the study variables. RESULTS: The recognition status for fumigant carbon disulfide was 74.5%, but the recognition level was low (know well 27.5%). The path of recognition was 45.1% and 15.7% for neighbor and rural technology center, respectively. The recognition status for warning label of fumigant carbon disulfide was 52.9%. Recognition for warning label of fumigant carbon disulfide was tended to increase with high educational attainment, bigger owning land area. Recognition on the content of warning label were 29.4%, 27.5%, 21.6%, and 21.6% for inflammability, toxicity, hazard, and explosiveness, respectively. Using personal protection equipment was tended to increase with the high status of awareness on fumigant carbon disulfide. CONCLUSIONS: Health education programs for using fumigant carbon disulfide are needed for chestnut farmers. In addition, publicity information activities about prevention and protection of carbon disulfide poisoning are needed for high risk farmers.
Carbon Disulfide* ; Carbon* ; Chungcheongnam-do ; Farmers* ; Fumigation ; Health Education ; Humans ; Poisoning ; Public Relations ; Weevils*