In agriculture, chemical insecticides are widely used to protect crops from insect pests. Over a period of years, some insects such as Colorado potato beetle （CPB） succeed in developing resistance to most of the reg...In agriculture, chemical insecticides are widely used to protect crops from insect pests. Over a period of years, some insects such as Colorado potato beetle （CPB） succeed in developing resistance to most of the registered chemical insecticides. Consequently, heavy applications of chemical insecticides to control this pest become ineffective on a long-term basis and can lead to serious health and environmental problems. The use of natural enemies to control CPB is an interesting alternative to chemical means However, hand release of predators is not feasible on a large scale in the field. The main objective of this research study was to design and build a test bench to investigate the technical feasibility of mechanically releasing predators. The test bench consisted of a vertical chain conveyor mounted on two vertical shafts driven by an electric motor. Since the predators are small and fragile, they were placed in a specially designed container to preserve their physical integrity. Trials using this test bench showed that a carrier material was required, because most of the predators remained inside the container. The success of this mass predator release system will be highly valuable for the biological control of insect pests in many crops.展开更多
The insecticidal efficacy of the diatomaceous earth against granary weevil, Sitophilus granarius L. （Coleoptera： Curculionidae）, with two essential oils for the degree of repellent activity, was evaluated in an exp...The insecticidal efficacy of the diatomaceous earth against granary weevil, Sitophilus granarius L. （Coleoptera： Curculionidae）, with two essential oils for the degree of repellent activity, was evaluated in an experimental model in laboratory tests. The diatomaceous earth was obtained from three Romanian sources （Patirlagele, Urloaia and Adamclisi） and was applied at four doses of 100, 300, 500 and 900 ppm （5, 15, 25 and 45 mg, respectively） on three replicates each variant. Mortality of S. granarius adults was estimated after 7, 14 and 21 d of exposure on treated grain. The insecticidal efficacy of the examined diatomaceous earth against the granary weevil was highly influenced by exposure time, dose and essential oil type. The longer exposure times increased weevil mortality in the case of low doses （100 ppm and 300 ppm）. After 60 d from the experiment initiation, the exposed grains from each variant were assessed about the progeny production. For the model proposed as bio-experiment, two essential oils in concentration of 80μL/L air and 125μL/L of Thymus vulgaris L. and Satureja hortensis L., respectively, were tested compared with untreated control in laboratory conditions. Both plant species belong to the family Lamiaceae, and the major active insecticidal compound was thymol among other providing to terpenoid class, such as eugenol and linalool. The species S. granarius chosen for experimental model was grown in the Research-Development Institute of Plant Protection （RDIPP） Bucharest bio-base. The results show that mortality induced from diatomaceous earth was at the level between 83.33% and 100% in all variants after 21 d, compared with untreated control and a standard product Silicosec.展开更多
Since forestation of pure forest of Pinus massoniana is liable to suffer from pest calamity, soilerosion, decrease of soil fertility, and difficulty in wood production in the hilly areas of southern China, weconducted...Since forestation of pure forest of Pinus massoniana is liable to suffer from pest calamity, soilerosion, decrease of soil fertility, and difficulty in wood production in the hilly areas of southern China, weconducted an investigation on the three types of forests in Gaoan County of Jiangxi Province, namely, thepure forest of Pinus massoniana, the pure forest of Schima superba, and the mixed forest consisting of thetwo species, setting up standard stand, measuring and studying the growing stock, biomass, leaf area, roots,soil, vegetation, pests, litters, soil erosion, microclimate, etc., with the following results. ① The averageheight, diameter at chest height, and volume of the mixed forest are higher than those of the pure forest ofPinus massoniana by 30.9%, 31.7% and 10.6%, respectively. ② The biomass of the mixed forest is 2.24times as much as that of the pure forest of Pinus massoniana. ③ The litters of the mixed forest is 3.37 timesand 1.96 times as much as the litters of the pure forest of Pinus massoniana and the pure forest of Schimasuperba respectively. ④ The occurrence of pest calamity per tree is lower and the conditions of soil erosionand microclimate are better than those of the pure forest of Pinus massoniana. ⑤ The mixed forest of the twospecies is an excellent mixed type of needle-leaf and deciduous forest worth being popularized in Chinassubtropical areas, especially in the low hilly areas. It is recommended in plantation that the mixed patterns bebetween trees, lines, small blocks, or scattered-dots, the ratio of mixture of Pinus massoniana and Schimasuperba be 5 to 1, or 3 to 1, and the initial space between trees be 1.2, 1.5, or 2.0 m while the initial densitybe 6 944 to 4 440 trees per square hectare.展开更多
文摘In agriculture, chemical insecticides are widely used to protect crops from insect pests. Over a period of years, some insects such as Colorado potato beetle （CPB） succeed in developing resistance to most of the registered chemical insecticides. Consequently, heavy applications of chemical insecticides to control this pest become ineffective on a long-term basis and can lead to serious health and environmental problems. The use of natural enemies to control CPB is an interesting alternative to chemical means However, hand release of predators is not feasible on a large scale in the field. The main objective of this research study was to design and build a test bench to investigate the technical feasibility of mechanically releasing predators. The test bench consisted of a vertical chain conveyor mounted on two vertical shafts driven by an electric motor. Since the predators are small and fragile, they were placed in a specially designed container to preserve their physical integrity. Trials using this test bench showed that a carrier material was required, because most of the predators remained inside the container. The success of this mass predator release system will be highly valuable for the biological control of insect pests in many crops.
文摘The insecticidal efficacy of the diatomaceous earth against granary weevil, Sitophilus granarius L. （Coleoptera： Curculionidae）, with two essential oils for the degree of repellent activity, was evaluated in an experimental model in laboratory tests. The diatomaceous earth was obtained from three Romanian sources （Patirlagele, Urloaia and Adamclisi） and was applied at four doses of 100, 300, 500 and 900 ppm （5, 15, 25 and 45 mg, respectively） on three replicates each variant. Mortality of S. granarius adults was estimated after 7, 14 and 21 d of exposure on treated grain. The insecticidal efficacy of the examined diatomaceous earth against the granary weevil was highly influenced by exposure time, dose and essential oil type. The longer exposure times increased weevil mortality in the case of low doses （100 ppm and 300 ppm）. After 60 d from the experiment initiation, the exposed grains from each variant were assessed about the progeny production. For the model proposed as bio-experiment, two essential oils in concentration of 80μL/L air and 125μL/L of Thymus vulgaris L. and Satureja hortensis L., respectively, were tested compared with untreated control in laboratory conditions. Both plant species belong to the family Lamiaceae, and the major active insecticidal compound was thymol among other providing to terpenoid class, such as eugenol and linalool. The species S. granarius chosen for experimental model was grown in the Research-Development Institute of Plant Protection （RDIPP） Bucharest bio-base. The results show that mortality induced from diatomaceous earth was at the level between 83.33% and 100% in all variants after 21 d, compared with untreated control and a standard product Silicosec.
文摘Since forestation of pure forest of Pinus massoniana is liable to suffer from pest calamity, soilerosion, decrease of soil fertility, and difficulty in wood production in the hilly areas of southern China, weconducted an investigation on the three types of forests in Gaoan County of Jiangxi Province, namely, thepure forest of Pinus massoniana, the pure forest of Schima superba, and the mixed forest consisting of thetwo species, setting up standard stand, measuring and studying the growing stock, biomass, leaf area, roots,soil, vegetation, pests, litters, soil erosion, microclimate, etc., with the following results. ① The averageheight, diameter at chest height, and volume of the mixed forest are higher than those of the pure forest ofPinus massoniana by 30.9%, 31.7% and 10.6%, respectively. ② The biomass of the mixed forest is 2.24times as much as that of the pure forest of Pinus massoniana. ③ The litters of the mixed forest is 3.37 timesand 1.96 times as much as the litters of the pure forest of Pinus massoniana and the pure forest of Schimasuperba respectively. ④ The occurrence of pest calamity per tree is lower and the conditions of soil erosionand microclimate are better than those of the pure forest of Pinus massoniana. ⑤ The mixed forest of the twospecies is an excellent mixed type of needle-leaf and deciduous forest worth being popularized in Chinassubtropical areas, especially in the low hilly areas. It is recommended in plantation that the mixed patterns bebetween trees, lines, small blocks, or scattered-dots, the ratio of mixture of Pinus massoniana and Schimasuperba be 5 to 1, or 3 to 1, and the initial space between trees be 1.2, 1.5, or 2.0 m while the initial densitybe 6 944 to 4 440 trees per square hectare.
