| Brontispa longissima (Getro) is a new harmful insect invading in China, which feeds on the palmaceous plants. Studies on the population dynamic of B. longissima and its control were carried out. Main research was focused on the following aspects: the investigation of the annual development dynamics of laboratory population and field population of B. longissima; the establishment of the life tables of laboratory population and field population of B. longissima; the repellence and poisonous effects of plant extracts on B. longissima laboratory population; the poisonous effects of some kinds of chemical insecticides on B. longissima in the laboratory and their control effects on the natural population. The main results were as follows:1 The annual population dynamic of B. longissimaThere were two developmental peaks when feeding on Roystonea regia . The first peak was from the beginning of May to the last ten-day of June, and the second peak was from the middle ten days of October to the beginning of January of the next year. The population was lowest during the last ten-day of February to last ten-day of March. The number.of the larvae was largest among the population, the peak was from the first ten-day of May to last ten-day of June. The peak of adult was from the last ten-day of June to last ten-day of July. The major peaks of egg were from the last ten-day of March to middle April and the last ten-day of May to first ten-day of July. The quantity of pupae was lowest among the population, the peak was in July.There was one peak when feeding on Phoenix roebelenii, which was from the last ten-day of April to the middle ten days of July.The laboratory population dynamics showed that the major peaks of population werefrom the first ten-day of April to last ten-day of June and the first ten-day of September to first ten-day of December. The quantity of larva and adult was higher than the other stages.2 Life tables of B. longissima laboratory and natural populationThe index of laboratory population trend (I) of B. longissima on Cocos nucifera, Archontophoenix alexandraev/as and Roystonea regia were 34.43, 25.52 and 13.98 respectively. While the index of natural population trend (I) of B. longissima. on Cocos nucifera, Archontophoenix alexandraev/as and Roystonea regia were 17.83, 12.28 and 7.83 respectively. The result from both laboratory and nature population life table showed that Cocos nucifera was the best host plant. Life table also showed that the major factors affecting the population were prey, illness and others, that meant the natural enemies and Metarhizium anisopliae provided important suppression effect on B. longissima. 3. The bioactivity of alcohol extracts from plant species on adult of B. longissimaThe effect of ethanol extracts from 36 plant species on feeding, survival and repellency of adult of B. longissima were studied. The result showed that 4 extracts, Artemisia brachyloba Franch., Croton tiglium L., Lannata cmara L. and Rhizoma Acoori Graminei (stalk and leaf) showed good effect on feeding deterrent; 5 extracts, Momordica charantia Linn., Ageratum conyzoides L., A. brachyloba, L. cmara and Mikania micraintha L. showed good oviposition deterrent, the interfere index of population control (IIPC )were all lower than 0.15; 5 extracts, Paris verticillata M. Bieb., Rhizoma Acoori and A. brachyloba could increase the mortality of B. longissima; Commelina communis L., A. brachyloba, M. micraintha and L. cmara showed significant repellency effect.4 The virulence of Abamectin and Beta-cypermethrin on B. longissima populationThe LC5o of Abamectin impacting on the egg, larva, pupae and adult was 0.4253 ug/ml, 0.2246ug/ml, 0.5206ug/ml and 0.2801 ug/ml respectively. The influence of Abamectin on these 4 stages could be described by the Virulence Regress Equations: Y\= 5.5000 + 1.3465*1, r2=6.0055+1.5503*2, Jy=5.6290+2.2180*3 and 74=5.5360+1.2759*4 respectively. The LC50 of Beta-cypermethrin impacting on the egg, larva, pupae and adult was 1.8767ug/ml, 2.6499u.g/ml, 1.7890uï¿¡/ml and 1.6696u.g/ml respectively. The influence of Beta-cypermethrin on these 4 stages could be described by the Virulence Regress Equations: y,=4.4767+1.9140xi, y2=4.2935+1.6693x2, y3=4.5439+1.8056x3 andy4=4.5861+1.8594x4 respectively.5 The control efficacies of three chemical insecticides on natural population of B. longissimaThe control efficacie of 3 kinds of chemical insecticides, 1.3% Rotenone-Fenvalerate emulsion, 0.3% Azadirachtin EC and 1.8% Abamectin EC at 3 concentrations, 0.1%, 0.05% and 0.033% were studied in the field. The result showed that all 3 kinds of insecticides at concentration of 0.1% gave good control on adult, larva and pupae of B. longissima Seven days after Rotenone-Fenvalerate application, the corrected mortalities (CM) of adult, larva and pupa were 98.52%, 100% and 100% respectively; But when using at concentration of 0.05%, the effect on pupa was not as good as 0.1%, the CMs of the 3 stages were 97.76%, 98.37% and 87.01% respectively; 0.033% was effective on adult, but not effective on larva and pupae, the CMs of the 3 stages were 97.30%, 64.48% and -1.19% respectively. After using Abamectin at concentration of 0.1%, the CMs of adult, larva and pupa were 99.06%, 92.49% and 91.07% respectively; The CMs of adult were 96.80% and 95.16% respectively at concentration of 0.05% and 0.033%,but the effect on pupa was not good. After using Azadirachtin, the CMs of adult, larva and pupa were 94.87%, 94.65%, 94.90% (concentration 0.1%) and 95.72%, 92.32% and 91.07% (concentration 0.2%) respectively; the effect of concentration 0.033% on larva and pupa was not good. These 3 kinds of insecticide could be recommended in the control of B. longissima population.
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