Study On Food Identification Signal And Larvae Population Dynamics Of Cyrtotrachelus Bugueti

Bamboo was the main raw material for paper making industry and the key economic resourse for bamboo farmers, and bamboo industry had been developed into a sunrise industry. Cyrtotrachelus bugueti, the main bamboo forest pests of cluster bamboo forest, had seriously constrained the improvement of bamboo produce and the income increase of bamboo farmers. The insect had been taken as one of dangerous forestry pests by the State Forestry Administration since 2003.The food identification signal of C. bugueti, including its ultrastructure of touch sensilla and smell sensilla, as well as the volatiles effecting on C. bugueti from different varieties and types of bamboo shoots, were studied by using the scanning electron microscopy, the gas chromatography-mass spectrometry (GC-MS), the elctroantennogram (EAG) technique respectively. The larvae population dynamics of C. bugueti and its relationship to climate factors were analyzed too. The study combined climate factor effecting on larvae density with food identification signal of C. bugueti for controlling the bamboo pest by the nature chemistry between C. bugueti and bamboo shoot.This study provided theoretical basis for harmony among control of bamboo pest, utilization of insect resource and protection of environment. The results were as follow:1 Antenna ultrastructure and food identification sensilla of C. buguetiAbservation using scanning electron microscopy showed that the head sensilla of C. bugueti mainly distributed in antenna and mouthpart, and the antenna consists of the scape, pedicel and seven flagellomeres. The sensillaes of flagellomeres in the end of antenna were over 95%of antenna sensilla. In antenna, one type of sensilla basiconic, two type of sensilla trichodea, one type of sensilla column, one type of bud-shaped sensilla and one type of hand-shaped sensilla were distinguished with the shapes and distribution of sensilla. The sensilla basiconic with olfactory function were the largest density sensilla, the second was the sensilla trichodea with the pheromones feeling function. Mouthparts also distributed a large number of long columns sensilla trichodea with taste function. The results showed that volatiles from bamboo shoots were apperceived mainly through the sensilla basiconica in flagellomeres of antenna. 2 Study on relationship between volatile components of bamboo shoots and C. bugueti28 bamboo shoot volatiles were discovered by GC-MS, and the results showed that the volatiles from the tine of cluster bamboo shoot were with high content of benzaldehyde, linalool,4-hydroxy-benzaldenhyde and 8-chlorocapric acid, the volatiles from the bottom of cluster bamboo shoot were with high content of 4-hydroxy-benzaldenhyde,2,5, 8,11,14-pentaoxahexadecan, (3-methyl-oxiran-2-yl)-methanol, benzaldehyde, and the volatiles from the tine of scattered bamboo shoot were with high content of 4-hydroxy-benzaldenhyde, hexadecanoic acid, linoleic acid and stigmast-5-en-3-ol (3.beta.24s). The results suggested that the high content or the special volatiles of the tine of cluster bamboo shoot might be the important substance attracting C. bugueti.EAG reaction suggested that the antenna of C. bugueti imago reacting to the different volatiles from bamboo shoots showed different electrophysiological reaction, and benzaldehyde, linalool and 8-chlorocapric acid and so on could caused C. bugueti imago significant electrophysiological reaction. With them trapping C. bugueti imago, the results showed that benzaldehyde could attracted the most imagoes. The study suggested that C. buqueti might identified the bamboo shoot by the chemistry finger map with primary benzaldehyde and special proportion of components.3 Overground propagatation of C. buqueti was markedly impacted by temperature. From 2004 to 2008, the eggs and larvae of C. buqueti in all bamboo shoots of three bamboo forests were regularly investigated in the Muchuan Sichuan. The principal component analysis, as well as correlation and path analysis and decision coefficient, was exerted to study the effect of main climate factors on larvae population dynamics, and eight functions were used to analyze the relationship among C. buqueti larval density and mean temperature and minimum temperature. The results showed that the larvae population fluctuation was single peaked, with the peak in August. The larvae population was low before mid-July and evidently reduced after mid-September and gradually tended to zero level after early October. The results of four analyzing methods suggested that the most important limiting-factor and the most important decision factor of larvae population fluctuation was respectively the mean temperature and the minimum temperature, two forecasting models for the larvae population fluctuation were established, i.e., C. buqueti larvae density (Y) and mean temperature(X) follow the equation of Y=-0.535+0.031X, and C. buqueti larvae density(Y) and minimum temperature (X) follow the equation of Y=-1.594+0.6001nX. Based on these results, the forecast tables for C. buqueti larvae density were provided, and for controlling larvae density of C. buqueti, mean temperature 21.5℃of ten days and minimum temperature 17.7℃often days were suggested too.4 The emergence of C. bugueti had the intrinsic unity with rainfall, temperature and bamboo shoots. During overground propagatation of C. buqueti, the growth of bamboo shoot was facilitated by the more rainfall of July and the higher temperature of August, and provided abundand food for C. buqueti. Therefore, the high larvae population came into being.