Forecasting, Spatial Distribution And Sampling Technique Of Eucryptorrhynchus Brandti And Eucryptorrhynchus Scrobiculatus

Eucryptorrhynchus brandti(Harold) and Eucryptorrhynchus scrobiculatus Motschulsky both feed on and are harmful to Ailanthus altissima. The main hazards include boring branches by E. brandti and boring root by E. scrobiculatus. In the Ningxia region, the two weevils often occur and causes harm together, causing serious damage to local Ailanthus. In view of the serious harm caused by the two kinds of weevils, this paper focuses on the study of spatial pattern, forecasting and sampling techniques in order to provide better prevention and treatment to theoretical guidance. All the research results are as the follows.1. In the natural changing temperatures of the lab that the developmental threshold temperature and effective accumulated temperature of E. scrobiculatus was calculated by weighted regression. The results showed that the developmental threshold temperatures of the egg, larvae and pupae were respectively 8.84℃,15.37℃ and 5.95℃, and their respective effective accumulative temperatures were 190.50℃,667.06℃ and 322.50℃.2. We used the common local trees and crops to establish a phonological table. When the ailanthus sprouts and corn is sown, the overwintering adult E. brandti appears; when the ailanthus and corn flowers, it is the spawning peak for E. brandti; when the ailanthus produces seeds and the corn heading, it is the peak of emergence for E. brandti; when the ailanthus leafs and Jujube sprouts, mainly overwintering adult of E. scrobiculatus appears; when the ailanthus and corn flowers, mainly adult of E. scrobiculatus lay eggs.3. Through variance analysis and multiple comparisons, we got the distribution of Ailanthus on different levels and directions for adult of E. scrobiculatus. The number of west is significantly more than the others, the number of north and south has no significant difference, and the number of east is significantly less than the others. The number of lower is significantly more than the middle and upper, the number of middle and upper has no significant difference. The spatial distribution of adults for E. scrobiculatus is aggregated distribution, based on the habits of E. scrobiculatus and tree growth. This established the Iwao regression model showing mutual attraction among individuals for E. scrobiculatus and relatively strong aggregation habits. The fitting model parameter is obtained by using the GS+. The best fitting model is the index, with a range of 66.00 meters.4.The emergence holes of E. brandti were mainly distributed on Ailanthus within 2 meters. The number of emergence holes within 0-1 meters and 1-2 meters were significantly more than number other emergence holes within the height range. The fitting model parameter of adults and larva for E. brandti is obtained by using the GS+. The best fitting model of adults is index, with a range of 39.00 meters while the best fitting model of larva is also index, with a range of 36.00 meters.5. In the traditional sampling method according to the regression model, the optimum theoretical sampling under the different population density was obtained. The sequential sampling table of adults for E. scrobiculatus was drawed. In the spatial sampling method showed the stratified sampling has most precise results and minimal errors.