Studies On The Bio-ecological Characteristics And Monitoring Techniques Of Chorophorus Sp.

Caragana spp. is a genus of deciduous shrub in the Leguminosae Caragana, including C. microphylla, C. intermedia and C. korshinski. It is one of the most important plant species for the vegetation restoration, ecological reconstruction and regional economy in desert and semi-desert areas. Chlorophorus sp. belonging to Chlorophorus genus of Cerambycidae family, Coleoptera class. The shrubs are mainly damaged by larvae of the long-horned beetle boring into the cadres of branches, causing the lost of plant vigor and even death of whole plants. In recent years, Chlorophorus sp. occurred widely in Zhongwei and Lingwu city and Yanchi country in Ninxia Hui Autonomous region, threatening to the large areas of planted and natural Caragana forests.There were no previous reports and related researches on this insect in China. In this paper, we have conducted systematic researches on the bioecology, population dynamics, changes in chemical substances in damaged Cagarana, and plant volatile attractants available for monitoring and controlling the insect. The main results are as follows:1. Laboratory and field observations of the biological characteristics of Chlorophorus sp. show this insect has one generation per year, the mature larva pupate in early May, and adults emerge in late June and peak in July, and disappear in mid August. Eggs are laid centralized in the cracks of the barks and emergence holes. The insect lays a total of 12-21 aggs.. The egg period is 16 days and about 83% hatch. Parasitoids include Xorides(Xorides) irrigator (first discovered in Ningxia Province) and Iphiaulax impostor, with a parasitism rate of 6.75%.2. Larvae and adults of Chlorophorus sp. are mainly distributed in the branches of Caragana spp. from 0 to 100cm, mostly from 0 to 40cm, and the individual number decreases from bottom to top. Larvae mainly attack Caragana spp. which are more than 4 years old, especially those 6 to 8 years old. The number of adult beetles increase gradually with the increase of diameter of caragana branches.3. The basic component of population distribution was individual group and the distribution was aggregated pattern. Aggregation was caused by environmental factors and the aggregation behavior of insects. We established the theoretical sampling limit formula and sequential sampling decision-making model of Chlorophorus sp. larvae. The optimal sampling was determined for investigation, prediction and controlling of this pest.4. With tank trapping and net fishing,3617 beetles belonging to 15 families were collected, Tenebrionidae (3213) accounted for 88.18%. The trend of beetle family richness, diversity and dominance was 5a instar＞15a instar＞25a instar, while uniformity trends were 15a instar＞5a instar＞25a instar. The individual number of beetles and uniformity of seasonal changes were very similar to 5a instar and 15a instar and 25a instar, while family richness and diversity of seasonal changes were highly similar for 15a instar and 25a instar. Seasonal changes in the Caragana spp. forest of different ages showed that uniformity section is lowest in July; the individual number is highest in July. Changes in family richness is roughly the same and the trend of family diversity in plantations of 15 and 25 years is similar.5. The chemical content in xylem, phloem and leaves of C.korshinskii, which were healthy or damaged by Chlorophorus sp., was measured and the results showed that:①The levels of carbohydrate, fat, phosphorus, zinc, potassium, iron, arginine in xylem were decreasing; The levels of protein and total amino acid content in xylem increased while methionine did not change.②In the phloem, the content of protein, phosphorus (p＜0.05), zinc, potassium reduced; the content of iron, fructose, glucose, lysine content increased; but carbohydrate, serine and proline did not change; In addition, the fat of 0-40cm and 16 amino acids were reducing; in the first 1-10cm of the branch, but from 10-40cm the fat, and cysteine increased, the glycine and methionine did not change, and the other 12 amino acids decreased;③, total amino acids, protein, fat, phosphorus iron in the leaves increased, while carbohydrates, zinc, potassium, fructose and glucose decreased.6. Thermal desorption-gas chromatography/mass spectrometry were used to identify and analyze the volatile components from stems and leaves of Caragana spp.. Sixteen volatile compounds have been identified, including alkanes, aldehydes, ketones, esters, monoterpenes, and sesquiterpenes. Five volatile substances, making up a large percentage of the components, were determined by area normalization. The relative percentages were used to decide the proportions of various combinations, and resulted in 25 synthetic attractants. Four optimal attractants had effects of 8.65～17.33 individuals per trap, with a sex ratios between 0.545 and 0.476 (♀/♂), and a duration of 37 to 50 days. Attractive efficiency was up to 63.81%.7. Several measures were put forward to establish an integrated technology system against disasters by Chlorophorus sp.. The measures included fundamental methods of monitoring and forecasting technology, tending stump and developing plant varieties with resistance against the insect. Ecological control measures, including plant volatile attractants, protection of natural enemies, and environmentally harmonious chemicals, were needed to be utilized.