| Japanese wax scale, Ceroplastes japonicus Green belongs to Ceroplastes of Coccoidae in Coccoidea, Hemiptera. It is distributed widely in China and its host plants are more than 150 species. In the mid-south of Shanxi Province, the Japanese wax scale was one of the important pests damaged the persimmon trees. For many years, chemical control has been used as a main method to against the pest. However, Japanese wax scale can secrete wax substances that form wax tests and cover on the surface of their bodies to protect themselves from chemical insecticide. Therefore chemical control was little useful. In order to know the variation rule of chemical communication substance and to use it in the pest biological control, in this paper, the semiochemical existing persimmon tree-Japanese wax scale-natural enemy was studied including the relation and dynamic rhythm. Based on this study, we could better comprehend physiological and biochemical reaction of the damaged persimmon trees to the Japanese wax scale, the main attraction volatiles to natural enemies and its release rhythm change with seasons, the density of pest and the pests' developmental stages. As a result, screen out some functional volatiles as chemical attractant to synthetic imitate and release in the forest that damaged seriously by the scale insect in order to attract natural enemies. Therefore we could remain the natural enemies longer in the damaged forest and control scale insect. The content and conclusion is summarised as follow:1. In the persimmon experiment forest in Wanrong County, Shanxi Province, we found three dominant predatory natural enemies, a green lacewing, Chrysopa sinica Tjeder and two ladybugs, Harmonia axyridis Pallas and Chilocorus kuwanae Silvestri. Their olfactory tendency preferenceto the kinds of odor sources in different period was studied. The results showed that in the two periods respectively from May to June and from July to August, the damaged host persimmon trees did not show the significant attraction to the natural enemy insects. However, in the period of September and October, the attractive action showed strongly, especially in the midnight and in the afternoon. Contrastively it was found that the source of volatiles also could come from the Japanese wax scale itself and the damaged host trees deprived insects for 6 hours. Contrast with the blank control, the undamaged and slightly damaged twigs and leaves had no attraction to natural enemies.2. The volatile compounds in May included terpenoids, alcohols, esters, aldehydes, ketones, nitrogen-containing compounds, sulfur-containing compounds, and some other compounds in a little content, that is furans, hydrocarbons and fatty acids, through analysis and compare the volatile compounds in one day's 4 stages in May. Among these compounds, esters relative content were the highest. In 4 stages of one day, the volatile of the damaged persimmon trees was with the most compositions, 25 kinds of compounds at 13:00 in the afternoon. To be contrasted, the volatile compounds were the least at 1:00, only 14 kinds. Relative content of every compound changed with the different stages of a day. Terpenoids, alcohols, aldehydes and ketones and nitrogen-containing compounds had the larger changing range than esters, sulfur-containing compounds and hydrocarbons. Relative content of furans decreased gradually with time.3. In the 3 periods of 2005 (May, July, September), the study about volatiles demonstrated that the damaged persimmon trees released more kinds of compounds than undamaged trees. From May to September, both damaged and undamaged tree increased their compositions in the volatiles. Besides, the compounds of later time always included most of the earlier ones. In May, the most kinds of volatile compounds from damaged persimmon trees were terpenoids, and the largest relative content was esters. Contrastively in both kinds of the trees the terpenoids were the most kinds ofcompounds and the largest relative content in July. However, terpenoids and hydrocarbons were great in damaged and undamaged persimmon trees in September, but alcohols, aromatics and esters etc. were a little. Terpenoids were with the largest relative content and hydrocarbons were the most kinds of compounds. Relative to the volatiles of undamaged persimmon trees, the volatiles of damaged persimmon trees gained 4 kinds of terpenoids, 2 kinds of hydrocarbons, 2 kinds of alcohols and 2 kinds of aromatics. In the volatiles of damaged persimmon trees, the relative content of terpenoids and ketones decreased, however, the relative content of alcohols, aromatics, esters etc. increased.4., Variation of insect-resisting substances in damaged and undamaged persimmon trees was studied from March to September in 2005. It showed that, whether leaves or phloem, content of nutrition in damaged persimmon trees decreased and resistant substances increased. Variety of tannin, amino acid and sugar in phloem in March and May was larger than that in July and September. However, variety of them in leaves was less.
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