The Selection Of Loxostege Sticticalis The Host Plants And Determination Of The Biologically Active Substances

Meadow moth, Loxostege sticticalis L.(Lepidoptera:Pyralidae) is a kind of worldwide pest imperiled agriculture and pasture, which often outbreak in the North China, Northeast, and Northwest of China. Meadow moth often causes serious loss in husbandry production, normally it feeds on35Families and over200species, and a lot of economic crops are included. In order to understand the occurrence and damage pattern of L. sticticalis, and improve the prediction level and the control techniques, and develop green and environment friendly control methods, I analyzed the data which had already had in scientific research at home and abroad thoroughly in this dissertation, combined outdoor field investigations with indoor physiological and biochemical experiments. This study was also involved with the influence of nutritional effect and physiological reaction of the larva feeding different host plants, and nectariferous plants to the reproduction, meanwhile, the volatile components of diverse host plants, and active chemicals toward antennae of the adults were identified. The major progresses obtained from these studies are summarized as follows:1. The preference of the meadow moth to different host plants and its influencing factors.The preference of the meadow moth to different host plants is investigated in both the grasslands of Inner Mongolia and the field of Jilin Province, in which the meadow moth often occurs. The result shows that an obvious preference of the wild adults to the oviposition plants is existed in the natural conditions. Besides the strongest preference to the alfalfa, nectariferous plants are obviously attractive to the meadow moth. The climatic factors, mainly in temperature and humidity, greatly restrict the fitting zones of wild meadow moth. The impact on different temperature and humidity combination to the fecundity of the female adults indoor was investigated. The results show that the temperature is the key factor in the restraints, and humidity factor may impact the fecundity.2. The influence of the nutritional effect of different host plants and digestive enzyme in the midgut of the larvae when they are feeding.The nutritional effect of the larvae feeding on different host plants separately is obviously differed. The treatment group feeding on Chenopodium Album L. is evidently superior to the other four groups which feed on the other host plants in the scores among the relative consumption rate, the relative growth rate, and the efficiency of conversion of ingested food. Both the soluble sugar content and the starch content of leaves in various host plants are obviously different, in which the potato leaf is the highest when comparing soluble sugar content, but the lowest when referring to the starch content; the sunflower leaf is totally reverse. Besides, the result also clearly shows that there are no correlations between the nutritional efficiency and the soluble sugar content or the starch content. The digestive enzyme in the midgut of the meadow moths which feed on different host plants respectively are obviously changed, and the significant differences appear reciprocally; the content and the proportion of the digestive enzyme are distinctly altered as time goes.3. The influence of nectariferous plants to the oviposition and the lifetime of meadow mothThe experimental results show that nectariferous plants are the necessary nutrition sources for the oviposition of meadow moths, although different nutrient sources have significant impacts on the fecundity of the female adults. Most importantly, the fecundity of meadow moth feeding on honey than that feeding on simple sugar. Moderate starvation treatment could be beneficial to the oviposition, but much longer time for starvation could be worse. The detailed results show that the meadow moth which feeding on rhamnose exhibits lower physiological parameters among the fecundity, lifespan and hatching rate of the female adults than the other eight treatment groups. The meadow moth feeding after consecutive starvation for two days has higher scores on the fecundity and hatching rate of the female adults, and the control groups which are feeding on water or starving are quite low. No significant differences are shown on the fecundity, preoviposition period and hatching rate of the female adults among the starvation treatment after regular feeding in five days, the feeding treatment after three days’starvation and the regular feeding, respectively.4. Identification of the volatiles emitted from host plants of the meadow mothApplying the dynamic headspace collection device, I succeeded to collect volatiles from nine different host plants, and then I analyzed the effective components by gas chromatography-mass spectrometry (GC-MS). Fifteen chemicals were extracted from Zhongmu No.1, and the content of cis-3-Hexen-1-o1acetate is the highest in the15chemicals. Eleven and eight chemicals were extracted from the alfalfa and the sweet clover, separately. Ten and nine chemicals were extracted from Astragalus adsurgens Pall and white clover, respectively. Nine and14chemicals were extracted from tall fescue and Lolium perenne L. as perennial plants, separately. Ten and eight chemicals were extracted from Elymus dahuricus Turcz. and Elymus sibiricus L., respectively.5. The EAG response of Loxostege sticticalis to volatile compoundsDuring EAG recordings,1-Heptanol and1-Octanal, which are volatile compounds of green leaves, have been found to elicit a higher EAG response on their antennae than other compounds, indicating these componds effect the behavior of Loxostege sticticalis.