| Meadow moth, Loxostege sticticalis L. (Lepidoptera: Pyralidae) is one of the recurrent polyphagous insect pests of agricultural and animal husbandry in the northern of China. In order to explain the systematic of population development of Loxostege sticticalis L. and to improve the level of forecasting technique for the occurrence of meadow moth, the influence to the development of the larvae on the tested natural food and artificial diet were observed and the larval cold tolerance with several physiological factors was studied under simulating different environment condition in lab. The major progress obtained from these studies are summarized as fellows:Lambsquarter is affirmed as the favorite host plant for the larvae of meadow moth. Rearing of meadow moth was studied by feeding on lambsquarter,Chenopodium glaucum L., alfalfa , Medicago sativa. L. and spinage , Spinaciaoleracea L. and token note the larval development duration ,average purpal weight,survival rate purpal duration and eclosion rate ,the results show significantly differences among the three natural host plants tested. Lambsqurter is the favorite food to meadow moth larvae and spinage is the second choice for the pest in the test. Alfalfa , however, is the host plant with longer larval duration , lower survival rate and lower emergence rate.Two artificial diets with potential superiority for the pest population growing are screened during evaluating the protein content, and the water content etc. for the larval growth among 7 artificial diets in the experiment. The results show that high content protein is suitable for the larvae, which can catalyze larval feeding behavior. Low contents protein and high water content will bring on larval high death rate, the artifical diet will mildew when low antiseptic content .on the contrary, high antiseptic content of diet is influence on larval feeding behavior, and lead its death rate.The key environmental factors inducing the larval diapause are understood in the experiment. The experiment found that the larvae of meadow moth wound diapausedon ten hour photo and non-diapaused on seventeen hour light everyday , the super-cooling points (SCP) and freezing point (FP) of the diapaused larvae of meadow were lower than the non-diapaused larvae's. The means of SCP of the diapaused larvae is -25.84 °C,the means of FP is -6.95°C, the means of SCP is -12.72 °C,and the means of FP is -2.68°C .the results showed marked different between the diapaused larvae and the non-diapaused in cold -hardiness, As well the means SCP and FP of the earlier diapaused larvae are -17.69°C and-4.08°C. the result show marked different with the non-diapaused and the diapaused larvae's. The SCP and FP of non-diapaused larvae are decline at 4°C during in different time, and the result show marked different on the SCP and FP , The same to the diapaused larvae during at 4°C and — 20°C,the studies show the diapaused larvae and the non-diapused larvae could observably enhance the cold hardiness after a period of chilling, but the SCP and FP would be unchanged in a steady temperature at long time, for example, the non-diapaused larvae in 4°C, which SCP is from-12.72°C to -22.42°C,and FP are from -2.68°C to -5.45°C.and the diapaused larvae at 4°C with 20d and 30d,which SCP are from— 25.82°C to -26.79°C,FP are from-5.59°C to -9.13°C,but when its at 4°C with 40d , its SCP are -26.75°C, FP are -9.16°C.the results are show marked different between 20d's , 30d's and 40d's,the results also show no marked different between 30d's and 40d's. The temperature significantly affected cold-hardiness of the larvae of meadow moth, When the diapaused larvae were treated with -20°C after 24h, the SCP are from -26.06°C to -27.56°C, and FP are from -8.87°C to -9.72°C.So that we can concluded the larvae of meadow moth must adjust its chemical substance to season with changing temperature in environment. At the same time, the cold-hardiness of the diapaused larvae also enhanced in normal temperature along with temporal process. These results showed that the cold-hardiness of meadow moth larvae were growed up with passed time, and will get stronger with the deep of diapause and low temperature. This conclusion adapted to the actual condition of meadow moth that live through the winter. The cold-hardiness ability of larvae will change with the alteration of environment, so meadow moth had strong adaptive ability.The present research studied the effect of energy compounds on cold-hardiness...
|
PDF Full Text Request