Host Plants Of The Meadow Moth Growth And Reproduction And Physiological Effect

Loxostege sticticalis L.( Lepidoptera:Pyralidae) is an important agriculture pest in the world. It has characteristics of wide distribute range, many host plants, strong ability of migration. In China it mainly happened in northeast, northwest and north China area. It is a kind of polyphagous pest, and it's host including 35 families 200 species of plants. It cause high disaster frequency, endanger becoming more serious. This research based on the insect nutrition ecology theory and in view of the L. sticticalis L. bioecology characteristic, the systemic research of the influence of L. sticticalis L. development, the population dynamics, the nutrition utilization and the physiological reaction of L. sticticalis L. to the different host plants were conducted. The results were summarized as follows.1. Relationship between the nutrition contents and the fecundity of adult Loxostege sticticalis L.The newly emerged moths of L. sticticalis L. were fed individually with four levels of compensatory nutrition, (Ⅰ) 10% honey dilution every day, (Ⅱ) 5% honey dilution every day, (Ⅲ) 10% honey dilution the first day and then water the rest days, or (Ⅳ) water every day in the laboratory. The results indicated that the mean pre-oviposition, fecundity and longevity of female moths were significantly different; the average in the treatmentⅠwas higher than that of the treatmentsⅡ,ⅢandⅣ, the mean pre-oviposition, fecundity and longevity of female adults in the treatmentⅠwere 5.71 d, 359.14 eggs, 21.0 d, respectively. While there were no obvious effects of compensatory nutrition conditions on male adults longevity and egg hatching rate. Further_more, there were no significant differences on the oviposition period of female adults between the treatmentⅠandⅡ, or the treatmentⅢandⅣ; their oviposition period were 10.57 d and 8.0 d , 4.0 d and 3.14 d respectively; but the difference between the treatmentⅠ,Ⅱand the treatmentⅢ,Ⅳwas significant. The female adults age-specific oviposition probability were effected by the compensatory nutrition. Therefore, the compensatory nutrition condition was a key factor affecting on the population dynamics. 2. Effects of host plants on the development-reproduction of Loxostege sticticalis L.Individuals of L. sticticalis L. were reared to test the relationship between the nutrition contents of five host plants (lambsquarter, soybean, alfalfa,sugarbeet and sunflower) and L. sticticalis development, reproduction in Pest Control Laboratory of Heilongjiang University. The results indicated that the height order of five plants for total sugar contents was sunflowe>soybean>alfalfa>sugarbeet>lambsquarter, for crude protein contents was sugarbeet> alfalfa>sunflowe>soybean>lambsquarter and for water contents was sugarbeet>alfalfa>sunflowe>lambsquarter >soybean. The egg development duration (2.42 d) was shortest on the group of lambsquarter and the longest development duration (3.90 d) on the group of sugarbeet. The larvae fed on the sugarbeet had the shortest developmental days (10.00 d), meanwhile the larvae fed on the alfalfa had the longest development days (12.63 d). The pupal period (11.30 d) was shortest on the group of sunflower and the longest pupal period (16.00 d) on the group of alfalfa. The female adults fecundity and period of oviposition were the highest (345.00 eggs/female, 10.42 d) on the group of lambsquarter, whereas the lowest numbers (138.83 eggs/female, 6.58 d) on the group of alfalfa. Total sugar content for the tested host plants was positively correlated with the pre-oviposition period. The protein content, total sugar content, the host plant of C/N ratio and the water content had no significant correlation with the meadow moth growth and the biological parameters of reproduction.The life-table parameters of L. sticticalis were established by calculating the immature development time, the survival rate at mature and the adult reproduction stage. The net reproductive rate (R₀), the innate capacities for increase ( r_m) and the finite rate of increase (λ) varied respectively from 59.7728 to 169.1941,0.0976 to 0.1352 and 1.1025 to 1.1448 with R₀,r_m,λhighest on lambsquarter and lowest on alfalfa plants. The mean generation time (T) and the doubling time (t) varied from 37.5080 to 41.9158 and 5.1265 to 7.1014.3. Effects of host plants on the nutrition utilization and the physiological reaction of Loxostege sticticalis L. The nutrition indexes of 3^th instar larvae on consumption of the five host plants indicated that the relative growth rate (RGR=0.91) and the approximate digestibility (AD=63.89%) in larvae feeding on the lambsquarter were significantly higher than those on the soybean, alfalfa, sugarbeet and sunflower. The efficiency of conversion of ingested food (ECI=24.65%, 24.96%) and the efficiency of conversion of digested food (ECD=38.70%, 41.41%) were no significant differences in larvae feeding on the lambsquarter and soybean. The efficiency of conversion of ingested food (ECI=10.63%) and the efficiency of conversion of digested food (ECD=25.89%) in larvae feeding on the alfalfa were significantly lower than the four plants.Preliminary physiological reaction of testing 5th instar larvae showed that the contents of protein in haemolymph of larvae feeding on the soybean were significantly higher than that of feeding on the four plants and the contents of protein in mid-gut of larvae feeding on the sunflower was the highest. The esterase in mid-gut of larvae feeding on the lambsquarter and soybean were significantly higher than that of feeding on the three plants.Comprehensive comparison the effects of five kinds of host plant on the biology, nutrition and physiology, lambsquarter is considered the most appropriate host, followed by soybean, sugarbeet, sunflower and alfalfa.