| Athetis lepigone(M?schler) is a species of newly occurred insect pest which damages the corn seedlings and has caused serious losses to summer corn in the Huang-Huai-Hai Region of China. It is a generalist insect which can feed the seedlings of corn, peanut, wheat and soybean, wheat sprout and kernels and other plants. In the research, the biological characteristics of A. lepigone reared on 5 diets were studied, and the raw data were analyzed by using the age-stage, two-sex life table technique. The enzymatic activity of three protective enzymes of A. lepigone larvae reared on 5 diets was determined. The researches aim to explore the effects of 5 diets on the pest and to explain the mechanisms that A.lepigone occurred in an outbreak level and caused serious damage to summer corn seedlings and also provide some scientific bases for the prediction and the integrated control of this insect pest. Main research results were as follows:The ecological characteristics of A. lepigone reared on an artificial diet, corn(Zea mays),peanut(Arachis hypogaea), wheat(Triticum aestivum) and wheat sprout were analyzed by the age-stage, two-sex life tables at 25°C ± 1°C and RH 70% ± 5% in the lab. The durations of different developmental stages, fecundities, sex ratios and some demographic parameters,such as net reproductive rate(R0), the intrinsic rate of increase(r), finite rate(?) and the mean generation time(T) were obtained.Different diets had significant effects on the growth, development, survival and reproduction of A. lepigone. Larvae instars ranged from 5 to 7 when reared on 5 diets; the larvae fed on artificial diet and newly-germinated wheat sprout had 5 instars, on corn had 6instars; when reared on wheat, some larvae had 5 instars and the others with 6 instars. Similar situation also occurred on peanut, some larvae had 6 instars, and the other 7 instars. When A.lepigone larvae were reared on corn, wheat, artificial diet, peanut and newly-germinated wheat sprout, the mean fecundities(F) of were 163.77, 173.30, 390.82, 150.30 and 290.31eggs/?, the net reproductive rate(R0) were 7.12, 23.42, 166.36, 23.20 and 99.97; the intrinsic rate of increase(r) were 0.0445-1, 0.0650-1, 0.1411-1, 0.0568-1and 0.1002d-1and the finite rate(?) were 1.0445-1, 1.0671-1, 1.1515-1, 1.0585-1and 1.1054d-1; The mean generation time(T) were 44.08 d, 48.53 d, 36.25 d, 55.32 d and 45.96 d. The population growth was simulatedusing an initial population of 10 eggs for 80 days based on the population parameters.When the larvae were reared on the above 5 diets, the activity of three protective enzymes, T-SOD, CAT and POD, of larvae in the 4th and 5th instars was determined. The results indicated that the activity sizes of three protective enzymes were in turn on corn>on wheat>on peanut>on newly-germinated wheat sprout>on artificial diet. The enzymatic activity was higher in the 4th instar than in the 5th instar.All the above researches showed that newly-germinated wheat sprout is the suitable host,while corn, wheat and peanut are not the suitable hosts. The artificial diet we have prepared is an ideal one for the pest to grow, develop, survive and reproduce. |
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