To pursue an effective way to control freshwater algae, four extracts from a submerged macrophyte Hydrilla verticillata (Linn.f.) Royle were tested to study its inhibitory effects on Anabaena flos-aquae FACHB-245 and Chlorella pyrenoidosa Chick FACHB-9. Extract with the highest inhibiting ability was further studied in order to reveal the inhibitory mechanism. The results demonstrated that H. verticillata extracts inhibited the growth of A. flos-aquae and C. pyrenoidosa, and methanol extract had the highest inhibiting ability. The mechanism underlying the algal growth inhibition involves the superoxide anion radical generation that induces the damage of cell wall and release of intracellular components.

Athetis lepigone (M€ oschler) is a new insect pest that feeds on corn seedlings in summer corn region of China. It is an omnivorous insect, which not only infests corn, soya bean, peanut and other crops, but also feeds on fallen and decaying leaves of some crops and weeds. Effects of host plants, corn, cotton, peanut, wheat and soya bean, on larval and pupal development and survival, and the fecundity of adults of A. lepigone were studied under laboratory conditions. The developmental time from egg to adult was the shortest (30.78 days) on germinating wheat kernels and the longest (40.13 days) on corn leaves. Larval survival was the highest (80%) on germinating wheat kernels and lowest (55%) on soya bean leaves. Hatching rate was the highest (92.98%) where eggs were oviposited by the females developed from larvae that were fed on germinating wheat kernels. Similarly, fecundity was the greatest on germinating wheat kernels (337), while the lowest fecundity (145) was observed on cotton leaves. The highest intrinsic rate of increase (0.22) and net reproduction rate (181.39) were found on germinating wheat kernels. Germinating wheat kernels were recognized as the most suitable host plant for A. lepigone because of the shortest developmental period, highest survival and highest fecundity. The results correspond with the field habits of A. lepigone and clearly show differences in development and adaptability on the five tested host plants. The findings will serve as baseline information to better understand the biology of the pest, which can be utilized in an effective management programme.

The present study evaluated the effects of different doses and different adaptation time of ginger powder on rumen fermentation in vivo. In Experiment 1, four sheep were used in a 4 x 4 Latin square design to evaluate the effects of three concentrations (5, 10, and 20 g/kg) of ginger powder on rumen fermentation. Total volatile fatty acid (VFA) concentration was decreased (P<0.05), but the fatty acid compositions, acetate-to-propionate ratio, pH, and ammonia-N concentration were unchanged by the addition of ginger powder. In Experiment 2, eight sheep were used to study the long-term adaptation of ginger powder on rumen fermentation. The addition of ginger powder decreased (P<0.05) the total VFA concentration from days 5 to 20, but these differences disappeared thereafter. Other rumen fermentation parameters were unchanged when ginger powder was added. Therefore, data from short-term in vitro fermentation studies may lead to erroneous conclusions and should be interpreted with caution.