Effect of a postfire environment on the establishment of Prosopis caldenia seedlings in central semiarid Argentina

Abstract The objective of this work was to evaluate postfire environmental effects on the emergence, survival and growth of Prosopis caldenia seedlings in relation to different controlled fire frequencies, seed scarification methods, and planting site. Seedling emergence was significantly higher in experimental units exposed twice and three times to controlled fire than in unburned experimental units. The highest average seedling survival was recorded with triple exposure to controlled fires. Emergence, survival and growth of seedlings from seeds exposed to acid scarification and 600°C for 5 min were higher in the burned experimental units than in the unburned ones. In the former, seedling survival was higher beneath a P. caldenia canopy than in an adjacent open site, though seedling emergence was similar in both planting sites. Our results suggest that postfire conditions characterized by a reduction in the vegetative cover and competition interference and an increase in soil temperatures and nutrients levels (e.g. nitrogen and phosphorus) may facilitate the establishment of P. caldenia seedlings in the Caldenal.     

从卵巢发育特点揭示新疆地区棉铃虫迁飞习性

为探索棉铃虫成虫在新疆地区是否具有迁飞性,在新疆北部石河子垦区146团和147团、乌苏、新疆南部阿克苏地区(阿克苏市、阿瓦提县、12团)和麦盖提,监测了棉铃虫田间卵巢发育和交配频率.结果表明:雌蛾卵巢发育到l级时开始出现交配,且交配次数与卵巢发育级数呈显著正相关;146团、147团、乌苏、阿克苏第3代棉铃虫以及阿瓦提县第3代和第4代棉铃虫卵巢发育级别3级以上的个体均占到65％以上,表明其种群主要由外地迁入;高峰期棉铃虫雌蛾平均交配率和交配频率分别为81.63％和1.96.各监测区域棉铃虫雌蛾的交配率和雌雄比例均符合迁入种群的生理特征,表明新疆地区棉铃虫存在迁飞.探明棉铃虫在新疆地区的迁飞和交配情况将为该地区棉铃虫的区域防治提供重要科学依据.     

Physiological studies of a hybrid between populations of Dactylis glomerata from contrasting climatic regions. II. Intra population variation

Mushroom compost was treated with nematicides and infested with Aphelenchoides composticola at the time of filling into growing containers. Yields of mushrooms from infested untreated control composts were reduced to 40–60% of yields from uninfested control compost. Yields from infested compost treated with fenamiphos emulsifiable concentrate (e.c.) at 10 or 20 mg a.i./kg, thiabendazole wettable powder at 40 or 60 mg a.i./kg or oxamyl granules at 20 mg a.i./kg were as high as from uninfested controls. Compost treated with granules of AC 64,475 up to 20 mg a.i./kg or ethoprophos or thionazin up to 80 mg a.i./kg gave yields significantly lower than uninfested controls. Numbers of nematodes rose to about 10⁶/20 g of compost in untreated compost and then fell, and a similar peak occurred in treatments in which yields were substantially reduced by nematode damage. Treatments which yielded as well as the uninfested controls held maximum nematode numbers down to about 10V20 g of compost but populations stayed at this level or tended to rise while numbers in untreated compost fell. Incorporation of fenamiphos in casing or its application to the surface of beds 3 wk after cropping began gave lower yields than the uninfested control but mushrooms were being produced late in the cropping cycle. Fenamiphos e.c. at 20 mg ai./kg incorporated in compost is considered a practical preventive measure for control of A. composticola.     

FOCUSED DIFFERENCE TESTING FOR THE ASSESSMENT OF DIFFERENCES BETWEEN ORANGE JUICES MADE FROM ORANGE CONCENTRATE

Focused difference testing was applied to two orange juices prepared from frozen concentrate. Differences were noted between the juices for darkness of color, visual appearance of pulpiness, resistance to tongue movement, flavor by mouth, odor, overall taste and taste other than sweetness. The logic and approach of focused difference testing is discussed and contrasted with other sensory analytical techniques.     

Blood-feeding of the gerbil flea Nosopsyllus laeviceps kuzenkovi (Yagubyants), vector of plague in Inner Mongolia,China

Abstract. The gerbil flea Nosopsyllus laeviceps (Wagner) (Siphonaptera: Ceratophyllidae) is an important Palaearctic vector of enzootic plague among sylvan and campestral rodents. Laboratory blood-feeding experiments with the subspecies N.l.kuzenkovi (Yagubynts) from Inner Mongolia, China, using three rodent species including the natural host Meriones unguiculatus (Milne-Edwards), demonstrated a positive relationship between per cent feeding and time allowed for feeding, particularly for female fleas. Also the bloodmeal size was proportional to sucking time and was significantly greater in females, which are larger, than in males. However, on all four strains of host tested, there was no significant correlation between the feeding success rate of the fleas and the amount of blood they imbibed. Fleas fed better on active compared to confined M.unguiculatus. These findings agree with studies of other flea species.     

Antimalarial activities of gedunin and 7-methoxygedunin and synergistic activity with dillapiol

Gedunin from Cedrela odorata (Meliaceae), a potent in vitro antimalarial agent, was investigated for its in vivo efficacy in CD‐1 mice infected with Plasmodium berghei. When orally administered at 50 mg kg‐1 day‐1 for 4 days, gedunin was able to suppress the parasitaemia level by 44%. However, no clear dose‐response effects were observed in the 0–100 mg kg‐1 day‐1 dose range. Preliminary pharmacokinetics in Sprague‐Dawley rats showed poor absorption. However, a binary treatment of 50 mg kg‐1 day‐1 gedunin with 25 mg kg‐1 day‐1 dillapiol, a cytochrome P450 inhibitor, increased parasitaemia clearance in mice to 75%. A clear dose‐response was observed in the 0–50 mg kg‐1 day‐1 gedunin dose range when administration was combined with 25 mg kg‐1 day‐1 dillapiol. In addition, 7‐methoxygedunin, a semi‐synthetic derivative which is more stable to degradation than gedunin, suppressed the level in mice by 67% at 50 mg kg‐1 day‐1. When administered at this dose in combination with 25 mg kg‐1 day‐1 dillapiol, clearance increased to 80%. These results demonstrate the potentialefficacy of antimalarial drugs and phytomedicines based on gedunin and the value of the combination therapy.