Resistance of wheat varieties (lines) to the different geographic populations of Sitobion miscanthi

采用田间成株期自然感蚜法和室内苗期接虫法,鉴定12个小麦品种(系)对5个不同地区荻草谷网蚜Sitobion miscanthi (Takahashi)种群的抗性.结果表明,小麦品种(系)室内苗期的抗性表现与田间成株期基本一致;Amigo、KOK、北京837、铭贤169和红芒红对5个地理种群荻草谷网蚜的抗性表现相同,丰产3、中4无芒、JP①、晋麦31、L1、885479-2和小白冬麦对5个地理种群荻草谷网蚜种群的抗性表现则存在差异.研究表明我国荻草谷网蚜对抗蚜作物品种具有致害性分化.     

Individual breeding decisions and long-term reproductive strategy in the King Penguin Aptenodytes patagonicus

Although studied for 35 years, knowledge of the reproductive biology of the King Penguin Aptenodytes patagonicus remains incomplete. The chick requires more than 12 months of care, which extends the breeding cycle, including moult, to more than one year, i.e. the King Penguin is neither annual nor biennial. In an attempt to resolve ambiguities in the literature and to elucidate the long-term breeding strategy of the species, we studied breeciing frequency at the individual level, considering the decision to breed in relation to breeding history over the previous few years. Although adult birds attempted to breed annually (0.83 breeding attempts per year), successful rearing occurred, at best, every two years only (maximum of 0.41 fledged chick per pair). Comparing successive years, the number of breeding birds in the colony was stable but the number of fledged chicks varied from 29 to 278 over eight years. These results suggest that King Penguins adopt (as individuals) an opportunistic reproductive strategy, in that they usually lay an egg every year, even when failure is certain. Nevertheless, the decision to breed was not entirely blind, and we identified groups of birds that invested differentially in breeding attempts. The decision to breed was related to the previous breeding frequency, i.e. 81% of the birds that had bred continuously in the past started a new breeding attempt, but only 67% of birds that had missed a year did so. In intermittent breeders, birds that had bred frequently, more often started a new breeding attempt than birds that had largely missed years (71% versus 57%, respectively). Classes of breeders could correspond to age classes, to birds of different breeding quality or to alternative breeding strategies coexisting in the species. Testing the hypothesis that reproductive effort increases with age should be possible in future.