Invertebrate predation of 15N-marked prey in semi-field wheat enclosures

One of the most famous examples of successful, classical biological control in Japan is the introduction of the parasitoids Coccobius fulvus and Aphytis yanonensis against the citrus pest arrowhead scale Unaspis yanonensis. Together, they comprise a host‐parasitoid system that has been demonstrated to be stable. To test the conventional theory that successful biological control of pests occurs through the establishment of a low stable equilibrium, brought about by the density‐dependent responses of natural enemies to the pest species, sampling was carried out at five sites in the field during 2000 and 2001 to examine the relationship between the rate of parasitism by C. fulvus and the density of its host. The data were analysed using three statistical techniques at nine spatial scales. Contrary to conventional theoretical predictions, each method of analysis detected very little density‐dependence at any spatial level in this study. Parasitoid aggregations independent of host density were not sufficient to stabilise host–parasitoid interactions. Our results suggest that neither spatial density‐dependent nor density‐independent parasitism is necessary for successful biological control, or for the stability of the host–parasitoid system. We propose an alternative mechanism: a spatial refuge induced by parasitoid introduction may stabilise a system.     

松突圆蚧花角蚜小蜂的生物学

松突圆蚧花角蚜小蜂Cocvobius azumai Tachikawa是松突圆蚧Hemiberlesla pitysophila Takagi的重要寄生蜂,1987-1989年从日本引入我国广东省。对松突圆蚧花角蚜小蜂的形态、发育、繁殖、成虫寿命和取食寄主行为等生物学特征进行了观察。该蜂的雌性幼虫是松突圆蚧雌蚧的初级内寄生蜂,而雄性幼虫则是次级寄生蜂,重寄生在同种或它种膜翅目的老熟幼虫、预蛹和蛹上。雌雄两性的形态在所有发育阶段均不相同。交配过的雄蜂喜欢寄生产卵初期和盛期的雌成蚧,对巳寄生的寄主具有识别能力。在19.7℃一30.9℃变温条件下每头雌蜂平均产卵14.95粒,约60%的卵是在最初3天内产出。松突圆蚧花角蚜小蜂雌性蜂在21℃,24℃,27℃和30℃时从卵发育到成虫的平均历期分别为41.24,32.60,25.60和23.00天,发育起点温度10.1℃,有效积温448.3日度。该蜂在广东省一年发生。9-10代。     

Visual fields,foraging and collision vulnerability in Gyps vultures

The visual fields of vultures contain a small binocular region and large blind areas above, below and behind the head. Head positions typically adopted by foraging vultures suggest that these visual fields provide comprehensive visual coverage of the ground below, prohibit the eyes from imaging the sun and provide extensive visual coverage laterally. However, vultures will often be blind in the direction of travel. We conclude that by erecting structures such as wind turbines, which extend into open airspace, humans have provided a perceptual challenge that the vision of foraging vultures cannot overcome.     

Cryobanking of lemur spermatozoa

Artificial inseminations using fresh semen were successful inLemur fulvus mayottensis. Inseminations with frozen semen are in progress.     

花角蚜小蜂对松突圆蚧的控制效能及其稳定作用的评估

从日本冲绳引入的松突圆蚧花角蚜小蜂Coccobius azumati Tachikawa是1989年在惠东 县首批释放定居成功的。经五年系统研究表明,花角蚜小蜂释放一年后,在中心区50m以内最高寄生率达55.8%～64.2%,雌蚧密度由每针束3.14头下降为0.64头;二年后控制松突圆蚧的有效半径增至300m左右,寄生率稳定在20.8%～32.9%,每针束雌蚧密度保持在0.6头左右,二者处于低密度的平衡状态。未放蜂对照区的雌蚧密度则由每针束3.40头上升到4.22头,高出放蜂区5～10倍。此外本报告还对花角蚜小蜂的扩散速度、种间竞争能力和数量稳定水平作了探讨和分析,得出瘦柄花翅蚜小蜂Marietta cdrnesi(Howard)在花角蚜小蜂释放区内的重寄生率仅为3.1%～5.3%,对花角蚜小蜂的控制效能没有影响的结论。     

不同无性系蔗茅抽穗开花特性的观察和花粉贮藏条件的研究

来源于较低海拔地区的3个蔗茅无性系的抽穗期较短,来源于较高海拔(大于1500m)地区的16个蔗茅无性系的抽穗期较长,且抽穗期与原产地海拔呈显著负相关(F=-0.827**).蔗茅的这一特性在集中种植后仍能相对稳定地表现出来.蔗茅花粉量较多,花粉发育良好.在自然条件下,蔗茅新鲜花粉仅能存活1 h左右;而经低温(10℃)硅胶干燥2 h后贮藏于-80℃条件下,其生活力保持可超过360d.蔗茅贮藏花粉生活力的下降比率与花粉含水量呈显著正相关(r=0.933**);含水量降至10%以下的花粉在低温中贮藏时才能保持较高生活力.     

Avian nest predation by a semi-captive collared lemur (Lemur fulvus collaris)

A lemur (Lemur fulvus collaris) in a semi-captive group of six animals at the Duke University Primate Center (DUPC) was observed eating an egg from the nest of a mourning dove (Zenaida macroura). The manner in which the animal had been foraging prior to this incident, and the fact that wild birds at the DUPC frequently direct antipredator behaviors, such as mobbing toward thisL. f. collaris group, suggest that nest predation is part of normal foraging behavior in these animals.     

利用信息化学物质研究松树小蠹虫的扬飞规律

于2005～2006年在辽宁省千山利用信息化学物质野外诱捕黄色梢小蠹Gryphalus fulvus、红松根小蠹Hylastes plumbeus、横坑切梢小蠹Tomicus minor及纵坑切梢小蠹Tomicus piniperda成虫,结果显示:这4种小蠹在4月18日至8月10日期间都明显出现2次扬飞高峰。第1次扬飞高峰持续均为30d左右,第2次扬飞高峰期约为15d;黄色梢小蠹和红松根小蠹第1次扬飞高峰期在5月上中旬出现,第2次扬飞高峰期分别在7月中下旬和上中旬;横坑切梢小蠹与纵坑切梢小蠹的扬飞高峰期基本一致,第1次扬飞高峰期为4月下旬到5月上旬,第2次扬飞高峰在7月上中旬;结果同时还表明诱虫量第1次扬飞高峰一般都明显大于第2次,只是黄色梢小蠹在首次利用信息化学物质进行监测且密度较高时例外。