桑白蚧的重要寄生蜂——桑白蚧恩蚜小蜂的鉴别与利用

桑白蚧恩蚜小蜂Encarsia(=Prospaltella)berlesel(Howard)是寄生桑白蚧Pseudaulacaspls pentagona(Targioni-Tozzctti)的重要寄生蜂,许多国家进行了引进移植,对控制桑白蚧的为害取得明显的成效．本记述了桑白蚧恩蚜小蜂形态特征的鉴别。以及各国引进利用的概况．并讨论了利用寄生蜂防治桑白蚧的重要性．     

Heterogeneity of heparan sulfate proteoglycans synthesized by PYS-2 cells

Antibodies to the basement membrane proteoglycan produced by the EHS tumor were used to immunoprecipitate [35S]sulfate-labeled protoglycans produced by PYS-2 cells. The immunoprecipitated proteoglycans were subsequently fractionated by CsCl density gradient centrifugation and Sepharose CL-4B chromatography. The culture medium contained a low-density proteoglycan eluting from Sepharose CL-4B at Kav = 0.18, containing heparan sulfate side chains of Mr = 35-40,000. The medium also contained a high-density proteoglycan eluting from Sepharose CL-4B at Kav = 0.23, containing heparan sulfate side chains of Mr = 30,000. The corresponding proteoglycans of the cell layer were all smaller than those in the medium. Since the antibodies used to precipitate those proteoglycans were directed against the protein core, this suggests that these proteoglycans share common antigenic features, and may be derived from a common precursor which undergoes modification by the removal of protein segments and a portion of each heparan sulfate chain.     

Suitability of stages of femaleEncarsia pergandiella [Hymenoptera: Aphelinidae] for development of conspecific male hyperprasites

Encarsia pergandiella Howard females develop as primary parasitoids of immature whiteflies, whereas ♀♀ develop as secondary parasitoids on ♂♂ of their own species or on other primary whitefly parasitoids. In this experiment, maleE. pergandiella development was examined in the laboratory at 24°C, using different stages of immatureE. pergandiella females [enclosed within the cuticle ofTrialeurodes vaporariorum (Westwood)] as hosts. Unmated adult femaleE. pergandiella were caged individually for 24 h on leaves of plants with either 5-day (early to late 3^rd instar larval), 7-day (late 3^rd instar to prepupal), or 9-day (pupal) hosts. In a control treatment, hosts were allowed to complete development without exposure to unmated adult females. Subsequent emergence of ♂♂ (hosts) and ♀♀ from all treatments was recorded daily. Pupal (9-day)E. pergandiella females were found to be the most suitable hosts for development of ♀♀. Nine- and 7-day hosts were attacked at a similar rate, as indicated by a similarly low proportion of host emergence, but ♀♀ emerged at a significantly higher rate in the 9-day treatment than in the 7-day treatment. Development time of ♀♀ was 15±1 days in the 9-day treatment, and 16±1 days in the 7-day treatment (p<0.005). The proportion of hosts emerging from the 5-day treatment was not significantly different from the control treatment. The data suggest that the colonizing ability ofE. pergandiella in greenhouses is likely to be limited by the delay of 7–9 days between oviposition of female eggs and the suitability of these ♂♂ for oviposition of male eggs. Since development time of the 2 sexes is similar this delay should cause a lack of synchrony in the emergence and mating of F₁ ♂♂ and ♀♀.      

Interpretation of light scattering associated with prolonged neural activity and temperature changes

Changes in light scattering from lobster giant axon which accompany the action potential were observed during periods of prolonged stimulation and as a function of temperature. At an initial temperature of 10°C most (more than 90%) axons produced positive light scattering signals which increased in amplitude when the temperature was lowered. At 2 and 5°C approximately half of the axons produced positive scattering signals. The remaining half produced negative scattering signals which became positive when the temperature was raised to 10°C. The amplitude of the negative signals followed sigmoid transition to positive values as a function of time. The time and temperature dependence of the signal are interpreted in terms of differential changes between the indices of refraction of the membrane matrix and the open or closed early activation channel.     

寄生红蜡蚧的扁角跳小蜂属6个种(膜翅目:跳小蜂科)的系统发育支序分析

选用寄生红蜡蚧的扁角跳小蜂属(Anicetus)6个种的14个形态特征和2个其他特征(寄主种数和是否寄生软蚧)作为内群性状,以柯氏花翅跳小蜂(Microterys clauseni)作为外群,运用PAUP(Version 4．0b10)程序做了支序分析。所得支序树状图有如下参数：树长=28;一致性指数=0．6786;稳定性指数=0.4375。6种扁角跳小蜂中,亲缘关系表示为：(A．annulatus,((A．rubensi,(A．beneficus,A．rarisetus)),(A．howardi,A.ohgushii)))。软蚧扁角跳小蜂(A.annulatus)与其他5个种的亲缘关系相对较远,与传统分类学观点一致。     

REVISION OF THE GENUS APHYTIS (HYMENOPTERA: APHELINIDAE) WITH DESCRIPTIONS OF TWO NEW SPECIES FROM EGYPT

Abstract  The Egyptian species of the aphelinid genus Aphytis Howard are reviewed. Aphytis azai Abd-Rabou and Aphytis matruhi Abd-Rabou are described as new species from Egypt. Each species is briefly diagnosed and known information on hosts and distributed is given. A. azai sp. nov. is similar to A. melinus but different in the measurement of antennal segments. A. matruhi sp. nov. differs from A. lepidosaphes by the relative length of propodeum, metanotum and scutellum. A key to the Egyptian species of Aphytis is provided.     

Evolution with material symbol systems

Pattee's semantic closure principle is used to study the characteristics and requirements of evolving material symbols systems. By contrasting agents that reproduce via genetic variation with agents that reproduce via self-inspection, we reach the conclusion that symbols are necessary to attain open-ended evolution, but only if the phenotypes of agents are the result of a material, self-organization process. This way, a study of the inter-dependencies of symbol and matter is presented. This study is based first on a theoretical treatment of symbolic representations, and secondly on simulations of simple agents with matter-symbol inter-dependencies. The agent-based simulations use evolutionary algorithms with indirectly encoded phenotypes. The indirect encoding is based on Fuzzy Development programs, which are procedures for combining fuzzy sets in such a way as to model self-organizing development processes.     

Savanna fires and their impact on net ecosystem productivity in North Australia

Savannas comprise a large area of the global land surface and are subject to frequent disturbance through fire. The role of fire as one of the primary natural carbon cycling mechanisms is a key issue in considering global change feedbacks. The savannas of Northern Australia burn regularly and we aimed to determine their annual net ecosystem productivity (NEP) and the impact of fire on productivity. We established a long‐term eddy covariance flux tower at Howard Springs, Australia and present here 5 years of data from 2001 to 2005. Fire has direct impacts through emissions but also has indirect effects through the loss of productivity due to reduced functional leaf area index and the carbon costs of rebuilding the canopy. The impact of fire on the canopy latent energy exchange was evident for 40 days while the canopy was rebuilt; however, the carbon balance took approximately 70 days to recover. The annual fire free NEP at Howard Springs was estimated at −4.3 t C ha⁻¹ yr⁻¹ with a range of −3.5 to −5.1 t C ha⁻¹ yr⁻¹ across years. We calculated the average annual indirect fire effect as +0.7 t C ha⁻¹ yr⁻¹ using a neural network model approach and estimated average emissions of fine and coarse fuels as +1.6 t C ha⁻¹ yr^‐1. This allowed us to calculate a net biome production of −2.0 t C ha⁻¹ yr^‐1. We then partitioned this remaining sink and suggest that most of this can be accounted for by woody increment (1.2 t C ha⁻¹ yr^‐1) and shrub encroachment (0.5 t C ha⁻¹ yr^‐1). Given the consistent sink at this site, even under an almost annual fire regime, there may be management options to increase carbon sequestration by reducing fire frequency.