Pest problems: The view of New Zealand federated farmers

Abstract

Agriculture is fundamental to the well being of the New Zealand economy. We are very much a trading nation and will continue, for the foreseeable future, to depend upon primary production for the generation of New Zealand's wealth.     

Haematological and biochemical reference intervals for farmed channel catfish

The reference intervals for biochemical variables and red blood cell indices of healthy intensively bred channel catfish Ictalurus punctatus were determined. The blood variables were determined using standardized clinical methods. The reference intervals (25th and 75th percentiles) were established using a non-parametric method. Reference intervals for plasma glucose, serum total protein, sodium, potassium, calcium, magnesium, chloride concentration, primary and secondary red blood cell indices were established. The haematological and biochemical reference intervals established may allow important clinical decisions about channel catfish.     

ALTERNATIVE HOSTS OF TRICHOGRAMMA DENDROLIMI MATSUMURA IN DIFFERENT HABITATS (HYMENOPTERA: TRICHOGRAMMATIDAE)

Abstract  This paper deals with alternative hosts of an egg parasitoid. Trichogramma dendrolimi Matsumura in three habitats: mixed forest, pure stand and sparse wood. The experiment was conducted in Liuyan County which is located in the eastern part of Hunan Province. The results suggested that there are 103 species of alternative Lepidopteran hosts for T. dendrolimi . There were two critical periods throughout the year when there were no eggs of Dendrolimus punctatus Walker and few eggs of alternative hosts available for ovipsition by the parasitoids.     

Cryopreservation of leucocytes of channel catfish for subsequent cytogenetic analysis

Channel catfish leucocytes cryopreserved with glycerol or dimethyl sulphoxide (DMSO) had significantly higher ( P <0.05) viability and recovery rates than did cells cryopreserved with methanol. After 7 days of frozen storage, a 24 to 27% reduction of viability was observed for cells cryopreserved with glycerol; a 25 to 43% reduction for cells frozen with DMSO, and a 67 to 100% reduction for cells frozen with methanol. The concentration of cryoprotectants affected the viability of cryopreserved cells significantly ( p <0.05). The viability reduction was 36% for cells frozen with 5% of cryoprotectants, 30% for cells frozen with 10% of cryoprotectants, and 49% for cells frozen with 15% of cryoprotectants. The viability of cells frozen at the slower rate (-2.7°C min⁻¹) was significantly higher ( p <0.05) than that of cells frozen at the faster rate (-45°C min⁻¹). Best results were obtained for cells cryopreserved with 10% of glycerol or DMSO and frozen at the slower rate. The chromosomes prepared from cells cryopreserved using this procedure were identical to those prepared from fresh cells, and to those reported in the literature for channel Catfish.     

人工补充寄主卵对松林内卵蜂种群消长的影响

在不同生境的松林中,人工补充寄主卵都能提高寄生效果。但林地生境不同,寄生率有明显差异。在松阔混交林中补充寄主,其寄生率比对照提高5.5—16.2倍。植被稀疏的纯松林效果较差,补充的寄生率比对照提高3.0倍。 卵蜂种群消长随季节温度而变化,全年以5月中旬至6月下旬和9月中旬至10月中旬为两个寄生高峰。卵蜂种群与松毛虫种群的消长存在较明显的相依关系,卵蜂种群随着松毛虫种群的消长而消长。施药对卵蜂种群有较大影响,施药区比对照区的寄生率约降低一倍。在混交林中填充寄主卵,能促进卵蜂种群世代延续。在逐步改善林地生境的基础上,利用人工补充寄主,可以代替人工繁蜂放蜂。     

Five New Species of Henneguya (Protozoa: Myxosporida) from Ictalurid Fishes*

SYNOPSIS. Four new species of Henneguya (myxosporidan) are described from Ictalurus punctatus Rafinesque (channel catfish). They are as follows: Henneguya postexilis sp. n. and Henneguya longicauda sp. n. from the gills; Henneguya adiposa sp. n. from the adipose fin; and Henneguya diversis sp. n. from the liver, kidney, connective tissue of muscles and fins, and tumor-like external growths. Henneguya pellis sp. n. is described from the dermis of Ictalurus furcatus (LeSueur) (blue catfish). The development stages of all described species are discussed. Henneguya exilis Kudo was found on the gills of one I. punctatus; notes on its spore characteristics are presented.     

害虫,天敌和食料的数学模型

本文从实际问题出发,结合已有的描述群落生态的数学模型,提出了一组描述马尾松毛虫(Dendrolimus pnnctalus,walker)、条毒蛾(Lymantria dissoluta,Swinhoe)、天敌和食料之间动态关系的数学模型: w(k+1=(a_1x(k+1)/(1+a_2x(k+1)/_z(k))+a_3w(k)/(1+a_4w(k)/y(k)) x(k+1)=b_1w(k)/(1+b_2w(k)/y(k))+b_3x(k)/(1+b_4x(k)/z(k))+ y(k+1)=c_1z(k)/[1+c_sz(k)+c_3y(k)][1+c_4w(k)+(k+1)] z(k+1)=d_1z(k)/[1+d_2z(k)][1+d_3x(k)+d_4w(k)] 对于这个模型的线性化形式,详细讨论了控制松毛虫的暴发所需的条件及其生态学机制。     

Observations on the histochemistry and ultrastructure of regenerating caudal epidermis of the tuatara Sphenodon punctatus (Sphenodontida,Lepidosauria, Reptilia)

Study of the histology, histochemistry, and fine structure of caudal epidermal regeneration in Sphenodon punctatus through restoration of a scaled form reveals that the processes involved resemble those known in lizards. Following establishment of a wound epithelium (WE), subjacent scale neogenesis involves epidermal downgrowths into the dermis. Although the process is extremely slow, and most new scales do not overlap, their epidermal coverings reestablish epidermal generation (EG) formation. As in lizards, the flat, alpha-keratogenic, WE cells contain lipids as revealed by their affinity for Sudan III. A few mucous cells that store large PAS-positive mucus-like granules also occur in WE. During differentiation of WE cells, among the bundles of 70-nm tonofilaments are many lamellar bodies (LBs) and mucous granules (MGs) that discharge their contents into the cytoplasm and extracellular spaces producing a strongly PAS-positive keratinized tissue. Richness of epidermal lipids coexistent with mucus is a primitive characteristic for amniote vertebrates, probably related to functions as a barrier to cutaneous water loss (CWL). As scale neogenesis begins, beneath the superficial WE appear 3-5 layers of irregularly shaped cells. These contain tonofilament bundles surrounded by small, round keratohyalin-like granules (KHLGs) and a keratinized matrix with beta-keratin packets and a 3-5-nm thick keratin granulation. This mixture of alpha- and beta-keratogenic capacities resembles that seen in the innermost cells of a normal tuatara epidermal generation. As in the latter, but in contrast to both normal and regenerating lizard epidermis, no definable shedding complex with interdigitating clear layer and oberhautchen cells occurs (Alibardi and Maderson, 2003). The tortuous boundaries, and merging beta-keratin packets, identify subjacent keratinizing cells as precursors of the typical stratified, squamous beta-layer seen in long-term regenerated caudal skin wherein the entire vertical sequence of epidermal layers resembles that of normal scales. The sequence of events in caudal epidermal regeneration in S. punctatus resembles that documented for lizards. Observed differences between posttrauma scale neogenesis and scale embryogenesis are responses to functional problems involved in, respectively, restoring, or forming, a barrier to CWL while accommodating rapid somatic growth.     

马尾松毛虫幼虫的捕食天敌及其捕食作用的研究

根据林间调查和室内观察资料,分析了江西省万年县不同松林中马尾松毛虫不同发生代别低龄幼虫期的主要捕食天敌种类及数量。结果表明低龄幼虫期捕食无敌有13科31种,其中以蜘蛛类最多,其次为蚂蚁类。不同林型中捕食天敌的种类和数量在年份间代别间均存在一定差异,数量差异尤其显著。在室内研究了几种主要捕食无敌对马尾松毛虫低龄幼虫的捕食作用及其功能反应,结果表明功能反应为S型,由此建立了它们的功能反应模型。     

应用球孢白僵菌防治马尾松毛虫的策略及其生物多样性基础的研究

对３种不同方式应用球孢白僵菌防治马尾松毛虫的结果表明,３个林场的虫口在连续４年内均被抑制在低水平,但松毛虫种群动态不同：以淹没式施放白僵菌为主,但有时也淹没式施放化学杀虫剂的麻姑山林场平均虫口密度为３．１６±４．９４条·株－１,波动最大;长期接种式应用白僵菌的戴公山林场平均虫口密度只有０．０９±０．１４条·株－１,一直处于低密度状态;以化学农药处理小面积虫源地结合不频繁地淹没式施放白僵菌的金寺山林场平均虫口密度为１．４５±２．２９条·株－１,偶可达防治指标．对群落组成的调查结果表明,从麻姑山、金寺山到戴公山,动物和虫生真菌群落各物种的总个体数递减,而总物种数、总物种数与总个体数的比值,天敌与害虫种数和个体数的比值以及群落多样性指数皆递增,表明群落多样性渐趋丰富,食物链网渐趋复杂,群落稳定性和对害虫的自然控制能力逐渐增强．对群落动态的主成分分析进一步表明,从麻姑山、金寺山到戴公山,动物和虫生真菌群落的演化时序分明,趋于稳定,自我调节力强．