Insecticides and electrophysiological symptoms: A comparative study on a tarsal motor nerve of Locusta migratoria

Spontaneous discharges of a tarsal motor nerve preparation of the jumping leg of Locusta migratoria were recorded extracellularly under the influence of various insecticides applied to the in situ metathoracic ganglion of the insect. Insecticides from different chemical classes were found to exhibit rather specific electrophysiological symptoms: cholinesterase inhibitors produced groups of action potentials with highly increased frequencies, and led to the appearance of new units which were not present in untreated control insects. They also caused transitory phases of conduction blocks, the length of which increased as intoxication proceeded. The DDT analog tested could be characterized by pronounced repetitive dischanges, whereas the neuroactivity of pyrethroids was typically associated with a very regular spike pattern in continuous phases of extremely high frequencies. Also chlordimeform, a formamidine insecticide, was found to increase the spike frequency, but to a much lesser extent than that observed for the other insecticides tested.     

Pyrethroid toxicology in the frog

Adult Rana pipiens pipiens (Shreber) are highly sensitive to insecticidal α-cyano-3-phenoxybenzyl esters administered subcutaneously, i.e., LD₅₀ 0.13–0.35 mg/kg for deltamethrin and the most potent isomer of each of cis-cypermethrin, fenpropathrin, and fenvalerate and 0.65 mg/kg for (1R,αS)-trans-cypermethrin. Pyrethroids lacking the α-cyano substituent [pyrethrins, S-bioallethrin, kadethrin, and the Cis- and trans-isomers of (1R)-tetramethrin, (1RS)-resmethrin, (1R)-phenothrin, and (1R)-permethrin] vary greatly in their toxicity (LD₅₀ 0.14 to > 60 mg/kg) and the trans isomers are much less toxic than the corresponding cis isomers. The trans/cis specificity is due in large part to relative detoxification rates based on synergism studies with the resmethrin and permèthrin isomers and liver pyrethroid esterase assays with the permethrin and cypermethrin isomers. Poisoning by the noncyano compounds involves hyperactivity and tremors whereas by the cyanophenoxybenzyl esters involves tonic seizures and choreoathetosis, i.e., types I and II syndromes, respectively. Picrotoxinin, t-butylbicyclophosphate, and five other small cage compounds give a third type of syndrome with clonic seizures. Diazepam and its 2′-fluoro-4-methyl-4,5-dihydro analog (RO 5-3636) are more effective than 23 other compounds tested in protecting against deltamethrin toxicity. Diazepam is most effective in alleviating the Type II syndrome, intermediate with the type I syndrome, and is not active with picrotoxinin.     

Correlation of blood and brain levels of the neurotoxic pyrethroid deltamethrin with the onset of symptoms in rats

Rats were injected intraperitoneally with ¹⁴C-labelled deltamethrin at the threshold doses required to produce the motor symptoms of toxicity of tremor and choreoathetosis. Blood and brain samples were analysed for their total radiolabel content, and were also extracted with ethyl acetate to determine the levels of extractable parent deltamethrin and 3-phenoxybenzyl-derived acid (the final radiolabelled metabolite after oxidative cleavage) and the residual radiolabel after this extraction. There was a clear correlation between symptom onset and blood and brain levels of deltamethrin. It was found that certain threshold levels of parent deltamethrin in the blood and brain were required for symptom development, and that the symptom persisted for as long as this threshold was maintained. The distribution of the radiolabel in various tissues was also followed over the time course of the blood and brain studies.     

The occurrence of inclusion bodies in leaf epidermis cells of sandal affected with spike disease

Round or slightly oval inclusion bodies were found in low numbers in epidermal cells of spiked (expressing spike disease symptoms) leaves. They could not be demonstrated in epidermal tissue of apparently healthy leaves. The intracellular inclusions stained with phloxine and rose bengal. Their relationship to sandal spike virus is discussed.     

Effects of metaldehyde and acetaldehyde on specific membrane currents in neurones of the pond snail Lymnaea stagnalis

Bath application of metaldehyde or acetaldehyde led to tonic depolarization and bursting activity in identified neurones in the isolated central nervous system of Lymnaea stagnalis. This activity was sometimes accompanied by paroxysmal depolarizing shifts in membrane potential. Those neurones which possessed type 2 action potentials showed marked spike broadening in response to metaldehyde, but little increase in action potential duration in the presence of acetaldehyde. Under voltage clamp, metaldehyde caused a reduction in the delayed rectifier and A-currents, both of which are outward potassium currents. Acetaldehyde also reduced the delayed rectifier but had no effect on the A-current. In type 2 neurones, voltage-dependent calcium current appeared to increase in the presence of metaldehyde, but was decreased by acetaldehyde. The action of metaldehyde and acetaldehyde on firing activity, as well as their differential effects on action potential duration, may be partly explained by alterations in these specific membrane currents.     

小米红叶病的研究Ⅰ.红叶病,小米的一个新的病毒病害

 最近六年来,在我国的主要小米产区,包括山东、河北、河南和山西四省均报道有小米植株变红的现象,农民称它为红叶病或红丝病。     

Little leaf disease of Piper nigrum in Sri Lanka

In recent years Black pepper ( Piper nigrum ) in Sri Lanka has become affected with'Little leaf'disease. The main symptoms are chlorosis of leaves, shortening of internodes, proliferation of branches, greening and enlargement of floral bracts. Detailed measurements within experimental plots of two improved varieties Panniyur 1 and Kuching, indicated that leaf size, the number of flowers per spike and berry weight were reduced on infected vines. Seeds from infected vines germinated less well than those from healthy vines. In a field trial, disease spread was similar in plots planted with pepper at different spacings and receiving different fertilizer treatments.     

不同生育阶段灌水处理对糜子农艺性状及产量的影响

在年降雨量不足40 mm的甘肃省敦煌市,以陇糜10号为指示品种,研究了不同生育阶段灌水处理对糜子主要农艺性状及产量的影响,应用灰色关联度法分析了主要农艺性状与产量的相关性。结果表明：水分亏缺延迟糜子成熟,延长了拔节至抽穗阶段的生长发育天数;生育期内任何阶段水分亏缺都降低了糜子株高、千粒重和产量,主穗长缩短,主茎粗变细,抽穗灌浆期水分亏缺极显著地影响单株穗重、单株粒重及单位面积穗数。不同土壤水分条件下,糜子单株粒重、单株穗重、千粒重、株高、主茎粗、主穗长、单位面积穗数都与糜子产量相关性较大。     

Amplified fragment length polymorphism markers linked to a major quantitative trait locus controlling scab resistance in wheat

ABSTRACT Scab is a destructive disease of wheat. To accelerate development of scab-resistant wheat cultivars, molecular markers linked to scab resistance genes have been identified by using recombinant inbred lines (RILs) derived by single-seed descent from a cross between the resistant wheat cultivar Ning 7840 (resistant to spread of scab within the spike) and the susceptible cultivar Clark. In the greenhouse, F(5), F(6), F(7), and F(10) families were evaluated for resistance to spread of scab within a spike by injecting about 1,000 conidiospores of Fusarium graminearum into a central spikelet. Inoculated plants were kept in moist chambers for 3 days to promote initial infection and then transferred to greenhouse benches. Scab symptoms were evaluated four times (3, 9, 15, and 21 days after inoculation). The frequency distribution of scab severity indicated that resistance to spread of scab within a spike was controlled by a few major genes. DNA was isolated from both parents and F(9) plants of the 133 RILs. A total of 300 combinations of amplified fragment length polymorphism (AFLP) primers were screened for polymorphisms using bulked segregant analysis. Twenty pairs of primers revealed at least one polymorphic band between the two contrasting bulks. The segregation of each of these bands was evaluated in the 133 RILs. Eleven AFLP markers showed significant association with scab resistance, and an individual marker explained up to 53% of the total variation (R(2)). The markers with high R(2) values mapped to a single linkage group. By interval analysis, one major quantitative trait locus for scab resistance explaining up to 60% of the genetic variation for scab resistance was identified. Some of the AFLP markers may be useful in marker-assisted breeding to improve resistance to scab in wheat.     

SEED PRODUCTION OF AGROPYRON REPENS (L.) BEAUV. IN ARABLE CROPS IN ENGLAND AND WALES IN 1969

Summary. Spikes oi Agropyron repens (L.) Beauv. were collected from field crops (mostly spring barley and winter wheat) in England and Wales near the time of crop harvest. Seeds per spike were counted and their germination tested in soil in the glasshouse.
About 95% of the samples contained viable seeds; about one third of the samples had fewer than 5 viable seeds/spike, a third between 6 and 15 and a third more than 15. The average number of viable seeds/spike for all samples was 13. Spikes from spring barley (152 samples) had an average of 11 and a maximum of 51 viable seeds and those from winter wheat (42 samples), 20 and 48 respectively. Samples collected within 3 weeks after mid-July had fewer viable seeds/spike than those collected later. Samples containing morphologically-different spikes had more viable seeds/spike than apparently uniform samples, and spikes from dense field populations more seeds than those from sparse populations.     

水稻产量及产量构成的稳定性和高产相关性分析

为了给干旱和半干旱地区水稻品种审定和推广应用提供科学依据,将黑龙江省垦区6个水稻品种（系）种植在6个不同生态点,利用AMMI模型对水稻产量及产量构成因素（每穴穗数、穗粒数、千粒重、结实率）进行了稳定性分析。结果表明：基因型（G）×环境（E）对水稻产量和产量构成因素的影响明显;本试验中的各水稻品种（系）在不同地点种植,产量和产量构成要素的稳定性存在差异,垦稻08-924产量最稳定;850农场和军川农场较适合水稻进行区试试验;二次枝梗数和穗长除与结实率、产量相关性不显著外,与其他指标相关性均达到显著或极显著水平;产量除与穗数达显著正相关外,与其它性状均未达显著相关性。     

沟灌渗透对直播水稻干物质积累和产量的影响

采用田间对比试验、植株分析方法,研究了相同畦宽(200cm)、不同灌水量的沟灌渗透栽培和常规淹水栽培对直播水稻茎蘖生长及干物质积累的影响。结果表明:不同时期直播水稻茎蘖生长、干物质积累、冠层叶性状和产量在不同处理之间均存在一定的差异;其中,以处理1(节水38.6%的沟灌渗透)的茎蘖生长适宜,分蘖质量高,干物质积累量大,冠层叶叶绿素含量高,有效穗数、穗长、穗粒数、实粒数和千粒重显著高于常规淹水处理,增产达8.74%。     

Pyrethroid resistance in a strain of Spodoptera littoralis is correlated with decreased sensitivity of the CNS in vitro

The effects of permethrin and cypermethrin on the isolated abdominal nerve cord of insecticide-resistant [R] and -susceptible [S] strains of Spodoptera littoralis larvae have been studied. Above ca. 19°C, permethrin at 10^?7M caused a prolonged spike train to follow electrical stimulation of the nerve cord. The time of onset of this repetitive firing was significantly greater for the [R] strain. Moreover, cypermethrin, to which this strain shows negligible resistance, did not cause such repetitive discharges. Thus, resistance to permethrin but not to cypermethrin appears to be based on a qualitative difference between the pyrethroids. Nerve blockage by the two pyrethroids was also investigated, with particular reference to temperature. Once again, differences were apparent: when considered relative to untreated controls, permethrin caused quicker nerve blockage as temperature was reduced whereas the blocking action of cypermethrin was not affected by temperature. However, the times taken to cause nerve blockage by permethrin in [R] and [S] larvae were not significantly different, making it unlikely that nerve blockage plays a major role in this resistance. Two methods were employed to reduce the resistance factor in vitro. The synergist dodecyl imidazole failed to significantly reduce the time taken for permethrin to cause either repetitive firing or nerve blockage. However, reducing the calcium concentration in the saline did significantly reduce the latency of repetitive firing caused by permethrin in [R] larvae, thus increasing the nerve sensitivity to approximately the same level as normal calcium, [S] insects.     

RESPONSE OF SPRING WHEAT TO THE APPLICATION OF 2,4-D AT VARIOUS GROWTH STAGES*

Summary. Two Triticum aestivum and two T. durum varieties were sprayed at five different growth stages with 0–5 and 1 kg/ha 2,4-D on the same day. The most sensitive stage was that of spike initiation, the most resistant phase followed the completion of spike differentiation, and plants close to caring were again very sensitive. Grain yield reductions of up to 19% with the low dose and 34% with the high dose were observed. The yield reductions at all growth stages were mainly due to a decrease in the number of kernels per spikelet. Application of 2,4-D during tillering also reduced the numbers of spikes per plant and spikelets per spike. Malformations of the spikes occurred in some plants of T. aestivum treated at spike initiation, but these spikes did not differ in grain yield from normal spikes from equally treated plants.     

寒地粳稻产量及其主要构成性状间的关系

对138份寒地粳稻材料的产量及其主要构成性状间关联性进行分析.结果表明,产量非直接构成因素株高和穗长与产量呈显著正相关(0.32??和0.25??),株高和穗长均与穗粒数呈显著正相关(0.49??和0.45??),而穗长与结实率呈显著负相关(-0.20?).在产量直接构成因素互作分析中,除穗数×穗粒数×千粒重三者互作与...     

In vivo neurotoxic effects of dieldrin on giant nerve fibers and escape reflex function in the earthworm, Eisenia foetida

Neurotoxicological effects of dieldrin were assessed in adult earthworms, Eisenia foetida, using noninvasive electrophysiological recordings of escape reflex activity. After 48 hr body surface exposure to aqueous suspensions of dieldrin, dose-dependent reductions in medial and lateral giant nerve fiber conduction velocities were seen within a concentration range of 1.4 to 288 ppm. At a high concentration (288 ppm) the decreases in velocity occurred in as little as 90 min, but at low concentrations decreases in velocity occurred much more gradually. Other physiological and behavioral effects of dieldrin treatment included (i) after-discharges of giant fibers following brief mechanical stimulation, (ii) spontaneous bursts of giant fiber spikes, (iii) reductions in the amplitude of giant fiber-mediated muscle potentials, (iv) tonic spasms involving end-to-end shortening and body stiffening, (v) ataxia, and (vi) reduction in body weight. Thus, the in vivo effects of dieldrin in earthworms are characterized by a diverse and complex set of physiological and behavioral symptoms. Possible mechanisms underlying these effects are discussed in relation to the generally accepted mode of dieldrin action on synaptic transmission.     

水硫及其互作对冬小麦光合特性及产量的影响

在大田条件下,选用大穗型品种兰考矮早八号和多穗型品种豫麦49-198为试验材料,研究了不同施硫量和灌水次数对冬小麦光合性能及产量的影响.结果表明,不同施硫处理,以硫60 kg/hm2处理产量最高,并达到显著水平.兰考矮早八和豫麦49-198的增产幅度达19.32%和9.24%,此处理下的光合速率和SPAD值高于硫30 kg/hm2和硫0 kg/hm2处理.在本试验条件下,2品种在灌水处理间产量有差别,兰考矮早八以不灌水产量最高,豫麦49-198以仅拔节期灌水产量最高.     

Influence of defoliation on reproductive capacity and growth in Buddleja davidii

This study aims at quantifying the effects of defoliation on seed production and germination in Buddleja davidii , and determining the potential for reducing the invasive success of the species. The effects of defoliation on seed production and germination at the flower spike and plant levels were investigated for control plants and plants that were defoliated by 66% at monthly intervals from mid-summer (January) to mid-autumn (April). Seed samples for germination were collected in late autumn (May). Defoliation reduced flower spike number per shoot, seed number per flower spike and average seed mass by 9%, 22% and 13% and 30%, 33% and 17% on main and side shoots, respectively. In contrast, emergent leaf area per shoot in the defoliated plants exceeded that for the control plants by 89%. The ratio of total seed mass per plant/emergent leaf area per shoot was significantly lower in the defoliated compared with the control plants by 50%. Defoliation did not affect the timing or rate of seed germination. Defoliation of B. davidii resulted in a marked decrease in reproductive capacity, consistent with the priority allocation of resources to compensational leaf area growth.     

玉米疯顶病种子传播研究

连续3a对不同来源的玉米种子,利用显微镜镜检和试种观察植株发病显症的方法,检测其携带玉米疯顶病病菌状况。结果表明,病株病穗籽粒、病株健穗籽粒、病田健株籽粒都有较高的带菌率。因此,病菌随种子调运远距离传播是造成各地病害突发的主要原因。     

燕麦DNA导入普通小麦变异观察及RAPD分子验证

利用花粉管通道将健壮燕麦(Avera sativaL.)的总DNA导入普通小麦宁春4号中,获得12个稳定变异的品系。农艺性状变异观测结果显示多数变异品系的叶面积、穗长、主穗粒数、主穗粒重和千粒重等性状都显著地超过了受体宁春4号小麦;对受体、供体和稳定变异的品系进行RAPD分析,在68个随机引物中有8个引物检测出DNA的多态性,并且在后代基因组中找到了受体没有而供体特有的DNA片段,从DNA分子水平上证明了燕麦DNA可以通过花粉管通道进入受体,并与其基因组DNA整合,在后代中遗传和表达。