bluuebunny/crossref_metadata_2025_split huggingface dataset:
TOXICITY TO THE GRAIN WEEVIL OF SOME ALKYL COMPOUNDS APPLIED AS VAPOURS
Authors: HASSALL KENNETH A. 
Published: February 2008

A simple fumigation technique is described, which allows twenty to thirty tests to be made at once with different concentrations of vapour. The 50% lethal doses (LD 50's) of different substances were estimated by the probit method of analysis, the slopes of the probit lines also being recorded.The present work had two aims, the first being the investigation of the relationship of the molar LD 50's of different substances to one another. The substances were so chosen that comparison could be made both within homologous series and, for compounds with the same alkyl groups, between them. The second aim was to find out to what extent the slopes of probit lines varied for compounds believed to have like and unlike modes of action.Some of the series were known to contain substances with an anaesthetic or narcotic effect, symptoms which are frequently attributed to substances with some type of physical action. Other series included compounds which had little or no observed narcotic effect, which were lethal at low vapour concentrations and for which evidence exists that they possess chemical toxicity for some organisms. A series which might reasonably be expected to have some of the attributes of both the ‘physical’ and chemical toxicants was also used.On plotting log molar LD 50's against the number of alkyl carbon atoms, the well‐known linear relationship was noted for the series with an observed narcotic effect, the constant logarithmic difference being large in all except the alcohol series. However, the upper members of the series which were presumed chemically toxic also possessed toxicities which showed a constant logarithmic difference, but a much smaller one than that characteristic of the first group. The bromide series had for its higher members a constant difference in the log LD 50's intermediate between these two groups. On the other hand, the lower members of the bromide, iodide and thiocyanate series had log LD 50's which were not related in any obvious way. These experimental results are discussed in terms of phase distribution and chemical reactivity.Two poisons whose modes of action on a given organism are much alike often show parallel probit regression lines, especially if they possess similar chemical constitutions. There is, however, no reason why this should necessarily be the case, and in the present investigation it was found that compounds with an observed anaesthetic or narcotic effect often had very different probit slopes. Within most series, the slope was not greatly different except for the lower and higher members, for which it often appeared higher than for the intermediate ones. Between series, a rough correlation often existed between probit slope and median response vapour pressure.
The Control Of Blowflies Infesting Slaughter‐Houses
Authors: GREEN A. A. 
Published: February 2008

Field experiments on the control of blowflies have been carried out at a large slaughter‐house which was heavily infested both by flies breeding on the premises and by those attracted from surrounding districts.The control of breeding by admixture of a larvicide with slaughter‐house refuse proved to be impracticable. Although a single treatment of the surface of refuse was ineffective, daily applications of DDT or BHC markedly reduced the degree of infestation and killed some emerging adults.The introduction of a scheme for rotational storage and collection of refuse and a general improvement in sanitary conditions, together with a daily application of 5% DDT dust to refuse and nearby vegetation, resulted in the prevention of breeding on the premises and a very considerable reduction in the adult population.Results of experimental applications are compared with those obtained in practice using unskilled labour.
BIOLOGICAL INVESTIGATIONS INTO THE VALIDITY OFCONTARINIASPECIES LIVING ON THE CRUCIFERAE, WITH SPECIAL REFERENCE TO THE SWEDE MIDGE,CONTARINIA NASTURTII(KIEFFER)*
Authors: STOKES BARBARA M. 
Published: February 2008

Biological investigations have proved thatContarinia nasturtii(Kieffer),C. isatidisRübsaamen and C.ruderalis(Kieffer) are in reality one species. The namesC. isatidisRübsaamen andC. ruderalis(Kieffer) are therefore synonyms ofC. nasturtii(Kieffer). Considerable doubt has been thrown on the authenticity of several other species.The host plant range ofC. nasturtiiwas already known to be very extensive. Fourteen additional host plants, including two tetraploid varieties and several weeds have been added during this investigation. Eight were established by experiments, and the remaining six have previously been recorded as host plants ofC. ruderalis. In addition,Brassica nigra, Lepidium sativumandRapistrum rugosumhave since been established as host plants ofContarinia nasturtiiin Holland.Diplotaxis tenuifoliaandLunaria annuaare suspected as host plants, but the evidence is not yet conclusive.
OBSERVATIONS ON THE OCCURRENCE OF THE EELWORM, PRATYLENCHUS PRATENSIS FILIPJEV, IN DELPHINIUM ROOTS
Authors: STONE L. E. W. 
Published: February 2008

Pratylenchus pratensis has been found associated with lesions on delphinium roots: its presence in the tissues is best demonstrated by a modification of the Flemming staining method.At specific sites, the severity of delphinium root‐rot was correlated with the soil population of P. pratensis. After infested soils had been fumigated with methyl bromide, delphiniums grown in the treated soils had more vigorous root systems, containing fewer eelworms per unit weight than those grown in untreated soil. The use of D‐D also shows promise as a control measure against P. pratensis.No pathogenic fungus has been found in the delphinium root lesions.
THE VEGETATIVE DEVELOPMENT OF THE POTATO PLANT
Authors: TAYLOR C. E. 
Published: February 2008

A study of the vegetative growth of potato plants indicated that all varieties grown under identical conditions are likely to show similar growth rates during the early stages of development.Differences in total leaf area per plant between varieties became apparent at the stage when rapid development of axillary shoots from the main axis occurred. The maincrop varieties, Stormont Dawn and King Edward, attained a greater total leaf area than the early varieties, Ulster Chieftain and Arran Pilot, because of the greater development of axillary shoots.It is suggested that the number of nodes produced beneath the terminal inflorescence on the main axis approximates to a constant value, independent of variety. Varietal differences were manifested in the distribution between leaves above ground and stolons below, the early varieties producing fewer leaves above ground than the maincrop, in inverse proportion to the number of underground stolons.The yields of tubers per plant are given for four varieties. Differences between varieties in the rate of tuber formation are related to differences in the development of haulms.It is considered probable that the potato plant exhibits a basic growth form which is modified in each variety in a characteristic manner according to the stage in the growth cycle and the rate at which the growth substances are distributed to the various organs of the plant.
EXPERIMENTS ON THE POSSIBLE CONTAMINATION OF HONEY WITH SCHRADAN
Authors: JONES G. D. GLYNNE , THOMAS W. D. E. 
Published: February 2008

The reported low toxicity of schradan to honey‐bees has been confirmed. This has led to the consideration of the possibility that this systemic insecticide might be present in nectar and subsequently appear in honey in an unchanged form.Using radioactive schradan labelled with 32P, it has been shown that spray applications of this insecticide to mustard and borage plants result in the contamination of nectar. A series of nectar samples taken over a 4‐week period following spraying showed on radio assay a progressive decrease in total 32P content and also in the amount of schradan present in proportion to the decomposition products. The highest figure recorded for the schradan content of nectar was 21 p.p.m.Tests on the stability of schradan in contact with the honey stomach of the bee and also in contact with the enzyme invertase, in vitro, showed that no appreciable breakdown occurred. Furthermore it was shown that schradan was stable in contact with honey over a period of 2 1/2 months.It is concluded that this systemic insecticide may appear in an unchanged form in the honey obtained from the nectar of plants which have been sprayed less than 4 weeks previously.
THE INFLUENCE OF IRON SUPPLY ON TOXIC EFFECTS OF MANGANESE, MOLYBDENUM AND VANADIUM ON SOYBEAN, PEAS AND FLAX
Authors: WARINGTON KATHERINE 
Published: February 2008

The investigations were carried out in nutrient solution with iron as ferric citrate and nitrogen in the form of nitrate.Addition of 2.5 p.p.m. vanadium to plants in which iron chlorosis was already‐established, either by a lack of iron or by excess manganese, failed to counteract the condition, and caused toxic symptoms.Reduction of the standard iron supply to ½ or ⅓ accentuated the toxicity of 2–5 or 5 p.p.m. V to soybean and flax, but a similar reduction in phosphorus had no influence. Toxicity to peas, however, was increased when the phosphorus was reduced to 1/10, provided the iron level was high (20 p.p.m. Fe).Raising the iron supply to 20 or 30 p.p.m. Fe counteracted the toxicity of manganese (10 p.p.m.), molybdenum (40 p.p.m.) and vanadium (2.5 p.p.m.), but the result was less marked when these three elements were combined. Iron supplied in successive, small doses proved less efficient in overcoming molybdenum or vanadium, but not manganese excess, than the same amount of iron supplied in fewer and larger quantities. Varying the iron supply had little effect when the concentration of the three elements was low. When increased iron supply had reduced the chlorosis caused by high manganese or vanadium, it also reduced the manganese and vanadium contents of the shoot (p.p.m./d.m.), but the molybdenum content was only lowered by high iron when given in non‐toxic concentration (0.1 p.p.m. Mo) combined with excess manganese.The iron content of the shoot (%/d.m.) was scarcely affected by the amount of iron supplied, but was generally reduced by high concentrations of manganese, molybdenum or vanadium.Results regarding the effect of vanadium on the phosphorus content of the shoot were conflicting, and differences occurred only when the iron supply was low. Here the phosphorus content of soybean and peas was generally reduced, while that of flax was increased.Yield data for soybean and flax indicated an interaction between manganese with both molybdenum and vanadium if the iron supply was low, but none between molybdenum and vanadium. The effect of all three metals was additive in respect to iron.
A MICRO‐DROP APPLICATOR AND ITS USE FOR THE TREATMENT OF CERTAIN SMALL INSECTS WITH LIQUID INSECTICIDE
Authors: HEWLETT P. S. 
Published: February 2008

An instrument has been constructed for applying minute drops of liquid insecticide to selected parts of individual insects. The principle of the instrument, which is not original, is to express minute amounts of liquid from a hypodermic syringe, and blow the drop from the needle tip by a puff of air. This model is considered to have advantages over previous models working on the same principle. In particular, a very convenient form of fitting was developed for blowing the drop from the needle tip, and fittings of this type could be incorporated in existing similar applicators with little modification of the latter. The high directional accuracy of dropfire necessary for treating selected parts of small insects was achieved.An immersion method was developed for determining the sizes of individual drops of Shell oil P31 delivered, and hence the uncontrolled variability of drop‐volume. It showed that the standard deviation in the volumes of drops intended to be equal in size was about 9% of a mean volume of 0.017 μ1. falling progressively to about 2% as the mean volume increased to 0.33 μl. These standard deviations, however, are of limited value, because the sizes of successive drops delivered appeared frequently to be correlated. A method in which the drops are delivered on to an oleophobic surface for measurement of the diameters of the oil lenses formed was found insufficiently accurate for determining the relative variability of drops of P31.A suction method was devised for manipulating, without anaesthetization or chilling, small beetles such as Calandra and Tribolium. This enabled large numbers to be individually treated with the applicator in a reasonable time. A similar but slower method was used successfully with the larvae of Ephestia. The biological results achieved have been very satisfactory.The effects of uncontrolled variation in drop size on dose‐response data are discussed.
THE EFFECT OF BODY WEIGHT ON THE RESISTANCE TO INSECTICIDES OF THE LAST‐INSTAR LARVA OF DIATARAXIA OLERACEA L., THE TOMATO MOTH
Authors: WAY M. J. 
Published: February 2008

At a constant temperature of 24° C. the final larval instar of Diataraxia oleracea lasts about 10 days, during which its resistance to DDT and γ‐BHC as contact insecticides progressively increases up to the 5th or 6th day. It then suddenly decreases, this coinciding with cessation of feeding and the beginning of prepupal formation.Between the 2nd and the 6th days the gross body weight of the last‐instar larva increases from about 0.27 to 0.65g. Under the conditions of the experiments, the LD50 of parathion, as a stomach poison, was linearly related to body weight; on the same basis TEPP was slightly less, and lead arsenate, slightly more, toxic to the larger than to the smaller larvae. However, DDT as a stomach or contact insecticide, and γ‐BHC as a stomach poison were notably less toxic to the larger larvae. For example, the increase in LD50 for an increase in larval body weight of × 2 was about × 11 for DDT as a stomach poison and about × 12 as a contact insecticide.The order of effectiveness of the above insecticides as stomach poisons for the last‐instar larva of D. oleracea was parathion > DDT > γ‐BHC > TEPP = lead arsenate. Zinc fluoarsenate and rotenone were relatively non‐toxic. Larvae of D. oleracea were repelled by food leaf treated with an extract of natural pyrethrins.
THE CONTROL OF MANGOLD FLY (PEGOMYIA BETAE CURTIS) WITH DDT AND OTHER CHLORINATED HYDROCARBONS
Authors: JONES F. G. W. , DUNNING R. A. 
Published: February 2008

Laboratory and field trials were carried out in the period 1948–52 with DDT, BHC, and other chlorinated hydrocarbon insecticides and with parathion for the control of mangold‐fly larvae (Pegomyia betae Curtis) mining in the leaves of sugar beet. Kills ranging from 85 to 99% were obtained within 6 days with ‘high’‐ and ‘ low‐volume’ sprays using 6–24 oz. of DDT per acre in the form of an oil emulsion applied as a top cover only. Formulation in oil improved the action of the DDT, it being necessary to use dusts and wettable powders at excessive rates to obtain equivalent kills. DDT was usually superior to BHC when compared at customary rates of application for both insecticides. When oil emulsions were compared side by side, however, as ‘low‐volume’ sprays, DDT was not significantly better than BHC. In the same trial, toxaphene, aldrin and dieldrin also gave kills of the same order as BHC and DDT. With the possible exception of parathion, none of the insecticides used appeared to have any effect upon eggs.Plot yields of two of the trials were determined in the autumn, but only at one trial was there a significant increase in yield on the treated plots. At this trial the mangold‐fly infestation was severe, there being twenty‐five unhatched eggs and twenty larvae per plant at the time of treatment. Attempts were made to assess the degree of defoliation and to relate it to the larval population and to the effect on yield.Commercial insecticides of the ‘stock emulsion’ and ‘miscible oil’ types occasionally caused phytotoxicity when applied to sugar beet at excessive, ‘high‐volume’ rates and concentrations. More serious phytotoxicity was observed in tests of commercial insecticides used at ‘low‐volume’ rates and concentrations. Out of ten products tested, only three were acceptable over the whole range of rates and concentrations employed, whilst four caused injury over the whole range.The results obtained in the field and the laboratory were in agreement but did not always agree with the findings of other workers. BHC has previously been recommended largely on the basis of experiments on larvae mining very small beet plants when in, or just beyond, the cotyledon stage. All the trials by the authors were on sugar‐beet seedlings with about six foliage leaves and normal in size for the time of the year. On these plants BHC proved ineffective both as dust and ‘high‐volume’ spray when used at customary rates, but was effective as a ‘low‐volume’ spray in oil emulsion.The successful control of mining larvae by DDT and other chlorinated hydrocarbons is probably due to penetration of the leaf tissue by the insecticide.
THE DISTRIBUTION OF VIRUSES IN DIFFERENT LEAF TISSUES AND ITS INFLUENCE ON VIRUS TRANSMISSION BY APHIDS
Authors: BAWDEN F. C. , HAMLYN BRENDA M. G. , WATSON MARION A. 
Published: February 2008

Exposing both surfaces of leaves systemically infected with cabbage black ring spot virus (CBRSV) or henbane mosaic virus to ultra‐violet radiation decreases the infectivity of expressed sap to about one‐fifth. As irradiation probably inactivates virus mainly in the epidermis, which occupies about one‐quarter the volume of the leaves, these viruses seem to occur at much higher concentrations in sap from the epidermis than in sap from other cells. By contrast, tobacco mosaic virus seems not to occur predominantly in the epidermis.CBRSV and henbane mosaic virus are normally transmitted most frequently by previously fasted aphids that feed for only short periods on infected leaves, but aphids treated like this transmit rarely from leaves that have been exposed to ultraviolet radiation. Irradiation has relatively little effect on the proportion of aphids that transmit after long infection feedings. Fasting seems to increase transmission by increasing the probability that aphids will imbibe sap from the epidermis of leaves they newly colonize. With longer periods on infected leaves, the ability of fasted aphids to transmit probably decreases because they then feed from deeper cells and their stylets contain sap with less virus. Only virus contained in the stylets seems to be transmitted, not virus taken into the stomach. About half the transmissions of henbane mosaic virus by aphids that have colonized tobacco leaves for hours may be caused by insects that temporarily cease feeding on the phloem and newly penetrate the epidermis.Irradiating infected leaves affected the transmission of sugar‐beet mosaic virus in the same way as that of henbane mosaic virus, but had little effect on the transmission of beet yellows virus, whose vectors become more likely to transmit the longer they feed on infected plants.
STUDIES OF THE TOXICITY TO WORKER HONEY‐BEES (APIS MELLIFERA L.) OF CERTAIN CHEMICALS USED IN PLANT PROTECTION
Authors: JONES G. D. GLYNNE , CONNELL JOAN U. 
Published: February 2008

Laboratory techniques are described for the estimation of the stomach poison, direct and residual film contact poison and fumigant poison effects of chemicals to adult worker honey‐bees.The toxicity of eleven chemicals used in plant protection has been investigated by these methods. The order of effectiveness as stomach and contact poisons was: parathion, TEPP, γ‐BHC, dieldrin, aldrin, chlordane, o, o‐diethyl‐o‐ethylmercaptoethyl thiophosphate (constituent of Systox), bisdimethylamino fluorophosphine oxide, toxaphene and the sodium salts of 2:4‐D and MCPA: as residual films, dieldrin, aldrin, γ‐BHC, parathion, chlordane, and o, o‐diethyl‐o‐ethylmercapto‐ethyl thiophosphate (constituent of Systox); toxaphene, TEPP and bisdimethylamino fluorophosphine oxide had no measurable effect; as fumigants, dieldrin, γ‐BHC, aldrin, parathion, and chlordane; the remainder had no measurable effect.
BIOLOGICAL TECHNIQUES FOR THE EVALUATION OF FUNGICIDES
Authors: COLHOUN JOHN 
Published: February 2008

The effectiveness of fungicides for the control of Plasmodtophora brassicae Woron. in pot tests under controlled conditions is influenced by spore load, duration of storage of spores prior to inoculation, time of year and temperature. Many fungicides are less effective in soil which has been heavily treated with calcium hydroxide than in unlimed soil or in soil treated with calcium carbonate. In general, fungicides are less efficient when very heavy attacks of the disease occur. If experiments are made under comparable conditions consistent conclusions can be obtained.A schedule of testing is recommended, and it is suggested that fungicides found to be satisfactory in a preliminary test should be subjected to a detailed test. The proposed method of evaluation of a fungicide is to compare its efficacy with that of a standard treatment under comparable conditions. For comparative purposes the efficiency of a fungicide is measured by the percentage number of diseased plants occurring in treated soil and also by the disease index.
A STUDY OF THE EFFECT OF MILDEW INFECTION ON THE REACTION OF WHEAT VARIETIES TO BROWN RUST
Authors: MANNERS J. G. , GANDY DOREEN G. 
Published: February 2008

The effect of the presence of Erysiphe graminis tritici on the reactions of each of five wheats, Malakoff, Democrat, Mediterranean, Hussar and Webster, to Puccinia triticina was studied. Under normal environmental conditions, mildew increased the susceptibility to rust of Malakoff and Democrat, though not, except in isolated instances, that of Mediterranean or Hussar. High light intensities enhanced the effect of mildew on the reaction of Democrat to P. triticina. The susceptibility of Webster to rust was unaffected or decreased by the presence of mildew.In all varieties there was a decided tendency for rust and mildew to develop on different parts of the leaf, and when a leaf was heavily mildewed the development of P. triticina was sometimes almost entirely inhibited. The reason for this is obscure, since spores of P. triticina and E. g. tritici germinate well in each others presence, and cytological studies revealed several cases of the presence of both mildew and rust haustoria in a single living host cell. Anatomical investigations also showed that the effect of mildew on rust infection was confined to rust pustules within 1 mm. of mildew colonies.The results obtained are in accordance with Gassner's theory that susceptibility to rust is due to the presence of certain specific proteins in the host leaf.