bluuebunny/crossref_metadata_2025_split huggingface dataset:
Toxicological studies on a beetle, Alphitobius laevigatus (F.)
Authors: HEWLETT P.S. 
Published: February 2008

SUMMARYAs a first stage in obtaining information basic to full interpretation of experiments involving topical dosage of insects, relations between quantal response and two dose factors, concentration of toxicant and volume of solution, have been examined.The test insects, lesser mealworm beetles, Alphitobius laevigatus (F.), were dosed with solutions of n‐valeryl 1,3‐indandione (n‐valone), DDT, dieldrin, and allethrin in a non‐volatile mineral oil, Shell Risella 17. Drops of 0.02‐0.10μl. were shot on to the mesoscutella of the beetles by an improved form of the air‐pulse micro‐drop applicator described by Hewlett (1954a); the beetles were positioned by means of a micromanipulator designed for the purpose. Control over the drop size was better than that by the previous applicator, as shown by an improved version of the immersion method of drop measurement used before. Beetles retained their doses satisfactorily, though transfers of minute quantities of solution between dosed beetles caged together, were shown to be possible. The toxicants appeared to act by contact only. Under certain conditions, which were avoided, the responses of individual beetles dosed with dieldrin or allethrin and caged together were not independent, probably because active beetles disturbed those affected.The toxicants differed markedly in the signs of poisoning that they produced and in speed of action, though none induced appreciable hyperactivity of the beetles. However, for investigating dose‐response relations, ‘end‐point mortalities’ or a near‐equivalent were determined. Planes for regression of probit response on log concentration and log volume fitted the data satisfactorily. For DDT and allethrin the coefficient for regression on log concentration was significantly higher than that on log volume; for dieldrin the difference was not significant, and for n‐valone the results were variable. The estimate of the LD50 for DDT, in terms of μg. DDT per beetle, was about 50% higher when the DDT was applied in 0.08 μl. of solution than when in 0.02 μl.; the corresponding figure for allethrin was about 30%. The greater toxicity of the more concentrated solutions is discussed.Houseflies, Musca domestica (susceptible strains), appear to be more susceptible than A. laevigatus to DDT, dieldrin and allethrin.
The absolute efficiency of insect suction traps
Authors: TAYLOR L. R. 
Published: February 2008

SUMMARYThe ways in which insect size, sampling rate and velocity, and wind speed affect the efficiency of suction traps were measured and an expression obtained to give total efficiency for most insects caught in most traps at most wind speeds. Tables converting log. catch per hour directly into log. density per 106 cu.ft. air, corrected for changes in volume of air sampled and for losses in efficiency under various working conditions, are given for 9, 12, 18, and 30 in. traps.In an appendix, a net is described that samples isokinetically in high winds and works efficiently as a whirligig trap in low winds.
Insecticidal control of paedogenetic cecid larvae in mushroom beds
Authors: HUSSEY N.W. , WYATT I.J. 
Published: February 2008

SUMMARYLoss of about 10% in mushroom yield was demonstrated through infestation by large larval populations of Heteropeza pygmaea Winn., following infestation of the beds soon after spawning.Experiments are described in which γ‐BHC and aldrin were used to prevent such attacks. These insecticides were tested by incorporation at different rates in the casing and compost, and also by applying emulsions to the surface of the casing on cropping beds. The most successful method was mixing γ‐BHC at 50 p.p.m. in the casing before its application to the beds.
The epidemiology of apple scab (Venturia inaequalis (Cke.) Wint.)
Authors: HIRST J.M. , STEDMAN O.J. 
Published: February 2008

SUMMARYThe prevalence of Venturia inaequalis ascospores in orchards was compared both in terms of the number of spores per volume of air (dose) and the number produced per area of dead leaf (productivity). The two parameters often gave divergent estimates, probably because dose depends on total leaf per unit area of ground whereas productivity does not. Differences in the amount of dead leaf surviving until bud‐burst in different orchards or years were enough to explain the anomalies and suggested that because earthworms often removed over 90% of the fallen leaves by spring, they exercised an important control of ascospore number.Assessments of fruit surface scabbed, an accepted way of judging scab control, were not related to ascospore productivity the following spring, but estimates on the percentage of all leaves infected at leaf‐fall were. Other natural variables, like the dates when leaves were formed or fell, seemed of minor importance, especially when compared with effects of earthworms or chemicals. Applying dinitro‐ortho‐cresol to dead leaves in spring decreased the number of ascospores liberated by at least 90% and there is evidence of a similar effect from broadcast ammonium sulphate. The spring and summer spray programmes were also important. Measurements in several orchards during an 8‐year period showed that dose and productivity both declined to less than a hundredth of the highest levels, but in a single wet year productivity in sprayed orchards increased several times and by 40‐fold on unsprayed trees. Ways to prevent high ascospore doses occurring are discussed, together with possible causes of past severe attacks of apple scab at Wisbech.
Some components of the air‐spora in Jamaican banana plantations
Authors: MEREDITH D. S. 
Published: February 2008

SUMMARYThe air in several Jamaican banana plantations was sampled from July 1960 to September 1961 with an automatic volumetric spore trap. In dry weather, many fungi showed typical diurnal periodicity. Group I fungi (Deightoniella, Nigrospora, Cordana, Corynespora, Zygosporium and Zygophiala) first appeared shortly after 06.00 hr., reached a peak before 09.00 hr. and then showed a rapid fall. Group II fungi (Cladosporium, Alternaria, Curvularia, Cerebella, Pithomyces, Periconiella, Memnoniella, Ustilago and others) and pollens had peak concentrations between 09.00 and 14.00 hr. Groups I and II formed the majority of the spore catch during daylight, but they were practically absent between 20.00 and 06.00 hr. Group III fungi (represented chiefly by ascospores, especially of Leptosphaeria spp., basidiospores and splash‐dispersed types) first appeared near 20.00 hr., attained a maximum between midnight and 06.00 hr. and a minimum during daylight. In dry weather, Cladosporium conidia accounted for 23% of the total catch; coloured fusiform spores for 18%; coloured basidiospores for 16%; unclassified minute spores (including Sporobolomyces) for 14%; and Deightoniella only 0.2%.During rain, the typical dry‐air‐spora decreased and was replaced to varying extents by group III ascospore types and splash‐dispersed spores. When, after rain, the plantation dried out during daylight, group III fungi decreased while groups I and II briefly reappeared before the typical night‐time flora developed. When rain was continuous during daylight, groups I and II were rare; ascospores and splash‐dispersed spores dominated the traces. All fungi occurred in low concentrations during heavy rain, periods of drought and strong wind. With rain or under‐tree irrigation or both, the following days had varying increases of all group I fungi and certain group II fungi, probably because favourable humidity conditions caused increased sporulation.
Effects on subsequent generations after γ‐irradiation of larvae of Lyctus brunneus (Steph.) (Coleoptera, Lyctidae)
Authors: BLETCHLY J.D. 
Published: February 2008

SUMMARYThe effects of a single irradiation at 4000 roentgens on larvae of the powder‐post beetle Lyctus brunneus (Steph.) are described. These included a reduced and delayed emergence of the first generation. The number of beetles produced per female returned to normal in subsequent generations. The vigour of emerged beetles as judged by their average weights did not appear to be much affected. Irradiation at a sublethal dosage thus seems unlikely to be a practical method of employing γ‐radiation for the treatment of infestations by wood‐boring insects. One of the chief limiting factors in the employment of lethal dosages for such treatments is the mass of screening required, hence a technique enabling lower dosages to be used would be of value.
The etiology of tulip‐root disease in susceptible and in resistant varieties of oats infested by the stem nematode, Ditylenchus dipsaci (Kühn) Filipjev
Authors: BLAKE C.D. 
Published: February 2008

SUMMARYThe number of pre‐adult larvae of Ditylenchus dipsaci which invaded seedlings of the oat variety Sun II growing in sand was linearly related to the number of larvae in the inoculum. In seedlings growing on pads, invasion rates were higher but were limited to about 200 nematodes per plant. The respective numbers of larvae invading the susceptible varieties Sun II and Powys and the resistant varieties Manod and Pennant were not significantly different after 3 days. Reproduction occurred in the susceptible varieties, and after 28 days the number of nematodes per plant in the susceptible varieties was about double that in the resistant ones.When the resistant variety Manod was infested at germination, 32.5% of the seedlings were killed after 14 days compared with 45% of the susceptible variety, Sun II, and this difference was significant at the 5% level. Oat and lucerne seedlings were invaded by larvae of both the lucerne and oat races of D. dipsaci but only in the compatible host did reproduction occur. More larvae invaded the pseudostems of oats than the root systems and this difference was significant at the 0.1% level. The nematode reproduced only in the pseudostems.A method for classifying plants attacked by stem nematodes is proposed based on the reaction of the tissues and the multiplication of the nematode within them.
The etiology of tulip‐root disease in susceptible and in resistant varieties of oats infested by the stem nematode, Ditylenchus dipsaci (Kühn) Filipjev
Authors: BLAKE C.D. 
Published: February 2008

SUMMARY Ditylenchus dipsaci caused cells to enlarge and separate in tissues of the susceptible oat variety, Sun II. Cytoplasm was withdrawn from the cells, the walls of which collapsed to form a cavity around the nematodes. In the resistant variety Manod, separation and hypertrophy were slight, but cytoplasm was withdrawn and cavities formed similar to those in Sun II; hyperplasia or necrosis was not seen.The body and gonads in nematodes from Manod plants were shorter than from Sun II, but the de Man ratios and the ratio of males to females were the same. Fourth‐stage larvae matured to adults more slowly in Manod seedlings. Nematodes grew by a series of steps caused by alternating periods of slow growth before an ecdysis and rapid growth afterwards. In Manod, D. dipsaci grew more slowly but the form of the growth curve was as in Sun II. Gonads lengthened rapidly and continuously during the late fourth larval and early adult stages and especially during the period before the fourth ecdysis when body length stopped increasing.
Some factors affecting rhododendron bud blast and its control
Authors: HOWELL P.J. , WOOD R.K.S. 
Published: February 2008

SUMMARYIn studies of the relationship between rhododendron bud blast, caused by Pycnostysanus azaleae, and the leaf hopper Graphocephala coccinea, laboratory experiments provided no conclusive evidence that the fungus entered the bud tissues through the wound produced by oviposition. The primary brown necrotic lesions of the disease were frequently found to contain the insect's eggs.In the field healthy buds which had been enclosed in muslin to exclude the insect did not become infected. Buds enclosed with the fungus but not the insect showed very few infections. Most infections occurred when both insects and diseased material had been enclosed with the bud. Although the muslin was found not to impede the passage of P. azaleae spores, fewer buds became infected when the insect was enclosed without the diseased material. The possibility that the insects may be contaminated by spores is discussed.Field trials in 1956/57 and 1957/58 showed that the disease could be reduced both by certain fungicides and by a DDT insecticide. A colloidal sulphur spray was the most effective on Rhododendron var. Prince of Wales in both years and had no apparent phytotoxic effects. Some phytotoxicity was shown by Bordeaux mixture and phenyl mercury acetate sprays.
Mechanical transmission of cocoa swollen‐shoot virus to and from cocoa and other hosts
Authors: BRUNT A.A. , KENTEN R.H. 
Published: February 2008

SUMMARYCocoa swollen‐shoot virus, hitherto transmitted only by mealybugs and grafting, was transmitted mechanically to cocoa from cocoa and eight other hosts. The virus was more readily transmitted from Adansonia digitata L. and Bombax brevicuspe Sprague than from the other hosts and most readily from B. brevicuspe. Transmission rates varied from 0 to 46% and rarely exceeded 5%. With a single exception, infective slurries were prepared only when the extracting fluid (pH 8‐8.5) contained a reducing agent (cysteine, ascorbate, thioglycollate or sulphide) in addition to phosphate.Only cocoa half‐beans and A. digitata seedlings have been infected mechanically; of these, cocoa half‐beans were the more convenient test material.
The toxicity to rainbow trout of spent still liquors from the distillation of coal
Authors: HERBERT D.W.M. 
Published: February 2008

SUMMARYFrom a survey of the literature on the toxicity of ammonium salts, phenol, cyanide and sulphide to rainbow trout, and from determinations of the toxicity of sodium thiocyanate and sodium thiosulphate, it is postulated that the toxicity of spent still liquors from the distillation of coal should be due mainly to their content of ammonia and monohydric phenols. This is confirmed by experiments showing that the toxicity of an equivalent mixture of ammonium chloride and phenol is nearly as great as that of a spent liquor from a gas works, and that phenol is almost as toxic as mixtures of the monohydric phenols known to be present in such liquors.Experiments on the effect of pH value, hardness, dissolved‐oxygen concentration and temperature on the threshold concentration of monohydric phenols are described and compared with similar data for ammonia.Experiments with ammonia and phenols suggest that a mixture of these substances is at its threshold concentration when AS/AT+PS/PT= 1, AS and PS being the concentrations of un‐ionized ammonia and monohydric phenols in solution and AT and PT being the threshold concentrations of these substances when tested individually in the same dilution water. The effect of dissolved‐oxygen concentration on the toxicity of an ammonia‐phenol mixture is examined and compared with the effect of this variable on the individual toxicities of ammonia and phenols.A method based on these experiments for predicting the toxicity of ammonia‐phenol mixtures from the chemical composition of their solutions is described, and evaluated against laboratory determinations of the toxicity of spent liquors from a coke oven, and against the death or survival of trout held captive in a stream polluted with spent liquor from a gas works. It is concluded that the correspondence between the predicted and observed toxicities is good enough for the method to be used as a basis for assessing whether trout could live in a stream to which a particular spent still liquor was discharged, or when deciding what treatment the effluent should receive to make it safe for such fish after discharge.
Studies on parsnip canker
Authors: CHANNON A. G. 
Published: February 2008

SUMMARYTwo main types of canker on the shoulders and crowns of parsnips are described, (a) black canker, caused by Itersonilia or Phoma, or both together, and (b) orange‐brown canker, of unknown cause. Black canker is the more common.A large number of isolates of Itersonilia were obtained from diseased parsnip roots and leaves and from the air within parsnip crops in widely separated localities. The dicaryophase only of these isolates was studied. The majority possessed many chlamydospores and agreed with the descriptions by Olive and by Sowell & Korf of isolates obtained from and pathogenic to parsnips. Although these authors identified such isolates as I. perplexans, the writer considers that they should be regarded as a new species, I. pastinacae. The remainder of the isolates from these sources and a number from other hosts possessed few or no chlamydospores and more closely resembled I. perplexans Derx. Tests showed that I. pastinacae was pathogenic to parsnip roots and leaves, but not to chrystanthemum flowers, while an isolate of I. perplexans pathogenic to chrysanthemums, did not attack parsnips. Of the other isolates resembling I. perplexans, only those obtained from cankered roots were pathogenic to parsnip roots.A Phoma sp. causing black canker was isolated from parsnips in four out of thirteen localities. In laboratory pathogenicity tests it attacked only parsnips (both seedlings and mature roots), and may thus be different from other Phoma spp. Parsnip foliage was readily infected artificially, but natural leaf infection has not been observed in the field.Attack by both I. pastinacae and Phoma sp. was enhanced by wounding of the parsnip roots.
Potato haulm resistance to Phytophthora infestans
Authors: LAPWOOD D. H. 
Published: February 2008

SUMMARYHaulm susceptibility to Phytophthora infestans (Mont.) de Bary of fourteen widely differing potato varieties was compared in laboratory and field tests with the maincrop variety Majestic as a standard. These two tests gave similar results except that the early varieties Viola and Arran Pilot were more resistant in the laboratory than in the field.The sequence of infection within the crop canopy was the same in susceptible and resistant varieties, starting first mainly on the lowest leaves on the stem, then the middle and finally the uppermost. This sequence was lost when haulm became prostrate. Varieties differed in the rate that infection spread and leaves were destroyed, some being attacked more rapidly, and others more slowly, than Majestic.In the field the fungus spored on different varieties as in the laboratory test; the annulus was wide and sporulation intense on susceptible varieties, but narrow and sparse on resistant ones.
A comparison of competitive effects of some common weed species
Authors: WELBANK P. J. 
Published: February 2008

SUMMARYIn a series of four pot experiments single plants of kale and sugar beet or wheat were grown alone and with sixteen plants of several different weed species for from 7 to 11 weeks. Two levels of nitrogen were included.The effects of different weeds on dry‐weight growth of the crop plants were used as a measure of their competitive abilities. The results from each experiment were corrected on the basis of the effects of Chenopodium album, which was included as a standard in all experiments. The order of competitive abilities obtained was: with kale, first Sinapis arvensis, then Polygonum convolvulus and Alopecurus myosuroides, then Chenopodium album, Polygonum uviculure and P. persicaria, followed by Matricaria maritima ssp. inodora, and finally Stellaria media, Capsella bursa‐pastoris, Veronica perszca and Anagallis arvensis; with wheat, a similar order, but Polygonum convolvulus had less competitive ability than Alopecurus and about the same as Chenopodium and P. aviculure, and Matricaria had about the same value as Veronica.The effect of nitrogen on kale and on sugar beet was statistically significant, but on wheat it was significant in only one experiment. Weed effects generally were not significantly decreased by high nitrogen; the effects of Sinapis on kale, and of Chenopodium on wheat were increased, The leaf nitrogen percentage of kale and sugar beet was greatly increased by high nitrogen, but usually only slightly affected by weeds; nitrogen deficiency seems not to have been the sole cause of the weed effects. In two experiments with wheat, although high soil nitrogen increased the leaf nitrogen percentage of plants with weeds, it had little effect on their leaf dry weight, so that competition for nitrogen appeared non‐effective. In a third experiment Alopecurus and Sinapis both appeared to compete with wheat for nitrogen.In spite of the greater number of weeds per pot, their yields were usually decreased by adding a single indicator plant to their pots. Those weeds were least affected which themselves most reduced the growth of the indicators.The method used is judged to give results similar to those that might be found in the field, and to have advantages over alternative methods for estimating the relative importance of weeds as competitors of crops.
The response of the feral pigeon when offered the active ingredients of commercial repellents in solution
Authors: DUNCAN C. J. 
Published: February 2008

SUMMARYThis paper describes the response of the feral pigeon to solutions of the active ingredients of commercial repellents. Among the repellents tested, marked rejection of solutions of β‐naphthol was found.It is suggested that some commercial repellents may operate by an irritant action rather than by true gustatory repellency.When offered many of the solutions, the pigeons demonstrated a surprisingly high degree of discriminatory ability.
Eyespot (Cercosporella herpotrichoides) and other factors influencing yield of wheat in the six‐course rotation experiment at Rothamsted (1930‐60)
Authors: GLYNNE MARY D. 
Published: February 2008

SUMMARYYeoman wheat, in the six‐course rotation experiment (potatoes, rye, sugar beet, barley, clover, wheat) at Rothamsted between 1937 and 1960 averaged 34% of straws at harvest infected, 19% severely, with Cercosporella herpotrichoides, the cause of eye‐spot. In different years infected straws ranged from 2 to 99%, which included 1–81% with severe lesions. Straws severely infected increased by about 7% in each succeeding 6‐year cycle, presumably because the amount of infectious material steadily increased. The small amount of eyespot at the beginning of the experiment can be explained by the few cereal crops taken on the land before the experiment began.The fungus survived 5 years between wheat crops partly on spring‐sown barley and autumn‐sown rye, which (1952‐60) each averaged 8% infected straws, only 2% severely, while wheat had 45 % infected, 27 % severely.Other factors that probably influenced yield in some years include lodging (which occurred in 10 years, when straw yield or severe eyespot were above average), other diseases and pests, notably wheat bulb fly, weeds and differences in cultivations and treatments.Mean yield of grain in the 30 years was 28·5 cwt./acre, the maximum 41·1, minimum 18·7. In a neighbouring field, Yeoman wheat, unharmed by soil‐borne diseases and pests and given the same amount of nitrogen (0·6 cwt./acre) yielded about 40 cwt./acre with a year‐to‐year variance of only 5 cwt./acre compared with a range of 19·1 cwt./ acre in the six‐course wheat in the same period (1952‐58), the same weather having different effects on healthy and diseased wheat.The number of straws per foot row (adjusted to 7 in. spacing) averaged annually 21·3 (maximum 28·0, minimum 14·8). Regression analyses showed that 18% of the variance in grain yield was accounted for by the number of straws and that when the number with severe eyespot lesions was included as a depressing factor, together they accounted for 48%. These figures further indicate that severe infection of all straws would almost halve the yield, and that the mean loss attributable to severe eyespot lesions at harvest (1942‐60) was about 12%.