ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1965.tb07932.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYMean weight‐on‐age curves for eighty‐two male and sixty‐five femaleRattus rattusreared in the laboratory show that at birth the males were slightly heavier on the average than the females; for a week or two the females gained weight more quickly, but at 5–6 weeks of age the males became significantly heavier again and remained so. A change in growth rate seemed to occur in both sexes at about 7 days and again at about 6 weeks in the males and at 8–9 weeks in the females. In the females initial weight was significantly correlated with maximum weight: in the males it was significantly negatively correlated with the age at which maximum weight was achieved.In both sexes, at all ages from birth onwards, some rats weighed twice as much as others. This militates against the use in the field of weight as a guide to age. Variability in weight was very largely a consequence of differences between litters.The mean maximum weight attained by seventy‐two males was 215g.; the heaviest weighed 305g. The mean maximum reached by fifty females was 173g. and the heaviest weighed 260g. The mean age of attainment of maximum weight was 504 days for males and 553 days for females: the difference was not significant.The mean age at death of the males that died of 'natural' causes was 779: that of the females was 837 days. This difference was also non‐significant. Longevity was significantly correlated with both maximum weight and the age at which it was attained. Life tables are presented for male and female rats that survived to 35 days and died both from 'natural' causes and from all causes. Factors are given for calculating the corresponding probabilities of survival from birth.The average number of rats per litter was 6·2: the ratio of the two sexes at birth did not differ significantly from unity.No differences in body weight could be distinguished between the two colour forms ofRattus rattusthat are comm

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1965.tb07933.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYAphis fabaewere reared on two varieties of field bean (Vicia faba) on which they differ in fecundity, and the total amounts of solids and nitrogen ingested and assimilated during larval life and during the reproductive and early post‐reproductive life were estimated. Larvae ingested 0·7–0·8mg. solids containing 0·02–0·03mg. nitrogen in 7 days of larval life; they ingested and excreted more solids and nitrogen from one variety. Adult virginoparae ingested 4·4–4·9mg. solids containing 0·08–0·09mg. nitrogen during the reproductive life of 3 weeks; they ingested almost equal amounts of solids from each variety and, like the larvae, assimilated about 20%; their dry weights increased slowly during reproductive life and rapidly during early post‐reproductive life. Adults assimilated 70% and larvae 50% of the nitrogen ingested and, although larvae assimilated and excreted significantly more nitrogen on one variety, the adults assimilated more nitrogen on the other variety, on which they produced significantly more larvae. The nitrogen content of the sap of both varieties seems more than adequate for the aphids to grow and reproduce and did not

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1965.tb07934.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYThe commonest Thysanoptera in mass flights between ground level and 1000 ft. in south‐east England are females of species dwelling on grasses and cereals. Individuals with immature ovaries probably disperse over the greatest distances. Aerial densities as large as 60,000 thrips per 106cu. ft. were recorde

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1965.tb07935.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYThe use of chemical soil treatments to control the nematode,Longidorus elongatus, which transmits raspberry ringspot and tomato blackring viruses, was studied in a 4‐year field trial.In untreated soil, after an overwinter fallow, the nematodes lost their infectivity, but regained it in the spring from germinating infected weed seeds. In soil treated with D‐D (with or without a surface seal of solubilized xylenols) at 400 lb./acre, 95% of theL. elongatuswere killed. This treatment, and that with 20% quintozene at 1200 lb./acre, prevented transmission of virus to Talisman strawberries throughout the 4‐year experiment.In both treated and untreated soils,L. elongatuspopulations increased about fourfold each year after strawberries were planted but, because of the initial kill, the populations in the D‐D plots at the end of the experiment were approximately only one‐eighth of those in the control plots.After the first year, both D‐D and quintozene treatments led to significant increases in crop, reaching 130% in the third fruiting season.Metham‐sodium and thiram, at the doses used, were only partially effective as nematicides: by the end of the second growing season the numbers ofL. elongatusin the plots receiving these treatments equalled those in the untreated soil, and the infectivity had returned almost to its o

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1965.tb07936.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYInfection of two varieties ofNicotiana tabacumwith the common strain of tobacco mosaic virus caused no permanent change in the apparent photosynthetic rate of the inoculated leaves in the first few hours after infection. Photosynthesis slowed transiently after inoculation as an effect of rubbing, but the leaves quickly recovered. These results are in conflict with those of Owen (1957b) (Ann. appl. Biol.45, 456); the differences between these two studies have not been rationalized.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1965.tb07937.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYOf sixty herbaceous plant species, which were inoculated with beet mild yellowing virus (BMYV), fourteen species were susceptible to isolates of BMYV collected from sugar beet in eastern England. Three of these,Beta vulgarisL.,Claytonia perfoliataDonn. andCapsella bursa‐pastoris(L.) Medic, had already been used as test plants for BMYV. The new hosts were six species in the genusBeta, Spinacea oleraceaL.,Senecio vulgarisL.,Sinapis albaL.,Spergula arvensisL. andArmaria leptoclados(Rchb.) Guss.Stellaria mediaL. (Vill.) is also probably a host of BMYV but results of susceptibility tests were inconclusive.Senecio vulgarisproduced well‐defined symptoms when infected with BMYV and was a useful additional test plant. Similar experiments on the host range of beet yellows virus (BYV) generally confirmed the results of previous work. It seems likely that in recent years weeds have been important primary foci of BMYV infection, but probably not of BYV infection, in Great Britain.The host range studies have indicated that BMYV may be related to at least one part of the American beet western yellows virus (BWYV) comp

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1965.tb07938.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYIn studies on movement of diquat dibromide (1,1'‐ethylene‐2,2'‐bipyridylium dibromide) in broad bean, french bean and soybean, discoloration of tissues was used as an indication of its presence.The presence of cuticular wax on leaves interfered with the entry of diquat. Movement of diquat within the plant occurred readily in either light or darkness. Ringing experiments showed that movement took place predominantly in the xylem, and defoliation experiments indicated that movement was associated with the transpiration stream.In light, movement of diquat in the plant occurred when the relative humidity was near 100% but was markedly less than that occurring at 50%r.h. High temperature and low humidity promoted rapid drying of treated leaves which confined the diquat to these leaves and prevented movement to untreated parts of the plant. In stems diquat moved from the xylem to the outer cortical parenchyma; cell‐to‐cell diffusive movement also occurred in leaves.Movement of diquat in the plant is shown to be a sequential process, the part responsible for most extensive distribution being movement in the transpiration stream. Therefore, conditions which favour transpiration (without undue desiccation) will promote movement

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1965.tb07939.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYGas chromatography has been used to study the capacity of wheat and pea stem tissues and growing seedlings to degrade the side chain of γ‐(2,4,5‐trichlorophenoxy)butyric acid. The substance was converted to its acetic derivative in wheat, presumably undergoing β‐oxidation within the tissues. No evidence for such breakdown was obtained in pea stems. The results are fully consistent with the earlier findings of Wain and Wightman who studied these same systems by other

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1965.tb07940.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY

摘要:

SUMMARYAt low wind speeds of up to 4 m.p.h. in a horizontal tunnel, deposition of air‐borne oil droplets, up to 60 μ in diameter, occurred more readily on tsetse flies at rest on obstacles representing approximately the shapes of branches and leaves than on the obstacles themselves. Under some conditions deposition occurred on all flies irrespective of resting position, although the obstacle remained completely free from deposit.At 1 m.p.h. deposition was largely by sedimentation; at higher wind speeds it was largely by impaction.The optimum drop‐size range for deposition on tsetse flies at rest on the obstacles appeared to be from 10 to 30 μ. Deposition of these drops by impaction on the obstacles themselves, however, was less than that of larger

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1965.tb07941.x

出版商:Blackwell Publishing Ltd    

年代:1965

数据来源: WILEY