bluuebunny/crossref_metadata_2025_split huggingface dataset:
Notes on East African Bush Locusts with special Reference to Phymateus aegrotus (Gerstaecker 1869) (Orth., Acrid., Pyrgomorphinae)
Authors: Kevan D. Keith McE. 
Published: July 2009

The term “Bush Locust” is defined.The synonymy and known distribution of Phymateus aegrotus are given and previously published records of its occurrence are reviewed.The occurrence of hopper-bands, and of adults, in East Africa for the years 1938–47, inclusive, is outlined.P. aegrotus and other species of the genus are normally unimportant economically as adults, but the hoppers form bands after the manner of, though on a much smaller scale than, true locusts. Outbreaks of these hopper-bands appear to be sporadic but they are sometimes destructive to crops.P. aegrotus has usually been of only local importance as an agricultural pest but areas in which the crops have been damaged are noted. Among wild host-plants there appears to be a preference for Euphorbiaceae although the hoppers are more or less polyphagous.Other East African species which form hopper-bands and which are known to attack crops are mentioned.The life-history of P. aegrotus is described so far as it is known, and observations made by Dr. H. B. N. Hynes on the closely related species, P. pulcherrimus, in Ethiopia are also recorded.Reflex actions in Phymateus species, including such phenomena as autohaemorrhage and colour display by the adults when alarmed, are noted and the literature on the subject is reviewed.Observations are made on hopper behaviour and band-size of P. aegrotus. The latter is usually only a square yard or two in extent but bands up to 25 square yards in area have been observed by the author and there are reports of even larger ones. These bands are very dense both when marching and when stationary (60–80 finalinstar hoppers per square foot). Notes on areas of infestation are also given.In most cases it is sufficient to beat out the bands with branches. Poison bait and dusting with 7 per cent, di-nitro-ortho-cresol are also successful.Detailed descriptions of the coloration of final-instar hoppers of P. aegrotus and the other East African Phymateus species discussed are given. Keys for the identification of these hoppers and of the adults of the four species, P. aegrotus (Gerst.), P. pulcherrimus I. Bol., P. viridipes Stål and P. purpurascens Karsch (for all of which standardised English names are proposed), are also included.
Studies on the Action of DDT on Anopheline Mosquitos and House-flies
Authors: Johnston A. N. 
Published: July 2009

Experimental results indicated that the mortality rate of Anophelines depends on the time of exposure. No evidence of differential reaction between the various stages of larvae was found.Definite and positive evidence of the action of DDT on mosquito pupae was obtained.Laboratory trials indicated that mortality of adult Anophelines following contact with DDT is relatively slow, and the period of exposure required for a lethal dose is approximately 15 minutes.Adult flies required a much shorter period of exposure, viz., 30 secs., and the rate of mortality was higher.Evidence of the mechanical transference of DDT by flies is also presented.
Responses of Pests to Fumigation. II. Toxicity of Hydrogen Cyanide toCalandraspp. under Reduced Pressure
Authors: Salmond K. F. 
Published: July 2009

Adults ofCalandra granariaandC. oryzaehave been fumigated with hydrogen cyanide by the methods of sustained pressure reduction and preliminary pressure reduction, the main criterion of response being death. Of the factors studied, starvation and sex of the insects are without influence. With pressure reduction, Haber's Rule relating mortality, concentration and period of exposure is not followed; for a given concentration-time product, the mortality is higher, the shorter the period of exposure.Preliminary pressure reduction increases mortality much less than sustained pressure reduction. With the latter the mortality ofC. oryzaeis higher than that ofC. granaria. The increases in susceptibility are largely accounted for by increases caused by pressure reduction alone in the absence of fumigant. The number of eggs laid by untreated females and by females surviving treatment was excessively variable and no discrimination between factors could be made.
A Critique on the Time Factor in Biological Control
Authors: Sellers Wendell F. 
Published: July 2009

C. P. Clausen's and W. R. Thompson's concepts on the time factor in biological control are compared with the writer's experience. All three viewpoints emphasise the influence of environment correlated with time. As Thompson points out, we are almost always forced to ascribe the limitations of the numbers of pests to a combination of factors, biotic and physical, varying from time to time and from point to point. Clausen's views concerning the maximum time (three host generations or three years) necessary for an introduced parasite to demonstrate that it will be fully effective are supported by the observed facts. There is associated with the initial establishment of introduced parasites, however, a time lag that is not evident in the control of subsequent outbreaks. The principal factors are the attainment of an “equilibrium of distribution” and the rate of dispersal in building up a controlling density. When effective biological control can be anticipated, it is characteristic that marked outbreaks are brought rapidly under control, and the pest population then oscillates at a relatively low level. Several examples of fully effective parasites and their limitations are discussed which indicate that the value of a parasite or predator should be regarded not as a constant but rather as a variable.An equilibrium of distribution is obtained when there is no decrease in the density of a parasite due to outward dispersal into the uncolonised area; the forward and backward surges of dispersal offset each other, producing a minimum uniformity of distribution independently of other influences. Parasites with slow dispersal rates produce an equilibrium of distribution and effective control more rapidly, but in a proportionately smaller area, than those with fast dispersal rates.When these considerations are applied to the introduced, partially effective parasites of the gipsy moth, the time element is seen to be proportionately extended beyond the three-year period. After establishment, however, the effectiveness of these parasites is conditioned by the normal duration of the heavy outbreaks of the gipsy moth which rarely exceeds three years. Many of these enemies are as effective in the new environment as in the old. The degree of control of the gipsy moth achieved in the north-eastern United States does not differ greatly from that which occurs in central Europe. Examination of this relationship indicates that an enemy that is to become useful, but not completely effective, does not show its value within three years; consequently the adoption of Clausen's conclusions involves a danger of discontinuing programmes prematurely.
Studies on Anopheles gambiae and A. melas in and around Lagos
Authors: Thomson R. C. Muirhead 
Published: July 2009

The differences between the eggs of A. gambiae and A. melas form an absolutely reliable diagnostic character for distinguishing the two species in the Lagos area.Identification of eggs laid by wild-caught females has formed the basis of work on the seasonal incidence of gambiae and melas adults in houses in different localities in and around Lagos.In the area as a whole both melas and gambiae are abundant in most localities, but the greater part of Lagos town on Lagos Island is an almost pure gambiae area.The sporozoite rate of gambiae—10·0 per cent.—is consistently much higher than that of melas—3·5 per cent.—in all catching stations. Fluctuations in sporozoite rate in relation to population density have been studied in both species.The composition of the mosquito population in houses, and in outside resting places has been studied in relation to the movements of mosquitos into and out of houses. Melas makes use of outside resting places to about ten times the extent of gambiae.In African village houses about 90 per cent. of the blood feeding by these two species takes place after midnight, the peak of activity being the hour or two before dawn.An improved design of experimental hut and window trap is described. It has been used in studying the exodus of mosquitos from houses after feeding, and on experiments on host selection by Anopheles.Swarms of male “gambiae” in nature have been described. In captivity both melas and gambiae have been persuaded to mate by using artificial light.By cross fertilisation between melas and gambiae a generation of healthy hybrid adults can be obtained. Of these the females are evidently normal sexually, while most if not all of the males are sterile.The breeding places of melas and gambiae in and around Lagos have been studied in relation to control. In this lagoon area, where conditions are very different from those of Freetown Estuary, melas breeds under a variety of conditions, and Avicennia mangrove is only of limited value in indicating major breeding grounds.
Biological Control of Diatraea mauriciella, Wlk., in Mauritius.—I. Investigations in Ceylon in 1939
Authors: Vinson J. 
Published: July 2009

AbstractThe Sugar Industry of Mauritius is suffering heavily from damage by stem-borers, especially the “Spotted Borer,” Diatraea mauriciella, Wlk. It has been estimated (Moutia, 1934) that this species alone is responsible for an average reduction of 15 per cent, in the field, per arpent, and that the loss in sugar averages 2-3 per cent., i.e. 16 per cent, of the sugar in cane. This means a gross loss of about 1£ million rupees per annum for the whole island, or a net loss of approximately 125,000 rupees.
The Viburnum Aphis, Aphis (Doralis) viburni, Scop.
Authors: Jones Margaret G. 
Published: July 2009

1. The Viburnum aphis, Aphis (Doralis) viburni, Scop., is described and compared with two other species, A. fabae, Scop., and Ceruraphis eriophori, Wlk., also found on Viburnum opulus.2. Transference experiments show that colonies can be established artificially on Euonymus europaeus and Rumex obtusifolius, but not on other common host plants of A. fabae.3. The sexupara is apterous and produces mixed colonies, thus differing from A. fabae where an alate gynopara produces only oviparae, the males arising from an apterous mother on the summer host.
Physiological and Ecological Studies of the Species of Capnodis in Palestine (Col., Buprestidae). II.—Studies on the Larvae
Authors: Rivnay E. 
Published: July 2009

(1) The methods of breeding larvae of Capnodis are described.(2) A description of the larva and of its methods of locomotion is given.(3) A study of the reaction of the larva to external stimuli is presented. It is pointed out that phototropic or geotropic reactions have no influence on the activity of the larva and that it is guided to its food through stereotactic and chemotropic reactions.(4) The larva can detect roots or twigs from a distance of about 40 cm., and it can distinguish between the odour of various plants.(5) Of various fruit trees, the odour of stone fruit was most attractive, and of these, almond comes first and apricots second.(6) After the larva has located the root, and moulted, the sense of smell weakens gradually until it disappears. A comparative morphological examination of the antennae of neonate and mature larvae shows the olfactory organs are not present in the latter, while distinctly developed in the former.(7) The larva feeds on the bark, tearing off minute particles, which it chews and finally discards.(8) The tearing off of the fibres is facilitated by a fluid secreted from the mouth of the larva which softens the wood.(9) Physiological tests show this fluid to contain a cellulose, a pectinase and an amylase.(10) Development from hatching to pupation at 33° C. lasts about 60 days, at 27° C. about 100 days.(11) From empiric data it is apparent that the threshold of development is about 18° C.(12) From measurements and calculations according to the law of Dyar, the larva must moult at least nine times before pupating.(13) The larvae resist temperatures above 42° C. for eight hours, but die after a few days in such temperatures.(14) Practical considerations for the fruit grower based upon this study are presented.
Experiments with DDT in Solutions and Emulsions against Mosquito Larvae in West Africa
Authors: Buxton P. A. 
Published: July 2009

(a) Small field experiments (not attempts at control) are described with DDT in emulsion and in solution in mineral oils, 5 per cent, pure DDT in each material. These were tested on mosquito larvae (mainly A. funestus) under conditions that provided good opportunities for repetition and measurement of dose per unit area. Considerable day to day fluctuations were observed in numbers of larvae obtained by dipping, before the insecticide was applied.(b) Preliminary work showed that kerosene, or dieseline without DDT, were not larvicidal in doses up to 0·5 cc./sq. yard. The dose of oil that was harmful was not determined.(c) It is clear that DDT, either in oil or as an emulsion, is a very effective larvicide, as is well known from work (mostly unpublished) in many parts of the world.(d) One may compare the effectiveness of DDT as an emulsion (Mixture A) and in solution in dieseline, as follows:—It is clear that, under these rather precise conditions of testing, the dieseline solution is more effective than the emulsion both in the minimum amount required to kill, and in lasting effect.(e) Field tests seem to indicate that DDT dissolves from oil into water, so as to make a larvicidal solution, at least when the water is shallow.(f) Even if one puts down a relatively high dose (say 0·10 cc. of 5 per cent. DDT per sq. yard, at least ten times the quantity that will kill all larvae) the effect passes off in a few days, even on stagnant waters. It is not known what happens to the DDT, and difficult to know why it disappears.(g) A heavy dose of DDT (0·50 cc. as above) gives a period of complete kill, followed by a period of partial irregular control. This was more often observed with solutions of DDT than with emulsions and might last as much as four weeks. No explanation of this irregular effect is put forward. It seems most difficult to understand how an insecticide, applied over an area of only a few square yards, can continue to kill some but not all larvae for a period of weeks.(h) Except in one experiment, in which emulsion destroyed small fish, there was no evidence that creatures which prey on mosquito larvae were destroyed. There was no reason for thinking that after the population of mosquito larvae got back to normal it rose to exceptionally high figures (as it might have, had the predators been decimated).
Moonlight and house-haunting Habits of female Anophelines in West Africa
Authors: Ribbands C. R. 
Published: July 2009

1. 97 per cent, of the ♀ A. gambiae, A. funestus and A. melas remained until after dawn in the huts in which they had fed.2. ♀ A. melas seldom left suitable huts in the daytime.3. There was a high positive correlation between the time at which ♀ A. funestus entered huts and the time of moonlight. The maximum correlation coefficient was between the size of the catch at 8 p.m. and the duration of moonlight after this period, and its value was –0·783±0·068.4. During moonless periods, the flighting of ♀ A. funestus was partially inhibited, and when the moon came out, the waiting mosquitos entered the huts in greatest numbers. The average proportion caught when the moon rose during catching periods ending 10 p.m., midnight and 7 a.m. was approximately 50 per cent., 100 per cent. and 400 per cent. greater, respectively, than the proportion caught during these periods on moonless nights. On moonless nights many mosquitos waited until twilight of the following evening before entering the huts, and in consequence the average proportion caught in the period ending 8 p.m. was six times greater on moonless nights than on the nights after full moon.5. The records for ♀ A. melas are less complete, and the correlation coefficient for the relation between time of entry and time of moonlight has the value 0·421±0·184, a result which is barely significant. In view of the highly significant correlations found in the case of A. funestus it is unlikely that this correlation is fortuitous.6. The average rate of entry of ♀ A. funestus throughout one complete lunar cycle at Krabonekrom, Gold Coast, was 27 per cent. before 8 p.m., 22 between 8 p.m. and 10 p.m., 21 between 10 p.m. and midnight and 30 after midnight. The similar rates for A. gambiae (based on very few records), were 10, 20, 30 and 40 per cent. respectively. Comparable rates for A. melas in Sierra Leone are not available, but at least 45 per cent. entered before 10 p.m. (= 11 p.m. Gold Coast time).7. The essential difference between the behaviour of ♀ A. funestus and that of A. gambiae is that the former flight earlier than the latter. A. funestus also seem to be more active at dawn, so that they are more crepuscular in their habits than A. gambiae.8. 58 per cent, of the Anophelines caught at 8 p.m. were unfed. This indicates that early entrants usually rest after entry and before feeding, and average time of biting is later than average time of entry. Gravid or half-gravid mosquitos and those containing partly-digested blood, did not enter the huts; there was evidence that Anophelines usually became fully gorged at one feed. Of the Anophelines caught in huts after dawn 95 per cent, were fully fed.
Notes on the SubgenusCoquillettidiaDyar (Diptera, Culicidae)
Authors: Gillett J. D. 
Published: July 2009

Notes are recorded on some of the habits of members of the subgenusCoquillettidiaof the genusTaeniorhynchus, with an account of catching and rearing methods employed. Fourth-stage larvae of eight different species have been caught and successfully reared to the adult stage, four of these for the first time. One new species is included in the list.Keys are given for larvae and pupae, together with full descriptions of the larvae and pupae of the eight species dealt with.Errors in the previous descriptions ofT. auritesandmicroannulatusare pointed out.
Laboratory Studies on the Bionomics of the Rat Fleas,Xenopsylla brasiliensis, Baker, andX. cheopis, Roths
Authors: Edney E. B. 
Published: July 2009

1. The original purpose of the present work was to confirm a previous finding that, in unfed adultXenopsylla, longevity varies according to the humidity during the cocoon period, and to find whether this is due to differential loss of water during the prepupal period. The previous finding has been confirmed, but the cause is shown to lie in loss of water during the pupal and not the prepupal period.2. Prepupae are shown to gain in weight by the absorption of water vapour from the air if kept at 24°C. and any relative humidity from 50–90 per cent. If kept below 45 per cent. R.H. they rapidly dry and fail to pupate.3. During this period (about three and a half days from cocoon spinning to pupation at 24°C.) the dry weight decreases by about 2 per cent, of the original total weight, and the total weight increases by from 4–29 per cent., with a mean of 14 per cent.4. The amount of water absorbed is independent of relative humidity within the range 50–90 per cent., and is approximately equal to the increase in total weight.5. The critical relative humidity, below which the insects die and above which they absorb water, is shown to be substantially the same (from 45 to 50 per cent. R.H.) at 12°, 24° and 35°C.6. After pupation the insects begin to lose water and continue to do so throughout the period. The rate of loss increases with decreasing humidity, though the effect of humidity is not very great.7. Adults emerging from pupae kept at higher humidities weigh more, have higher percentage water contents, and live longer without food, than those emerging from pupae kept at lower humidities.8. The results are discussed in the light of previous work, and suggestions as to the mechanism of the process of absorption of water are made.
The Development of a Helicopter Spraying Machine
Authors: Ripper W. E. , Tudor P. 
Published: July 2009

Experiments were carried out to study the possibilities of using ground or crop interference with the spray laden slip-stream of a helicopter flying slowly in the ground cushion to obtain a high dynamic catch of spray droplets. Experiments were carried out in 1945 and 1946 with a Sikorski type Y.R.4.B. helicopter and experimental spraying gear designed for the purpose.The forward portion of the slip-stream annulus was explored by means of spraybars placed in three different positions. The position in the sector between angles of 15° and 45° with the direction of forward flying was found to give the best all-round cover and was the position in which the spray deposit was less influenced by alterations in the control-surfaces of the helicopter.To obtain a fairly wide swathe of approximately 70 ft., the equivalent of two rotor diameters, the forward speed of 6–8 m.p.h. was found to be optimal, and it was observed that not only was good cover of the upper surfaces of the leaves obtained but the spray-laden slip-stream also gave a good cover of the vertical surfaces of the plants outside the rotary periphery and, in certain boom positions, descended and in rebounding produced a cover of the lower surfaces.In order to obtain maximum dynamic catch and a good cover of the lower surfaces of leaves, spray-bars must not be more than 6 ft. above ground.Helicopter spraying is wind dependent and in wind velocities above 12 m.p.h. uniform cover of spray deposit does not appear to be feasible.The performance of the flattened out slip-stream and rebound depends on the type of crop, and as this affects the dynamic catch to a considerable degree, this phenomenon will be the subject of a special investigation.The forward portion of the slip-stream was found to give a more even spray deposit than the aft portion because in the latter case vortices are caused by the rotor blades which affect the spray deposit.In view of its limitations as regards speed and dependence on wind velocity, economic application of spray chemicals by helicopter at a degree of efficiency and workmanship equal to that of ground machines is only possible with a heavy load-carrying helicopter. A specification for such a machine has been issued to the manufacturers of rotory wing aircraft.It is hoped that this report will be followed by a report on the performance data of the new spraying apparatus designed for the Sikorski S.51 which is based on the results of these investigations.
Laboratory Experiments on the Effect Of DDT and BHC on certain aphidophagous Insects and their Hosts
Authors: Way M. J. 
Published: July 2009

Experiments were carried out during 1945 and 1946 to determine the effect of insecticides, particularly DDT and BHC, on certain species of Syrphids and Coccinellids. In addition, some preliminary data was obtained on toxicity to parasitic Hymenoptera and a predatory Cecidomyiid species.In some experiments other insecticides were used for comparative purposes and where possible data were obtained on the effect of the insecticide not only on the predator but also on the host and the host-predator relationship.