bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observations on the Occurrence of Larval Infestations of Wheat Bulb Fly, Leptohylemyia coarctata (Fall.)
Authors: Long D. B. 
Published: July 2009

The efiect of the previous crop on the subsequent infestation of winter wheat by the Wheat Bulb Fly, Leptohylemyia coarctata (Fall.), mainly on the clay-loam of Rothamsted Experimental Farm has been investigated for the years 1954 to 1956. By far the highest larval populations followed fallows, the next highest potatoes, which are a low, open cover crop, whilst much lower populations followed the tall crops of beans and wheat, and very small infestations followed the grass mat covers. This confirms the results of previous workers under different agricultural conditions.Previous applications of dung and straw influenced the infestation following fallow in dry summers but not in a wet year. The effects of other manurial treatments were inconclusive.An experiment designed to determine the effect of the crop density on oviposition was inconclusive due to the failure to establish an infestation.Wheat was shown to influence the flight path and to interfere with local egg-laying behaviour, producing a horizontal effect of up to twice its own height.Apart from the foregoing factors, at Rothamsted, where the wheat fields are well separated, the differences in the level of infestation that were observed could be explained by close proximity or otherwise to a centre of heavy fly infestation.Reasons are put forward for suggesting that the effect of the previous crop on oviposition may be interpreted in terms of the opportunity existing for contact with the soil rather than as a preference on the part of the fly.
The Effect of Temperature on the Growth Rate and Survival of the Immature Stages ofAëdes aegypti(L.).
Authors: Bar-Zeev Micha 
Published: July 2009

The effect of temperature on the growth rate and survival of the immature stages ofAëdes aegypti(L.) was studied by rearing them at each of a series of constant temperatures from 14–38°C. in water to which adequate food (bakers' yeast) was added. Larvae were hatched, by immersing eggs in water, in four successive groups with an interval of six hours between each, and six hours after the last group hatched, and every 24 hours thereafter, those surviving in each group were recorded and transferred to fresh water and food, the exuviae remaining being recorded. The average time at which any given stage was reached was taken as the mid-point of the 6-hr. period within which the number of individuals that had completed the previous stage reached 50 per cent, of the total that finally did so.The curve relating temperature and time of development from newly hatched larva to adult is hyperbolic, except at the extremes. The later the instar, the lower is the temperature at which growth is most rapid. The threshold of development was between 9° and 10°C., the developmental zero 13.3°C., and the average thermal constant (between 16° and 32°C.) 2,741 degree-hours. The highest and lowest temperatures permitting development from newly hatched larva to adult were 36° and 14°C., respectively. The average durations of the four successive larval stages and the pupal stage, expressed as percentages of the time taken for newly hatched larvae to reach the adult stage, were 14.6, 13.9, 17.5, 33.3 and 20.6, respectively.
Responses of Pests to Fumigation.VII.—The Relation between Fumigation Techniques, Mortality, and the Amount of Hydrogen Cyanide sorbed by Calandra spp.
Authors: Bhambhani H. J. , Blackith R. E. 
Published: July 2009

The relation between fumigation techniques, mortality and sorption of fumigant was investigated by two factorial experiments in which adults of Calandra granaria (L.) and C. oryzae (L.) were exposed to hydrogen cyanide at concentrations of 12, 26 or 44 mg. per litre and pressures of 2, 27, 52 and 76 cm. mercury for 30, 60 or 90 min., or at given concentration-time products (36, 72 or 108 mg. hr. per litre), in each of which the time component was 1, 4 or 12 hr., and pressures of 2, 37 and 76 cm. mercury. The methods of fumigation and estimation of sorption and mortality were those used in earlier investigations and the results are shown in a series of graphs.For both species, sorption of hydrogen cyanide increased as the total pressure was reduced, about three times as much being sorbed, in the first experiment, at a pressure of 2 cm. as at atmospheric pressure, the increase in sorptive capacity being greater in the case of C. oryzae than in that of C. granaria. In the second experiment, sorption by both species, for a given concentration-time product, was greater at a high concentration applied for a short period (1 hr.) than at a lower concentration applied for a long period (12 hr.); in the former conditions, C. granaria consistently sorbed more fumigant than did C. oryzae, in the latter, the reverse was the case, and in intermediate conditions (4 hr. exposure), the amounts sorbed by the two species did not differ materially. This result was inconsistent with that of the first experiment, in which C. oryzae sorbed more than did C. granaria during short exposures (30.90 min.).These effects on sorptive capacity of differing conditions of fumigation could account for most of the reported departures from the rule that the biological effects of fumigation can be described by the product of the mean concentration of fumigant applied and the period of exposure. Comparison between mortality and sorption at pressures of 27–76 cm. in the first experiment showed, however, that while these were broadly associated, the increased mortality at higher concentrations was greater than would be expected from the associated increase in sorption, and this discrepancy was significantly larger for C. oryzae than for C. granaria.
The Yield ofLasioderma serricorne(F.) (Col., Anobiidae) from a given Quantity of Foodstuff.
Authors: Bull J. O. , Solomon M. E. 
Published: July 2009

An experiment was designed to ascertain the maximum yield of adults of the Cigarette Beetle,Lasioderma serricorne(F.) that could be reared from a given quantity of foodstuff. Equal numbers of eggs of this species were added to batches of tubes containing different weights of wheatfeed, and the resulting adults were removed, counted and weighed.The weights of wheatfeed had been chosen so that in some of the batches of tubes it would not be completely exploited. When emergence of adults was complete, further numbers of eggs, which were calculated to produce approximately the number of larvae necessary to complete the process in each batch of tubes, were then added, and the resulting adults again removed, counted and weighed.The maximum biomass (wet weight) of adults ofL. serricornewhich could be reared from egg to adult per gramme of wheatfeed at 25°C. and 70 per cent. relative humidity was found to be 0.214 g. (108 to 129 specimens, all more or less undersized, and many with a retarded rate of development, compared with insects given ample food). In addition to the 21 per cent, of the food converted into adult insects, another 27 per cent. by weight of the original foodstuff was lost, presumably as water and carbon dioxide, leaving just over 50 per cent. undigested residue, most of which was faecal matter that would have passed through the insects at least once.The yield of insects per g. loss of weight of the foodstuff was 0.46 g. (wet weights), which is very close to the corresponding figures calculated from the results of Fraenkel & Blewett forDermestes maculatusDeg.,Tribolium confusumDuv. andEphestia KuehniellaZell. on various foods, but three times as great as the corresponding figure calculated from Richards' results forCalandra granaria(L.) in wheat.There was evidence suggesting that a truly maximal yield (slightly greater than in these experiments) might be attained by adding an optimal number of eggs to the food at the start, instead of adding a second population to an incompletely exploited food supply.
A Preliminary Survey of the Distribution and Host-specificity of Ticks (Ixodoidea) in the Bechuanaland Protectorate
Authors: Zumpt F. 
Published: July 2009

SummaryTwenty one species of ticks (Ixodoidea), one of which is represented by two subspecies, are recorded from the Bechuanaland Protectorate. Localities, dates and the hosts are given; general distribution and medical and veterinary importance are discussed under each species.The shrub desert formations of the Kalahari are shown to be unsuitable habitats for most species of ticks; only a few are able to survive under severe desert conditions.In medical respects, Ornithodoros moubata (Murr.), as the transmitter of relapsing fever, is the most important tick in the Protectorate. It has been found in the eastern part up to Francistown and in Ngamiland and near Tsane; its further distribution has not yet been established. Larvae and nymphs of various members of the Ixodidae infesting domestic and wild rodents are potential transmitters of tick-bite fever.Cattle in the eastern area and in Ngamiland were found to be infested by ten species, of which Amblyomma hebraeum Koch, Hyalomma rufipes Koch, H. truncatum Koch, Rhipicephalus appendiculatus Neumann, R. evertsi evertsi Neumann, R. simus simus Koch and Boophilus decoloratus (Koch) are the most important ones, both in respect of the numbers infesting cattle, and of their significance as transmitters of redwater, anaplasmosis, heartwater and sweating sickness.Sheep, goats, pigs and horses were found to be infested by nine of the species listed above as occurring on cattle.Dogs were mainly parasitised by Rhipicephalus simus which outnumbered by far the two recognised dog-ticks, Rhipicephalus sanguineus sanguineus (Latr.) and Haemaphysalis leachii leachii (Aud.).Wild Bovids and zebra are infested by species which also live on domestic ruminants, but the percentage of the different species present varies according to the host and to the locality.Wild carnivores are infested by the same species as are dogs, but in this group, too, there are differences in the relative abundance of the various tick species.Small birds are hosts of immature stages of Amblyomma and Hyalomma species. Their importance as carriers for the dispersal of cattle-infesting ticks is noticed.
Enumerating Populations of Adults of the Red Locust, Nomadacris septemfasciata (Serville), in its Outbreak Areas in East and Central Africa
Authors: Scheepers C. C. , Gunn D. L. 
Published: July 2009

SummaryA method is described of estimating the total numbers and frequency distributions of adults of the Red Locust, Nomadacris septemfasciata (Serv.), in outbreak areas of hundreds of square miles, based upon counting the numbers that fly up in a two-yard strip in front of a moving vehicle. The method has proved itself valuable for indicating both immediate and future requirements for killing the locusts, but it requires refining for some research purposes.By this method, the importance has been clearly shown of the process of congregation of scattered adult locusts in forming emigrant swarms that could start a plague. The locusts do not congregate but actually disperse just before laying eggs.The total population in part (189 sq. miles) of the North Rukwa Outbreak Area (a self-contained area of 253 sq. miles) in Tanganyika Territory has been followed for four years. There are indications that a small migrant swarm contains 5–10 million locusts, that a total population in the whole of the North Rukwa Outbreak Area of 20 million locusts is unlikely to yield a migrant swarm, but that 50 million locusts could readily do so.In 1953, after poor rains, no natural mortality was detected between July and October by the assessment methods described. In 1957, after good rains, natural mortality of 70–90 per cent. was revealed by the same methods, although the dry season was not fully covered by the assessments.
The Initial Stage of Migration in Salt-marsh Mosquitos
Authors: Nielsen Erik Tetens 
Published: July 2009

SummaryThe departure of the newly emerged adults of the salt-marsh mosquito, Aëdes taeniorhynchus (Wied.) from the breeding sites was studied in Florida. The departures, which are presumed to be the initial stage of the migratory flight, have been observed to take place only in the dark period of the 24 hours, and, the vast majority of individuals being ready to take off at dusk, spontaneous mass departure took place at that time.Samples of the resting population of mosquitos were taken at intervals before and after the mass departure, and from the departing migrants. The average age of the males in each sample was estimated by the proportion in different stages of hypopygial rotation, from which it is concluded that migratory activity begins when the insects are six or more hours old. The end of the migratory period is not yet known. In all of 21 female departing migrants examined, the ovaries were immature and the spermathecae empty.
Studies on Aqueous Suspensions of Insecticides. Part VII. The Influence of Relative Humidity upon the Sorption of Insecticides by Soils
Authors: Barlow F. , Hadaway A. B. 
Published: July 2009

SummaryChanges in relative humidity had a very marked influence upon the biological activities of γ BHC, dieldrin and DDT sorbed on Uganda mud blocks. In agreement with field observations, kills of mosquitos increased as the humidity increased and this effect was rapidly reversible.Disappearance of insecticide particles from the mud surface was inversely related to humidity, the rate increasing as humidity decreased. On the other hand, the rates of diffusion of sorbed insecticide away from the surface were greater at higher humidities.It is suggested, therefore, that when the biological activity of a mud surface is increased by increasing the humidity, the insects acquire a greater dose of insecticide not because the concentration of insecticide in the surface layers is greater but because the insecticide that is already present acquires a greater mobility. This greater mobility results in a more rapid diffusion in the mud itself away from the treated surface and a greater potential for diffusion into insects resting on the mud surface.Support for these conclusions was obtained by showing that on transferring dieldrin-treated mud blocks from low to high humidity the change in biological activity occurred at about the same rate as the increase in water content of the blocks.The influence of humidity upon the sorption of DDT and dieldrin on a selection of soil samples of widely differing origin was observed. Both insecticides disappeared from the surface more rapidly at low than at high humidity on all the soils.
Observations on Oviposition in the Wheat Bulb Fly,Leptohylemyia coarctata(Fall.)
Authors: Long D. B. 
Published: July 2009

SummaryIn laboratory cultures of Wheat Bulb Fly,Leptohylemyia coarctata(Fall.), a daily oviposition rhythm was observed in which egg-laying was virtually restricted to the afternoon and evening with maximum laying occurring in the two hours before nightfall. The time of oviposition coincided with that part of the diurnal flight rhythm, earlier observed, in which the flies actively congregated on wheat and this, it is suggested, could account for the fact, already recorded, that laying has been found to occur mostly on sites close to an infested crop.The oviposition rhythm was maintained for 24 hours in absence of light and therefore appeared to be partly inherent. However, it could be influenced by the times of exposure to light and disappeared in constant light. Darkness did not appear to affect the egg-laying rate but a temporary increase followed exposure to continuous light. Within the course of the experiments the rate was not affected by small changes in temperature.The individual fly laid up to 180 eggs in the laboratory in periodic batches of up to 42 eggs laid over periods of 1 to 6 days. This periodicity was obscured in cages containing a number of flies. Disproportionately small decreases in the mean daily laying rate occurred with increases in this laying period. Within the laying period the rate progressively increased with each successive day. The total number of eggs laid was not related to the number of ovarioles. In the laboratory, the rate of laying increased with age and most of the eggs were laid by relatively few flies.The rate of egg-laying and survival at different stages in the field is discussed and it is suggested that about two per cent. of the eggs successfully develop as matured females which lay an average of about 50 eggs each.
An Attempt to eradicate Glossina palpalis (R.-D.) and G. tachinoides Westw. from Riverine Vegetation in Benue Province, Northern Nigeria, by Spraying with DDT
Authors: Davies J. B. 
Published: July 2009

During 1955 and 1956 two attempts were made to eradicate Glossina, palpalis (R.-D.) and G. tachinoides Westw. from 8¼ miles of heavily forested perennial river in Benue Province of the Northern Kegion of Nigeria by using DDT.Descriptions of the rivers and the means employed in applying the DDT using knapsack sprayers are given, together with the effect of the insecticide on the fly population.It was found that it was possible to eliminate G. palpalis from this type of habitat, where the forest is largely restricted to the immediate vicinity of the rivers, but that isolation must be carefully undertaken to prevent reinvasion, which would appear to be more extensive than had been expected. G. palpalis was completely absent for 18 weeks.G. tachinoides, which was present in much smaller numbers, also disappeared on the treated river, but because of a similar disappearance on the control river it is not possible to attribute this to the insecticidal treatment.The cost of spraying was about half the cost of clearing by normal current methods.
The Reproduction of the Red Locust, Nomadacris septemfasciata (Serv.) (Orthoptera, Acrididae), in an Outbreak Area
Authors: Robertson I. A. D. 
Published: July 2009

During the breeding seasons 1952 to 1955, samples of females of the Red Locust, Nomadacris septemfasciata (Serv.), were caught in the Rukwa Valley, Tanganyika Territory, and the ovaries classified according to egg length. Ovaries designated Class V were those regarded as containing eggs ready for oviposition. Population estimates and rainfall records were also taken.The data suggested that the eggs in the ovaries develop very rapidly, becoming ready to be laid about seven days after the start of development.The increase in weight of an individual female during ovary development is related to absolute size, and it was found that, during ovary development, the weight increases by approximately one-half.The most important factor initiating ovarian development seemed to be a drop in daily maximum temperature to below 36°C. The factors of high humidity and rainfall were of less importance but their influence is not fully understood. The possibility of change in length of day being an important factor in the initiation of ovarian development is discussed.The limiting factors for the number of egg-pods laid in a season are considered to be the dates of the drop in daily maximum temperature and of the drop or decline in parental population. The date of drop or decline in parental population seemed to be connected with the date of drop in daily maximum temperature.The percentage of females laying more than one egg-pod was calculated, and the resuJts were found to vary considerably from year to year, although the average of 1 pods per female agreed with past estimates. Also, the average period of 16 days between successive egg-layings agreed with past work.Drought, during the laying period, seemed to cause the females to retain their ripe eggs.The evidence tended to confirm the possibility of a Red Locust population being able to increase 100-fold in a single year.
Revision of the Genus Amblypelta Stål (Hemiptera, Coreidae)
Authors: Bkown E. S. 
Published: July 2009

SummaryIn view of the discovery of several new species and subspecies of Amblypelta (Hemiptera, COREIDAE), some of which are either known to be or else threaten to become of economic importance, a revision of the whole genus has become necessary.The genus Amblypelta, as defined in the present paper and as known so far, is confined to Australia north of Sydney, the islands between Australia and New Guinea, New Guinea and, to the west, the Kai Is., Timor and Java; the Bismarck Archipelago, the Solomon Islands including Bougainville, Eennell and Bellona; the New Hebrides and New Caledonia. In the present revision of the genus, twelve species and five subspecies are included, of which all but seven species are new to science. Apart from the descriptions of the new species and subspecies, taxonomic notes on the previously known species are given as well as a key to all the species.The known distribution of each species is stated, and consideration given to the zoogeography of the genus as a whole, and of certain species-groups which can be recognised within the genus.
Movements of the Vectors of Virus Diseases of Cacao in Ghana. I.—Canopy Movement in and between Trees
Authors: Cornwell P. B. 
Published: July 2009

An examination was made of the movements of Pscudococcus njalensis Laing, the dominant vector of swollen-shoot disease, on cacao in Ghana. The mobile population is composed almost entirely of first-instar nymphs (92%). Movement is initiated at about 23·5°C. and activity becomes more pronounced at higher temperatures. Movement is maximal during mid-afternoon when many hundreds of insects become mobile on heavily infested trees. The density of mobile mealybugs increases from the base of the trunk and reaches a maximum at a few feet below the top of the canopy. Under experimental conditions, nymphs walked at least 28 ft. in search of favourable feeding sites and their dispersion increased proportionately with the number of canopy bridges. On cacao, adults are occasionally carried by the ant, Crematogaster striatula, Emery.Using insects labelled with radioactive phosphorus, the assumption was confirmed that P. njalensis is capable of walking from tree to tree via the canopies of farmers' cacao. In a plantation of 8-year-old Amelonado cacao, 40 per cent, of the branches were in contact at 4-ft. spacing and about 20 per cent, at spacings between 5 and 7½ ft. No branches were in contact where the trees were spaced more than 12 ft. apart. At the closest spacing, the ratio between the number of mobile mealybugs that reached adjacent contact trees and those that did not was about 9:100, this ratio being reduced to 1 or 2:100 amongst trees growing 5 to 7½ ft. apart.The significance of the movement of mealybugs in the canopy in relation to virus spread is emphasised. Methods of preventing vector dispersal by pruning, wide spacing and interplanting with a secondary tree crop are discussed. The importance of a closed canopy in preventing attack on the trees by Miridae is stressed.