bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the Coconut Pest, Pseudotheraptus wayi Brown (Coreidae), in Zanzibar.
Authors: Vanderplank F. L. 
Published: July 2009

SummaryIn the second of this series of papers on the losses caused by the Coreid, Pseudotheraptus wayi Brown, to coconuts in Zanzibar, descriptions are given in summary form of a number of Government-owned plantations of coconuts on the island, together with the yields recorded over the 12 years, 1944–55. The variation from year to year in any group of plantations is not large, and over all those considered does not exceed 25·8 per cent, of the 12-year mean.In the plantations on poorer soils, predominantly occupied by the ants Anoplolepis longipes (Jerd.) or A. custodiens (F. Sm.), the vidaka damage rate (V.D.R.) during 1955 varied from 60–80. The plantations on better soils are occupied predominantly by a complex of Oecophylla longinoda (Latr.) and Pheidole punctulata Mayr and the V.D.R. determined on a part of these in 1955–56 varied from approximately 41 to 55, with a mean of 47·1. The mean value of the V.D.R. calculated from 200 localities taken at random in Zanzibar during June–August 1955 was 60·6. Taking a value of 50 as a conservative estimate of the V.D.R. for the whole island, and inserting this in the regression equation Y = a + bX relating yield (Y) with V.D.R. (X), derived in the first of this series of papers, together with the average values of the constants a and b obtained therein, it is shown that about two-thirds of the potential crop of coconuts is lost as a result of damage by P. wayi.Comparison of the yields from palms occupied by Oecophylla in two of the plantations on better soil with those of the whole of those plantations suggests that about one-half of the potential crop is being lost.The annual value of the total exports of unconverted nuts and coconut products (copra and coconut oil) varied from £636,254 to £1,008,194 during 1949–56, and the annual value of the total production of nuts, calculated from the estimated total acreage (104,000), the number of palms per acre (50), the 12-year average yield per palm on Government-owned plantations (22·5 nuts per annum) and the market price in 1948–56 (Shgs. (E.A.) 90–150 per thousand nuts), is £526,500 to £877,500. Taking into consideration the lower and upper estimates of the amount of crop lost and of the value of what remains, the minimum and maximum estimates of the financial loss caused by P. wayi in Zanzibar are of the order of £500,000 and £2 million, respectively.
Insecticide Studies on East African Agricultural Pests. III.—Seed Dressings for the Control of the Bean Fly, Melanagromyza phaseoli (coq.), in Tanganyika
Authors: Walker P. T. 
Published: July 2009

The bean fly, Melanagromyza. phaseoli (Coq.), the larvae of which tunnel in the stems of Phaseolus vulgaris, is a pest of this crop in Tanganyika. Field trials there in 1956 on haricot-type beans showed that dressing the seed with chlorinated-hydrocarbon insecticides could prevent attack for at least 30 days after germination; organophosphorus insecticides were less effective. In four further field trials (A-D), in 1957, the insecticides and types of formulation used were aldrin (wettable powder and emusifiable concentrate (EC)), endrin (EC), γ BHC (dry dressing and EC), dieldrin (dry dressing and EC) and a proprietary organophosphorus systemic (dry dressing). Wet dressings were applied by treating the seeds with the liquid and drying immediately, and in one treatment aldrin as a wettable powder was applied dry and the seeds then damped and dried at once.Damage was assessed on an arbitrary scale on trials A and B, and yields measured on trials A, C and D. Results varied between insecticides and under different growing conditions, but wet dressing with endrin at 213 mg. per 100 g. seed, of which about 50 per cent, was retained on the seeds, resulted in the lowest damage, amounting to 7·7 compared with 52·6 for the control (no dressing), and the highest yield, amounting to 13·5 units compared with 8·6 for the control. All treatments, except that with the organophosphorus dust, reduced the damage significantly below that in the control. Wet dressings were usually more effective than dry dressings with the same insecticide, as regards both yield and reduction in damage. This may be associated with the better retention of wet dressings, which was shown by the results of chemical analysis of the residues on the seeds left in the drill hopper after sowing.
Some recent Observations on Busseola fusca (Fuller) (Lep., Noctuidae) in Southern Rhodesia
Authors: Smithers C. N. 
Published: July 2009

The life-history and seasonal cycle of the Lepidopterous borer, Busseola fusca (Fuller), the most serious pest of maize in Southern Rhodesia, have been studied there.There are two generations in the year, the majority of the full-grown larvae of the second entering diapause, in which condition the dry season is passed in the maize stem, but a proportion of the second-generation consists of short-cycle individuals that give rise to moths irregularly during the dry season.In the field, the egg stage lasts about 7–11 days, according to the time of year. In the laboratory, there are six, very occasionally seven, larval instars in the first generation, occupying about 37 days, and the pupal stage lasts about 17 days. In the second (diapausing) generation there may be one or two additional moults without appreciable change in size, and there is considerable variation in the length of instars and in the date of entry into diapause, but by mid-June the bulk of the larvae that will survive are in diapause. The majority of diapause larvae pupate in early November, the pupal stage lasting about 23 days.The feeding habits of the larvae are described and reference is made to other food-plants.The length of life of the adult, in cage conditions, averages 6–7 days, but there is great variation. When provided with diluted honey, adults were not observed to feed, and absence of such food did not appear to impair egg-laying. The sex ratio was 1:1, but in catches at a light-trap the ratio of males to females was 5:1. Copulation takes place shortly after emergence, and oviposition may begin within 24 hours of emergence.The average number of eggs laid per female in cages was 360 over an average of four days, one female laying 1,032. Several batches of eggs may be laid in one night. A single mating appears to be sufficient, but males may copulate with more than one female. Eggs laid by virgin females do not hatch.Diapause is thought to be induced by larval feeding on drying food. Continuous rearing of non-diapause generations can be achieved by feeding the larvae on fresh, green maize. Similarly, in the field, irrigated out-of-season maize will support non-diapause generations and constitute a source of infestation that may render ineffectual the normal routine destruction of all plants of the previous dry-land farming season.The main parasite is the Tachinid, Sturmiopsis parasitica (Curr.), which may destroy more than 33 per cent, of the larvae in either generation.
The availability of the coconut bug, Pseudotheraptus wayi Brown, (Coreidae)
Authors: Vanderplank F. L. 
Published: July 2009

Reasons for the large day-to-day variations in the numbers of nymphs and
adults of the Coreid bug, Pseudotheraptus wayi Brown, taken in the crowns of coconut palms in Zanzibar by the searching technique over a period of six years were investigated in 1957–58. Data are given showing the results of searches (each occupying less than 20 minutes) carried out on two young palms at different times of day and night and in different weather conditions. For each successive 2-hour period between 6.0 a.m. and 2.0 p.m. (in the case of nymphs) or 4.0 p.m. (in the case of adults) the proportion of searches in which P. wayi was observed was significantly greater on dull days than on bright, sunny days, but there were no such differences that were significant in respect of any other 2-hour period for which comparisons could be made, except 4.0 to 6.0 p.m., when the proportion of searches disclosing nymphs was greater on bright days. During the hours of bright sunlight, the adults and nymphs hide in crevices and in the debris found in the leaf axils, but both remain in the open from dusk to dawn. During heavy rain they take shelter in dry crevices and niches.It is pointed out that this behaviour must be taken into consideration if the searching technique is used to assess the result of an application of insecticide.
The control of frit fly, Oscinella frit (L.), in sweet corn (Zea mays) by Thimet (O, O-diethyl S-ethylthiomethyl phosphorodithioate).
Authors: Jepson W. F. , Mathias P. 
Published: July 2009

Sweet corn (Zea mays) is frequently attacked by Oscinella frit (L.) in southern England because the optimal sowing date (1st–20th May) determines the appearance of the seedlings at the peak of the spring flight (13th–30th May).A Latin-square experiment including three Thimet treatments and controls showed that almost complete protection could be given by seed-furrow and surface placements along the rows of an 8 per cent, granular formulation at the rate of 2 lb. actual Thimet per acre.The crop on the untreated control plots was more than halved by the naturally occurring infestation of 45 per cent, of the primary shoots.Estimation of Thimet residues in cobs taken from the seed-furrow treatment showed that only a very minute trace of toxic material was present.Tasting tests on cobs from treated plots revealed no detectable taint.
A note on Glossina medicorum Aust. (Diptera) in Ghana.
Authors: Chapman R. F. 
Published: July 2009

Glossina medicorum Aust. was collected in considerable numbers in thicket near to Accra, Ghana. The habitat was unusual in that the thicket rarely exceeded 15 ft. in height and big trees were entirely absent. Grassy open spaces within the thicket provided the feeding grounds and a list of possible hosts is given.There was some suggestion of an association between the abundance of flies and the rainfall in 1958 but noti in 1959, while the size of the flies was inversely correlated with the saturation deficit.
The effect of temperature on the consumption of fat during pupal development inGlossina.
Authors: Bursell E. 
Published: July 2009

The size-specific fat content of tsetse flies recently emerged from their puparia was determined and by comparison with the size-specific fat content of newly deposited larvae an estimate was obtained of the consumption of fat during pupal development. Experiments withGlossina morsitansWestw. were carried out at a number of different temperatures and it was found that the amount of fat consumed was least at temperatures between 22 and 24°C.Knowing the duration of the pupal period at different temperatures, the rate of fat consumption could be calculated and the logarithm of this rate was found to be linearly related to temperature. The occurrence of an optimum temperature in respect of fat consumption thus reflects the fact that at high temperatures the rate of fat consumption is greatly increased without a corresponding reduction in the duration of the pupal period, whereas at low temperatures the pupal period is very greatly lengthened without a corresponding decrease in the rate of fat consumption.
The effect of repeated insecticidal applications on a natural tsetse population.
Authors: Yeo D. , Simpson H. R. 
Published: July 2009

Using a deterministic model of a tsetse population, theoretical calculations have been made of the effect of repeated applications of a non-persistent insecticide upon a natural population. It has been assumed that the insecticidal applications instantaneously reduce the adult population, and that there is no residual effect.For the numerical work it has been assumed a female fly has a pupal period of four weeks and an average expectation of life of six weeks and produces her first larva three weeks after emergence, and subsequent ones at intervals of one-and-a-half weeks.Results have been calculated for kills of females varying from 50 per cent, to 95 per cent, per application, for series of up to eight successive applications, and for intervals between successive applications of from one to six weeks and also for the case when the population is allowed to become stable between applications.
A modified Lumsden suction-trap for biting insects
Authors: Morris M. 
Published: July 2009

SummaryA detailed tsetse-fly survey of 41,000 sq. miles in the inland savannah zone of the Gold Coast (Ghana) was completed in five years using an entirely African staff and working only six months each year.This undertaking was made possible because studies of the species of Glossina concerned, G. palpalis (R.-D.), G. tachinoides Westw. and G. morsitans sub-morsitans Newst., had provided knowledge of their habitat, food-hosts and activity rhythm, on which could be based a standard yet simple survey technique, within the compass of independent native teams.The restricted activity rhythm of the flies, subject to both daily and seasonal variations, meant that nothing less than a ‘day’ of eight hours of observation could be accepted as a valid sampling unit.With tsetse flies at low densities, a day's search was inadequate, giving only 40 per cent, reliability compared with 6-day observations. Four days' search gave 90 per cent, reliability and was adopted as the minimum period of search.Each survey team was under the charge of a Kecorder or Field Assistant, with fly-boys devoting the whole of their time to catching. Comparability of survey data was ensured by keeping teams to the same size, two fly-boys being the optimum, since it was found that the size of the catch was not always proportionate to the number of boys, the relationship varying according to a variety of factors.In surveying G. palpalis and G. tachinoides the ‘picket’ system of more or less stationary teams, measuring their catches by the ‘day ’, was found overwhelmingly superior to the ‘fly-round’ technique.The survey procedure described for savannah woodland country was not effective in sampling G. nigrofusca Newst. in the Ashanti forest or G. longipalpis Wied. in the coastal savannah, but Morris's ‘animal’ traps were found to take both species readily in places where they had not been detected or only occasionally caught by fly-boys. Experiments showed that trap catches were superior, both numerically and in giving a more representative sample of the tsetse population present. It was also shown that trapping could be a valuable means of studying the biology of these two ‘man-shy’ species of Glossina. Traps were also effective in taking G. pallicera Big. and G. medicorum Aust.The greater value of traps compared with fly-boys as a means of sampling various species of tsetse fly is discussed, and suggestions are put forward for developing trapping as a method of survey.The type of trap employed is regularly catching insects of several other families, including a number of species among the Tabanidae, and of several other orders.
Studies on the Life-History of Aëdes (Skusea) Pembaensis (Theobald) (Diptera, Culicidae)
Authors: Worth C. Brooke , de Sousa Jacinto , Weinbren M. Paul 
Published: July 2009

SummaryThe observation in Kenya that Aëdes (Skusea) pembaensis (Theo.) associates with the crab, Sesarma meinerti, was duplicated in Lumbo, on the northern coast of Mozambique. Eggs were seen abundantly on crabs inhabiting certain colonies among mangroves at the edge of a tidal estuary. Females of A. pembaensis were caught in gradually decreasing abundance at collecting sites progressively further inland from the head of the estuary, while males were almost totally confined to the breeding area. Swarms of males were not seen, and it was suspected that mating took place within crab burrows.Populations of A. pembaensis in 1959 and 1960 were approximately equivalent at Lumbo, whereas some other mosquito species with fresh-water larval stages were reduced in 1960 owing to failure of the rains. The estuarine environment, regulated by the tides, is apparently more stable than are terrestrial habitats. Cycles of A. pembaensis may therefore be less variable than among dry-land forms.Females of A. pembaensis disturbed at a crab colony were found to bite spontaneously in the day-time. Captured specimens showed a marked discrimination in biting preference for one human out of three tested. The preferred individual experienced a severe reaction to the bites, while the other two had none whatsoever.Precipitin tests indicated human beings as the only source of blood in A. pembaensis, although the method of collection probably lends bias to this observation. Eight strains of an apparently new virus were isolated from females of A. pembaensis in 1959 and four in 1960. In addition, two strains of a virus of the Bunyamwera group were isolated in 1960. The source of these viruses and their significance in A. pembaensis require further investigation.
The mating behaviour ofPieris brassicae(L.) in a laboratory culture
Authors: David W. A. L. , Gardiner B. O. C. 
Published: July 2009

SummaryAs part of a general study of the conditions required for satisfactory maintainance ofPieris brassicae(L.) in laboratory culture, an investigation was made of the factors affecting mating behaviour. Notes are given on certain characteristics of the culture from which the experimental material was drawn.It was established thatP. brassicae, over one day old, mated readily at temperatures between 20 and 32°C. provided the daylight illumination was above about 200 lumens/sq. ft. Mating occurred more readily at the higher temperatures and illumination levels than at the lower. It was depressed at very high atmospheric humidities. The size of the cage in which the insects were held was not critical, and pairs formed readily in cages as small as one cubic foot. The population density in the cage was also varied over wide limits without significantly influencing the rate at which pairs formed.Mating took place much less readily in the artificial lights which were tested than in daylight. The most satisfactory light was found to be bilaterally arranged ‘daylight ’-type fluorescent lamps. The level of mating in this light would probably have been sufficient to maintain a culture but it was far lower than in daylight of the same intensity.After mating, the females do not usually pair again for five or more days. The males, however, mate more frequently and will often pair several times in the same day.
Observations on natural mortality, parasites and predators of Wheat bulb fly, Leptohylemyia coarctata (Fall.)
Authors: Dobson Ronald M. 
Published: July 2009

SummaryObservations in eastern England during 1957, 1958 and 1959 showed natural mortality of pupae of wheat bulb fly, Leptohylemyia coarctata (Fall.), to be high. The part of this due to parasitisation is considered in some detail.At Rothamsted, the main parasite was Trybliographa spaniandra Kerrich & Quinlan, and this affected about 10 per cent, of the population in 1957 and about 5 per cent, in 1958. At Whittlesey and Peterborough, in 1959, parasitisation affected 5·5 and 13·7 per cent, of the populations, respectively. The two main parasites found were Aleochara bipustulata (L.) and A. inconspicua Aubé (Coleoptera, Staphylinidae). Phygadeuon trichops Thoms. (Hymenoptera, Ichneumonidae) also occurred but was much less frequent. Notes and original observations on the biology of these parasites are given.Several insects and other small arthropods were observed to prey on various stages of wheat bulb fly. Details of these and notes on the biology of some of them are given.
Aircraft applications of insecticides in East Africa
Authors: Foster R. , White P. J. , Yeo D. 
Published: July 2009

SummaryFollowing successful small-scale trials, an attempt was made, by aircraft application of insecticide, to eradicate Glossina morsitans Westw. and G. pallidipes Aust. from an isolated block of savannah woodland, approximately 11 sq. miles in extent, at Chungai in the Central Province of Tanganyika between July 1958 and January 1959. A single-engined aircraft, fitted with two belt-driven rotary-cage atomisers, was used to apply a 5 per cent, solution of γ BHC in power kerosene at a nominal dosage of 0·08 gal. per acre (0.04 lb. γ BHC per acre). Seven applications were made at approximately 28-day intervals, the time taken to complete an application varying from five to eight days. The operation failed to control the flies. Although each of the first two applications reduced the apparent density of G. morsitans by about 90 per cent, and that of G. pallidipes by a lesser, although still considerable, factor, later applications gave varying and often low mortalities, and the populations increased slowly for some time, the insecticide applications causing only temporary depressions in numbers. Numbers fell towards the end of the operation, but final reductions were only about 50 per cent, or less. Kills of female flies were low, and this undoubtedly led to the eventual failure.The low volume-dosage, a drop spectrum that possibly contained too few droplets of the required size, meteorological conditions, and biological factors that apparently favoured the survival of female flies are suggested as contributory elements to the low mortalities.Operational costs were considerably lower than in previous work.
The life-history and reproductive potential of Cryptolestes pusillus (Schönherr) (Col., Cucujidae) at high temperatures and humidities
Authors: Ashby K. R. 
Published: July 2009

SummaryA study has been made of the development of Cryptolestes pusillus (Schönh.) at various combinations of high temperatures and humidities. Larval development is much quicker at 90 than at 70 per cent. R.H., and the optimal temperature is probably about 37°C. Under optimal conditions the developmental period is less than has so far been recorded for other species of Cryptolestes, the mean duration of the larval stage being as little as 8½ days at 33°C. and 90 per cent. R.H. The oviposition rate is similarly much increased at both high temperatures and high humidities. There is evidence that middle-aged females lay more rapidly than either younger or older individuals. Under optimal conditions the average oviposition rate can exceed 7 eggs/ ♀ /day, about 17 per cent. of the weight of the adult.In cultures of adults on flour, there was no clear indication of a reduction of the oviposition rate or of a juvenile mortality at densities ranging from 1·5 g. per adult down to 0·03 per adult, but there were signs that the latter density was near a critical value.Eggs of C. pusillus were cultured on whole English grain with the germs in poor condition, at humidities ranging from 50 to 90 per cent. The endosperm rather than the germ was attacked in almost all cases. At 50 per cent. R.H., only one individual out of 21 completed its development whereas at 90 per cent. R.H. few failed to do so. Humidity had a considerable effect on the rate of development in the larval stage. At 90 per cent. R.H. it was only slightly slower on grain than on flour.