bluuebunny/crossref_metadata_2025_split huggingface dataset:
Further Observations on the Persistence of Larvicides against Culicoides and a Discussion on the Interpretation of Population Changes in the untreated Plots
Authors: Kettle D. S. , Parish R. H. , Parish Jean 
Published: July 2009

This paper presents further observations on the continued persistence of larvicidal treatments applied to small plots (10 yd. × 10 yd.) on Soutra Hill, Midlothian, to control larvae of the biting midge, Culicoides impunctatus Goetgh. Before doing so, consideration is given to the nature of the observed fluctuations in larval population encountered in the untreated plots. Evidence is produced which indicates that this is not due either to delayed hatching of eggs (this, if it occurs, is of minor importance), to change in technique or to the application of insecticide to neighbouring plots, but is due to the larvae responding to an oscillating factor (or factors) in the breeding site. It is suggested that one such factor might be soil water level. Therefore, it follows that changes in the untreated larval population must be taken into account when assessing the degree of control achieved by treatments, especially when the larval population is declining.As regards insecticidal persistence three years after application: —(i) Nine of the eleven DDT treatments (wettable powder, water-miscible concentrate and dust at 12, 50 and 200 mg. p,p′DDT/sq. ft.) gave 100 per cent. control. The other two (both wettable powder at 12 mg./sq. ft.) produced 75 and 22 per cent. reduction.(ii) Only one of seven γ BHC treatments (wettable powder at 50 mg. γ BHC/sq. ft.) gave complete control and one treatment (w.p. 12 mg./ sq. ft.) was completely ineffective.(iii) DDT retained its superiority to γ BHC as a larvicide against Culicoides, achieving 93 per cent. control compared with 55 per cent. for γ BHC.(iv) The lowest dosages of dieldrin (3 mg./sq. ft.) and chlordane (6 mg./ sq. ft.) had begun to lose their larvicidal power, control declining from 76 to 53 per cent. and 67 to 29 per cent., respectively. There was no change at 6 mg. dieldrin/sq. ft. but the other treatments (12 and 25 mg. dieldrin and 12, 25 and 50 mg. chlordane/sq. ft.) had improved. Dieldrin at 12 and 25 mg./sq. ft. and chlordane at 50 mg./sq. ft. attained complete control.The spray-volume treatments, now in their second year, showed an increase in activity. This was most marked in the wettable-powder treatments at 25 mg. p.p′DDT/sq. ft. which a year ago were completely ineffective and now five out of six trials gave complete control and the other 97 per cent. Improvement in the treatments at 50 mg./sq. ft. was less (from 43 to 83%) due in the main to the complete failure of one treatment (10 gal./acre).It is confirmed that spray volume in itself is unimportant in larvicidal applications providing the coverage is adequate.
Immature Nutfall of Coconuts in the Solomon Islands.
Authors: Brown E. S. 
Published: July 2009

In the British Solomon Islands Protectorate, the incidence of the immature nutfall of coconuts that is caused by species of Amblypelta depends upon the distribution of (1) the species that are concerned, which determines on what islands nutfall occurs, and (2) certain species of ants, which affects the local distribution of nutfall on those islands. A. cocophaga China is the most important member of the genus as regards responsibility for nutfall; A. cristobalensis Brown and to a less extent A. costalis Van Duzee also frequent the coconut palm and cause nutfall, but not on a serious scale; A. gallegonis Lever rarely, if ever, attacks coconut.The current view that Oecophylla smaragdina (F.) protects coconuts against Amblypelta, and that Pheidole megacephala (F.) and Iridomyrmex myrmecodiae Emery give little or no protection, is accepted, but evidence is brought forward showing that Iridomyrmex appears to give some protection against A. cristobalensis on San Cristobal. Most attention has been given to a fourth species of ant, Anoplolepis longipes (Jerd.), the relation of which to nutfall has hitherto been in some doubt; evidence from various sources shows that, at least on Guadalcanal and Malaita, it gives nearly, if not quite, as much protection against Amblypelta as Oecophylla does.A method based on crop estimation is used to give some indication of the losses due to nutfall in the European plantations that have been surveyed. The accuracy of the method is discussed in an Appendix. Varying numbers of nuts survive to maturity in nutfall areas, depending on the intensity of attack. In addition to the loss caused by the failure of nuts to survive to maturity, Amblypelta attack causes further losses by reducing the amount of copra obtainable from surviving nuts, and by rendering plantations where the attack is sufficiently severe unprofitable to work, so that they become, in effect, a total loss, even though a proportion of the nuts may survive attack.An attempt is made to evaluate and compare the fraction of the crop lost on some of the principal islands, but it is impossible to give an even approximately accurate figure for the losses due to nutfall in the islands as a whole, because essential data, comprising the planted acreage of each plantation and island, and, except for a very few plantations, details of annual production figures over a period of years, are often lacking; also, limited time has made it impossible to survey many of the plantations in sufficient detail for an accurate assessment of nutfall.A list is given of the species of ants recorded from coconut plantations during the present work.
Studies on Stomoxys calcitrans (L.) in Uganda, East Africa.
Authors: Parr H. C. M. 
Published: July 2009

The importance of certain species of Stomoxys in Uganda, the possibility that these species may be responsible for the mechanical transmission of trypanosomiasis, and the effects of severe biting of Stomoxys on cattle causing loss in milk yields and weight in beef animals, is pointed out.A satisfactory method is described for rearing large numbers of Stomoxys calcitrans (L.) under the conditions that prevail in East Africa.A description of special cages for keeping the adults and for egg production is given, together with a technique for supplying the adults with 0·2 per cent, citrated bullocks' blood.A satisfactory egg-laying and breeding medium contained 9 oz. of dried cow dung, 5 oz. of dried blood granules and 1 oz. of sugar.A detailed description of the construction and working of a constant-temperature and humidity room for rearing larvae and pupae is given, the temperature and relative humidity of the room being maintained at 90°F. and 90 per cent., respectively.The maximum number of eggs that can be introduced into 1-lb. and 2-lb. Kilner jars without causing overcrowding and subsequent under-nourishment in the later larval instars was found to be 200 and 400, respectively.
A preliminary Note on Helopeltis spp. damaging Cashew in Tanganyika Territory
Authors: Swaine G. 
Published: July 2009

Cashew, Anacardium occidentale, an increasingly important cash crop in the coastal region of Tanganyika, is damaged by two widely distributed species of Helopeltis, H. anacardii Miller and Helopeltis sp.At Bagamoyo, in June 1955, the period from egg to adult for H. anacardii occupied 35·9 days; that for Helopeltis sp. occupied 39·2 days.Damage is caused to the leaves, shoots, buds, young fruits and to the cashew apple. Damage in a young tree is more marked than that in an old tree and may result in its being malformed or stunted.The build-up of Helopeltis populations on cashew follows the main growth period of the crop which begins shortly after the end of the main rains in May. The insects are readily found from July to October-November, when the crop matures.Application of a 0·5 per cent, γ BHC dust and a 5 per cent. DDT dust to two-year-old trees increased the amount of crop but the increase was not economic owing to the fact that the trees were coming into bearing for the first time. Cross-infestation from untreated plots may also have reduced the effectiveness of the treatments.Three or four applications by a knapsack-type power duster of 0·5 per cent. γ BHC dust at 15-day intervals previous to flowering of the main crop gave promise of successful control in the field.
An Investigation into the possible Control of the Mealybug Vectors of Cacao Swollen-shoot Virus by Trunk Implantation with Dimefox
Authors: Hanna A. D. , Heatherington W. , Mapother H. R. , Wickens R. 
Published: July 2009

SummaryPreliminary experiments having shown that dimefox (bis(dimethylamino) fluorophosphine oxide) placed in holes drilled at ground-level in cacao trees gave encouraging results in controlling the most important of the mealybugs that transmit swollen-shoot virus (Pseudococcus njalensis (Laing), Planococcus citri (Risso) and Ferrisiana virgata (Ckll.)), two further experiments to investigate the technique and determine the optimum dosage were performed in Ghana in April-June and September-November 1953, respectively. A randomised-block layout was used, with four replicates (each comprising a plot of seven trees) of each treatment at Tafo and, in the first experiment, another two at Bunso. The first experiment disclosed no significant difference in effect when the implantation holes were spaced four inches as against two inches between centres and the former spacing alone was used in the second experiment. The dosage levels of dimefox, based on the weight of the aerial part of the tree estimated from the girth—weight ratio, were 75, 150, 225 and 300 parts per million w/w in each experiment, the lowest representing about one-twelfth of the soil-application rate, and also 375 p.p.m. in the second experiment. The results were assessed in terms of the total number of mealybugs, of all three species, counted on the various parts of the trees, which were felled and examined six weeks after treatment; counts made on a duplicate set of trees in the second experiment that were felled at nine weeks were significantly greater.Statistical analyses of the logarithmic transformations of the population figures obtained at six weeks showed the regression of population on dosage to be a curve of quadratic form. There was thus a limit to the response obtained, the minimum populations of total mealybugs (adults + nymphs) being achieved at a dose rate of 281 p.p.m. in the first experiment and 317 p.p.m. in the second. In the former, the minimum value of the average population of total mealybugs per tree was below that required for efficient control (one per tree), but the variability of the response was such that the population on 35 per cent, of trees so treated would have been above that level; in the latter, the minimum average value attainable was only slightly less than one, and consequently the population on nearly half the trees would have exceeded the level for effective control. Analysis of the combined results from those replications of each experiment that were sited at Tafo showed that a given dosage rate appeared only about half as effective, in terms of the residual population (expressed logarithmically), in October-November as in April-May, but concurrent records from untreated control trees suggest that this may partly have been because populations were falling naturally at the earlier date. Slight leaf-shedding occurred in some of the treated trees.
Observations on the Mosquito, Aëdes (Stegomyia) aegypti (L.), in East Africa. I.—The Biting Cycle in an Outdoor Population at Entebbe, Uganda
Authors: McClelland G. A. H. 
Published: July 2009

In an outdoor population of Aëdes (Stegomyia) aegypti (L.), mainly consisting of subsp. formosus (Wlk.), in Uganda, a series of ten 24-hour catches has shown a sharply-defined biting cycle which corresponds closely to an observed diurnal cycle of flight activity. A main peak of activity occurs one or two hours before sunset, and a lesser peak two or three hours after sunrise.Comparison with recent work in Kenya suggests that, in comparing the behaviour of populations out of doors with those indoors, a distinction must be made between ssp. formosus and the other two forms of A. aegypti, in which no similar cycle has yet been demonstrated.Ssp. formosus, which is presumed to be the wildest form of A. aegypti, is shown to have a cyclical behaviour very similar to a related forest species. A. africanus (Theo.).
The Biology of Nausibius clavicornis (KUG.) (Col., Cucujidae)
Authors: Breese M. H. , Wise Thelma E. 
Published: July 2009

Nausibius clavicornis (Kug.) is a cosmopolitan Cucujid that has frequently been recorded from sugar. It is commonly found in this commodity in Trinidad, where it has not been collected from any other.The adult and other stages are described, and an account is given of the life-history on Haydak's formula at 85°F. and 75 per cent. R.H. Development has also been studied on two types of unrefined sugar.Copulation can take place within one day of the emergence of either sex and the female may begin laying within four days of copulation. The average number of eggs laid was 275 and the overall viability was 85 per cent. The average incubation period was just under five days.The larvae of both sexes may undergo only five moults in development, but the more usual number for females is six. When larvae are disturbed during development, both sexes tend to have six larval instars. Severe disturbance may induce a seventh moult. The mean development period from oviposition to the emergence of the adult was 30 days when there were five larval instars; when there were six, development took about two days longer. Larval mortality on Haydak's formula was low.Ovipositing females lived for up to 163 days under controlled conditions, but males tended to outlive females by about 50 days.On unrefined sugars (e.g., raw or yellow-crystal sugar), adults lived for almost as long (73:99) as on Haydak's formula, but oviposition was greatly reduced and the viability of the eggs was much lower. Larval mortality was high, especially in the first instar, and the total development period was greatly increased.It is unlikely that N. clavicornis could multiply rapidly in raw or unrefined sugar, and any deterioration in stored sugar directly attributable to it would probably be small in comparison with that caused by other factors.
Studies on the Dermestid Beetle, Trogoderma granarium Everts. II.—The Occurrence of Diapause Larvae at a Constant Temperature, and their Behaviour
Authors: Burges H. D. 
Published: July 2009

The development of the khapra beetle, Trogoderma granarium Everts, and the cycle of movement of insects between the food and hiding places has been studied at 30°C. The results have been correlated with observations at maltings, its chief habitat in Britain.In populations at 30°C., many larvae delay pupation and enter diapause, the remainder spending most of their time in the food and completing development quickly. The diapause larvae leave the food in the fourth and in later instars in search of hiding places. Disturbing the food stimulates the larvae to leave it a little earlier. Larvae resting in diapause moult occasionally, and at long and irregular intervals they emerge, presumably to replenish their food reserves by feeding, after which some pupate and the rest hide again.The hidden diapause larvae can persist for a very long time; in cultures, 16 per cent, remained after four years. Apparently, as the food stored in the fat-body is depleted, they become readier to emerge from the crevices to feed. Replacing stale food by new food causes some larvae to emerge and the effect of disturbing the larvae is variable. After feeding, some of these larvae complete development and the resulting adults breed, presumably producing both quick developing and diapause larvae among their offspring.When denied a hiding place, the diapause larvae remain inactive in the food without increasing their rate of pupation. However, they feed more, producing heavier beetles, an effect also obtained by regularly providing fresh food.It is concluded that when a malt store is loaded, some diapause larvae remain in the fabric of the store and others emerge and feed; after feeding, some larvae re-enter crevices and others complete development and breed; the offspring contain some diapause larvae, which accumulate in the crevices and on the walls just below the malt surface; after the malt is unloaded, diapause larvae may persist in empty stores for a number of years, because they can restore their food reserves by occasionally eating grain residues.
Observations on the Mosquito, Aëdes (Stegomyia) aegypti (L.), in East Africa. II.—The Biting Cycle in a Domestic Population on the Kenya Coast
Authors: McClelland G. A. H. 
Published: July 2009

Since the sharply defined biting cycle shown by outdoor populations, in Uganda, of Aëdes aegypti (L.), which closely resembles oviposition and general activity rhythms, could not be reconciled with the ill-defined patterns found in domestic populations, on the Kenya coast, in the absence of knowledge of the composition of the population involved there, 24-hour baited catches were made at Ganda on the Kenya coast, and the abdominal colour pattern of each individual was noted. In the series there was gradation from the darkest to the palest.Of 427 females taken biting, 82·1 per cent, were of var. queenslandensis (Theo.) in the generally accepted sense, 14·5 per cent, of the type form and 0·9 per cent, of subsp. formosus (Wlk.). The material of var. queenslandensis was further divided into two groups in which the lateral spots on the abdominal tergites were of silver and matt white scales, respectively.Very similar biting cycles, with the main peak in the hour before sunset, occurred both inside a hut and within an adjacent compound, although catches were not concurrent and were made under different seasonal conditions.The distribution of the various colour forms in the total catch was independent of the hour of capture.There is a resemblance between these cycles and those reported in comparable situations in Nigeria, where, with the exception of the paler forms, the population of A. aegypti is similar to that at Ganda. It is concluded that the main biting peak is shortly before sunset. Subsidiary peaks, when present, occur with increasing intensity as the day progresses.The relationship of biting activity to other aspects of general activity is discussed, and it is concluded that several aspects require further investigation.The following hypothesis is offered to account for the various patterns of biting cycle observed in different situations. It is suggested that A. aegypti possesses an endogenous multi-peaked diel rhythm of activity. Activity impulses occur in a cycle of waves of increasing intensity from dawn onwards, reaching a maximum at the end of the daylight period, and a biting peak will result when such an impulse coincides with environmental conditions within the range between upper and lower thresholds of activity.
Studies on the Biting Habits and Medical Importance of East African Mosquitos in the GenusAëdes. I.—SubgeneraAëdimorphus, BanksinellaandDunnius
Authors: Haddow A. J. 
Published: July 2009

The biting behaviour of East African species of Aëdes in the subgeneraAëdimorphus, BanksinellaandDunnius, as shown in numerous series of 24-hr, catches made predominantly in Uganda, is discussed. It is shown that with the single exception ofA. (A.) natroniusEdw., which is arboreal, all the species encountered have been most prevalent at ground level. They bite mostly by day, butA. cumminsi(Theo.) shows a marked peak of activity from just before to just after sunset, andA. natroniusis crepuscular. When, however, samples were obtained in environments less favoured than the forest floor, and in which the mosquito concerned was less abundant, the biting cycle might be altered. Thus various species which were essentially diurnal at ground level in forest might be nocturnal in the canopy or in banana plantations.In some cases there seemed to be a tendency towards a group pattern of behaviour. For example, in theabnormalis(Theo.) andtarsalis(Newst.) groups of Edwards it was found that at least three species showed very similar biting cycles. A fourth species,A. nigricephalus(Theo.), which occurs in Nigeria, is reported there to differ in its biting habits, and is also strikingly different in appearance and in the structure of the terminalia.Members of all three subgenera have been involved in various isolations of virus, but it is not possible to prove that they, rather than other species ofAëdesincluded in the infected lots, were the vector mosquitos, except in the case of theA. tarsalisgroup, from which there have been two definite isolations of Rift Valley fever virus, and in that ofA. circumluteolus(Theo.), which has been shown by recent work in South and East Africa to be of major importance, well over 20 isolations of virus having been made from this species. So far as is known at present, seven separate viruses and one distinct variant have been isolated fromA. circumluteolus, and other members of the subgenusBanksinellaalso appear to be involved in transmission.
The Control of Onion Fly, Delia antiqua (MG.), with Seed Dressings
Authors: Carden P. W. 
Published: July 2009

Seed treatments of calomel, DDT, dieldrin and aldrin were compared in three seasons′ field trials for use against onion fly, Delia antiqua (Mg.). Excellent control and also improved germination were obtained with 0·5 oz. actual dieldrin per lb. of seed applied with a sticker, with or without thiram. Similar results were obtained with 0·1 and 1·5 oz. actual dieldrin per Ib. of seed, but 3·2 oz. reduced germination. Aldrin at the same rates gave excellent control but reduced germination. DDT at 1·5 oz. and 3·2 oz. gave good control early in the season, but was not sufficiently persistent and seriously reduced germination. Calomel gave little control, although it improved germination.Although kerosene used as a sticker for a dust was satisfactory, it was liable to reduce germination seriously when used alone, except at very low rates.Seed treated with DDT, dieldrin or aldrin may be stored safely for a month or two in unsealed containers but not in sealed containers.There was close correlation between the percentage of plants attacked and the yield per 100 plants in the original stand. For every 10 per cent. of plants killed by onion fly there was a 10 per cent. loss of the potential yield.Even where the onion-fly attack was heavy, comparatively few plants showed symptoms of damage at any one time, which suggests that the level of attack is frequently under-estimated.
Observations on Simulium neavei Roubaud, with special reference to a focus of onchocerciasis in the Belgian Congo
Authors: Browne S. G. 
Published: July 2009

Parts of a district situated in the tropical rain-forest of the Belgian Congo in which onchocerciasis was generally endemic, were investigated to identify the vector and to ascertain its phoretic host, breeding places, habits, etc.The vector found biting human bait (usually less than 1 metre from the ground) was Simulium neavei Eoub. Dissection of adult females revealed developmental forms of Onchocerca volvulus.Larvae and pupae were found on crabs of the genus Potamon in fast-flowing stretches of the numerous small streams flowing into the Eiver Congo.
The infested streams in the main focus of onchocerciasis were treated by DDT emulsion at a concentration of one part per 500,000 for 30 minutes, every ten days for ten applications.The good results observed initially were partly offset by the reappearance six months later of small numbers of Simuliids apparently developing from eggs laid by females entering the disinfested area from without.