bluuebunny/crossref_metadata_2025 huggingface dataset:
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

Changes 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

In 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.
Taxonomic Notes on Leucoptera meyricki Ghesquiere and Leucoptera coffeella (Guerin-Meneville) (Lepidoptera, Lyonetiidae)
Authors: Bradley J. D.
Published: July 2009

Records of Leucoptera coffeella (Guér.) from Kenya and Tanganyika have been found to be based on misidentifications and to refer to a distinct species, Leucoptera meyricki Ghesq. Other records of coffeella from the Old World seem open to doubt and require to be reinvestigated since they may also be based on misidentifications. L. coffeella seems likely to be a Neotropical species predominant in the West Indies. A lectotype is designated for meyricki, but the type material of coffeella cannot be traced and the identity of the latter species remains to be properly established. The present generic assignment of meyricki and coffeella in the genus Leucoptera Hübn. needs to be reconsidered in the light of the new genus Perileucoptera Silvestri (1943).
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.
Observations on the Biology of Trox procerus Har. (Coleoptera, Trogidae), a Predator of Eggs of the Desert Locust, Schistocerca gregaria (Forsk.)
Authors: Roffey Jeremy
Published: July 2009

Published records and recent unpublished field observations on Trox procerus Har. in Asia and Africa are assembled. All stages of the life-cycle are figured, and brief descriptive notes on the egg, larval and pupal stages, are given. It is pointed out that the egg and larval stages have only been recorded from egg-fields of the Desert Locust, Schistocerca gregaria (Forsk.), and that the larvae feed on the eggs of the locust, sometimes causing considerable mortality. In contrast, the adults appear to survive independently of the locust, and it is suggested that the apparent concentration of adults of T. procerus in areas where Desert Locusts are ovipositing is due to their being attracted to the numerous dead locusts that are present in such areas.
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

In 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.
An illustrated Key for Identification of Larvae of the Cotton-pest Species of Pectinophora Busck and Platyedra Meyrick (Lepidoptera, Gelechiidae)
Authors: Capps Hahn W.
Published: July 2009

The cotton stem moth, Platyedra vilella (Zeller), was not known to occur in the United States prior to 1951. In August of that year, larvae of the species were found infesting hollyhock plants at Mineola, New York, by J. H. Maheny, a plant quarantine inspector of the port of New York. Adults were reared from additional material collected the following year, an indication that the species had become established. How or when P. vilella was introduced has not been determined, but doubtless it was only recently.
Acaricide Resistance in the Blue Tick, Boophilus decoloratus (Koch).—Part I
Authors: Whitehead G. B.
Published: July 2009

Using laboratory tests described, the effectiveness of a number of insecticides on both larval and adult, fully engorged examples of the Blue Tick, Boophilus decoloratus (Koch), was determined. The results of tests using adult ticks were expressed as histograms of the percentage control exerted by varying concentrations of insecticides. The test using larvae was more sensitive and enabled results to be expressed as dose-response curves from which the LC50 could be accurately calculated. By comparing ticks from different localities in South Africa, resistance to a number of insecticides was demonstrated. Adult ticks from the farms Allandale and Ferndale in the East London district were three to four times more tolerant of sodium arsenite than were the sensitive ticks from Frankenwald farm near Johannesburg. Both larval and adult ticks from Ferndale and Allandale, when compared with Frankenwald ticks, were highly resistant to γ BHC, which conferred some cross-resistance to toxaphene, chlordane, dieldrin and aldrin. Ticks from Allandale, in addition to being resistant to sodium arsenite, BHC, toxaphene, chlordane, dieldrin and aldrin were highly resistant to DDT. DDT resistance conferred a cross-resistance to Dilan.

The organo-phosphorus insecticides tested, malathion and diazinon, were equally effective against all ticks.
The Termites of the Solomon Islands
Authors: Harris W. V. , Brown E. S.
Published: July 2009

Twelve species of termites occurring in the British Solomon Islands Protectorate are listed, and an illustrated key to their soldier castes is provided. An analysis of the 114 records has been made in order to indicate, in a general way, the relative abundance of the various species. Notes are given on distribution within the islands, on habitats and nests, and on the occurrence of termites on coconut palms and in buildings. Damage to buildings is discussed and suggestions made for control measures applicable to local conditions.
Some injurious Curculionidae (Col.) from New Guinea
Authors: Marshall Guy A. K.
Published: July 2009

Among a number of insects sent in for identification by Dr. J. J. H. Szent-Ivany, of the Department of Agriculture, New Guinea, were several species of weevils that are reported as causing serious injury to cacao and coffee plants. Four of these are described below, and the types have been deposited in the British Museum (Natural History).
A Laboratory Study of the Cigarette Beetle,Lasioderma serricorne(F.) (Col., Anobiidae) with a critical Review of the Literature on its Biology
Authors: Howe R. W.
Published: July 2009

The paper includes a review of the published literature on the biology of the Cigarette Beetle,Lasioderma serricorne(F.). A list is given of foods on which this species has been found breeding. Information on the duration of the various developmental stages is tabulated and the data on oviposition are summarised. Observations are collected together on the rate of increase of the species in warehouses, on the number of generations per year, on sex ratio, on the use of traps to catch adults and on the spread of the pest and the damage that it causes. The lengths of exposure to various high and low temperatures that are required to give a complete kill of the species are tabulated, and the known natural enemies are listed.

Original work includes a morphological comparison ofL. serricorneand the closely related common storage speciesStegobium paniceum(L.). The experimental work consists of a study of the life-cycle ofL. serricorneon wheatfeed over a wide range of combinations of constant temperature and humidity. Development was possible from just under 20°C. to 37·5°C. at favourable humidities. Larvae died at 90 per cent. R.H. at 37·5°C. The lower humidity level for development was under 25 per cent. R.H. at 30°C. but change of temperature, both up and down, raised the lower humidity limit so that, at 20°C. and 37·5°C., all larvae died at 40 per cent. R.H. When fed on foodstuffs such as groundnuts, which contain less water than wheatfeed at all humidities, the effects of low humidity are more rigorous. The effect of a number of foodstuffs on the length of the developmental cycle was investigated. The duration of larval instars on wheatfeed at 30°C. and 70 per cent. R.H. was found. The adults obtained in the experiments were weighed. The heaviest insects were obtained at 25°C. and 100 per cent. R.H. Higher temperatures and low humidities reduced weight. Females were heavier than males. The sex ratio was unity.

The oviposition rate was investigated at 70 per cent. R.H. over a wide temperature range. Under all conditions the eggs were laid quickly. At this relative humidity, no fertile eggs were laid at 37·5°C. and few pairs laid at 20°C. The total number of eggs laid per female at 20°C. was low, otherwise temperature had little effect on the number of eggs laid, but the rate of oviposition was increased by high temperature. The theoretical rate of increase at 70 per cent. R.H. was calculated for several temperatures and shown to increase with temperature up to 35°C.

The conclusions on the distribution and multiplication of the species which can be drawn from the laboratory results are discussed.
Two new Species of Pseudodoniella China & Carvalho (Hemiptera, Miridae)
Authors: Miller N. C. E.
Published: July 2009

The genus Pseudodoniella was proposed by China & Carvalho (1951) for the species pacifica from Keravat, New Britain. Recently two more species have come to hand, from Lae, New Guinea and Popondetta, Papua. They are new and are described and figured here. It has been found that in the genus Parabryocoropsis China & Carvalho (1951), two of the species then described, cheesmanae from Kokoda, Papua and duni from Keravat, New Britain, were incorrectly placed and should have been assigned to Pseudodoniella.
The Simuliidae (Diptera) of Northern Nigeria
Authors: Crosskey R. W.
Published: July 2009

Fourteen species of SIMULIIDAE (of which one occurs in two forms) are recorded from Northern Nigeria. Localities for each species are given on distribution maps. Most of the species are of fairly general occurrence in the Ethiopian Region, although Simulium kenyae De Meillon is recorded for the first time from West Africa. No new species was found in an extensive survey of about 200,000 square miles.

Some notes are included on the breeding habits of the species, particularly the type of breeding site preferred, the altitudes at which breeding occurs, and the months in which immature stages have been found.

Some discussion is given of the distribution of SIMULIIDAE in Northern Nigeria and the factors which appear to influence it, partly illustrated by maps. The most important factor is thought to be the geology of the country, which determines the areas of rivers suitable for breeding. Other factors such as climate, altitude, or vegetation zones, seem to play little part, except in the far north.
The specific Status of Callosobruchus maculatus (F.) and Callosobruchus analis (F.)
Authors: Southgate B. J. , Howe R. W. , Brett G. A.
Published: July 2009

Two of the species in Callosobruchus, C. maculatus (F.) and C. analis (F.), are compared and redescribed, together with a description of the male and female genitalia of both species. The species Bruchus vicinus Gylh., B. ornatus Boh., B. ambiguus Gylh., B. sinuatus Fhs. and B. quadrimaculatus F. are shown to be synonymous with C. maculatus (F.). Bruchus jekeli Allib. and B. glaber Allib. are almost certainly synonyms of C. analis (F.), but this could not be verified as no type specimens are available.
Penetration through the Egg-shell ofPieris brassicae(L.)
Authors: Beament J. W. L. , Lal R.
Published: July 2009

The structure of the shell of eggs ofPieris brassicae(L.), together with changes in it and associated membranes during embryonic development, have been investigated in relation to the penetration and toxicity of simple chemicals. The rigid outer shell consists of two proteinaceous layers, covered externally by a relatively hydrofuge cement, by which the egg is attached to the leaf surface. The egg has respiratory pores over its surface, and a single apical micropyle penetrating these layers. The inside of the rigid shell is lined with a layer of unsaturated oil—an unusual feature for an insect egg. When the egg is first laid, the vitelline membrane is directly applied to the inner surface of the solid shell over the region immediately around the micropyle, but within four hours this contact is broken, and the oil layer flows into this region also, and becomes complete. As development proceeds, the vitelline layer is replaced by membranes of embryonic origin, but before eclosion both these epembryonic layers, and also the oil, are resorbed.

The egg is remarkably resistant to water-soluble poisons which have no oil-solubility, except during the first four hours of development. This resistance is attributed almost entirely to the oil layer, and the early susceptibility to its absence over the micropylar region. These changes are not reflected in the effect of oil-soluble poisons or fumigants. The solid portions of the shell do not seem to be of great importance in restricting the entry of liquid poisons, even though the cement is comparatively hydrofuge; from experiments with wetting agents and with eggs immersed in poisons under vacuum, it does not appear that the respiratory air spaces in the shell are preferential channels of access; rather, the poisons penetrate through the solid portions of the shell. This penetration, even of oil-soluble materials, is slow, for they can be effectively washed out of the shell again, some considerable time after dipping. On the other hand, non-volatile oily materials can interfere with the respiration of the egg by blocking the air spaces in the shell.

The secretion of epembryonic layers does not appear to change the resistance of the egg to water-soluble materials; this is to be expected, for they do not contain lipoid. On the other hand they do add appreciably to the resistance to oil-soluble materials. There is no evidence that poisons are accumulated in these epembryonic membranes, and released during the pre-eclosion period. Experiments with covalent compounds, such as mercuric chloride, suggest that their oil-solubility accounts for their toxicity, whereas electrovalent compounds containing similar heavy metals are only effective while the direct micropylar path of entry is available to them.
On the Parasites and Predators of the Cockroach. II.—Evania appendigaster (L.)
Authors: Cameron Ewen
Published: July 2009

A detailed account of the biology and development of an important parasite of cockroaches, the Evaniid, Evania appendigaster (L.), is given. Adult and immature stages of the parasite were obtained and studied from collections of oöthecae of Periplaneta americana (L.) made in Saudi Arabia, some 25–29 per cent, of which were parasitised. There are at least three or four generations a year, a rate of multiplication which gives the parasite a very decided advantage over its much slower-breeding host (P. americana takes at least a year or more to pass through one generation).

The Evaniids are a neglected group of parasitic Hymenoptera and so far very little has been published about them.

Adult parasites emerged from the material collected in Saudi Arabia in or about February, May and October. Oviposition in this species is carried out in a rather peculiar manner. The female lies on her side and, with legs braced against the oötheca, penetrates the tough integument of the egg-capsule after about half-an-hour's hard labour. Only one egg (hymenopteriform type) is laid in an oötheca, and the larva which develops from it is solitary in habit, and completely devours all the eggs in the egg-capsule of its host. The number of larval instars was determined by an examination of the cast skins in the residual material of parasitised oöthecae, a task rendered easier by the very distinctive mandibles of the various stages. Altogether there are five separate larval instars, the first easily identified by the serried arrangement of small denticles on the mandibles. The mandibles of the next two stages are tridentate and shaped like a gauntlet glove, while those of the last two instars are sub-triangular and bidentate. The mature larva is described in detail, and recognition characters for eggs, larval instars and adults are provided.

An appraisement of the value of the two important parasites, Tetrastichus hagenowii (Ratz.) and E. appendigaster, in the biological control of cockroaches is made. It is pointed out that T. hagenowii in certain areas destroys from 15–57 per cent, of the eggs of its host and E. appendigaster 25–29 per cent. Both the former, with up to six generations a year, and the latter, with three or more, multiply much more rapidly than their host. Between them the two parasites appear to be capable of destroying up to 50 per cent, of the cockroach population.

The host records and general distribution of five species of Evania, one each of the related genera Prosevania, Zeuxevania and Brachygaster, and two of Hyptia, all of which parasitise the oöthecae of cockroaches, are fully documented. E. appendigaster itself has been recorded from the main species of cockroach, P. americana, P. australasiae (F.), Blatta orientalis L., Cutilia soror (Brunner) and Neostylopyga rhombifolia (Stoll), and its distribution ranges from Europe (Hungary) and the Middle East (Palestine) to the Pacific (Hawaii and Fiji), America (Gulf and Atlantic States), and the West Indies (Jamaica).
A new Method of extracting Arthropods and Molluscs from Grassland and Herbage with a Suction Apparatus
Authors: Johnson C. G. , Southwood T. R. E. , Entwistle Helen M.
Published: July 2009

A new method of extracting free-living arthropods and molluscs from rough, matted grassland has been developed which gives extraction rates that are usually above 95 per cent. Its advantages over other known methods, especially sweeping, are that it is less liable to personal error, collects from otherwise inaccessible places in the habitat, permits selection of places within the habitat (e.g., tops and bases of grass) and does not depend on removal of parts of the habitat.

The apparatus consists of a light, portable but powerful electric suction pump of standard pattern, with a special compartment, containing a small collecting bag, fitted between the fan intake and the flexible hose that carries a nozzle 1 in. in diameter, which is inserted into the grass. It can be operated on several hundred yards of cable.

The sample obtained comprises a mass of plant matter and detritus from which the animals are easily sorted by hand in the laboratory.

The method is unsuitable for subterranean arthropods or for insects living inside or otherwise firmly attached to plants. But it should be possible to use it for a variety of habitats other than grassland.
The Response of Larvae of the Large White Butterfly (Pieris brassicae (L.)) to Diets of Mineral-deficient Leaves
Authors: Allen M. Delia , Selman Ireson W.
Published: July 2009

When larvae of Pieris brassicae (L.) were fed on leaves of plants showing symptoms of deficiency of nitrogen, phosphorus, potassium or iron, some or all of the following effects were recorded in each experiment: —

Reduction of larval weight (deficiency of (1) N, P, K throughout larval life, (2) Fe from time of hatching, from sixth day and for the last two larval instars).

Reduction of relative growth rate (deficiency of (1) N throughout larval life, (2) Fe from time of hatching, from sixth day and for last two larval instars).

Increased larval mortality (deficiency of N, Fe from time of hatching).

Delayed pupation (deficiency of (1) N, P, K throughout larval life, (2) Fe from time of hatching, from sixth day and for the last two larval instars).

The more detailed experiments with iron-deficient diet showed that similar effects were produced at whatever stage of larval development it was first supplied.

Larvae fed on iron-deficient leaves from the time of hatching appeared to have received a severe initial check to growth, but this was followed by some degree of recovery so that they showed a higher relative growth rate, a few days later, than larvae given the same diet six days after hatching.

Preliminary trials were made on the effects of the addition to diets of iron-deficient leaves of various nutrient substances sprayed on to them. No markedly beneficial results were noted.
Attraction of the sheep blowfly, Lucilia sericata (Diptera: Calliphoridae) to carrion bait in the field
Authors: Fisher P. , Wall R. , Ashworth J.R.
Published: July 2009

The facultative ectoparasite, Lucilia sericata (Meigen) has been described as a pioneer colonizer of carrion. This behaviour is believed to enable it to escape the intense interspecific competition which can occur between dipterous larvae within carrion. Such escape is necessary as this fly species has been thought to have reduced competitive ability, resulting from its evolutionary progression towards parasitism. In the work reported here, the attraction of L. sericata to carrion bait at different stages of decomposition (fresh to 28 days old) was investigated in the field. Trials were run over three years, with carrion bait presented in the presence and absence of sodium sulphide. Decomposition had a significant effect on the numbers of L. sericata caught; more decomposed bait caught greater numbers of L. sericata than fresh bait. However, this effect was not apparent if sodium sulphide was added to the carrion. With sodium sulphide added, there was no significant difference in the attraction of female L. sericata, regardless of bait age. There was no general relationship between carrion bait age and the number of female L. sericata caught in different stages of ovarian development. The present data, therefore, suggest that L. sericata does not act exclusively as a pioneer species. Furthermore, this work suggests that, if used with sodium sulphide, the stage of carrion bait decomposition does not significantly modify carrion bait attractiveness.
Vertical and seasonal variation in canopy arthropod communities in an old-growth conifer forest in southwestern Washington, USA
Authors: Schowalter T.D. , Ganio L.M.
Published: July 2009

Variation in canopy arthropod abundances and community structure were evaluated in an old-growth (500-year-old) forest at the Wind River Canopy Crane Research Facility in southwestern Washington, USA. Arthropods were sampled at three canopy levels and two seasons in each of four tree species (Pseudotsuga menziesii, Tsuga heterophylla, Abies grandis,andThuja plicata). The four tree species had distinguishable arthropod species compositions and community organization.Thuja plicata(Cupressaceae) had a particularly distinctive canopy fauna dominated by several mite taxa which did not occur on the other tree species (all Pinaceae).Pseudotsuga menziesiihosted a relatively diverse arthropod fauna with greatest richness of taxa and functional groups. Distinct arthropod assemblages were not observed among canopy levels and sampling dates, but these factors significantly influenced abundances of 63% of the arthropod taxa, either individually or interactively with other factors. These data indicate that forests managed for fewer tree species eliminate important components of arthropod diversity in Pacific Northwest forests and that sampling for biodiversity assessment also should represent season and canopy level.
Changes in eucalypt architecture and the foraging behaviour and development ofAmorbus obscuricornis(Hemiptera: Coreidae)
Authors: Steinbauer MJ. , Clarke A.R. , Paterson S.C.
Published: July 2009

Field surveys, manipulative field experiments and laboratory studies were employed to study the behaviour and development of a large coreid,Amorbus obscuricornis(Westwood), in response to changes in the architecture/foliar quality ofEucalyptus(Myrtaceae) hosts in Tasmania, Australia. Following tree decapitation and subsequent regrowth,A. obscuricornisnymphs were only associated with coppiced hosts. Eucalypts coppiced naturally by wild fire were found to carry significantly more nymphs than non-coppiced conspecific hosts. In contrast, adultA. obscuricorniswere found on both coppiced and non-coppiced hosts. The foliar quality of coppiced hosts was superior to that of non-coppiced hosts; being softer, having a higher moisture content and a lower C/N ratio. Field collected fifth instar nymphs were heavier when collected from coppice vs. noncoppice; but in bagged shoot experiments second instar nymphs gained less weight on coppice than non-coppice. It is suggested that because coppice is softer the shoots may deteriorate (i.e. wilt) more quickly than non-coppice shoots. Through different exposure regimes, it was confirmed that first instar nymphs need only water to ecdyse, while feeding is initiated in the second instar. Differences in the nutritional requirements of first and second instar nymphs were reflected in their behaviour. First instar nymphs did not discriminate between conspecific hosts on the basis of whether they were coppiced or not, whereas second instar nymphs preferentially chose coppiced conspecific hosts. The findings of this work are discussed in the context of the plant vigour and resource regulation hypotheses.
An Insectary Method for Rearing Cacao Mirids, Distantiella theobroma (Dist.) and Sahlbergella singularis Hagl
Authors: Raw F.
Published: July 2009

An insectary method for rearing the cacao Mirids, Distantiella theobroma (Dist.) and Sahlbergella singularis Hagl., is described. Adults are caged, for oviposition, on cacao seedlings grown in baskets. When the eggs hatch, the nymphs are transferred to, and reared on, unripe pods suspended in ventilated glass cages.
Studies on the Chemical Control of Cacao Mirids, Distantiella theobroma (Dist.) and Sahlbergella singularis Hagl
Authors: Raw F.
Published: July 2009

Laboratory and field tests were made to investigate the toxicity, mode of action and persistence of technical DDT and γ BHC when applied to cacao in Ghana to control the Mirids, Distantiella theobroma (Dist.) and Sahlbergella singularis Hagl. The insecticides were tested at concentrations previously used in field trials. D. theobroma, S. singularis and Tribolium castaneum (Hbst.) were used as test insects. Preliminary tests with aldrin, chlordane and dieldrin were also made.

Cacao pods were sprayed to drip point with the test insecticides and the deposit was allowed to dry. Mirid nymphs were placed on the pods and the rate of knockdown and the mortality after exposure for a test period was recorded. These tests showed that BHC had a higher toxicity and acted much more quickly than DDT. BHC greatly reduced feeding.

Fumigant action was tested by spraying cacao leaves to drip point with the test insecticides, allowing the deposit to dry, and then exposing Mirid nymphs and adults over discs cut from the leaves. BHC had a powerful but transient fumigant action; adults, fifth- and second-instar nymphs were killed after, respectively, ½, 4 and 3 hours’ exposure at 28–30°C. over leaves treated with 0·25 per cent, γ BHC. No fumigant effect was observed after prolonged exposure over leaves treated with 2·5 per cent, technical DDT.

Persistence was studied by treating cacao leaves and pods growing under natural conditions and then testing the residual deposit at intervals. Tests with T. castaneum showed that when leaves were sprayed to drip point the residual toxicity of 1·25 and 2·5 per cent, technical DDT fell steadily and was negligible after an interval of three and six weeks, respectively; that of 0·25–2 per cent, γ BHC was negligible after 2–3 days. Corresponding tests with Mirids on pods were less consistent but suggested that 2·5 per cent, technical DDT was still effective against first-instar nymphs after three weeks; 0·25 per cent, γ BHC had a residual toxic effect for at least several days and depressed feeding greatly for at least a fortnight. It is suggested that BHC may have a local systemic action which persists after the surface deposit becomes ineffective.

Of the other insecticides tested, aldrin had a high toxicity and powerful fumigant action and appeared to be the most promising alternative to BHC.

It was concluded that BHC would be more effective than DDT when treating mature cacao because, in addition to its higher toxicity and quicker action, its fumigant action would compensate for incomplete coverage by low-volume spraying.
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

Preliminary 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.