bluuebunny/crossref_metadata_2025 huggingface dataset:
The nutritional state of tsetse flies from different vegetation types in Rhodesia
Authors: Bursell E.
Published: July 2009

The nutritional state of males of Glossina morsitans Westw. (subsp. orientalis Vanderplank) obtained by two different methods from four vegetation types at two contrasted seasons during 1964–65 in Rhodesia was assessed by determining their fat content, haematin content and size. The results showed that even in the hot dry season, when Brachystgia and Commiphora woodlands were leafless, the nutritional state was better in flies from these two vegetation types than in those from evergreen riverine fringe vegetation; in the rainy season, the difference persisted but was smaller. Only in Combretum bushland, which is sparsely wooded, did the poor nutritional state of flies caught in both seasons accord with the relatively inhospitable appearance of this vegetation type.

The total food-reserves (fat plus the fat-equivalent of haematin) were higher in flies captured on fly-rounds than in those captured on bait-oxen, but the difference was smaller in populations under nutritional stress, e. g., in flies from riverine fringe vegetation and Combretum bushland in the hot season, which suggests that the period of sexual appetitive behaviour in males is shortened under conditions of nutritional stress.

The implications of these results are discussed in relation to methods of control that involve discriminating between parts of the tsetse habitat.
Observations on the biology and taxonomy of the eggs of Anopheles mosquitos
Authors: Hinton H. E.
Published: July 2009

A study of the egg shells of 11 species of Anopheles was made with the stereoscan electron microscope. A number of structures have been found that are useful in distinguishing between eggs of different species; all of them can also be seen with the light microscope. A list is given of these structures, together with others already known to be of taxonomic importance.

The functional significance of the network of the outer layer of the chorion of Anopheles eggs is discussed. It is suggested that the film of gas held by the network is of selective advantage in that it contributes to the buoyancy of the egg, provides it with a part of its protective coloration, and functions as a plastron when the egg is submerged. The plastron of A. labranchiae atroparvus Van Thiel resisted wetting at an excess pressure of more than half an atmosphere.

The relation of Anopheles eggs to the surface film is discussed. A highly stable line of contact with the water is formed, such that the water surface is depressed along the sides of the egg and raised at each end. Because like menisci are attracted and unlike ones repelled, eggs make contact with each other end to end or side to side, never end to side. Water spreads on most natural objects, forming menisci like those at the ends of the egg, which is thus provided with anautomatic trapping device that tends to attach the egg endwise to an object projecting from the water. The selective advantage of endwise over sideways attachment is not known, but it may facilitate hatching.

The structure of the egg of A. pseudopunctipennis Theobald has been disputed, and it is therefore described in some detail.
A possible genetic method for the control of insect pests, with special reference to tsetse flies (Glossinaspp.)
Authors: Curtis C. F.
Published: July 2009

The use of chromosome translocations for the control of pests, with particular reference toGlossina, is proposed. A translocation arises if two non-homologous chromosomes in the same cell undergo breakage and the fragments re-join with the wrong partners. At meiosis in an individual heterozygous for a translocation, gamete nuclei with several different combinations of chromosomes are produced. Some of these are diploid for one part and lack completely another part of the normal chromosome set; when such unbalanced gametes fertilise normal gametes inviable embryos are produced. It has been found in a number of organisms that about half the gametes of translocation heterozygotes are of the unbalanced type and such heterozygotes are described as semi-sterile. If an individual inherits the same translocation from both parents it is described as a translocation homozygote; this is often inviable but, if not, its fertility is usually normal.

Adult males ofG. austeniNewst. have been irradiated and each of their progeny are being screened for the occurrence of semi-sterility. Any individuals found to be semi-sterile would probably be translocation heterozygotes and their progeny will be inbred to try to produce a viable stock, homozygous for a translocation. If this can be done, large numbers of such translocation homozygotes could be reared and released into a wild population, where matings with wild types would produce heterozygotes, and hence a reduction in the fertility of the population.

Using simple assumptions, the effects of releasing translocation homozygotes were computed. Provided the numbers released were such that the translocation frequency approached the optimum value of 50 per cent., the reduction in population fertility would be prolonged for many generations after the releases had finished. It is shown that it would be more efficient to release the translocation homozygotes at successive generations rather than all at once and that the homozygotes released could with advantage be of both sexes. For this reason, and because of the prolonged effect of releases of translocations, it is concluded that the number of individuals that would have to be reared to achieve a given result by the translocation method might be considerably less than if the sterile-male method was used. However, the reduction in population fertility at each generation that can be achieved with the translocation method is limited, and the method would therefore be ineffective against populations whose size was strongly buffered by density-dependent factors.
A new species ofMycteromyiella(Diptera: Tachinidae) parasitic onOphicrania leveriGünther (Phasmida: Phasmatidae) in the Solomon Islands
Authors: Crosskey R. W.
Published: July 2009

A new species of Tachinidae,Mycteromyiella phasmatophagasp.n., from Guadalcanal in the Solomon Islands is described and figured; descriptive notes and figures are also given for the related speciesM. laetifica(Mesnil), to supplement the original description. Both species are recorded as parasites of the PhasmatidOphicrania levariGünther in the Solomon Islands.
The African and Malagasian species of Nephotettix Matsumura (Homoptera: Cicadelloidea)
Authors: Ghauri M. S. K.
Published: July 2009

The genus Nephotettix in Africa and Madagascar has been found to be represented by two species: one of them is N. modulatus Melich., the other is described as new and named N. afer sp.n. Both species are widely distributed in Africa, and a map is presented showing the countries in which each has so far been recorded.
Variation in toxicity of malathion when applied to certain body regions of Schistocerca gregaria (Forsk.)
Authors: Ahmed Hafiz , Gardiner B. G.
Published: July 2009

Further evidence is provided to show that the head of the desert locust is the most vulnerable body region to the toxic action of malathion (and malaoxon). The circulatory system is shown to play an important part in determining the toxicity of the insecticide by taking it towards or away from the sensitive areas. The rates of absorption, distribution and excretion of 3H-malathion for different applications are given.
Studies on the chemical control of wireworms (Agriotes spp.) III.—The direct and residual effects of BHC, aldrin and dieldrin
Authors: Raw F. , Lofty J. R. , Potter C.
Published: July 2009

To find out if it were possible to reduce wireworm populations by means of seed dressings which are convenient to use, and desirable in other ways, the direct and residual effects of insecticides on wireworms (Agriotes spp.) attacking spring-sown and winter-sown wheat were tested on a clay soil at Rothamsted, Hertfordshire. Treatments comprised dressing seed with dusts containing 20% (standard) and 60% (high-rate) γ-BHC and 40% (standard) dieldrin, all at 2 oz. per bushel, 60% dieldrin at 70 oz. per bushel (high-rate), or a liquid containing 30% dieldrin at 1 fl. oz. per bushel; combine-drilling 0.5% γ-BHC dust at 1 cwt. per acre with the seed; and spraying the soil surface after sowing with 1 gal. 30% aldrin in 40 gal. water per acre. The high-rate BHC and dieldrin seed dressings, the combine-drilled BHC dust and the aldrin spray significantly reduced wireworm populations when applied to spring- or winter-sown wheat, the reduction in the former case being apparent two years later in one experiment; these reductions were, in general, reflected in increased yields. The standard seed dressings tended to be less effective. Similar results were obtained in an experiment on a fen peat soil in Lincolnshire.

Tests done in one experiment on plots sown with dieldrin-dressed seed showed no evidence that birds grub up plants or seeds that would otherwise have germinated.
Observations on the Association of Ants with Coccids of Tea
Authors: Das G. M.
Published: July 2009

Certain species of COCCIDAE that excrete honeydew and are attended by ants or enclosed in their nests are quite prevalent on tea bushes and seed trees in the plains of Assam and West Bengal but those which are not attended by ants are kept under considerable check by the activities of their natural enemies. In Darjeeling, where the natural enemies are fewer, a number of species occur abundantly and are often responsible for serious damage to tea.

From the studies of the relative population of the ant, Crematogaster dohrni Mayr and the Coccid, Saissetia formicarii (Green), occurring on tea bushes it is doubtful if more than a small portion of the food requirement of the vast ant population in the nests which contain sexual forms could be met from the honeydew excreted by the small number of Coccids enclosed therein. The major part of food must, therefore, come from other sources. Insects attacking or visiting the tea bushes and tea seed trees or even those found on the ground appear to constitute the major part of the food of the ants, C. dohrni and Oecophylla smaragdina (F.).

Several factors are responsible for the decrease in the population or disappearance of the Coccids in the absence of attendant ants. In the plains, Eriochiton theae Green, Coccus hesperidum L. and S. formicarii entirely disappear in the absence of attendant ants either due to the activities of their natural enemies or by contamination with honeydew accumulation or both. Parasitism may be slightly higher in ant-free colonies, but no estimation was possible since, in the absence of ants, the Coccids are quickly destroyed by predators.

The ants do not protect the Coccids from Hymenopterous parasites; but their active movements hinder the parasites in their efforts to oviposit, and this leads to a reduction in the rate of parasitisation.

In the presence of the ants, O. smaragdina and Crematogaster dohrni, predators are rare; they are destroyed as are any other insects or any foreign bodies that happen to be near their nests, whether they constitute food or not. The larvae of predators which have a protective covering or which resemble Coccids, if they happen to have gained access to the Coccid colonies, are not attacked by the ants, because they are not recognised as different from the Coceids.

O. smaragdina does not normally transport Coccids, though young nymphs of E. theae and Coccus hesperidum may be aided in their dispersal, but Crematogaster dohrni and Crematogaster sp. are primarily responsible for the dispersal of S. formicarii and this takes place when an occasion arises to remove the Coccid to more favourable sites.

O. smaragdina does not destroy the nymphs and sedentary form of Coccus hesperidum for food, but sedentary forms which are unable to establish themselves on transfer from withered leaves to a new nest are eaten.

With the control of the attendant ants, the honeydew-producing Coccids disappear or at least they become rare. Conversely, where the Coccids are controlled, the ants automatically disappear.
Biology and Ecology of the Garden Chafer,Phyllopertha horticola(L.). vi.—The Flight Season: Reproductive State of Females
Authors: Milne A.
Published: July 2009

This part of the study of the garden chafer,Phyllopertha horticola(L) in the English Lake District deals with the reproductive state of the females during the flight season. Total egg-production depends entirely on stores (fat-body) accumulated in the final larval instar. On the average, the fat-body enables about 16 or 17 mature eggs to be manufactured per female, the usual range being 9–32. Rate of reproductive development is the same in the largest and smallest female adults. The outstanding mass features of the flight season are the two roughly equal and half-overlapping Phases: Phase 1, swarming over the grass sward, followed by Phase 2, swarming on the surrounding bracken, hedges and trees. Mass aspects of the female reproductive state throughout the two Phases are as follows.

At primary emergence on the grass sward, females always contain some fat-body together with some fully developed and/or immature eggs. On the average they have about one-third of their full complement of eggs matured, the range being from none (with about 50% of the original fat-body still remaining) up to four-fifths (with about 10% of the fat-body). Since primary emergences in a homogeneous population extend over about a fortnight, females taken from the grass sward throughout Phase 1 are in various reproductive states. Thus after the first few days of the Phase and until the last individual makes its primary emergence, sample females may have half their fat-body and no eggs yet fully matured or no fat-body and all their eggs actually laid, or any intergrade between these extreme states. Towards the end of Phase 1 (which finishes about a week after the last primary emergence), females have no fat-body remaining and have already laid most or all of their eggs; and a small proportion of them now has food in the gut.

In Phase 2, about 99 per cent, of females on bracken, hedges and trees contain no fat-body and therefore cannot manufacture any more eggs. On the average they have two mature or very nearly mature eggs left (range 0–26). This egg content is much the same as at death. The remaining 1 per cent, of females are aberrants with some fat-body still unconsumed. ‘ Bee-liners ’, the females which shoot out bullet-like from the bracken, hedges or trees to alight comparatively far afield, either have some fat-body remaining, or, if not, considerable numbers of eggs (mean about 9 as compared with the general mean of 2). Thus bee-liners are the phase-2 individuals with most eggs still unlaid. Obviously they are a minority.

Deductions as to individual behaviour are made from the mass aspects of the reproductive state and are to be examined in the next paper of this series.

Since females of the garden chafer have already laid all or most of their eggs before appearing on hedges and trees, gardeners will not control this pest by killing all they find on their hedges and trees.
Interaction of insecticide resistance genes in field populations of Culex pipiens (Diptera: Culicidae) from italy in response to changing insecticide selection pressure
Authors: Bonning B. C. , Hemingway J. , Romi R. , Majori G.
Published: July 2009

Culex pipiens Linnaeus larvae were collected from various locations in Italy and colonized as separate strains. These were analysed for elevated nonspecific esterase activity and frequency of altered acetylcholinesterase (AChE) mechanisms of insecticide resistance, and bioassayed, to define the cross-resistance spectra conferred by these to organophosphorus and carbamate insecticides. These mechanisms were further characterized by polyacrylamide gel electrophoresis. Elevated esterase A1 (formerly known as Est 3A) which predominated in C. pipiens from Italy in 1985 had been replaced by two esterases, A2 and B2. Altered acetylcholinesterase was still present at high frequencies. Altered and normal acetylcholinesterase were distinguished by differential mobility on polyacrylamide gel electrophoresis. Levels of insecticide resistance were higher in the Lucca region of Italy than in other areas sampled, in response to intensive use of temephos and to a lesser extent chlor-pyrifos, employed to reduce mosquito biting nuisance to tourists in this area.
Simulation of instability in genetic sexing strains: effects of male recombination in association with other biological parameters
Authors: Busch-Petersen E. , Baumgartner H.
Published: July 2009

Genetic systems have been developed in several insect species for separating males and females prior to releasing sterilized males in pest control programmes using the sterile insect technique. The systems generally depend on translocating a readily selectable gene onto the Y chromosome. A potential source of instability in such a system is genetic recombination in the male. Although such recombination was originally thought to be absent in most cyclorrhaphous Diptera, low levels have recently been found. We have developed a computer model which simulates the progression of instability in the presence of male recombination, which can be used to assess the influence of rate of recombination in combination with a range of associated genetic and biological parameters. Male recombination alone or fitness of the Y-linked translocation were found to contribute relatively little to the rate of progression of instability. By contrast reduced fitness or mating competitiveness associated with the selectable gene had a strong effect. The sex ratio and the ratio of carriers to non-carriers of the selectable gene showed patterns characteristic of the parameters modelled. The relevance of such data to the development of suitable strains for genetic sex-separation and the replacement of strains under mass rearing conditions are discussed.
Uscana lariophaga (Hymenoptera: Trichogrammatidae), an egg parasitoid of bruchid beetle (Coleoptera: Bruchidae) storage pests in West Africa: host-age and host-species selection
Authors: van Huis A. , Wijkamp M. G. , Lammers P. M. , Klein Goldewijk C. G. M. , van Seeters J. H. , Kaashoek N. K.
Published: July 2009

Uscana lariophaga Steffan is an egg parasitoid of bruchid species in West Africa. The hosts are Callosobrucbus maculatus (Fabricius) and Bruchidius atrolineatus Pic, insect pests of stored cowpea. Experiments were carried out to study the selection between hosts of different ages and of different species in choice and no-choice situations. Results were obtained through parasitization studies and by direct behavioural observations. A description of the parasitization behaviour of Uscana lariophaga is given. At 30°C, C. maculatus eggs of 0–2 day old are readily accepted for parasitization, but in a choice situation the 0 day old eggs are preferred. Of the older eggs only those of 3 days old are parasitized but significantly less than those of 0–2 days. At 30°C, B. atrolineatus eggs older than 24 hours are significantly less parasitized than younger eggs also in the no-choice situation. When eggs are older than one day, the time needed for penetrating the egg increases with host age. Both bruchid species are suitable hosts for U. lariophaga. In a choice situation B. atrolineatus is the preferred host and especially so when U. lariophaga has been reared on this species. However, in a no-choice situation the highest rate of successful parasitization is obtained on hosts of the species from which they have been reared. The higher parasitization rate of C. maculatus in the field in Niger can be explained by the difference in the susceptible period between the two host species.
Behavioural variation of Anopheles arabiensis (Diptera: Culicidae) populations in Natal, South Africa
Authors: Sharp Brian L. , le Sueur David
Published: July 2009

Anopheles arabiensis Patton populations occur in those areas of Natal in which intra-domiciliary DDT is used for mosquito vector control and in the unsprayed areas. Indoor resting collections from the unsprayed area showed a human blood index >90%, in contrast to the indoor collections from the sprayed area where only 31% had fed on man. In exit trap collections from the sprayed area, 66% had fed on man. These trends of a high human blood index in the exit trap collections and a low human blood index in the indoor resting catches were unaffected, despite the close proximity of a cattle kraal to the majority of homesteads.
A Morphological Comparison of the Adults ofOryzaephilus surinamensis(L.) andO. mercator(Fauv.) (Col., Cucujidae).
Authors: Slow Joan M.
Published: July 2009

The object of the work described in this paper was to compare adults ofOryzaephilus surinamensis(L.) and O.mercator(Fauv.) by morphological and biometric methods with a view to determining the status of the latter as either a variety ofO. surinamensisor as a separate species.

There are some marked and constant differences between the two insects in the structure of the male genitalia. These are listed.

The analysis of the biometric results shows a clear-cut difference between the two insects in the ratio of eye length to temple length. All the other ratios considered overlap, although the means may be widely different. Some of these ratios are illustrated by histograms.

A cross-breeding experiment gave no offspring from the mixed pairs.

It is concluded thatO. mercatoris a good species which can be recognised morphologically.
The Mating Behaviour of Females ofGlossina palpalis(R.-D.) in Captivity
Authors: Jordan A. M.
Published: July 2009

Experiments were carried out in the laboratory with individually marked females ofGlossina palpalis(R.-D.); various aspects of their mating behaviour, when placed with virgin 7-day-old males, were studied.

Using virgins, females 1–3 days old mated for an average period of about two hours, females 4–9 days old for about 75 minutes, and 10-day-old females for somewhat less than one hour.

Using virgins, mating was found to be relatively infrequent in 1-day-old females, maximal in females 2 and 3 days old and thereafter decreased as the age of the females increased.

Females up to 10 days of age were found to be willing to mate on a number of occasions; re-mating was more frequent among the younger flies. The number of older females ofG. palpaliswhich are prepared to re-mate is very small.

Previously mated females ofG. palpaliswere shown to be less willing to mate than virgin females of the same age. It seems that this is due to a decrease in desire for mating by the females rather than a loss of attractiveness to males.

The implication of these laboratory findings, in relation to fly behaviour in the field, is discussed. It is suggested that a considerable proportion of young females ofG. palpalisis prepared to re-mate in nature, on a number of occasions, but that the desire for mating is extinguished much sooner in life in mated females than it is in virgin females.
Biological Notes on the Tobacco Cricket, Brachytrupes membranaceus (Dru.) (Orthopt., Gryllidae), in Southern Rhodesia
Authors: Büttiker W. W. , Bünzli G. H.
Published: July 2009

The Tobacco Cricket, Brachytrupes membranaceus (Dru.), is a pest of young plants of tobacco, maize and other field and garden crops in Southern Rhodesia. During the period of investigations, 1949–52, it was found to be widely distributed in the Territory, the heaviest attacks occurring in areas of light sandy soil of granitic origin. All stages are nocturnal and each individual excavates and inhabits a permanent burrow in the soil, that of an adult averaging 50 to 80 cm. in depth. The burrow has an enlarged chamber in which the cricket lives and stores food.

There is one generation a year. Oviposition takes place in February and March, the average number of eggs per female, as shown by dissection, was 216. Incubation takes about 30 days and development of the young nymphs is at first rapid. From June to October, the period of dry and often scarce food, development is retarded but increases rapidly during the third and fourth (the last) nymphal stages in November. From November to May, when young and succulent food abounds, development is rapid. The adults start appearing early in December.

The eggs are laid in the burrows and the young nymphs on hatching crawl away from the parent burrow, in all directions, in search of suitable places in which to start digging. The mandibles are used to excavate the soil which is thrown outwards by the forelegs, and the mounds formed by the time the adult stage is reached may attain a height of as much as 30 cm. When an adult is evicted from its burrow, as soon as it finds a suitable place to dig, it will disappear within the space of a minute.

The burrows may be found in virgin land or in cultivated land, or along the borders of cultivated fields. The food consists of succulent or dry vegetable matter, according to the time of year, and is carried to and stored in chambers in the burrows. In the virgin veld it consists mainly of lush grasses, seedlings and root suckers of trees such as Brachystegia and Isoberlinia in the rainy season and of dried material of a similar nature during tha dry months. In cultivated land, tobacco, maize, field beans, garden vegetables, seedlings and young transplants are cut and stored.

Although the food is compacted in chambers in the burrows it has not been found in a mouldy or fermenting condition. It is thought that it is conditioned before storage, the more succulent material being allowed to wilt before being taken into the burrow and the dry material when softened by dew.
Field Observations on Adults of the Wheat Bulb Fly (Leptohylemyia coarctata (Fall.)).
Authors: Long D. B.
Published: July 2009

A study of adult populations of Wheat Bulb Ply, Leptohylemyia coarctata (Fall.), has been carried out in the field by routine sweeping at Rothamsted. It has been observed that the males emerge slightly before the females and that the emergence period may cover at least three weeks in late June and early July. Although the number of males may exceed the number of females at first, the females predominate later in the season due to the shorter life span of the males.

The numbers of flies on the wheat have been found to fluctuate appreciably throughout the day. During the first week of the emergence period the number of flies taken increased steadily throughout the day. After the date of population peak, however, the maximum numbers occurred in the crop in the very early morning and the late evening, which suggested a daily flight dispersion followed by a general or localised return of the flies to the crop. Further study of the data showed that the daily temperature rhythm was only partly responsible for this daily flight dispersion, and that there appeared to be an active return flight to the crop in the evening. Generally the males were more active than the females and did not settle so deeply in the crop.

The temperature threshold for flight was observed to be 12 to 13°C. Winds up to 8 m.p.h. did not appear to affect flight activity, but higher winds, e.g., 15 m.p.h., markedly reduced flight, the flies remaining deep in the crop near ground level. Gale-force winds, however, were observed to produce a permanent depletion in the number of flies infesting Broadbalk field, indicating that the population was probably localised.

Although portions of the populations dispersed fairly rapidly from the emergence sites, recaptures of radioactive flies labelled with 32P indicated that the extent of the dispersions was not very great. The females dispersed more than the males, and were influenced to some extent by the occurrence of wheat in flower. Frequently the flies were found to have congregated on the lee edge of the crop, but other preferred regions have been observed which could not be attributed to the influence of the wind.
Some Mosquitos of the Blue Nile Valley in the Republic of the Sudan
Authors: Lewis D. J.
Published: July 2009

The rainfall of the Blue Nile valley diminishes towards the north, and the number of mosquitos tends to do the same, but the natural state of affairs has been somewhat altered by irrigation works in the shape of the Sennar reservoir and the watering of cotton, sorghum and sunt trees (Acacia arabica, Willdenow), and will be further altered when the proposed dam at Roseires is constructed.

The latter dam will form a large reservoir in the Kiri-Roseires area where conditions are likely to differ from those of the Sennar reservoir. Anopheles funestus Giles and many other species occurred in the stretch downstream between Roseires and Abu Hugar in which riverside basins, overgrown with sunt trees, were flooded when the river was high.

Farther downstream, between Karkoj and Sennar, breeding conditions were affected by the Sennar dam, water at full storage level reaching different heights in the basins according to their distance from Sennar. Near Sennar the dualpurpose dam had a particular effect on the aquatic vegetation and the mosquitos.

A. gambiae Giles bred among Najas pectinata (Parl.) Magnus which, however, only occupied a small area in the reservoir, A. rufipes (Gough) bred in small numbers in various places, and A. pharoensis Theo. in a large area of creeping grass growing on silt under conditions which caused it to form a raft that rose and fell with the water. Adults of A. pharoensis, which was by far the commonest Anopheline, rested near houses by day at certain times of the year. Control of the grass was difficult and liable, to favour more dangerous species of mosquitos. Differences between the Sennar and Jebel Auliya reservoirs are discussed.

In the riverain area between Abu Geili and Soba, A. gambiae bred in residual pools in the river-bed in the dry season and in flooded sunt basins in the rains. Control of larvae was very difficult in these basins and much reliance was placed on residual sprays against adults in houses.

Breeding conditions in the Gezira irrigated area are described with particular reference to the type of clay soil. There were many larvae of A. gambiae in field channels at the end of the rains when irrigation began, and in March when the summer started. The latter increase was not reflected by any increase in the number of adults, probably owing to the reduction in length of life of the latter in the very hot dry weather. A. rufipes was sometimes found in houses. Control measures are briefly described.

Some mosquitos of Khartoum and a few other areas within the Blue Nile valley are briefly considered.
The relative Susceptibility to Pyrethrum in Oil of Coleoptera and Lepidoptera infesting Stored Products.
Authors: Lloyd C. J. , Hewlett P. S.
Published: July 2009

With a view to providing information useful in practical control, the relative susceptibility to pyrethrins, and to pyrethrins plus piperonyl butoxide, of a series of stored product insects has been determined. Adult moths and beetles of 31 species were investigated, together with the larvae of 16 of these, and that of one other.

The insects were treated with 1.3 per cent, pyrethrins, and 0.3 per cent, pyrethrins plus 3.0 per cent, piperonyl butoxide, in a heavy, highly refined mineral oil (Shell Risella 17). Both formulations were applied in two ways: insects were exposed on sprayed filter papers or were directly sprayed. Insects were also treated with the oil alone by both techniques. While confined on films, and after being sprayed, the insects were kept at 25°C. and 70 per cent. R.H.

Large differences in susceptibility were encountered. The adult moths and Bruchids were susceptible, the adult Ptinids rather resistant, but otherwise susceptibility showed little correlation with systematic classification. The larva of a given species was usually more resistant than the adult. Among the adults of the different species, susceptibility to pyrethrum appeared to be correlated with high activity of the normal insect.

On the whole, 1.3 per cent, pyrethrins and 0.3 per cent, pyrethrins plus 3.0 per cent, piperonyl butoxide were of about equal toxicity.
The Availability of Glossina morsitans Westw. in Ankole, Uganda
Authors: Harley J. M. B.
Published: July 2009

Two areas in Ankole, Uganda, were studied with a view to obtaining estimates of the standard availability of Glossina morsitans Westw. These estimates gave maximum and minimum fiducial limits of 2·0 and 0·19 per cent. These are considerably lower than the estimates, obtained by Jackson in Tanganyika, of approximately 10 per cent. This difference is of practical importance in that a single fly caught in Ankole indicates a much larger population, and this is the probable explanation of the trypanosomiasis problem round the edges of the flybelt, where routine catches showed flies to be scarce.
Laboratory Colonisation of the Mosquito, Eretmapodites chrysogaster Grah
Authors: Gillett J. D.
Published: July 2009

A colony of Eretmapodites chrysogaster Grah., sensu stricto, was maintained successfully for over a year without any reinforcement.

Identity of the mosquitos was established by starting the colony from a single batch of eggs laid by a single wild-caught female mosquito, and subsequent examination of the genitalia of the male progeny.

Mating occurred regularly after the first blood-meal of the female. In fact the females would not accept the males until they had started, or had finished, their first blood-meal.

Eggs were laid on the sterilised, water-filled bracts of banana flowers. Moist paper, moist cotton-wool or free water above paper or cotton-wool proved unsatisfactory as egg-laying media.

Larvae fed largely on the substance of the banana bracts on which the eggs had been laid. The banana bract also provided cover and so reduced the incidence of cannibalism among larvae.
Studies on Aqueous Suspensions of Insecticides. Part VI. Further Notes on the Sorption of Insecticides by Soils
Authors: Barlow F. , Hadaway A. B.
Published: July 2009

Quantitative measurements of the sorption of γ BHC and dieldrin in Uganda mud blocks have been made. Gamma BHC diffused more rapidly than dieldrin, and within a few weeks had achieved an almost uniform concentration throughout the sprayed blocks. Only when the uniform concentration had been reached did loss by evaporation from the blocks become marked. Increased dosages of γ BHC gave increases in biological activity which were roughly proportional to the dosages used. Sorption on to mud greatly prolonged the residual life of γ BHC as compared with similar deposits on glass.

Dieldrin behaved in the same way as γ BHC although because of its slower rate of diffusion the distribution in the blocks had only reached in 48 weeks the stage reached by γ BHC in eight weeks. There was no appreciable loss of dieldrin during this time, whereas about 90 per cent. of the deposit on glass plates had been lost.

Gamma BHC, dieldrin and DDT were recovered from the adsorbed state on mud and identified. Any decomposition is therefore likely to be negligible. Dieldrin was also recovered from two soils which had much higher “surface acidities” than the standard.

Active mud can only sorb the portion of insecticide vapour from an evaporating deposit which happens to diffuse in its direction. This is to be expected, but the system has some peculiarities because the evaporation of γ BHC from filter papers over mud blocks is much faster than in the absence of the mud.

Measurements of the distribution of DDT and dieldrin in soils less active than the standard Uganda one showed that both the initial adsorption and subsequent diffusion were very much slower.

The activity of Uganda soil was not reduced by removal of material soluble in organic solvents, and was only partly reduced by complete extraction of iron compounds.

Variation in temperature over the range 20 to 30°C. had only small effects on the diffusion of DDT and dieldrin within mud blocks.

Repeated applications of DDT and dieldrin to the same blocks did not result in any observable slowing in the rate of disappearance. The concentration of insecticide in the successive layers of mud, did, of course, increase with successive sprayings.
The Groundnut Bruchid, Caryedon gonagra (F.)
Authors: Davey Pauline M.
Published: July 2009

Information on the world distribution and host-plants of the Groundnut Bruchid, Caryedon gonagra (F.), has been summarised from the literature. As a result of misidentification of the species that attacks groundnuts and of differing views about its generic assignment, this information has been given under several different names. The records brought together here are believed all to represent C. gonagra, and in a number of cases this has been confirmed by examination of the material concerned by Mr. B. J. Southgate.

C. gonagra is widely distributed in the Old World tropics and sub-tropics, but it is absent from Australasia, and it has only a restricted distribution in the New World tropics. Almost all its host-plants belong to the Leguminosae, the principal one being the tamarind, Tamarindus indica, in the pod of which the beetle has been found to develop more quickly than in the groundnut.

Data on the life-history and habits, and on the duration of pre-adult development and adult life, are summarised from the literature.

Experiments are described to determine the optimum conditions for multiplication of C. gonagra, using groundnuts as food. When adult females were allowed to lay large numbers of eggs on shelled and unshelled nuts, only a small proportion of the resulting larvae completed their development, the number of adults that emerged averaging about 2·4 per kernel in shelled nuts and 3·2 in unshelled ones. The developmental period at 70 per cent. relative humidity was 42 days at 30°C. and 91–98 at 25°C.; the former figure is less than any recorded in the literature at higher or lower temperatures, and all subsequent experiments were therefore made at 30°C. and 70 per cent. relative humidity.

Adults confined for three weeks, starting when four days old, at the rate of 25 pairs on 160 g. of a mixture of broken and intact kernels gave rise to some 314 F1 adults; this total was virtually unchanged when 50 pairs were used, but lower densities, though giving rise to greater yields per parent adult, gave much lower yields per weight of food. Emergence of adults began six weeks after the date of egg-laying and reached its peak from one to three weeks later.

The yield from ten females on intact kernels was greater than from the same number on the mixture, but differed little whether the parent adults were left on for one week or three weeks, indicating that the majority of the eggs are laid in the first 11 days of adult life. The yield from unshelled nuts was nearly twice as great as that from shelled nuts, and also significantly larger than that from shelled nuts with ground shell added. Possible causes of this are discussed.

The sexes can be distinguished in the adult stage by differences in the terminal abdominal segments.
Studies of British Anthomyiid Flies. IX.—Biology of the Onion Fly, Delia antiqua (Mg.)
Authors: Miles Mary
Published: July 2009

The Onion Fly (Delia antiqua (Mg.)) was bred at Wye, Kent, under insectary and laboratory conditions to obtain further information on its biology and reactions to various temperatures.

A comparison of the times of emergence of overwintering generations of Onion Fly and Cabbage Root Fly (Erioischia brassicae (Bch.)) in an insectary showed that the former emerged consistently about a month later than the latter. This supported the observations of previous workers that the Onion Fly was not active in the field until late May.

A diet containing protein was necessary for oviposition. The length of the preoviposition period was affected by temperature. Flies maintained at 25°C. laid eggs in 10–24 days, with an average of 15 days. At spring and summer laboratory temperatures (12–29°C.) the preoviposition period was 10–25 days, with an average of 15 days; and in autumn and winter (11–20°) it was 11–46 days with an average of 21 days. Flies maintained at 6–8° did not lay eggs.

Flies in captivity laid up to 123 eggs at the rate of 1–45 per day. Intervals between batches of eggs varied from 1–9 days, and the oviposition period was 7–25 days. Flies lived up to 6 days after oviposition.

The incubation period depended on the temperature. Eggs at 25°C. hatched in 2 days; at 20° in 3–4 days; at 15° in 4–6 days; and at 7–10° in 9–14 days.

The temperature also affected the duration of larval and pupal stages. At 25°C. the successive larval stadia required 2, 2 and 5–9 days, respectively. Lowering the temperature increased the time for development until at 9–11° the three larval stadia required 8–12, 8–18 and 24–37 days, respectively. At 25° the pupal stage lasted 12–17 days; at 20° it was 16–25 days, and at 15° it was from 35 days to over a year. At 25–30° the development from egg to adult was completed in 25 days; at 25° it required 28 days; at 22–27°, 30 days; at 19–24°, 33 days.

At 25°C. the Onion Fly bred continuously without diapause. When larvae were reared at temperatures below about 18° pupal development was often retarded. Pupae formed from larvae reared at 12–18° and maintained at approximately that temperature, required 94–442 days to complete their development. By raising the temperature of pupae formed from larvae reared below 18°, it was demonstrated that a true diapause had been induced. Of 54 pupae raised to 25°, 8 (15%) completed their development in the expected time (13–16 days) and 46 (85%) required 94–208 days. Of 322 pupae formed from larvae reared in an insectary in May and June at 10–18° and exposed to July temperatures of 13–20°, 37 (11%) emerged in 25–35 days and 252 (78%) required 234–294 days. Similarly, of 283 pupae formed from larvae reared at 12–21° and exposed to a temperature of 15–23°, 30 (11%) completed their development in 21–31 days while 253 (89%) required 118–341 days. Exposure to low temperatures was not necessary to terminate pupal diapause.
Males of Culicoides anophelis Edw
Authors: Sen P. , Gupta S. K. Das
Published: July 2009

Culicoides anophelis Edw. is of wide occurrence in India, Ceylon, Burma, Malaya, Thailand, Indo-China, Sumatra, Tonkin, and as far as New Britain (Laird, 1946). From India the species has almost invariably been obtained in the act of engorging on female mosquitos, mostly Anophelines (A. annularis Wulp, A. hyrcanus nigerrimus Giles, A. barbirostris Wulp, A. subpictus Grassi, A. vagus Dön., A. aconitus Dön. and A. maculatus Theo.). But the species may also attack members of the Culicini, as observed by Fearnside (1900) in the case of certain unidentified examples of the genus Culex. We have also observed the species attacking Culex pipiens fatigans Wied. and Mansonia (Mansonioides) annulifera (Theo.), which suggests that the occurrance of the species is not so uncommon on members of the Culicini as was thought previously. The reason for the missing of the association of the species with the latter group of mosquitos by most workers seems to lie in the fact that the Culicini were not examined previously in large numbers (Edwards, 1922).
An Account of the Weevil Larvae bred from the Banana Plant in Uganda, with A Description of the Larva of Temnoschoita nigroplagiata (Qued.) (Col., Curc.)
Authors: Whalley Paul E. S.
Published: July 2009

The two weevils associated with the living stems of the banana plant in Uganda are Cosmopolites sordidus (Germ.) and Temnoschoita nigroplagiata (Qued.); the damage caused by the former has been known for many years but the latter, which usually breeds in rotting stems, has only recently been shown to attack living ones. T. nigroplagiata occurs in every banana-growing area in the territory and is particularly abundant in some parts of western Uganda where C. sordidus, which is otherwise widespread, is rare or absent. Other species of Temnoschoita associated with the banana plant that occur in Uganda but that are rare, are T. basipennis Duv., bred from larvae in rotting pseudostems, and T. erudita, Duv., known only from the adult.

The full-grown larva of T. nigroplagiata is described in detail and characters are given for separating the larva and pupa of this species from those of C. sordidus.
Density Distributions of Hoppers of the Red Locust,Nomadacris septemfasciata(Serv.) (Orth., Acrid.), in Relation to Control by Insecticides
Authors: Scheepers C. C. , Eyssell B. J. , Gunn D. L.
Published: July 2009

In continuation of a study of the process of swarm formation in the Red Locust,Nomadacris septemfasciata(Serv.), to enable rational plans for control measures to be made, the population distribution of about 44½ million hoppers of the Red Locust was investigated in an observation area of 1,052 acres in the Iku outbreak area of the Rukwa Valley, Tanganyika Territory, from 18th January to 24th February 1957. to see if the hoppers showed a tendency to concentrate, which would have the effect of producing, immediately after the last moult, adult swarms from hoppers that were originally more scattered. From 25th January onwards, the estimated population remained constant in numbers. Densities over 50 per sq. yd. were unusual and, taking any continuous infestation over one per sq. yd. as a band, the mean density of hoppers in bands was 15 per sq. yd. There was a tendency for such bands to become larger by fusion and for the area quite free from locusts to increase slightly but the number of dispersed locusts increased. There would therefore have been no advantage in withholding insecticide control in the hope of attacking denser and more economical targets. Nevertheless, such populations have to be controlled.

In the Red Locust, under the conditions described, it seems probable that the behaviour of the young adults is most important in the formation of dense swarms, while in certain other species but not in the Red Locust, concentrated egg-laying and the behaviour of the hoppers are also important.

Investigations are required on more economical enumeration of patchy gregarious distributions.