bluuebunny/crossref_metadata_2025 huggingface dataset:
Observations on the Mosquito, Aëdes (Stegomyia) aegypti (L.), in East Africa. I.—The Biting Cycle in an Outdoor Population at Entebbe, Uganda
Authors: McClelland G. A. H.
Published: July 2009

In an outdoor population of Aëdes (Stegomyia) aegypti (L.), mainly consisting of subsp. formosus (Wlk.), in Uganda, a series of ten 24-hour catches has shown a sharply-defined biting cycle which corresponds closely to an observed diurnal cycle of flight activity. A main peak of activity occurs one or two hours before sunset, and a lesser peak two or three hours after sunrise.

Comparison with recent work in Kenya suggests that, in comparing the behaviour of populations out of doors with those indoors, a distinction must be made between ssp. formosus and the other two forms of A. aegypti, in which no similar cycle has yet been demonstrated.

Ssp. formosus, which is presumed to be the wildest form of A. aegypti, is shown to have a cyclical behaviour very similar to a related forest species. A. africanus (Theo.).
The Biology of Nausibius clavicornis (KUG.) (Col., Cucujidae)
Authors: Breese M. H. , Wise Thelma E.
Published: July 2009

Nausibius clavicornis (Kug.) is a cosmopolitan Cucujid that has frequently been recorded from sugar. It is commonly found in this commodity in Trinidad, where it has not been collected from any other.

The adult and other stages are described, and an account is given of the life-history on Haydak's formula at 85°F. and 75 per cent. R.H. Development has also been studied on two types of unrefined sugar.

Copulation can take place within one day of the emergence of either sex and the female may begin laying within four days of copulation. The average number of eggs laid was 275 and the overall viability was 85 per cent. The average incubation period was just under five days.

The larvae of both sexes may undergo only five moults in development, but the more usual number for females is six. When larvae are disturbed during development, both sexes tend to have six larval instars. Severe disturbance may induce a seventh moult. The mean development period from oviposition to the emergence of the adult was 30 days when there were five larval instars; when there were six, development took about two days longer. Larval mortality on Haydak's formula was low.

Ovipositing females lived for up to 163 days under controlled conditions, but males tended to outlive females by about 50 days.

On unrefined sugars (e.g., raw or yellow-crystal sugar), adults lived for almost as long (73:99) as on Haydak's formula, but oviposition was greatly reduced and the viability of the eggs was much lower. Larval mortality was high, especially in the first instar, and the total development period was greatly increased.

It is unlikely that N. clavicornis could multiply rapidly in raw or unrefined sugar, and any deterioration in stored sugar directly attributable to it would probably be small in comparison with that caused by other factors.
An Ultra-low-volume Spraying Technique for the Control of the Desert Locust, Schistocerca gregaria (Forsk.)
Authors: Sayer H. J.
Published: July 2009

Studies of the physical and biological factors involved in the application of concentrated involatile oil solutions of a persistent insecticide (dieldrin) in the form of a fine spray to the low-density vegetation typical of the breeding areas of the desert locust, Schistocerca gregaria (Forsk.), have led to a technique of control of the locust hoppers with a dosage as low as 0·30 litres per hectare (approximately ⅕ pint per acre). A simple device for producing such a spray has been designed to work off the exhaust system of a light four-wheel-drive motor vehicle. Successful control of hoppers has been obtained under a wide variety of weather conditions in both desert and bush typical of locust breeding areas, using ‘target’ and ‘barrier’ spraying techniques. Both techniques involve the spraying of vegetation which it is judged will be subsequently eaten by the hoppers, but target spraying is done on or near a known hopper band, whereas barrier spraying is done, not necessarily in sight of hoppers, across an area known to be highly infested. Examples of such successful attacks are described from the Eritrean coast, Tripolitania and Ethiopia. The methods can replace the well established technique of poison-baiting individual bands, and have the additional advantage of producing highly persistent toxic swathes which can be exploited by the barrier technique for treating locust egg-fields and for creating widely spaced barriers for the control of extensive infestations.
Studies on the Dermestid Beetle, Trogoderma granarium Everts. II.—The Occurrence of Diapause Larvae at a Constant Temperature, and their Behaviour
Authors: Burges H. D.
Published: July 2009

The development of the khapra beetle, Trogoderma granarium Everts, and the cycle of movement of insects between the food and hiding places has been studied at 30°C. The results have been correlated with observations at maltings, its chief habitat in Britain.

In populations at 30°C., many larvae delay pupation and enter diapause, the remainder spending most of their time in the food and completing development quickly. The diapause larvae leave the food in the fourth and in later instars in search of hiding places. Disturbing the food stimulates the larvae to leave it a little earlier. Larvae resting in diapause moult occasionally, and at long and irregular intervals they emerge, presumably to replenish their food reserves by feeding, after which some pupate and the rest hide again.

The hidden diapause larvae can persist for a very long time; in cultures, 16 per cent, remained after four years. Apparently, as the food stored in the fat-body is depleted, they become readier to emerge from the crevices to feed. Replacing stale food by new food causes some larvae to emerge and the effect of disturbing the larvae is variable. After feeding, some of these larvae complete development and the resulting adults breed, presumably producing both quick developing and diapause larvae among their offspring.

When denied a hiding place, the diapause larvae remain inactive in the food without increasing their rate of pupation. However, they feed more, producing heavier beetles, an effect also obtained by regularly providing fresh food.

It is concluded that when a malt store is loaded, some diapause larvae remain in the fabric of the store and others emerge and feed; after feeding, some larvae re-enter crevices and others complete development and breed; the offspring contain some diapause larvae, which accumulate in the crevices and on the walls just below the malt surface; after the malt is unloaded, diapause larvae may persist in empty stores for a number of years, because they can restore their food reserves by occasionally eating grain residues.
Observations on the Mosquito, Aëdes (Stegomyia) aegypti (L.), in East Africa. II.—The Biting Cycle in a Domestic Population on the Kenya Coast
Authors: McClelland G. A. H.
Published: July 2009

Since the sharply defined biting cycle shown by outdoor populations, in Uganda, of Aëdes aegypti (L.), which closely resembles oviposition and general activity rhythms, could not be reconciled with the ill-defined patterns found in domestic populations, on the Kenya coast, in the absence of knowledge of the composition of the population involved there, 24-hour baited catches were made at Ganda on the Kenya coast, and the abdominal colour pattern of each individual was noted. In the series there was gradation from the darkest to the palest.

Of 427 females taken biting, 82·1 per cent, were of var. queenslandensis (Theo.) in the generally accepted sense, 14·5 per cent, of the type form and 0·9 per cent, of subsp. formosus (Wlk.). The material of var. queenslandensis was further divided into two groups in which the lateral spots on the abdominal tergites were of silver and matt white scales, respectively.

Very similar biting cycles, with the main peak in the hour before sunset, occurred both inside a hut and within an adjacent compound, although catches were not concurrent and were made under different seasonal conditions.

The distribution of the various colour forms in the total catch was independent of the hour of capture.

There is a resemblance between these cycles and those reported in comparable situations in Nigeria, where, with the exception of the paler forms, the population of A. aegypti is similar to that at Ganda. It is concluded that the main biting peak is shortly before sunset. Subsidiary peaks, when present, occur with increasing intensity as the day progresses.

The relationship of biting activity to other aspects of general activity is discussed, and it is concluded that several aspects require further investigation.

The following hypothesis is offered to account for the various patterns of biting cycle observed in different situations. It is suggested that A. aegypti possesses an endogenous multi-peaked diel rhythm of activity. Activity impulses occur in a cycle of waves of increasing intensity from dawn onwards, reaching a maximum at the end of the daylight period, and a biting peak will result when such an impulse coincides with environmental conditions within the range between upper and lower thresholds of activity.
Insect Infestation associated with French shelled Walnuts with particular Reference to the Occurrence of Aphomia gularis (Zell.) (Lep., Galleriidae)
Authors: Smith K. G.
Published: July 2009

Walnuts grown and shelled in the Dordogne and adjacent regions of France are exported to Britain and other countries. The inspection of cargoes arriving at Liverpool between July 1955 and July 1958 has shown that they may frequently be infested by a number of species of insect pests. Of the 20 species recorded, six occurred regularly. These were Oryzaephilus surinamensis (L.), Aphomia gularis (Zell.), Plodia interpunctella (Hb.), Cryptophagus subfumatus Kraatz, Nemapogon granella (L.) and Enarmonia sp. During that period, changes occurred in the levels of infestation on parcels and the relative abundance of the species. In particular, there was a considerable increase in the occurrence of O. surinamensis. Though the general levels of infestation were light, parts of 58 per cent, of the cargoes had to be fumigated to prevent pests being distributed to factories, bakeries and shops in Britain and on transhipped parcels to Canada, U.S.A. and the Eepublic of Ireland. Though many of the species found are already established in those countries where conditions are suitable for their development some are still limited in their distribution. These include A. gularis, a serious pest of nuts, dried fruit and cereals. If the further spread of this and the other pests is to be prevented there is need for a more general application of control measures in the country of origin with strict control and possibly fumigation of cargoes before shipment.
Studies on the Biting Habits and Medical Importance of East African Mosquitos in the GenusAëdes. I.—SubgeneraAëdimorphus, BanksinellaandDunnius
Authors: Haddow A. J.
Published: July 2009

The biting behaviour of East African species of Aëdes in the subgeneraAëdimorphus, BanksinellaandDunnius, as shown in numerous series of 24-hr, catches made predominantly in Uganda, is discussed. It is shown that with the single exception ofA. (A.) natroniusEdw., which is arboreal, all the species encountered have been most prevalent at ground level. They bite mostly by day, butA. cumminsi(Theo.) shows a marked peak of activity from just before to just after sunset, andA. natroniusis crepuscular. When, however, samples were obtained in environments less favoured than the forest floor, and in which the mosquito concerned was less abundant, the biting cycle might be altered. Thus various species which were essentially diurnal at ground level in forest might be nocturnal in the canopy or in banana plantations.

In some cases there seemed to be a tendency towards a group pattern of behaviour. For example, in theabnormalis(Theo.) andtarsalis(Newst.) groups of Edwards it was found that at least three species showed very similar biting cycles. A fourth species,A. nigricephalus(Theo.), which occurs in Nigeria, is reported there to differ in its biting habits, and is also strikingly different in appearance and in the structure of the terminalia.

Members of all three subgenera have been involved in various isolations of virus, but it is not possible to prove that they, rather than other species ofAëdesincluded in the infected lots, were the vector mosquitos, except in the case of theA. tarsalisgroup, from which there have been two definite isolations of Rift Valley fever virus, and in that ofA. circumluteolus(Theo.), which has been shown by recent work in South and East Africa to be of major importance, well over 20 isolations of virus having been made from this species. So far as is known at present, seven separate viruses and one distinct variant have been isolated fromA. circumluteolus, and other members of the subgenusBanksinellaalso appear to be involved in transmission.
The Control of Onion Fly, Delia antiqua (MG.), with Seed Dressings
Authors: Carden P. W.
Published: July 2009

Seed treatments of calomel, DDT, dieldrin and aldrin were compared in three seasons′ field trials for use against onion fly, Delia antiqua (Mg.). Excellent control and also improved germination were obtained with 0·5 oz. actual dieldrin per lb. of seed applied with a sticker, with or without thiram. Similar results were obtained with 0·1 and 1·5 oz. actual dieldrin per Ib. of seed, but 3·2 oz. reduced germination. Aldrin at the same rates gave excellent control but reduced germination. DDT at 1·5 oz. and 3·2 oz. gave good control early in the season, but was not sufficiently persistent and seriously reduced germination. Calomel gave little control, although it improved germination.

Although kerosene used as a sticker for a dust was satisfactory, it was liable to reduce germination seriously when used alone, except at very low rates.

Seed treated with DDT, dieldrin or aldrin may be stored safely for a month or two in unsealed containers but not in sealed containers.

There was close correlation between the percentage of plants attacked and the yield per 100 plants in the original stand. For every 10 per cent. of plants killed by onion fly there was a 10 per cent. loss of the potential yield.

Even where the onion-fly attack was heavy, comparatively few plants showed symptoms of damage at any one time, which suggests that the level of attack is frequently under-estimated.
Observations on Simulium neavei Roubaud, with special reference to a focus of onchocerciasis in the Belgian Congo
Authors: Browne S. G.
Published: July 2009

Parts of a district situated in the tropical rain-forest of the Belgian Congo in which onchocerciasis was generally endemic, were investigated to identify the vector and to ascertain its phoretic host, breeding places, habits, etc.

The vector found biting human bait (usually less than 1 metre from the ground) was Simulium neavei Eoub. Dissection of adult females revealed developmental forms of Onchocerca volvulus.

Larvae and pupae were found on crabs of the genus Potamon in fast-flowing stretches of the numerous small streams flowing into the Eiver Congo.
The infested streams in the main focus of onchocerciasis were treated by DDT emulsion at a concentration of one part per 500,000 for 30 minutes, every ten days for ten applications.

The good results observed initially were partly offset by the reappearance six months later of small numbers of Simuliids apparently developing from eggs laid by females entering the disinfested area from without.
The ‘White-clubbed’ form ofSyntomosphyrum(Hym., Eulophidae) parasitic on tsetse flies
Authors: Saunders D. S.
Published: July 2009

Cross-mating experiments are reported between adults of the typical, darkclubbed form ofSyntomosphyrum glossinaeWtstn., obtained from pupae ofGlossina pallidipesAust. from Kenya and ofG. palpalis(R.-D.) andG. morsitans submorsitansNewst. from Northern Nigeria, and the ‘white-clubbed’ form ofSyntomosphyrum, originally reported by Waterston from Nyasaland, obtained from pupae ofG. morsitansWestw. from Tanganyika.

Fertilised eggs, giving rise to offspring of both sexes, were produced only by crosses between the strains of typicalS. glossinae. Crosses in either direction between the ‘white-clubbed’ form and typicalS. glossinaeresulted in all-male progeny, presumed to develop from unfertilised eggs. It is considered that this is evidence of a physiological barrier to reproduction between the two forms. The ‘white-clubbed’ form is therefore regarded as a distinct species.
On the stages in the development of Syntomosphyrum albiclavus Kerrich (Hym., Eulophidae), a parasite of tsetse flies
Authors: Saunders D. S.
Published: July 2009

The life-cycle and immature stages of the Eulophid, Syntomosphyrum albiclavus Kerrich, a pupal parasite of tsetse flies (Glossina), are described. Measurements of the widths of the cephalic skeletons of larvae of all ages fell into four well separated groups, and confirmation that these represented the existence of four larval instars was given by Dyar's law, the application of which in this instance is not invalidated by the disproportionate length of the fourth instar or the effects of overcrowding, which do not become apparent before that stage.
The Measurement of Size in tsetse flies (Glossina)
Authors: Bursell E.
Published: July 2009

A convenient and accurate measure of size is necessary for studies on the physiology of tsetse flies (Glossina). Residual dry weight (i.e., dry weight minus fat) is adequate as regards the larva, pupa and teneral fly, but cannot be used for flies that have taken their first blood-meals. A linear measurement provides an index of size that remains constant throughout the life of the fly, but the use of the length of the middle part of the fourth longitudinal vein in the wing has certain disadvantages, and a measure of surface was thought preferable. That finally adopted was a function of the dorsal thoracic surface; details of it are given and a close correlation was demonstrated between it and residual dry weight for females ofG. morsitansWestw. bred in the laboratory from puparia maintained at 28°C.

The relation between this measure and the weight of the newly emerged fly is affected by the temperature at which the pupal stage is passed; above approximately 25°C. the surface area of flies of any given residual dry weight decreases quite sharply, so that puparia of a given weight produce smaller but relatively heavier flies at 30 than at 25°C. This holds good also forG. pallidipesAust. andG. swynnertoniAust. The dependence of surface area on the temperature at which development has taken place unavoidably complicates the use of this measurement in work on transpiration; it also limits the application of the theory that stresses acting on the pregnant fly may be gauged from the size of flies two months later, and suggests that where the mean temperature of pupal sites is likely to exceed 26°C, any inference should be based on puparial rather than adult size.
Observations on the Simulium neavei complex at Amani in Tanganyika.
Authors: Lewis D. J.
Published: July 2009

The paper deals with two members of the Simulium neavi Eoub. complex found at Amani in the forest of the Usambara Mountains, Tanganyika Territory. They have already been described but are at present termed the Amani unhanded and banded forms, scientific names being witheld until the taxonomy of the whole complex is better understood.

Some methods of study are described.

Pupae of the unhanded form constituted a large proportion of the total number found on the common local crab, Potamon (Potamonautes) lirrangensis Eathbun, which amounted to roughly one pupa to seven crabs. This form predominated in the lower and more open parts of the drainage system examined. The adults were not seen to bite man. This and the banded form were found at a much lower altitude than any hitherto reported for the complex, probably owing to the particular nature of the local climate. Neither form was abundant.

The larvae and pupae of the banded form, like the unhanded one, live externally on the crabs. The variability of wing size of the banded form is described. Observations were made on the internal anatomy of the adult with special reference to the ovaries in which the follicular relics are usually very large, indicating that the female probably bites soon after laying eggs. As in S. damnosum Theo. there is an easily recognisable class of old flies with clear Malpighian tubes. Nulliparous and parous flies have rather different biting cycles. The banded form bit man readily but only about five were taken per hour in good catching places and far fewer elsewhere.

Human onchorcerciasis has been reported from Amani but is not known to do any harm there. The existence of the disease in the presence of rather small numbers of Simuliids is of interest in relation to a belief that S. neavei is a more efficient vector of onchocerciasis than is S. damnosum. Out of 359 banded females dissected 41·2 per cent, were parous and 12·8 per cent, of these were infected with nematodes, at least some of which were not Onchocerca volvulus.

Taxonomy, the ovarioles and the Simuliid-crab association are discussed. The formation of the large follicular relics of the banded form is considered in relation to the history of the follicular epithelium before and after ovulation. The crab association is regarded as commensalism-, and it is suggested that the crabs benefit the Simuliids by carrying them a short distance to a suitable current and that they thus enable them to live in fast rivers and so extend their range.
The life-history of the melon weevil, Baris granulipennis (Tourn.), in Israel
Authors: Rivnay E.
Published: July 2009

Baris granulipennis (Tourn.), originally described from Egypt, has become a serious pest of water-melons (Colocynthis citrullus) in Israel, where hitherto its presence has not been recorded, and has been found on melons and cucumbers, but not on vegetable marrow or squash. Economically serious damage results from girdling of the stem end of the fruit by the female, prior to oviposition.

The incubation period of the egg, on average, is 3·7 days at 30° and 6 days at 22°C. The larvae feed on developing seeds inside the fruit and pupate there. The total development period occupied from 25 to 42 days in the summer, when the temperature fluctuated between 24 and 29°C. The cocoon is made by glueing minute pellets together. These consist of dried pulp from the fruit mixed with a secretion which is ‘milked’ from the anus, and is believed to be produced in the Malpighian tubules. The preoviposition period is about four days, and the length of adult life is several weeks. There are three generations a year, and four if weather permits. Adults overwinter in hibernation. It is suggested that the increase of cucurbit cultivation, and the lengthening, by irrigation, of the cropping period, may have permitted an increase in the weevil population to pest proportions.
An insect-proof doorway
Authors: Hocking B.
Published: July 2009

The factors which influence the passage of flying and crawling insects through a doorway were investigated. It was considered practicable to exclude flying insects from a building or to prevent their successful escape from cages or rearing rooms by means of a downward air current if the speed of this in ft./min. multiplied by the ratio of the length through the doorway to its height is not less than 550. A combination of reflex and illuminated edges, smooth shiny walls without a pattern visible to insects, and a floor grid and underlying screening treated with a long-lasting residual insecticide, will, at all natural population densities, reduce to an insignificant level the number of insects that crawl through and survive. Artificially higher densities, as in rearing rooms, may require that the doorway be fitted with sliding doors in addition. These may be arranged to switch on the air current and lights as soon as they are opened.
The identity of Pseudodoniella laensis Miller (Hemiptera, Miridae), associated with cacao in New Guinea and Papua.
Authors: Odhiambo Thomas R.
Published: July 2009

In the course of a recent preliminary revision of the MIRIDAE of the subfamily BRYOCORINAE in the British Museum (Natural History), the results of which will be reported in a paper now in preparation, the genus Pseudodoniella China & Carvalho was examined. The investigation revealed that the two species, P. laensis and P. szentivanyi, both described by Miller in 1957, are definitely conspecific. Because of the importance of the species as a pest of cacao in New Guinea and Papua, a short note is published here in advance in order to clarify this problem and make available a name for biological work.
Killing house-flies, Musca domestica L., by means of hanging drops of insecticide.
Authors: Gostick K. G. , Hewlett P. S.
Published: July 2009

Basic laboratory investigations have been carried out on a method for giving house-flies, Musca domestica L., relatively large doses of insecticide, with a view to possible applications in controlling, or preventing the appearance of, resistant strains of flies. The principle is that a relatively large drop of mineral oil will hang on the lower end of a thin vertical or near-vertical wire (e.g., a drop of up to 3 μl. on a wire 0·3 mm. in diameter), and a fleeting contact of a fly with the drop will generally transfer to the surface of the fly a substantial volume of oil. For investigational purposes pins were inserted obliquely into rods (e.g., about 700 pins into a rod 60 cm. long), and drops of up to about 1 μl. were formed on the ends of the pins by dipping the pin-bearing rods into solutions of insecticide in oil. In a typical experiment a rod with suspended drops was hung vertically from the ceiling of a chamber into which flies were released; flies then collected doses of insecticide when attempting to alight on the rod.
A biological and ecological study of the rice Pentatomid bug, Scotinophara lurida (Burm.) in Ceylon.
Authors: Fernando H. E.
Published: July 2009

The black rice bug, Scotinophara lurida (Burm.), is widely distributed in Ceylon in areas where rice is grown under irrigation. It first became a serious pest in 1940 and, periodically since, it has assumed epidemic proportions in the Southern Province where two crops of rice are grown annually. Each crop takes from 3½ to 4 months to mature, the fields lying fallow in the intervening periods. During these periods the insects aestivate, in the adult or late nymphal stages, in cracks in the bunds in the rice-fields or on neighbouring higher ground. They remain motionless for the most part during aestivation, are gregarious and occur as much as 2 ft. below ground-level.

The adults leave the aestivation sites in April and May and settle in the first crop when it is two to three weeks old, and a subsequent aestivating population behaves similarly in November and December for. the second crop. There is at first considerable flight activity at dusk, and at night, and after feeding for about a week on the rice seedlings copulation takes place and oviposition commences about ten days later.
Discriminative application of insecticide against Glossina morsitans Westw
Authors: Hocking K. S.
Published: July 2009

A dieldrin emulsion spray containing 3 per cent, dieldrin (w/v) was applied once to the putative resting places of Glossina morsitans Westw. throughout a comparatively isolated 17-sq.-mile fly-belt in the Kabiganda Valley in southwestern Uganda between October 1957 and September 1958. Concentration areas of the fly consisted of one or more tall trees with associated understorey and thicket. The lower sides of the branches of an average of 6·75 such trees per acre were treated at a rate of about one-fifth of a pound of dieldrin per acre and at a cost of about £250 per sq. mile.

Chemical analysis showed a deposit of approximately 0·8g. dieldrin per sq. metre on the surface sprayed, and although 90 per cent, of this had disappeared from the surface after about four months, it is thought that the application remains effective for this period.

A very great reduction in the tsetse population was achieved. Small numbers of flies continued to be caught, but it was thought possible that these were being brought in from neighbouring valleys by buffalo, and, hence, that insecticidal application of this sort, if carried out over a wide enough area, might eradicate a tsetse population.
The use of pyrethrum formulations to controlAntestiopsison coffee in East Africa
Authors: Crowe T. J. , Jones G. D. Glynne , Williamson Ruth
Published: July 2009

The history of the use of pyrethrum formulations to controlAntestiopsisspp. onarabicacoffee in Kenya is reviewed.

The material with which the present work was done comprised three distinct forms ofAntestiopsisof doubtful taxonomic status; these were not observed to differ in their response to the insecticidal treatments used.

Laboratory experiments showed thatAntestiopsiswas highly susceptible to pyrethrum and that the addition of piperonyl butoxide, a pyrethrum synergist, did not affect this response.

Preliminary field experiments showed that concentrations of pyrethrins higher than those found effective in the laboratory were required. A hypothesis is advanced and established that this was due to a variable proportion of insects becoming paralysed and falling off the tree before acquiring a lethal dose.

These observations and experiments suggested a two-phase method of control, using pyrethrum as a non-persistent foliage spray at an economical but effective concentration of 0·005–0·006 per cent, pyrethrins, coupled with a 5 per cent. DDT or 0·5 per cent, dieldrin dust applied to the bole of the tree to form a persistent toxic barrier. The spray removed the bugs from the tree whilst the dust prevented the return of or killed those that had only received a sub-lethal dose of pyrethrum. It seemed unlikely that such a localised application of the persistent insecticide would have any appreciable effect on beneficial insects.

This two-phase treatment has been used successfully both in trials and in commercial practice for the control ofAntestiopsis. When the initial population is in excess of 20 per tree, two spray applications and one dusting are necessary to effect control.
Some experiments to determine the methods used in host-finding by the tsetse fly, Glossina medicorum Austen
Authors: Chapman R. F.
Published: July 2009

Field and laboratory experiments were carried out in Ghana on the tsetse fly, Glossina medicorum Aust., to discover the senses used by the fly in finding its host. In laboratory experiments on vision a model locomotive with a black screen attached to it was used as a ‘host’. The flies were stimulated to move by the movement of the screen. When the screen was stopped and started for short periods the increase in activity became less each time the screen was put in motion but the fall off was less rapid than in experiments with continuous movement. The possible significance of this is discussed in the light of the normal habitat of the species in the field.

In the field, G. medicorum did not respond to a moving object more than 25 ft. away but G. morsitans Westw. showed a good response at distances up to 150 ft.

Tethered flies were attracted to the model screen and showed a preference for landing on the lower edge near the centre.

Laboratory experiments using a guineapig and a goat as sources of smell produced no response from the flies but a strong reaction was obtained with the vapour of dilute acetic acid. In field experiments, using cows which were not visible to the fly, a very marked response to the smell of the cows was obtained. Orientation to a source of smell probably involves orientation to air movement and G. medicorum showed a strong upwind orientation in a wind tunnel even when blinded.

It is concluded that G. medicorum, which lives in thicket or forest where visibility is poor, probably responds initially to the smell of a potential host. An upwind orientation would then bring it to the general vicinity of the animal and the final approach might be visual.
Studies on the dispersion and survival of Anopheles gambiae Giles in East Africa, by means of marking and release experiments
Authors: Gillies M. T.
Published: July 2009

An account is given of marking and release experiments with Anopheles gambiae Giles in a coastal area of Tanganyika. Laboratory-reared mosquitos were used, labelled either by the topical application of paint or by the introduction of radioisotopes into the larval breeding pans. Two different isotopes were used, 32P and 35S, and recaptures were recognised by autoradiography.

Routine catching stations were established within a circle of radius of 1¼ miles. Releases were made either in the centre or near the periphery of the experimental area, so that recaptures were possible up to a maximum of 2¼ miles.

The following results were obtained:

1. Of 132,000 mosquitos released, 1,019 were recaptured.

2. The mean flight range of females released in the centre was estimated to be 0·64 mile, and of males 0·52 mile. Of females released on the periphery, the mean range of dispersion was estimated to be 0·98 mile. Individuals of both sexes were caught at the maximum range of 2¼ miles.

3. The dispersion of recaptured mosquitos was shown to be non-random and to be related primarily to the distribution of human settlements.

4. In certain series of releases the direction of the prevailing wind had a definite effect on the dispersal of mosquitos. But in general this was a minor factor.

5. Dispersion during the first day or, in many instances, during the first two days after release was more restricted, compared with that of older mosquitos. But no difference in the distribution of catches was detected between those aged three-nine days and those more than nine days old.

6. Marked females were recaptured up to 23 days after release. Apart from the first two days, the regression of density on age amounted to a daily loss of 16 per cent, of mosquitos from the experimental area. The effect of emigration could not be assessed quantitatively, but it was held to be a minor component of the total daily loss. The relatively high level of mortality suggested by these figures is attributed to the use of laboratory-reared mosquitos.

7. The corrected sporozoite rate in marked females at the time of recapture was 0·8 per cent.

8. The survival of males was only slightly lower than that of females.

9. It is concluded from the survivorship curve that the mortality rate remained constant throughout the period in which marked females were recovered.
A study of the association between moorland vegetation and breeding sites of Culicoides (Diptera, Ceratopogonidae)
Authors: Kettle D. S.
Published: July 2009

A major problem in using larvicides to control Culicoides is to recognise the sites requiring treatment. The relationship between plant cover and breeding of Culicoides (mainly C. impunctatus Goetgh.) was accordingly investigated in moorland areas of Scotland. Two sites were examined on Soutra Hill, Midlothian, and one each on Bannachra Muir and at Luss, Dunbartonshire. Three vegetational zones were recognised on Soutra (site 1): bogland (I), acid grassland (III) and a zone (II) characterised by vegetation preferring a much wetter habitat than either of the foregoing. C. impunctatus was virtually the only Culicoides species found in zone I; it was relatively less abundant in zone II, where C. albicans (Winn.) reached its peak, and occurred most densely at the bogland edge of zone III, where it was associated with C. cubitalis Edw., C. heliophilus Edw. and C. obsoletus (Mg.). Further into the grassland, C. impunctatus decreased while the other three species became more numerous and other species, of the group of C. pulicaris (L.), appeared. Within each main zone there were no significant differences between the various floristic groups as regards larval densities.

Fluctuations in population density observed in late autumn were regarded as more apparent than real, and attributable to larval movement in response to an oscillating factor, possibly soil-water level. This movement was recognisable in all zones but was most strongly marked where the ground was uneven.

On Soutra (site 2), where only zones I and III were sampled, there was remarkable consistency among the larval densities of the various groups of samples examined. This applied whether the samples were classified on their angiosperm flora, moss cover or spatial arrangement. The main source of variation was within groups and it was found that two adjacent small plots (12 yd. & z.Times; 12 yd.) which were macroscopically identical showed consistent differences over a period of ten months, covering the transition from one generation to another.

On Bannachra Muir, the larvae of C. impunctatus were concentrated in an area covered by Juncus articulatus and Sphagnum where the water flowed down the hillside near the surface. C. impunctatus avoided both an area of drier leaf mould and a stagnant ditch. C. albicans, C. heliophilus and C. obsoletus preferred the ditch to the hillside flow.

Around a hillside trickle at Luss, larvae of C. impunctatus and C. truncorum Edw. were abundant in subequal numbers. In spite of the restricted size of the area (about 10 sq. yd.) they never occurred in equal numbers in any set of samples, but one or the other predominated. C. truncorum showed a preference for the very wet parts.
Laboratory studies on the biology ofSyntomosphyrum albiclavusKerrich (Hym., Eulophidae), a parasite of tsetse flies
Authors: Saunders D. S.
Published: July 2009

Laboratory studies are reported onSyntomosphyrum albiclavusKerrich, a Eulophid of interest as a pupal parasite of tsetse flies. Material for a laboratory culture was obtained from puparia ofGlossina morsitansWestw. collected in Tanganyika and sent to London by air.

‘ Natural’ and ‘unnatural’ hosts of this parasite were investigated.S. albiclavusparasitised all species of Cyclorrhaphous puparia offered in the laboratory, but has only been recorded from puparia ofGlossinaunder natural conditions. The conditions which make a host suitable forS. albiclavusare discussed. The most important of these is the presence of the ‘sub-puparial space’ in which the eggs are laid, without which the host is unacceptable.S. albiclavuswill also breed on dead pupae and in puparia containing other parasites.

The number of parasites emerging from the host puparium is shown to be directly proportional to its weight.

The fecundity ofS. albiclavusis shown to be very variable and dependent upon the weight of host material consumed during larval life, which, in turn, reflects the density of parasites in the host puparium from which the females emerged.

The duration of the parasitic phase of the life-cycle and the length of life of the adults are shown to be functions of the temperature. Length of life is also affected by the relative humidity, increased mortality occurring in low humidities and in saturated air, with an optimum for survival at about 80 per cent. R.H.

It is shown that a constant temperature of 35°C. is fatal to the eggs ofS. albiclavus.

The age at which females ofS. albiclavusbecome mature was investigated at three temperatures and it is shown that the rate of maturation of the ovaries is a function of the temperature.

At 25°C., females ofS. albiclavusare unable to lay eggs until the third day after emergence. The number of offspring produced then falls off with increasing age of the female and very old females, although attacking hosts, are unable to oviposit.
An assessment of the economic importance of the tsetse species of southern Nigeria and the Southern Cameroons based on their trypanosome infection rates and ecology
Authors: Jordan A. M.
Published: July 2009

Previous records and new data on infection rates in species of Glossina inhabiting southern Nigeria and the Southern Cameroons are presented, and the probable economic importance of each species is assessed.

The trypanosome infection rates were highest in those species of tsetse which fed largely on Bovidae.

The rarity of human trypanosomiasis in southern Nigeria and the Southern Cameroons is attributed largely to impersonal man/fly contact; under such conditions a low proportion of infected flies is to be expected. G. palpalis (R.-D.) is not an important vector of sleeping sickness, as it is in northern Nigeria. The incidence of infection in G. palpalis was generally very low; cases of bovine trypanosomiasis do occur in areas where G. palpalis is the only tsetse species present, but it is not considered to be an important vector.

Little information is available on G. tachinoides Westw. and G. caliginea Aust. in southern Nigeria; both have probably been at least partly responsible for some of the rare outbreaks of sleeping sickness reported from the south. G. tachinoides may be of some significance as a vector of animal trypanosomiasis.

The infection rate in G. longipalpis Wied. at the West African Institute for Trypanosomiasis Research Field Station at Ugbobigha was 21·5 per cent.; this species is believed to be of major economic importance because its presence must prevent the keeping of cattle in large areas of potential grazing.

At least 13 per cent, of examples of G. medicorum Aust., G. fusca (Wlk.) and G. nigrofusca Newst. were infected in the populations examined, and the first two species are considered to be of economic importance because they penetrate potential grazing areas.

G. pallicera Big., G. tabaniformis Westw. and G. haningtoni Newst. are confined to rain-forest and were found to be lightly infected; they are therefore not considered to be of economic importance, except possibly as a source of infection to cattle on trade routes.

No data are available for G. nashi Potts.
Length of life, fecundity and the oviposition cycle in Anthrenus verbasci (L.) (Col., Dermestidae) as affected by adult diet
Authors: Blake G. M.
Published: July 2009

A study has been made of the length of life, fecundity, oviposition and the effects upon them of adult nutrition in the varied carpet beetle, Anthrenus verbasci (L.).

The length of the inactive (unmated) life for males and females at 20°C. and 70 per cent. R.H. was 7·5 and 7·7 days, respectively. This period, which is spent in the moulted last larval skin, decreased with rise in temperature, from a mean of 32·4 days at 10°C. to 3·8 days at 25°C. Humidity differences had relatively little effect.

The effects of various diets on the length of life, oviposition cycle and fecundity of active adults were observed. The experimental diets were water, water with pollen, water with albumen, sugar solution, sugar solution with pollen, sugar solution with albumen, and the control group in which the beetles were deprived of food and water. The sugar solution was a mixture of equal parts of glucose, sucrose and fructose in water.

There were no differences in length of life between male and female beetles (males 18·2–20·9 days, females 22·1–26·1 days) given water, water with pollen, water with albumen and those deprived of food and water. But there was an increase for both sexes when the beetles were given sugar solution, and a further increase, to a mean of 58·3 days for males and 69·5 for females at 20°C. and 70–90 per cent. R.H., when albumen was added to the sugar solution. However, although sugar solution with pollen increases still further the length of life of the males, that of the females was no different from what it was on sugar solution alone.

The preoviposition period ranged from 3–14 days with a mode about the fourth day.

The oviposition cycle consisted of three clearly denned peaks of oviposition on about the 6th, 12th and 17th days. There was a similar pattern in all the groups except that those given sugar solution continued to lay, at a low rate, after the end of the third peak.

The fecundity of beetles deprived of food and water was 50·3 eggs; for beetles given water, water with albumen and water with pollen there was a significant decrease; for beetles given sugar solution there was an increase which became significant when pollen or albumen were given in addition to the sugar. Maximum fecundity occurred on a diet of sugar solution with albumen.

There was significant correlation between length of life and weight on emergence for males given water, water with pollen, or water with albumen, and for females given water with pollen or water with albumen. There was significant correlation between fecundity and emergence weight for females deprived of food and water, given water alone and water with pollen.
Pygostolus falcatus(Nees) (Hymenoptera, Braconidae), a parasite ofSitonaspecies (Coleoptera, Curculionidae).
Authors: Loan Conrad , Holdaway F. G.
Published: July 2009

Pygostolus falcatus(Nees), an endoparasitic Braconid of the subfamily Blacinae, was reared fromSitona lineatus(L.),S. hispidulus(F.) andS. humeralisSteph. of Swedish origin. The life-history and immature stages ofP. falcatuswere studied in the laboratory at 74°F. and in field cages preparatory to its liberation in Canada as a control agent of the sweetclover weevil,S. cylindricollisFhs.

The immature stages develop in the haemocoele of the weevil. After deposition, the egg increases in volume to a maximum of 335 times. At eclosion, the cells of the trophamnion dissociate and increase in volume in relation to the growth of the larva. Supernumerary larvae are eliminated soon after eclosion, and one larva only develops in a host weevil. At 74°F., the final-instar larva emerges from the host weevil 15–16 days after deposition of the egg. Development of many first-instar larvae in a wide range ofSitonaspecies was arrested by diapause. Five larval instars are described and illustrated. Oviposition is prevented in weevils in the summer of their development and eliminated in overwintered weevils by the parasite egg and first-instar larva. The weevil dies within hours of emergence of the parasite larva.

Reproduction is parthenogenetic and thely tokous. The maximum number of eggs laid by a female was 46; the number of eggs laid per day per female varied from 0 to 11. Oviposition takes place both in light and in complete darkness and a preference among species ofSitonawas not evident. The maximum number of weevils parasitised by a female in a field cage was 39; the number parasitised per day varied from 0 to 8.

The species overwinters as a first-instar larva in weevils which became adult in the previous summer. There were two discrete parasite generations in 1958 in Swedish weevils, both of which developed in early and mid-summer within overwintered weevils. The maximum rate of parasitism ofS. lineatusby larvae of the mid-summer parasite generation in 1958 was 73·3 per cent.

The value ofP. falcatusas a control agent ofSitonapopulations is limited by low parasitism of the new weevil generation of the current year and diapause of the first-instar larva.