bluuebunny/crossref_metadata_2025 huggingface dataset:
Seasonal patterns of age-composition of sylvan mosquito populations in Uganda (Diptera, Culicidae)
Authors: Corbet Philip S.
Published: July 2009

Fifty-two standardised weekly collections of female mosquitos were made by human catchers at ground-level in lake-side forest near Entebbe, Uganda. The numbers of nullipars and pars in each sample were recorded, in order to determine whether the capacity of these mosquito populations to transmit virus varied seasonally. Methods are described for handling large catches for the purpose of identifying and age-grading. The total sample comprised 31,978 mosquitos belonging to 37 or more species. Results for 15 species are presented in detail.

The nulliparous rate (i.e., the number of nullipars as a percentage of total females) differs markedly between species, but relatively little within species. Certain species of Mansonia (Coquillettidia), mainly swamp breeders, have the highest nulliparous rate, and species of Aedes and Eretmapodites, which breed in small containers, have the lowest. In some species, biting females show a lower nulliparous rate than those caught resting.

Culex annulioris Theo. and species of Mansonia, which are swamp breeders, have a main peak of abundance between May and July, during the main rains and when lake-level is highest. Species of Aedes (Stegomyia), which are tree-hole or small-container breeders, show small, irregular, short-term fluctuations in numbers.

The number of pars, an epidemiologically important parameter, is absolutely highest at or soon after the time of greatest abundance. For certain bird-biting mosquitos, namely, Culex annulioris and species of Mansonia (Coquillettidia), most pars are found during the main rains, when susceptible hosts are also most numerous. Implications of these findings on virus-isolation programmes are briefly discussed.
Notes on the habits and distribution of some Ghanaian bark beetles and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae)
Authors: Browne F. G.
Published: July 2009

Brief notes are given on the distribution and habits of 42 species of Scolytidae and 34 of Platypodidae that occur as common forest insects in Ghana. A considerable number of these can be considered as beneficial insects because they do little damage but assist in the rapid break-down of dead trees and felling slash. Others are injurious mainly as timber borers, shoot borers or, generally to a lesser extent, as bark beetles and seed insects. Trachyostus ghanaensis Schedl and Doliopygus dubius (Samps.) are of outstanding importance in their constant or frequent habit of attacking the wood of living trees of commercial value; Platypus hintzi Schanf., Doliopygus conradti (Strohm.) and D. brevis (Strohm.) are probably the most important ambrosia beetle borers of newly felled timber; and Xyleborus semiopacus Eichh. has been known to destroy whole plantations of young forest trees.
The spread of apterae of Myzus persicae (Sulz.) and of yellows viruses within a sugar-beet crop
Authors: Ribbands C. R.
Published: July 2009

Populations of the wingless form of Myzus persicae (Sulz.), infected with severe yellows (SBYV), mild yellows (SBMYV), and both viruses, were introduced to single sugar-beet plants which were growing in a normal crop.

The aphids and their progeny walked readily from plant to plant, both along and across the rows, during the following eight weeks. Although they were heavily attacked by ladybirds, their mobility saved the population from total destruction. They carried and transmitted the viruses; within a month patches of sugar beet more than 11 feet in diameter had become infected, and within two months the diameter had extended to about 20 feet.

SBMYV spread to more than twice as many plants as SBYV. When introduced alone, either virus spread to twice as many plants as when the two viruses were introduced together. The rate of increase of the infection fell off during the season; it was estimated as eight- to sixteen-fold per month in June—July, about three-fold in August, and 1·5- to 1·9-fold in September. Natural infections-appear to behave similarly.

Apterae of M. persicae are considered to be predominantly responsible for yellows virus transmission within the crop, and their mobility, in contrast to the immobility of those of A. fabae Scop., is considered to be the principal reason why M. persicae is a much more important vector than A. fabae.

The extent of spread of virus by apterae shown to occur in the root crop must inevitably be much greater in the seed crop, in which aphid populations are much higher. This consideration serves to explain why existing control measures in the seed crop do not protect the root crop from infection. The risk from the seed crop, which is the reservoir of the disease, would be countered if seed crops were grown only in alternate years.
Laboratory studies on dispersion behaviour of adult beetles in grain. II.—The saw-toothed grain beetle, Oryzaephilus surinamensis (L.) (Coleoptera, Silvanidae)
Authors: Surtees Gordon
Published: July 2009

Dispersion behaviour in adults of the saw-toothed grain beetle, Oryzaephilus surinamensis (L.), was studied under controlled laboratory conditions. The effect of density, temperature and moisture content on surface dispersion was studied using groups of insects in jars of 500 g. grain and vertical dispersion by using groups of insects in thin vertical plates of wheat held between two sheets of glass. The ethological basis of group behaviour was investigated by using isolated individuals.

Over the range of conditions used, 1–10 per cent, of the individuals comprising the groups studied appeared on the surface of the grain. In grain at 14 per cent, moisture content, at 25°C., 3·4 per cent, of the group appeared on the surface. A greater proportion was found on the surface of grain at 9 per cent, moisture content than at higher moisture contents at all temperatures tested (15–35°C.). At all moisture contents, surface numbers were relatively high at 15°C.

In grain at 14 per cent, moisture content and 25°C., individuals moved vertically and laterally at random but were more active in the evening than in the morning. In grain at 9 per cent, moisture, there was marked irritability, and at 15°C. and 14 per cent, moisture, there was continual but slow movement without any detectable diurnal pattern of activity. Activity was reduced at 30°C., and at 25°C. it was reduced in grain of 17 per cent, moisture content.

The significance of these results is discussed in relation to the detection of populations, group formation and the initiation of foci of heating in patches of damp grain.
Notes on borers of date palms in Iraq
Authors: Hussain Ali A.
Published: July 2009

Brief notes are given on five species of boring insects that attack date palms in Iraq and between them cause considerable damage, based on observations in 1957–62. They comprise the Pyralid Arenipses sabella Hmps., the larva of which mines the spathes and fruit stalks, preventing fruit maturation; the Cerambycid Pseudophilus testaceus Gah., the larva of which mines the frond bases and stem;the Dynastid Oryctes elegans Prell, of which the adult makes a surface mine in the frond mid-rib or fruit stalk and the larva develops, usually, inside the stem of dead or moribund palms; the Bostrychid Phonapate frontalis (Fhs.), which mines in the frond mid-rib; and the termite Microcerotermes diversus Silv., which makes covered galleries up the outside of the stem and mines within the stems and frond bases of weakly palms.
A simple method for marking haematophagous insects during the act of feeding
Authors: Knight R. H. , Southon H. A. W.
Published: July 2009

Blood-meals of two species of haematophagous insects, Glossina morsitans Westw. and Aedes (Stegomyia) aegypti (L.), have been ‘ marked ’ by allowing groups of adults to feed on an ox to which an aqueous solution containing 4 g. of trypan blue had previously been administered intravenously. The dyestuff is detected by a paper chromatographic procedure in which the blood-meal, mixed with 0·1N NaOH, is applied to a narrow strip of Whatman No. 1 chromatographic filter paper and the chromatogram is developed in 0·1N NaOH. Under these conditions, trypan blue remains at the origin, whereas the other coloured components of the blood-meal move away from the point of application. The duration of the mark in the ox and in the insects has been examined. The trypan blue was detected in four out of six fresh blood-meals of Glossina taken 38 days after injection of the dye into the ox, in six out of six examples of Glossina examined two days after blood-meals taken 24 days after the injection, in four out of six examples of Glossina examined eight days after blood-meals taken immediately following the injection, in six out of six examples of Aedes one day after blood-meals taken 14 days after the injection and in six out of six examples of Aedes two days after blood-meals taken immediately following the injection.
Studies on mosquitos (Diptera, Culicidae) biting birds, using twenty-four-hour catches, in the Entebbe area, Uganda
Authors: Williams M. C.
Published: July 2009

Series of 24-hour catches at different levels were made at Zika and Lunyo in the Entebbe area, Uganda, using fowls (White Leghorn cocks) as bait, and some comparative catches were made with man as bait.

Thirty-seven different mosquito species (including five species groups) were taken on the avian bait.

The vertical distributions and biting cycles of each of nine species (including one species group), Anopheles implexus (Theo.), Mansonia (Coquillettidia) aurites (Theo.) gp., M. (C.) fuscopennata (Theo.), M. (Mansonioides) africana (Theo.), Hodgesia cyptopus Theo., Aedes africanus (Theo.), A. apicoargenteus (Theo.), A. ingrami Edw. and Culex annulioris Theo. were similar on human and avian bait.

At Lunyo both A. africanus and C. annulioris had a marked diurnal peak, which had not been described previously.

Comparison of the numbers coming to avian and human bait indicate that species of Culex, H. cyptopus and most of the species of Mansonia (Coquillettidia) have a preference for birds.
Three new sandflies (Diptera, Psychodidae) from East Africa, with notes on other species
Authors: Minter D. M.
Published: July 2009

Notes are given on the use of a chloral hydrate solution for clearing sandflies (Phlebotomus). Descriptions are given of three new species of sandflies from Uganda and Kenya (Phlebotomus (Sergentomyia) edwini, P. (Sergentomyia) kitonyii and P. (Sergentomyia) teesdalei spp. n.) and of the male of P. (Sergentomyia,) multidens Heisch, Guggisberg & Teesdale. Supplementary descriptive notes are given on Phlebotomus (Phlebotomus) rodhaini Parr., Phlebotomus (Sintonius) graingeri Heisch, Guggisberg & Teesdale, with illustrations of the spermatheca in both species, and the occurrence of morphological variation in the male genitalia of Phlebotomus (Sergentomyia) schwetzi Adl., Thdr. & Parr, in Kenya is discussed in relation to season. Data are given showing natural infection rates with flagellate Protozoa in populations of Phlebotomus (Serigentomyia) garnhami Heisch, Guggisberg & Teesdale in part of the Kitui district of Kenya.
Ecology and host-relationships of ticks (Ixodoidea) infesting domestic animals in Kassala Province, Sudan, with special reference to Amblyomma lepidum Dönitz.
Authors: Karrar Gaafar , Kaiser Makram N. , Hoogstraal Harry
Published: July 2009

Amblyomma lepidum Dön., previously incriminated as a vector of heartwater (caused by Rickettsia ruminantium) among sheep and goats, and possibly camels, in southern Kassala Province, Sudan, is apparently the only Amblyomma species in this area. Systematic collections of all ticks infesting domestic animals were carried out in November 1959, just after the rains, in five ecologically differing areas in the region most severely infected with heartwater. Though rare in desert scrub (north of 16°N. latitude) and only moderately numerous in semidesert grassland (Butana area), incidence of A. lepidum is high in wooded savannah (River Atbara) and in the cultivated Gash Delta, and highest (15·5 per host) in the Acacia seyal savannah of the River Gash. Chief hosts of adults are cattle. Sheep are secondary hosts, and camels, donkeys, and goats are less heavily infested. Two males were taken feeding on humans. Mating (breeding) activity is only slight following the rains (November). Few larvae and nymphs were found during this period; those present were mainly on sheep and goats, with a few on cattle, and these were usually feeding on the hoofs of their hosts.

Rhipicephalus s. sanguineus (Latr.), the most numerous and widely distributed tick here, infests chiefly sheep and goats, is common on cattle, and also occurs on camels and donkeys. Mating activity of this species is high in November. Hyalomma dromedarii Koch is equally widely distributed and follows R. s. sanguineus in numbers, but is most frequent on camels, common on cattle, and rare on donkeys and sheep; goats were uninfested. Mating is moderately active at this season. The incidence of H. impeltatum Schulze & Schlottke, which occurs in each zone, equalled that of A. lepidum. Cattle are the chief hosts and camels are secondary hosts; donkeys, sheep, and goats are less frequently infested. Mating activity is moderate in November.

Other more or less common tick species on these domestic animals are Boophilus decoloratus (Koch), R. e. evertsi Neum., R. simus Koch, H. anatolicum excavatum Koch, H. truncatum Koch and H. marginatum rufipes Koch, evidence for the status of which as a subspecies of H. marginatum Koch is to be presented in a subsequent paper. Several other rare species are also recorded.
The effects of food shortage upon larvae of Lasioderma serricorne (F.) (Coleoptera, Anobiidae)
Authors: Lefkovitch L. P. , Currie J. E.
Published: July 2009

In a long series of experiments with Lasioderma serricorne (F.) carried out at 30°C. and 60 per cent. R.H. it was established that shortage of food prolongs development and reduces survival of the immature stages and also reduces the weight of the resulting adults. Competitive effects between larvae over and above those caused by food shortage alone were not detected. Larvae ate eggs and pupae only in the complete absence of any other food, and they did not appear to eat one another. There was no trend in the performance of the immature stages attributable to the age of the female parent at the time of oviposition. Variation between the times taken by different individuals to attain a subsequent stage was positively skewed. Adult females weigh more than males, this difference in weight first occurring during the third (penultimate) larval instar. There were no significant differences in the developmental periods of the sexes.
Laboratory studies on dispersion behaviour of adult beetles in grain. V.—Technique for three-dimensional analysis of dispersion patterns within small bulks
Authors: Surtees Gordon
Published: July 2009

A technique is described whereby a small bulk of grain can be broken down, all insects infesting it recovered and their positions recorded. A Perspex box, 12 inches cube, is loaded with 64 three-inch-cube bags of Terylene net (10 meshes to the inch) each holding 390 g. of Manitoba wheat, and the test insects (adult grain beetles) released on the surface, after which the box is sealed and left in darkness for the required time. The bags are then removed, the insects sieved out, and their numbers and positions recorded, thus enabling the pattern of group dispersion to be plotted. The net used did not appear seriously to impede the movement of the adults of Sitophilus granarius (L.), the largest species used in the study. Temperature gradients may be introduced and measured by thermocouples built into the bulk.
Studies on Theocolax formiciformis Westw. (Hym., Pteromalidae), a parasite of Anobium punctatum (Deg.) (Col., Anobiidae)
Authors: Taylor Jean M.
Published: July 2009

A description is given of the life-cycle in Britain of Theocolax formiciformis Westw. (Pteromalidae), a parasite of Anobium punctatum (Deg.) (Anobiidae). Adults emerge from infested wood in large numbers from April to June. Eggs are laid through the wood surface and use was made of this habit as a means of rearing this parasite under observation in the laboratory. Anobium larvae were placed individually in channels gouged in the surface of 3-inch squares of plywood. They were covered with tracing paper and the parasites were caged on this by means of a glass ring covered with a glass plate. Development from egg to adult at 22 and 25°C., and 75 per cent, relative humidity, averaged about five and six weeks, respectively, compared with 12 weeks outdoors in summer. The number of progeny per female was highest (approximately five) at 22°C., at which the ratio of males to females was 1:3. Only about one per cent, of the adults reared were winged. The use of Theocolax as a biological-control agent is not considered practical.
Mass rearing of the common field cricket, Gryllus pennsylvanicus burmeister (Orthoptera, Gryllidae), for use as a test insect in toxicological studies
Authors: Harris C. R. , Svec H. J.
Published: July 2009

A method of rearing Gryllus pennsylvanicus Burm. is described, designed to yield large numbers of first-instar nymphs of uniform age for toxicological investigations Nymphs are reared to the fourth instar in glass vessels containing a little soil, which prevents cannibalism, and then transferred to glass-topped stock cages having sides and floors of aluminium screening and each accommodating 250 individuals. A mixture of dog-food pellets, oatmeal and milk powder, with fresh oats or clover, is provided throughout as food, and petri dishes of moist fine sand for oviposition. After separation from the sand by sieving, the eggs are incubated in moist soil at 24°C. for one month, subjected to 4°C. for three months to eliminate the obligate diapause, and then returned to 24°C., when 70 per cent, hatch after 15–18 days. The diapause enables eggs to be stored at 4°C. until required. At 24°C., the nymphal stage lasted about 81 days, the adult males and females, which are produced in equal numbers, survived about 62 and 56 days, respectively, oviposition extended over 11 weeks and the average number of eggs laid per female was 970·6.
An investigation into the behaviour of Anopheles parensis Gillies at Malindi on the Kenya coast
Authors: Gillies M. T. , Furlong M.
Published: July 2009

In investigations made in January to November 1962, Anopheles parensis Gillies was found biting man in large numbers in a zone near Malindi, Kenya, in which house-spraying with DDT had been carried out between March 1961 and October 1962. Densities were greatest just outside villages, less so on the verandah of a house and least indoors. In one open type of unsprayed house, however, moderately large numbers were caught. The monthly average catch per night by two men was greatest (over 200) outdoors in July and August.

Biting activity reached two peaks during the course of the night, catches in all situations being greatest during the two hours following sunset and the three hours preceding sunrise. The evening peak was highest in the outdoor catches, and the late-night peak in the indoor collections. A distinct influence of moonlight on the catches was observed, the early evening peak under certain conditions being greater during the moon's first quarter and the late-night peak during its last quarter.

Numbers of examples were caught biting cattle, but owing to the absence of large herds of stock it is believed that most feeding took place on man. The proportion of nulliparous females was 64 per cent, in the sprayed zone and 50 per cent, in an unsprayed village, and in the latter the nulliparous rate in females resembling A. funestus Giles (the majority of which would have been that species) was 24 per cent. No specimen of A. parensis infected with sporozoites was found in the sprayed zone. In the unsprayed village, no infected glands were found in a small series dissected. Thus no evidence was obtained that A. parensis was acting as an exophilous vector of malaria in the sprayed zone. Moreover, in view of the high nulliparous rate observed in the unsprayed area, this species is considered unlikely to be of any importance under normal conditions.
An assessment by bioassay of the comparative toxicity and persistence of dieldrin and isobenzan deposits on riverine vegetation in the Northern Guinea Savannah zone of Nigeria in relation to the control of Glossina palpalis (R.-D.)
Authors: Baldry D. A. T.
Published: July 2009

The toxicity and persistence under natural field conditions of deposits of dieldrin and isobenzan, derived from dilutions of emulsion concentrates, on the leaves of riverine vegetation in the Northern Guinea Savannah vegetation zone of Nigeria were studied by a bioassay method, using teneral females of Glossina palpalis (R.-D.) as test insects. Although deposits of both insecticides were extremely toxic when first sprayed, neither product was found to have a long residual action, and isobenzan was found to be approximately half as efficient as dieldrin. It is suggested that because of its poor residual action isobenzan will be little used in tsetse control campaigns in areas similar to that in which the investigations were performed.
The biting habits of Aedes (Skusea) pembaensis Theo. and some other mosquitos of Faza, Pate Island, East Africa
Authors: van Someren E. C. C. , Furlong M.
Published: July 2009

Descriptions are given of 24-hour biting catches, made in and around Faza, a village on Pate Island, off the north-east coast of Kenya, East Africa.

Aedes pembaensis Theo. was the predominant mosquito in these catches but fair numbers of Aedes mombasaensis Mattingly were also taken; the biting cycles of these two are discussed. Six other species were taken in small numbers.

For Ae. pembaensis, biting cycles calculated on catches grouped for site, moon phases, neap tides and spring tides show that both moon and tide and light intensity influence the biting behaviour. Different but recurring patterns occur with various combinations of these factors.

For Ae. mombasaensis, the cycles have a very constant biphasic pattern. Catches grouped for moon phases, tides and catch sites, as for Ae. pembaensis, show that more biting females are taken at neap tides than at spring tides. Two patterns of behaviour occur, one associated with spring tides and the other with neap tides. An even level of biting activity occurs during the night with intense and prolonged moonlight; otherwise moon-phase cycles have little effect on biting behaviour.

It is felt that 24-hour biting catches can give useful information on behaviour patterns but it is desirable to have a long series of catches to analyse. For the purpose of calculating biting cycles, the results of catches showing similar modifications in behaviour should be treated separately.
Infestation of foodstuffs from the United States of America inspected in the United Kingdom between 1953 and 1961
Authors: Hurlock E. T.
Published: July 2009

Details of the insect and mite infestation encountered on food commodities imported into Britain from the United States of America between 1953 and 1961 are given. Twenty-eight species of insects and nine species of mites, thought to have been introduced with the goods are listed together with a further 35 species of insects thought to have been derived from ships' holds. Emphasis is laid on the dangers of foodstuffs acquiring infestation either by cross-infestation or from infested residues in the holds.
Resistance to BHC in the cattle tick Boophillus microplus (Can.) in India
Authors: Chaudhuri R. P. , Naithani R. C.
Published: July 2009

Cattle kept at the Latoli kraal of the Indian Veterinary Research Institute at Mukteswar in the Kumaon foothills of the Himalayas were heavily infested with the tick Boophilus microplus (Can.). In order to reduce the infestation, the animals were treated with BHC dusts every season for a number of years. In 1960, it was noticed that the treatment was not as effective as in the previous years. A series of concentration/response tests was therefore carried out in 1961–62 to see whether or not the tick had developed any resistance to BHC. Ticks collected from cattle in a village about five miles distant, where no acaricide had ever been applied, were used as the standard for comparison. BHC as a wettable powder was used to provide six different concentrations of γ BHC for engorged females and unfed larvae, respectively. Treatment was by appropriate dipping techniques. Analysis of the results showed that the population of B. microplus infesting cattle at the Latoli kraal had developed resistance to BHC. The LC50's of γ BHC for engorged females and unfed larvae, respectively, of the Latoli population were 0.5164 and 0.0182 per cent., and of the village population 0.0834 and 0.00069 per cent. This seems to be the first record of any species of tick developing resistance to an acaricide in India.

It was found that the mean number of eggs laid per tick in the control batches was higher in the village population than in the Latoli population and that the difference was highly significant.
An experiment on the eradication of Glossina swynnertoni Aust. by insecticidal treatment of its resting sites
Authors: Chadwick P. R. , Beesley J. S. S. , White P. J. , Matechi H. T.
Published: July 2009

In an experiment carried out in 1963 on the control of Glossina swynnertoni Aust. infesting open bushland in northern Tanganyika, 3 per cent, dieldrin or endosulfan was applied to certain of the resting sites of the flies. These had been determined by previous observations and consisted of the undersides of tree branches between 4 and 9 ft. from the ground, with diameters of 1 to 4 in. and inclined less than 35° from the horizontal. Eradication was achieved in an area of 35 sq. miles at a cost of £42 per sq. mile. In a subsidiary experiment, G. pallidipes Aust. infesting the narrow forest bordering a seasonal river was attacked by spraying the vegetation on the river bank up to a height of eight feet. Complete eradication was not attained, due, it is thought, to removal of the insecticide by heavy rain, so that some newly emerged flies escaped exposure to a lethal deposit. The flies were, however, eliminated from the greater part of the river at a cost of £12.5 per mile.
Seasonal changes in populations of phlebotomine sandflies (Dipt., Psychodidae) in Kenya
Authors: Minter D. M.
Published: July 2009

An account is given of seasonal changes in the incidence and relative abundance of a number of Phlebotomine sandflies which rest in termite hills in two widely separated areas of Kenya.

The annual pattern of rainfall distribution is shown to be of greater importance than the total precipitation in influencing the gross distribution and local abundance of many sandflies.

Kenya sandflies fall readily into ‘ perennial ’ and ‘ rainy-season ’ groups: the former have a wide distribution and appear to breed throughout the year. The distribution of the ‘ rainy-season ’ sandflies is relatively restricted, since these species are found almost exclusively in areas with a bimodal pattern of annual rainfall; it is suggested that they may survive the intervening dry periods in larval diapause. The length rather than the severity of the dry seasons is thought to be the limiting factor in the distribution of ‘ rainy-season ’ species.

Examples are given of the seasonal changes in structure of populations made up of several species sharing, in the adult form, the same termite-hill habitat.
The effect of site and sampling method on the size and composition of catches of tsetse flies (Glossina) and Tabanidae (Diptera)
Authors: Saunders D. S.
Published: July 2009

Two experiments on factors affecting the size and composition of catches of tsetse flies, principally Glossina pallidipes Aust., were carried out in 1963 in South Busoga, Uganda. Eight attractants were distributed between eight sites on eight successive days in a Latin square design for each experiment. The attractants comprised two black Zebu oxen and Morris traps covered with ordinary hessian (brown traps) or with hessian dyed black (black traps). Three of the sites were on the edge of a large thicket, two were close to isolated clumps of thicket in the midst of grassland and three were in the open grassland itself. Catching took place for 12 hours each day. The total numbers and sex ratio were recorded for each catch, and also, from dissections, the age composition and pregnancy states of the female portion of the catch. Examples of G. brevipalpis Newst., G. palpalis fuscipes Newst. and of 13 species of Tabanidae were also caught, but in smaller numbers, and were recorded in less detail.

Catches of G. pallidipes at sites close to the thicket edge were considerably greater than at sites away from the thicket, but, apart from an increased proportion of nulliparous females at the clump and grass sites, the composition of the female sample was unaffected by the type of site. The bait-oxen caught larger samples than the traps, but a smaller proportion of females, and these contained a higher proportion of young flies and of flies carrying an egg in the uterus. In comparison with brown traps, black traps caught smaller numbers of G. pallidipes, and a smaller portion of females, but a larger proportion of these were nulliparous. Although the two oxen had been selected for similarity of size and colour, they differed in the samples they attracted: one of them consistently attracted a larger sample of all the common species and, in the second experiment, a larger proportion of females in the samples of G. pallidipes. Most examples of G. palpalis fuscipes were caught at the three edge sites, and all but one example of G. brevipalpis were caught on the bait-oxen.

All examples of the 13 species of Tabanidae caught on the oxen or in the traps were females. Apart from Tabanus par Wlk. they were poorly represented in the trap-catches, and there was no obvious effect of site upon the size of the samples.
Inheritance of dieldrin-resistance in Cimex lectularius L. and Pediculus h. humanus L
Authors: Guneidy A. M. , Busvine J. R.
Published: July 2009

The mode of inheritance of dieldrin-resistance in Cimex lectularius L. and Pediculus h. humanus L. was investigated. The method involved the determination of dosage/mortality regression lines by exposing batches of insects to a range of dieldrin concentrations. Reciprocal crosses were made between normal (N) and resistant (R) strains of each insect, and the F1 and F2 progeny were examined for susceptibility levels over a wide range of concentrations of dieldrin. Back-crosses were made from the F1 generation to N and R strains, and the progeny were examined in the same way. In some cases, further back-crosses were made after elimination of susceptible individuals from the progeny of the first back-cross.

All the results with C. lectularius were consistent with monofactorial inheritance of dieldrin-resistance through a gene of intermediate dominance. With P. h. humanus, the results were complicated by an apparent maternal effect which caused the F1 and F2 generations from a N ♀ × R ♂ cross to be less resistant than those from a R ♀ × N ♂ cross. In general, however, the results indicated genetic segregation consistent with the same type of monofactorial inheritance as that found in C. lectularius.
Dieldrin-resistance in a strain of Aedes aegypti (L.) from Puerto Rico
Authors: Guneidy A. M.
Published: July 2009

The cross-resistance characteristics of a dieldrin-resistant strain of Aedes aegypti (L.) from Puerto Rico were investigated by comparative tests on the adults of this and of a normal strain, using various insecticides. A resistance spectrum typical of that associated with resistance to BHC/dieldrin in other insects was revealed, characterised by slight or negligible cross-resistance to DDT, malathion and diazinon.

The mode of inheritance of dieldrin-resistance was studied by determining resistance levels in the progeny of direct crosses of the resistant and normal strains and of back-crosses. The F1 generation of the direct cross was of intermediate resistance, and the F1 generation showed 1:2:1 segregation into normal, intermediate and resistant individuals. Both back-crosses showed 1:1 segregation into susceptible and intermediate individuals when the back-cross was to the susceptible parent, or into intermediate and resistant individuals when it was to the resistant parent, and these results were confirmed when one genotype was eliminated and the back-cross was repeated. These results indicate monofactorial inheritance of an autosomal gene with intermediate dominance, which is typical of the BHC/dieldrin type of resistance.
Observations on the dry-season survival of Simulium damnosum Theo. in Ghana
Authors: Marr J. D. M. , Lewis D. J.
Published: July 2009

Observations were carried out, chiefly between March and June 1962, in an area centred on Bolgatanga in northern Ghana in the hope of finding out how Simulium damnosum Theo. survives the ‘ dry season ’. The term ‘ dry season ’ is used here for the unfavourable season when running water in the rivers is evidently absent or is insufficient or perhaps unsuitable for the development of any, or more than a negligible number of, individuals of S. damnosum from egg to adult. The incidence of this season varies from year to year and does not correspond to the season without rain. It may usefully be divided into reduced-flow, main dry, pre-flow and early-flow periods.

Search was made for larvae and pupae before rivers began to flow, without result. Observations were made on the numbers of flies biting, general appearance, wing measurement, antennal colour, mid-gut, fat-body, ovaries and parasites, chiefly at the beginning of the rainy season, in an attempt to trace the history of the species during the preceding weeks. Flies appeared before the rivers began to flow but did not give evidence of having lived for months. On the days when two rivers began to flow, considerable numbers of flies were caught, and most of those dissected proved to be parous and had evidently been in the adult stage for some days. A nematode parasite of the Malpighian tubes was found only in April, with one exception up to 10th May, and was probably associated with the dry-season biology of the host.

The possibility that S. damnosum migrates from permanent foci, or exists near its breeding places in one or more stages at different times, is discussed. Migration from afar seems very unlikely. The species survives in the adult stage for at least part of the ‘ dry season ’, but more information is required to complete the picture.

Survival is apparently not dependent to a significant extent on perennial breeding locally, and there is, therefore, no easy solution to the problem of control. Operational research might show if there is a carry-over generation and if control after the rains and towards the end of the breeding season would prevent it from developing. There is some indication that the risk of infection with Onchocerca tends to be low at the end of the ‘ dry season ’, which is a time when control would be particularly difficult.

The results of observations on wing measurements, antennal colour and the peritrophic membrane are given in an Appendix.
The insect infestation of sorghum stored in granaries in Northern Nigeria
Authors: Giles P. H.
Published: July 2009

The majority of sorghum in Northern Nigeria is stored unthreshed in farmers' granaries made of dried mud or plant materials such as grass matting and cereal stems. During the course of survey work and insecticide trials in 1959–61 it was possible to examine many samples of unthreshed sorghum from granaries throughout Northern Nigeria. It was found that the distribution of insect species within the Region is not uniform. Sitophilus oryzae (L.) and Sitotroga cerealella (Ol.) are the major pests. Sitophilus zeamais Motsch. was found only in the southernmost area. Heavy infestations of Rhyzopertha dominica (F.), Lasioderma serricorne (F.), Cryptolestes ugandae Steel & Howe, Oryzaephilus mercator (Fauv.), Tribolium castaneum (Hbst.) and T. confusum Duv. usually occur. Attagenus gloriosae (F.), Ahasverus advena (Waltl), Palorus ficicola (Woll.), P. ratzeburgi (Wissm.) and P. subdcpressus (Woll.) are occasionally important.

R. dominica, Bruchidius sp., G. ugandae, Planolestes cornutus (Grouv.), S. oryzae, Brachypeplus sp., T. castaneum, Sitotroga cerealella (all of which occurred on the standing crop), L. serricorne, Typhaea stercorea (L.), O. mercator, Palorus spp. and Tribolium confusum were found in sorghum sampled before storage. Insects from infested stores were found to infest sorghum growing nearby. Prestorage infestation alone can result in subsequent heavy populations of insects in the store. Cross-infestation between granaries almost certainly occurs.

Under Samaru conditions, where sorghum is harvested in November–December, insect populations remain at a low level in granary-stored unthreshed sorghum until after June, when the moisture content rises in the rainy season. In sorghum stored for nine months in provincial trials, more damage occurred during the last three months than during the previous six months of storage.

Sorghum heads stored in granaries made of plant materials such as grass matting and cereal stems are more severely damaged by insects than those stored in dried-mud granaries. This is probably due to a higher rate of immigration in the former.

In threshed grain stored in a mud granary, moisture content and damage by the most abundant insect, Sitophilus oryzae, decreased with depth. The insect population rose to a peak in November, two months after the maximum moisture content. The numbers fell rapidly during the following dry season. The annual cycle of insect damage was also assessed by taking fortnightly samples of threshed grain from a local market. S. oryzae was the most numerous insect, but even this species was uncommon from December to May, during the dry season.
Observations on the biting habits of mosquitos in the forest canopy at Zika, Uganda, with special reference to the crepuscular periods
Authors: Haddow A. J.
Published: July 2009

The results of sixty 24-hour catches of mosquitos carried out with man as bait in the forest canopy at Zika, central Uganda, are discussed. In these catches the arrival of mosquitos was recorded to the nearest minute.

The rapid changes of light intensity in the equatorial twilight are discussed in relation to a series of readings made at Entebbe.

It is shown that among species that show a crepuscular peak of biting activity (Aedes ingramiEdw.,A. africanus(Theo.),Mansonia fuscopennata(Theo.) andM. aurites(Theo.)) the peaks do not all occur at the same time, but form a succession.

Moonlight (at least in the forest canopy) has no apparent effect on the timing of these crepuscular surges of biting activity.

One species (M. fuscopennata) also shows a peak of biting activity before sunrise. This peak is closer to sunrise than the evening peak is to sunset. A brief reference to current work carried out above the canopy, where foliage, shadows, etc., do not complicate the environment, shows that this phenomenon occurs in other species also. It is concluded that in these species the morning peak must almost certainly occur in light of much greater intensity than the evening peak.

The implications of these findings are discussed with reference to the questions of endogenous rhythm and exogenous stimuli.
A laboratory rearing method for the cocoa Mirid Distantiella theobroma (Dist.) (Hemiptera, Miridae)
Authors: Prins G.
Published: July 2009

A method is described for continuous rearing of Distantiella theobroma (Dist.) in the laboratory at approximately 75°F. and 65 per cent, relative humidity. Adults were caged on young cocoa twigs, and the mated females transferred to cocoa seedlings for egg-laying; 24 hours after hatching, the nymphs were transferred to unripe cocoa pods. The egg and nymphal stages lasted about 14–16 and 23 days, respectively.
The identification of blood-meals from Culicine mosquitos from Northern Nigeria
Authors: Service M. W.
Published: July 2009

Precipitin tests were performed on 238 blood-smears made from Culicine mosquitos collected from natural resting places at three sites, in the area surrounding a village, in uninhabited forest, and at an uninhabited rock outcrop in savannah vegetation in Northern Nigeria. In calculating the percentages of blood-meals that were positive for the various animals, the following criteria were applied: all negative results were subtracted from the totals tested; in calculating mammalian, but not avian or reptilian, percentages, all records that referred to “mammal, weak smear” were subtracted; “unidentified mammal” was included in the calculations. Results showed that Culex pipiens fatigans Wied. (taken only in the area surrounding the village) had fed mainly on man (45%) and birds (36%), and while Aedes vittatus (Big.) (taken only at the rock outcrop) fed to some extent on both man (14%) and birds (18%), the majority of blood-meals (54%) had been obtained from the porcupine (Histrix cristata). It is thought that these feeds on man from individuals of Ae. vittatus taken at an uninhabited site may have been obtained from villagers using a road about 150 yd. from the outcrop. Ae. luteocephalus (Newst.) (the majority of which were taken in forest) also fed to some extent on porcupine (11%) and birds (16%), but the principal host appeared to be Bovids (74%). It was established for the first time that Uranotaenia mashonaensis Theo. (the majority of which were taken in forest) bites man (29%); mammals other than man and birds accounted for 29 and 24 per cent., respectively. Half of the blood-smear samples obtained from females of this species did not react to any antisera, and were classified as negative.
The control of Hylemya arambourgi Séguy (Dipt., Anthomyiidae) on barley
Authors: Bullock J. A.
Published: July 2009

The larva of Hylemya arambourgi Séguy is an important pest of barley in Kenya; it attacks the shoots, causing death of the central leaf. Three to four shoots are destroyed by each larva, and an early, heavy infestation, under conditions of drought, may cause complete loss of the crop. Where a crop is obtained, the effect of an infestation on yield is difficult to assess, because climatic factors play a major part in determining ultimate figures.

The life-cycle is briefly described.

Trials with various methods of chemical control showed that only seed treatments were consistently effective. Other forms of pre-sowing treatment were ineffective at economic rates of application, while a spray applied after an attack had developed was of little value. Sprays applied prior to the development of an attack gave variable results but were usually ineffective.

The most satisfactory chemicals used as seed treatments were dieldrin and heptachlor. Aldrin and endrin were sometimes effective, while γ BHC, carbaryl, dimethoate and thiometon were ineffective. A formulation of chlordane was also ineffective, but this failure may have been due to poor dispersion on the seed. It is probable that the insecticide acted mainly as a systemic poison, since larvae rarely enter the soil before the time of pupation.

Both dieldrin and heptachlor were initially used at rates of 4·6–5·0 oz. of active ingredient per 100 lb. seed, but usually gave as good results at rates of 3·5 and 3·2 oz., respectively. Dieldrin gave a measure of control at even lower rates.

The prospects for cultural methods of control appeared slight. No evidence of varietal resistance was obtained, while the possibility of control by restrictions on the sowing season is ruled out by the lack of evidence of diapause and the probability that Pennisetum clandestinum and other Gramineae, such as Chloris gayanaand Setariasp., serve as alternative hosts. For the same reasons, it is considered unlikely that any change in the position of barley in the seven-year rotation would have any effect on the level of infestation.
Pests of cowpea and their control in Northern Nigeria
Authors: Booker R. H.
Published: July 2009

Crops of cowpea (Vigna unguiculata) in Northern Nigeria are normally subject to such heavy attack by insects that the potential yields are seldom realised. The most important pests are Maruca testulalis (Geyer), which damages flowers and pods, Piezotrachelus varium (Wagn.), which attacks seeds, and the Coreids Acanthomia brevirostris Stål, A. horrida (Germ.), Anoplocnemis curvipes (F.) and Mirperus jaculus (Thnb.), all of which destroy pods. Pests that attack the pre-flowering stages of the cowpea are economically less important. Field surveys showed that, in 1961, Maruca testulalis, P. varium and Coreids together destroyed 62, 92 and 19 per cent, of the potential crop of seed from sowings in June, July and August, respectively. The corresponding percentages for 1962 were 55, 75 and 29, respectively.

The effectiveness of insecticides in the control of the pests that attack after flowering has commenced was investigated in field trials at Samaru, Northern Nigeria, in 1961–63. The results showed that large increases in yield could be obtained by spray treatments starting at the first appearance of the flowers. The best of these, consisting of 1 lb. DDT with 0·1 lb. BHC per acre applied six times at weekly intervals, gave an average yield over the five trials of 1,623 lb. dry seed per acre, which is a substantial increase over the estimated national average of 158 lb. per acre. Three applications of DDT/BHC, and six or three applications of Sevin at 1 lb. per acre, gave poorer results on the whole. Insecticidal treatment reduced the incidence of all pests and led to a corresponding reduction in flower losses. It also compressed the flowering period, induced earlier flowering and pod production, and caused the bulk of the crop to mature at one time. Haulm production was also reduced, and crops grown for haulms rather than for seed should therefore not be treated with insecticides.