Glypta leucotretae, sp. n.

♀♂ Dark red ; head and antennae (except as follows), pro- and mesosternum to a greater or less extent, hind legs entirely (except as follows), apical third or fourth of the 4th tergite, the succeeding tergites, and the ovipositor sheaths, black ; apical joint of the scape, the extreme base and extreme apex of the hind femora, the extreme bases of the hind tarsal joints, and the hind tibial spurs, reddened ; the four anterior legs (except as follows), and the palpi, more or less red testaceous ; the clypeus, mandibles (except the teeth), scape below (in one ♂ specimen), the coxae and trochanters of the four anterior legs, a large elongate spot occupying the basal half of the dorsal surface of the hind coxae, the pronotum, the propleurae narrowly along their upper margin, and the wing-insertions of the fore-wings (but not the tegulae), white ; the ventrites and the ovipositor very pale ; stigma and wing-veins uniformly opaque brown.

A spray trial of a nuclear polyhedrosis virus (NPV) as an insecticide for Euproctis chrysorrhoea (L.) is described. The trial was carried out indoors in the spring on third-instar larvae emerging from overwintering nests onto small potted hawthorn trees (Crataegus sp.); the equipment used was the Turbair Fox Ultra Low Volume Sprayer. Dosages applied ranged from equivalents of 1 × 1011 to 1 × 1013 polyhedral inclusion bodies (PIB) per hectare. Infection was first detected in samples of live larvae after ten days and indicated rates of infection consistently lower than the final mortality attained. Larvae began to die of NPV infections 11 days after spraying, and mortality due to the virus ceased after ca 20 days; most larvae died in the fourth instar. Over the range of virus doses from 1 × 1011 to 5 ×10 12 PIB/ha mortality levels rose with dose, to a maximum of over 90%. Increasing the dosage to 1 × 1013 PIB/ha elicited no further increase in mortality. This preliminary trial suggests that the virus has considerable potential as a control agent, and field trials are, therefore, in progress.

Resistance involving penetrability of cotyledons of subterranean clover Trifolium subterraneum (Leguminosae) by the redlegged earth mite, Halotydeus destructor Tucker, was examined in this study using several approaches. Values of penetrability, presented as mechanical strength measured with a penetrometer with a tubulated probe, of cotyledons tested 11–13 days after seeding, from nine varieties of two subspecies of subterranean clover (T. subterraneum subsp. yanninicum and subsp. brachycalicinum) were negatively correlated with feeding damage caused by H. destructor in both 3 h pairwise choice tests in a Petri dish with detached cotyledons, and in 2 week multiple choice tests in containers with seedlings. Simulation tests with different artificial membranes (Parafilm and Gladwrap) making up sachets, containing 5% glucose as a feeding stimulant, indicated that within 3 h H. destructor preferred membranes with lower strength. Field-collected young adults had significantly higher physical fitness to feed and/or gather on the artificial membrane sachet containing 5% glucose, than those from the laboratory culture, when the sachet was compared with cotyledons of either resistant (DGI007) or susceptible (Dalkeith) varieties in the choice tests. Electron microscopic observations of mite infested cotyledons of the resistant variety (DGI007) reveal that upper epidermal cell walls around penetration holes are bent inwards. Anticlinal cell walls of palisade cells appear buckled following attack by H. destructor. The results from these studies were taken as further evidence for the involvement of mechanical factors in antixenotic resistance of subterranean clover cotyledons to H. destructor.

All available identifications of sibling species of the Simulium damnosum complex in southern Sierra Leone for the years 1983–1987 have been analysed for any evidence that they might provide on whether the appearance of S. sirbanum in this area in 1988 is indicative of a gradual southerly extension of range, or a unique occurrence. No evidence was found to suggest a long-term immigration trend over the five years prior to 1988, and the latter of the two possibilities is the more likely. No meteorological or other factors are known that might account for the sudden appearance of S. sirbanum in southern Sierra Leone in 1988, but the possible causes of such immigration into forested parts of West Africa and their epidemiological implications for human onchocerciasis in the region are briefly discussed.

For a wide range of insect species, the microbiota has potential roles in determining host developmental programme, immunity and reproductive biology. The tea geometrid moths Ectropis obliqua and E. grisescens are two closely related species that mainly feed on tea leaves. Although they can mate, infertile hybrids are produced. Therefore, these species provide a pair of model species for studying the molecular mechanisms of microbiotal involvement in host reproductive biology. In this study, we first identified and compared the compositions of microbiota between these sibling species, revealing higher microbiotal diversity for E. grisescens. The microbiota of E. obliqua mainly comprised the phyla Firmicutes, Proteobacteria and Cyanobacteria, whereas that of E. grisescens was dominated by Proteobacteria, Actinobacteria and Firmicutes. At the genus level, the dominant microbiota of E. grisescens included Wolbachia, Enterobacter and Pseudomonas and that of E. obliqua included Melissococcus, Staphylococcus and Enterobacter. Furthermore, we verified the rate of Wolbachia to infect 80 samples from eight different geographical populations, and the results supported that only E. grisescens harboured Wolbachia. Taken together, our findings indicate significantly different microbiotal compositions for E. obliqua and E. grisescens, with Wolbachia possibly being a curial factor influencing the reproductive isolation of these species. This study provides new insight into the mechanisms by which endosymbiotic bacteria, particularly Wolbachia, interact with sibling species.

Environmental temperature is an important driver of the population dynamics of tsetse (Glossina spp) because the fly's immature stages are particularly vulnerable to temperatures (T) outside the range T = 16–32°C. Laboratory experiments carried out 50 years ago provide extensive measures of temperature-dependent rates of development, fat consumption and mortality in tsetse pupae. We improve on the models originally fitted to these data, providing better parameter estimates for use in population modelling. A composite function accurately models rates of pupal development for T = 8–32°C. Pupal duration can be estimated by summing the temperature-dependent daily percentage of development completed. Fat consumption is modelled as a logistic function of temperature; the total fat consumed during pupal development takes a minimum for T ≈ 25°C. Pupae experiencing constant temperatures <16°C exhaust their fat reserves before they complete development. At high temperatures, direct effects kill the pupae before fat stores are exhausted. The relationship between pupal mortality and temperature is well described by the sum of two exponential functions. Summing daily mortality rates over the whole pupal period does not reliably predict overall mortality. Mortality is more strongly correlated with the mean temperature experienced over pupal life or, for T ≤ 30°C, the fat consumption during this period. The new results will be particularly useful in the construction of various models for tsetse population dynamics, and will have particular relevance for agent-based models where the lives of individual tsetse are simulated using a daily time step.

The distribution of Phlebotomus sergenti in Palestine, Syria and Mesopotamia has received special attention, because of the rôle of this species in the transmission of oriental sore.

Acetylcholinesterase (AChE), encoded by the ace gene, is a key enzyme of cholinergic neurotransmission. Insensitive acetylcholinesterase (AChE) has been shown to be responsible for resistance to OPs and CBs in a number of arthropod species, including the most important pest of olives trees, the olive fruit fly Bactrocera oleae. In this paper, the organization of the B. oleae ace locus, as well as the structural and functional features of the enzyme, are determined. The organization of the gene was deduced by comparison to the ace cDNA sequence of B. oleae and the organization of the locus in Drosophila melanogaster. A similar structure between insect ace gene has been found, with conserved exon-intron positions and junction sequences. The B. oleae ace locus extends for at least 75 kb, consists of ten exons with nine introns and is mapped to division 34 of the chromosome arm IIL. Moreover, according to bioinformatic analysis, the Bo AChE exhibits all the common features of the insect AChE. Such structural and functional similarity among closely related AChE enzymes may implicate similarities in insecticide resistance mechanisms.

The larvae of ten species of Ixodid ticks are described, particular emphasis being placed on the setation of the capitulum and palps, and a key is provided to the larvae of 14 species from the eastern Cape Province of South Africa that are common, economically important or difficult to separate. Important characters are illustrated in 62 scanning electron micrographs.

Five years ago, when a study was commenced of the Simuliid fauna of Uganda, 24 species were known from the whole of Africa. To-day, Uganda can claim more than that number within its own boundaries. In fact 30 species are known to occur in the country. And yet it is probable that many more species remain to be discovered, particularly as the investigation has not included the Northern Province, which will undoubtedly prove to be one of the richest in Simulium, since within its confines are the River Nile and its many subsidiary tributaries. Quite a number of species found in Uganda occur in other parts of the African continent. Some extend their distribution over to the west and also to the east coast, while other species do not confine their range to the tropics and are found as far afield as the Transvaal and Natal in the Southern Hemisphere. Early observations (1934) indicated a specialised Simuliid fauna on each of the high mountains in Uganda, and while this may still be true in the case of some species, subsequent investigations have shown that several have a wider distribution.

The epidemic of sleeping sickness in Central Kavirondo was introduced about 1903 from Usoga across a chain of islands, and finally from Mageta Island to the coast of Kadimu close by. Mageta was evacuated, and subsequent return of the population brought back the disease, leading to a second evacuation, second return, and renewal of the disease about 1920–21, leading to final evacuation two years ago.

Glossina palpalis occurs plentifully along the 100 miles of coast examined, between the Sio River and the mouth of the Kavirondo Gulf, except just south of Sio, and in the neighbourhoood of the mouths of the Yala and Nzoia Rivers. Ample evidence was obtained that non-mammalian blood is much preferred to that of the hippopotamus, which was the only source of mammalian blood, except man and cattle at some localities.

1. A serious form of coffee flower abortion that occurred in Kenya Colony in 1930 is described.

2. A Capsid, Lygus simonyi, Reut., is shown by experiments to be capable of causing this abortion.

3. It is shown that by feeding on the stamens at an early stage in the bud's development, the bug causes their early blackening and abortion, resulting in the complete failure of the flower.

4. Some notes on the life-history, habits, and natural enemies are included.

5. It is shown that owing to abnormal flowering conditions in 1930 the bug was enabled to do very serious damage.

6. Some other abnormal conditions of the buds, not considered to be caused by the bug are described.

7. A number of control measures that proved unsatisfactory are shortly described.

8. A detailed description is given of the application of a spray prepared by extracting the insecticidal properties of pyrethrum with paraffin. This spray is inexpensive, easy to apply quickly, and seems likely to prove efficacious on a large scale.

9. It is suggested that such sprays may have a considerably wider application.

My acknowledgements are due to the Senior Entomologist, Mr. T. J. Anderson, for kindly reading the manuscript; also to a large number of coffee-planters, in particular to Mr. P. J. Coldham, on whose estate much of the above work was done, and to whose interest and help, particularly with regard to cultural questions, I owe much.

It is being recognized that for a satisfactory solution of many of the wider problems of Applied Entomology, a study of insect ecology is of paramount importance. It is expected that a knowledge of the factors which influence distribution and abundance of insects will arm economic entomologists better in their warfare against pests. Just recently, Lathrop (1923), Shelford (1927), Buxton (1929), Uvarov (1929), Gryse (1929), and others have shown the importance of meteorological phenomena affecting the development, distribution, and activities of insects. Although our knowledge of the two factors so far studied—temperature and humidity—is far from being complete, still the results so far obtained have proved to be of considerable value. Indeed, instances of the practical application of such knowledge are already available. From his studies on the effects of temperature on household insects, Howard (1896) has shown that cold storage provides an effective control of these pests. Pierce (1916) has correlated the relative advance and retreat of the fall army-worm, Laphygma frugiperda, S. & A., with changes in temperature. He maintains that a proper fixation of the zone of effective temperatures may make it possible to alter the sowing time of winter crops to avoid damage from this insect. Barber (1925) explains the decrease of the European corn-borer, Pyrausta nubilalis, Hübn., during certain years on the basis of adverse environmental conditions. A. Howard (1921), from his observations in India, states that there exists a definite relationship between termite activity and soil temperature.

In the second of this series of papers on the losses caused by the Coreid, Pseudotheraptus wayi Brown, to coconuts in Zanzibar, descriptions are given in summary form of a number of Government-owned plantations of coconuts on the island, together with the yields recorded over the 12 years, 1944–55. The variation from year to year in any group of plantations is not large, and over all those considered does not exceed 25·8 per cent, of the 12-year mean.

In the plantations on poorer soils, predominantly occupied by the ants Anoplolepis longipes (Jerd.) or A. custodiens (F. Sm.), the vidaka damage rate (V.D.R.) during 1955 varied from 60–80. The plantations on better soils are occupied predominantly by a complex of Oecophylla longinoda (Latr.) and Pheidole punctulata Mayr and the V.D.R. determined on a part of these in 1955–56 varied from approximately 41 to 55, with a mean of 47·1. The mean value of the V.D.R. calculated from 200 localities taken at random in Zanzibar during June–August 1955 was 60·6. Taking a value of 50 as a conservative estimate of the V.D.R. for the whole island, and inserting this in the regression equation Y = a + bX relating yield (Y) with V.D.R. (X), derived in the first of this series of papers, together with the average values of the constants a and b obtained therein, it is shown that about two-thirds of the potential crop of coconuts is lost as a result of damage by P. wayi.

Comparison of the yields from palms occupied by Oecophylla in two of the plantations on better soil with those of the whole of those plantations suggests that about one-half of the potential crop is being lost.

The annual value of the total exports of unconverted nuts and coconut products (copra and coconut oil) varied from £636,254 to £1,008,194 during 1949–56, and the annual value of the total production of nuts, calculated from the estimated total acreage (104,000), the number of palms per acre (50), the 12-year average yield per palm on Government-owned plantations (22·5 nuts per annum) and the market price in 1948–56 (Shgs. (E.A.) 90–150 per thousand nuts), is £526,500 to £877,500. Taking into consideration the lower and upper estimates of the amount of crop lost and of the value of what remains, the minimum and maximum estimates of the financial loss caused by P. wayi in Zanzibar are of the order of £500,000 and £2 million, respectively.

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.

The control methods used to protect new-crop groundnuts stored in Kano against insect attack are described.

The main method used was the spraying of aqueous suspensions of DDT directly on to the sacking of piles stored in the open and on the walls of warehouses before the nuts were stacked. The solutions were applied with a slow-moving orchard power sprayer, and 50 per cent, wettable powder applied at the rate of 360 mg./sq. ft. was found satisfactory. The BHC wettable powder applied at about 12 mg./sq. ft. was cheaper and equally as good and has now been found safe. Treatment markedly reduced the Tribolium population but had little effect on Trogoderma. Sprays of oil solutions were little used and were not very satisfactory.

Oligonychus punicae and Oligonychus perseae (Acari: Tetranychidae) are the most important mite species affecting avocado orchards in Mexico. Here we used nucleotide sequence data from segments of the nuclear ribosomal internal transcribed spacers (ITS1 and ITS2) and mitochondrial cytochrome oxidase subunit I (COI) genes to assess the phylogenetic relationships between both sympatric mite species and, using only ITS sequence data, examine genetic variation and population structure in both species, to test the hypothesis that, although both species co-occur, their genetic population structures are different in both Michoacan state (main producer) and Mexico state. Phylogenetic analysis showed a clear separation between both species using ITS and COI sequence information. Haplotype network analysis done on 24 samples of O. punicae revealed low genetic diversity with only three haplotypes found but a significant geographical population structure confirmed by analysis of molecular variance (AMOVA) and Kimura-2-parameter (K2P) analyses. In addition, a Mantel test revealed that geographical isolation was a factor responsible for the genetic differentiation. In contrast, analyses of 22 samples of O. perseae revealed high genetic diversity with 15 haplotypes found but no geographical structure confirmed by the AMOVA, K2P and Mantel test analyses. We have suggested that geographical separation is one of the most important factors driving genetic variation, but that it affected each species differently. The role of the ecology of these species on our results, and the importance of our findings in the development of monitoring and control strategies are discussed.

Two new species of mealybug found on coffee roots are described from Africa. Planococcus fungicolasp. n. from Kenya is the species that has been known in Africa as the coffee root mealybug. This mealybug is almost always associated with the fungus, Diacanthodes novoguineensis (Hennings) Fidalgo. Planococcus radicumsp. n. is from Nigeria and Tanzania. Dactylopius coffeae Newstead is synonymized with Planococcus lilacinus (Cockerell) syn. n.

Megaselia chlumetiae Disney sp. n. is described from India. Its larva parasitizes larvae of Chlumetia transversa (Walker), a pest of Mangifera indica. Eggs are laid on the integument of the host larva. Newly emerged fly larva enter the host and develop by consuming the host's internal tissues. Pupariation normally takes place within the host's empty skin.