The suggestion that mosquitoes can discriminate ABO blood group status in man was re-examined and an attempt made to determine recognition mechanisms.

Host choice was assessed in the laboratory by recording landings on and blood-meals taken from the forearms of pairs of human volunteers in a 10-min exposure to 20 females of species A of the Anopheles gambiae complex, and an alternative procedure, which did not involve mosquitoes probing the host's skin, was developed and evaluated. The presence of weals on the host's skin was found to be an unreliable indicator of probing or feeding activity by mosquitoes. The effect of thermally induced sweating was also investigated.

No effect of ABO blood group status on host choice was found. Mosquitoes did, however, show a highly significant preference to land and feed on a subject when thermogenic sweating was induced. Secretor substances in the sweat did not influence host selection.

The predictive value of host variables such as MN blood group, skin temperature and humidity, skin colour and forearm hair density in determining host choice was examined. Very little of the observed variation in mosquito activity could be accounted for by these host variables within the ranges used.

Nucleotide diversity was examined at mitochondrial COI and r16S2 loci in eight Glossina swynnertoni Austen collections from northern Tanzania and from a culture maintained by the International Atomic Energy Agency. Eighteen composite haplotypes were observed among 149 flies, two of which were common to all samples and 10 were private. Mean haplotype diversity was 0.59 and nucleotide diversity was 0.0013. There were excess singular haplotypes and mutation-drift disequilibrium suggesting that populations had experienced an earlier bottleneck and subsequent expansion. Factorial correspondence analysis showed that haplotype frequencies varied much more temporally (GST = 0.18) than spatially (GST = 0.04). The estimate of effective population size Ne in Tarangire was a harmonic mean ~50 reproductive flies averaged over ~47 generations. The mean rate of gene flow was estimated to be ~5±1 reproducing females per generation but inflated because of mutation-drift disequilibrium arising from likely earlier bottlenecks.

The activities of the Australian Ladybird beetle, Cryptolaemus montrouzieri, Muls., are too well known to need recapitulation. It is sufficient to say that it has been introduced into many countries with a greater or lesser degree of success, generally for the control of “ mealy-bugs.”

The introduction of this beneficial insect into Egypt may present certain features of interest to other workers in spite of the fact that there is a great deal yet to be done. Series of experiments have been designed to elucidate certain points, but owing to the departure of the writer from Egypt these have been left to others to carry out. A detailed account of this work had been planned for a later date, but in the circumstances it may be as well to place on record what has been done up to the present time.

The following notes are based almost entirely upon actual rearing records, the hosts in most cases being insects of economic importance. The greatest attention has been paid to parasites of the small moth-borers of sugar-cane (Diatraea spp.). The systematic work has been done entirely at the British Museum and would have been impossible without the facilities in literature and collections there, and the great help of Mr. D. S. Wilkinson and Dr. C. Ferrière, of the Imperial Institute of Entomology. Types of new species are in the British Museum.

In the field in India, most eggs of Chilo partellus (Swinh.) hatched in the morning soon after first light. Laboratory experiments show that in continuous light hatching occurs after 250 hour-degrees of development above 12°C from the time at which the head capsule darkens (blackheading). Hatching may be advanced by a lights-on stimulus or retarded by darkness, and these effects account for the extensive hatching at dawn. Hatching is not entrained by a circadian rhythm. The significance of hatching at this time of day is discussed.

Pedronia festeriana Lizer y Trelles is found on Cereus aethiops, Cleistocactus baumannii, Eriocereus bonplandii and E. martinii in Argentina. It severely distorts the growing tips and could possibly be used to control these weed cacti. The species is transferred to Hypogeococcus and redescribed from material collected recently in Argentina. Pseudococcus eriocerei is described as new also from the roots of Eriocereus bonplandii.

The Indian custom of placing metallic mercury with the grain in the storage container to prevent infestation by insects has been investigated. It is found to have a sound scientific basis as the presence of mercury prevents the reproduction of certain of these pests.

Experiments showed that the vapour of mercury was fully effective in preventing reproduction of the grain weevil (Calandra granaria), the saw-toothed grain beetle (Oryzaephilus surinamensis), the lesser grain borer (Rhizopertha dominica), and the Angoumois grain moth (Sitotroga cerealella).

Zinc and tin amalgams and calomel were less effective than metallic mercury.

The efficiency of a given weight of mercury is increased by subdivision, a process which increases its total surface area.

A quantitative analysis of the foraging behaviour of Acromyrmex octospinosus (Reich) from three nests on 27 yam varieties of nine species was undertaken in Guadeloupe using a video-microcomputer device. In ants with no previous experience of the variety, foraging inhibition appeared only after at least a whole day of contact with resistant yam leaves. There was a negative correlation between leaf saponin content of the yam species and foraging intensity; however, the main yam sapogenin, the steroid diosgenin, had no effect on foraging behaviour, and tomatin, a steroid-alkaloidal saponin, induced only long-term deterioration of the fungus garden when incorporated in the nest. The saponins tested are thus not detected by the ants and are therefore unable to initiate the strong and rapid foraging inhibition observed with resistant yams.

Significant inter-crop variation in the abundance of phlebotomine sandflies, mostly Lutzomyia verrucarum Townsend, and five aphid species (Hemiptera: Aphididae), was demonstrated by repeated castor oil sticky trap collections in two valleys in the Peruvian Andes. Sandfly populations were significantly higher in fruit crops than in ground crops. Sticky trap collections also proved to be a suitable method for measuring aphid relative abundance in crops. As aphid honeydew is a natural sugar source for phlebotomine sandflies, the relationship between the activities of sandflies and aphids was investigated in inter-crop comparisons. Significant correlations were detected between sandfly abundance and two of the major aphid species, Aphis gossypii Glover and Eriosoma lanigerum (Hausmann), in one valley, but indirect explanations for these apparent associations cannot be ruled out.

The genus Cicadulina was erected in 1926 (Bull. Ent. Res., xvii, p. 43) to hold C. zeae, a new species injurious to maize in Kenya Colony. Thanks to the kindness of Mr. T. J. Naudé, I have since been able to examine specimens of Balchitha mbila, Naudé, which has been recorded as transmitting the virus of streak disease of maize in Natal. This species is undoubtedly congeneric with C. zeae and differs from typical Balclutha species in the shape of the head and pronotum, and in the venation of the tegmina. It should, therefore, be known in future as Cicadulina mbila, Naudé.

Colonization of a novel plant by herbivorous insects is frequently accompanied by genetic changes that progressively improve larval or adult performance on the new host. This study examined the genetic basis of adaptation to a marginal host (lentil) by the seed beetle Callosobruchus maculatus (F.). Quasi-natural selection in the laboratory rapidly increased the tendency to oviposit on lentil. The mode of inheritance of this increase in host acceptance was determined from crosses between three lentil-adapted lines and a line maintained on the ancestral host, mung bean. In each set of crosses, females from the lentil lines laid two to three times more eggs on lentil than did females from the mung-bean line. Hybrid females consistently displayed an intermediate level of host acceptance, which did not differ between reciprocal crosses. Alleles promoting greater oviposition on lentil thus were inherited additively, with no evidence of sex-linkage or cytoplasmic effects. In a time-course study, hybrid females initially resembled the parent from the mung-bean line, as few eggs were laid on lentil during the first 24 h. However, oviposition rates on lentil after 72 h were closer to the rate observed in the lentil-line parent. Inferences about additivity vs. dominance in genes affecting oviposition may, therefore, depend on experimental protocol. Comparison with earlier work suggests that inheritance patterns observed in crosses between recently derived selection lines (as in this study) may differ from those obtained in crosses between long-divergent geographic populations.

An account is given of a series of experiments on the feeding habits of Cryptophagus acutangulus, Gyll. It was shown that this species will feed readily on a wide variety of fungi and will only rarely ingest other foods. It thrived when fed exclusively on Penicillium conidia. C. acutangulus is capable of the internal mechanical and external transmission of fungi. Approximately 15 per cent. of the Penicillium conidia germinate after passing through the alimentary canal, and these conidia are so affected that they have an enhanced germination rate. The larvae feed exclusively on the spores and hyphae of fungi.

A complete life-history from egg to adult is given. The larvae and pupae are described for the first time, and a description of the adult is also given.

Ruminant dung is a highly ephemeral, patchily distributed resource, which is used by a diverse community of invertebrate species. In such environments, high levels of insect aggregation may be important in facilitating stability and coexistence across patchily distributed populations. The aim of the present work was to quantify the aggregation of the insects colonising cow-dung in cattle pasture in southwest England and to test the hypothesis that the dung-pat community assemblage observed was the result of stochastic colonization. This was examined using batches of ten standardised, 1.5 kg, artificial cow pats placed out in cattle pastures in each of 24 weeks between May and October in 2001. Pats were left exposed in the field for seven days before being brought back to the laboratory, where any insect colonizers were collected and identified. Individual pats contained, on average, only half the number of insect taxa present in an entire batch put out at any one time. All larval coleopteran taxa, 20 of the 22 adult coleopteran taxa and 22 of the 23 dipteran taxa, showed significant aggregation, with the abundance of most taxa within pats approximating a negative binomial distribution. A simulation analysis was used to show that the observed relative frequency of taxa within pats did not differ from that expected by chance if colonisation is a random binomial event in which each species colonises a pat independently of all other species. Aggregated populations, of even highly abundant insects, may be more susceptible to the deleterious effects of insecticidal contaminants in dung than if they were evenly distributed, if by chance they colonize a pat containing insecticidal residues from a recently treated animal.

Pyrethroid-impregnated bednets are being used nationwide in The Gambia. The future success of this malaria control programme depends partly on the vectors remaining susceptible to those insecticides used for treating the nets. The present study was carried out on the south bank of the river Gambia, during the first large scale trial of nets in this country. Thus this area represents a sentinel site for detecting insecticide resistance in local vectors. This study gives an example of how a system of early detection for resistance problems can be set up in a relatively complex situation where multiple vectors and non-vectors are present. Samples of the Anopheles gambiae complex were caught indoors using light traps in twelve villages used in the bednet study. In all villages A. gambiae sensu stricto Giles was the predominant member of the complex as determined using the rDNA-PCR diagnostic assay. Limited bioassays with DDT and permethrin, and biochemical assays for a range of insecticide resistance mechanisms suggest that the A. gambiae complex remains completely susceptible to all major classes of commonly used insecticides including pyrethroids. Biochemical assays suggest that a low frequency of DDT resistance may occur in A. melas Theobald. This is based on elevated glutathione S-transferase levels coupled with increased levels of DDT metabolism and does not involve cross-resistance to pyrethroids. Therefore we do not envisage a decline in the efficacy of treated nets against malaria vectors in the study area in the immediate future, although monitoring should be continued whilst wide-scale use of impregnated bednets is operational.

(1) Sprays that are atomised and mingled with air were unsuitable because they were wasteful in both material and labour.

(2) Knapsack oilers and modified stirrup pumps were efficient. Where labour is cheap hand-operated sprayers of this type are more economical than motoroperated machines.

(3) The relation between mosquito mortality and infectivity is discussed and it is calculated that any treatment which produces 75 per cent. mortality among the mosquitos exposed to it should effect malaria elimination.

(4) The effects of a DDT emulsion were much more durable than those of a similar quantity of DDT in kerosene solution. The difference was much less marked when Gammexane was used. Emulsions will probably displace kerosene solutions as vehicles for the application of residual films.

(5) The persistence of the effects of DDT was markedly increased by increased dosage, so that it will be most economical to apply DDT in heavy doses at long intervals.

(6) The persistence of Gammexane effects was not greatly increased by increased dosage because it evaporates much more quickly than DDT. It is not likely to be effective for much longer than 10 weeks.

(7) Treatments with DDT were usually effective against A. minimus for about twice as long as against A. vagus or Culicines, but treatments with Gammexane had similar effects on all species.

The subject of ticks and the diseases they convey is one of great practical importance to agriculturists and pathologists in such a country as the Congo. Of the species recorded from the Congo, one conveys relapsing fever to man and eight have been shown to convey diseases to domesticated animals in various parts of Africa.

A series of investigations was conducted to evaluate the comparative attractiveness of cattle, sheep and goats to Glossina morsitans morsitans Westw. and G. pallidipes Aust. in the Zambesi Valley, Rhodesia. It was shown that cattle are subjected to in excess of three times the challenge by male G. m. morsitans than either sheep or goats. Due to the repellent effect of man's presence on the attraction and feeding of female G. m. morsitansand both male and female G. pallidipes on the bait animals, no rational relationship could be postulated for them. Possible factors accounting for the difference of attractiveness between the three bait species are discussed.

In 1932 on an expedition in Brazil, Dr. J. G. Myers, of the Imperial Institute of Entomology, while in search for suitable parasites for introduction into this and other colonies in the West Indian area, discovered the Tachinid fly Metagonistylum minense, Towns., known generally now as the Amazon fly, as an important parasite of Diatraea saccharalis, F., in the vicinity of Santarem on the Amazon, and as the result of his investigations there, formed the opinion that it would be a suitable parasite for introduction into British Guiana.

The factors responsible for the biological control of insect pests fall into three main groups. The first group includes the micro-organisms (Protozoa, Bacteria, and Fungi) producing what is ordinarily called disease; the second comprises the entomophagous insects which lead, during part or all of their life-history (generally during the larval stage only) a parasitic existence, while the third contains a great assemblage of animals of various kinds which agree in being carnivorous in habit and are known as predators. It is difficult to formulate definitions of parasite and predator which are applicable to all cases. The most satisfactory general distinction is perhaps the one recently suggested by E. Rabaud (1928), who restricts the term “parasite” to species which remain permanently attached to a living host, and considers as predators all species which come into contact with the host organism only at feeding time. Each of these categories can be subdivided, according to the effect the parasite or predator exerts upon its host, into sublethal or benignant and lethal or malignant species. Few, if any, of the parasitic entomophagous insects are of the sublethal type, the species whose habits correspond most closely to the definition being perhaps the bee-louse (Braula coeca, Nitzsch), which, however, is rather a commensal than a parasite. A few parasitic insects, such as some of the dipterous parasites of Orthoptera and Dermaptera (Thrixion halidayanum, Rond., on Leptynia hispanica, Bol.— v. Pant el 1897; Rhacodineura antiqua, Meig. on Forficula auricularia, L.—v. Thompson 1928) do not actually kill their host before issuing, but it dies usually within a relatively short time. In the majority of cases the host is destroyed before the parasite has completed its larval development. Benignant predacious entomophaga are also uncommon among the Arthropods. Certain Chironomids, Simuliids and even Culicids suck the blood of caterpillars, adult dragonflies, moths and butterflies, and other insects, without necessarily killing them (v. Edwards 1923) ; but, in general, the entomophagous insect and Arachnid predators, being as large as or larger than their hosts, cause death, as do the vertebrate predators.