From a critical review of the literature, it is concluded that the role of carbon dioxide in host-seeking by mosquitoes comprises two distinct actions. Firstly, it acts as an ‘attractant’, orientation towards the host being mediated by kinesis and optomotor anemotaxis. When tested in the absence of moving air currents, orientation to the source is not possible and only the kinetic or ‘activating’ effect is manifested. Moreover, in the absence of other host factors, sustained flight takes place only in response to intermittent pulses of carbon dioxide; this response is not elicited in uniformly permeated airstreams. Secondly, carbon dioxide has a combined action with warm moist convection currents at close range and with odour factors at a distance from the host.

Single pair progenies (sibships) of three organochlorine resistant strains of Rhipicephalus appendiculatus Neum. from Kenya, Tanzania and Uganda showed similarity in dose-mortality response to γ-BHC. The homogeneous dose-mortality responses indicated such larvae have a similar high level of resistance, whereas the stepped nature of the dose-mortality curve for the heterogeneous sibships indicated that these sibships include both resistant and susceptible larvae. Crosses between the Uganda strain and the susceptible reference strain (Mwanza) indicated that a dominant gene exerts a major influence on resistance to γ-BHC and dieldrin. For some heterogeneous sibships the dose-mortality response indicated a significant departure from a 1:1 ratio of susceptible: resistant larvae. The deviation could be reduced by increasing the susceptible background genotype. The deviation differed in direction for different crosses, suggesting a genetic influence. The deviations occurred in all three resistant strains. Line selection of deviating sibships in either direction was unsuccessful.

A synoptic view is given of the data amassed by WHO, with technical assistance from the Imperial College of Science and Technology, on the origins of blood-meals in Anopheles samples collected from 1971 to 1978. Attention is focused on the proportion of each sample found to contain human blood and on the problems of interpreting from this the human blood index or degree of biting-contact with man exhibited by vector populations. The difficulties of overcoming bias in sampling, which are formidable in unsprayed areas, are further compounded where the dwellings are treated with a slow-acting residual insecticide which knocks down many engorged mosquitoes before they can be collected from their daytime resting places. There is evidence to suggest that the host-selection patterns of those vectors which are ‘opportunistic’ feeders may be heavily influenced, even from village to village or from month to month, by the changing availability of alternative hosts, particularly cattle. This suggests in turn that the possibilities of manipulating the degree of mosquito-man contact by encouraging deflection to animals (zooprophylaxis) or by measures to afford a degree of personal protection should not be under-estimated by malaria strategists. It may sometimes be found less difficult to reduce the vector’s human blood index than it is to measure it, but in view of the epidemiological importance of this parameter, suggestions are put forward for improving entomological field practice in this area. They include a quantitative survey of the biotopes available to the mosquito population as diurnal shelters, a longitudinal survey of the densities of blood-fed females per biotope, and a survey of the numbers and the respective distribution of people and domestic animals available as hosts. The work-load entailed by such a thorough form of investigation, to be repeated where necessary at different seasons of the year, underlines the necessity to concentrate efforts on a small number of localities, carefully chosen for the malaria situations they represent and the vector populations they support. A large-scale blood-meal sampling programme, confined to these selected localities, is most likely in our estimation to yield information of value for controlling malaria vectors.

Soil-dwelling tenebrionid larvae have developed in three evolutionary lines and are pests in all faunal regions. Description of and keys to most of the important species are available. However, revisional studies, on both adult and larval characters, are needed in many groups. The basic number of non-sex chromosomes appears to be 18, but the number and type of sex chromosomes are variable. Host ranges of both larvae and adults are usually extensive but usually only include plants. Development rates are related mainly to temperature, with life-cycles of one, two or three years. Larval development periods are rather long, and adults are long-lived. The number of instars is high, often above ten and frequently variable within a species. Sampling is best carried out by direct counts and pitfall trapping. In the species studied, mating follows a regular pattern and pheromones are involved. Species show definite temperature, moisture and soil-type preferences and these influence both spatial and temporal distribution. Recorded parasitoids include Diptera (mainly tachinids), Hymenoptera, mites, bacteria and fungi. Birds, carabids and a variety of other vertebrates are the main predators, but abdominal secretions and postural mechanisms provide some defence. Cultural control was formerly widely practised but has given way to chemical control.

At Nsukka in south-eastern Nigeria, nymphs of the wet-and dry-season generations of Zonocerus variegatus (L.) overlapped, both in time (January to March) and in space. Contrary to some previous suggestions, adults of the two generations also overlapped (mid-May to end-July), and copulation occurred between individuals of both sexes in the laboratory.

The effects were examined of constant temperature on the life-cycle of Paulinia acuminata (Deg.), a potential biological control agent for Salvinia molesta. Over the range of temperatures tested (25–36°C), the duration of the life-cycle varied from approximately 85 days to 38 days. Egg development was most rapid at 33–36°C, but percentage hatch was greatest at 33–34°C. The duration of the nymphal period continued to decrease up to 36°C. The optimum temperature for nymphal development appeared to be higher than for eggs since temperature did not significantly affect nymphal mortality, which was about 50%. There were sometimes five and sometimes six instars, six being rather more common at lower than at higher temperatures. Crowded nymphs developed more slowly than isolated ones. Population growth rate statistics were calculated by combining data from several series of experiments. In an attempt to predict the results of a release of Paulinia at Lake Kariba between Zambia and Zimbabwe, these statistics were related to the mean annual temperature on the lake. It was estimated that P. acuminata would undergo three generations a year, with the population increasing by a factor of 8000 per annum.

Energy values for Glossina morsitans morsitans Westw. and for the vertebrate blood which constitutes its food were determined. On this basis, energy budgets for the hunger cycle were drawn up over a range of temperatures. The results indicate that daily flight duration for females is limited to a few minutes, while for males it averages about 15 min in the hot season and more than twice as long in the cold season.

Field experiments were conducted in the Gambia, West Africa, on the density of mosquitoes approaching animal baits (two goats). Using an array of ramp-suction traps arranged radially around baits, it was found that the density of Mansonia males was significantly greater at a distance 3 m from the bait than at distances of 7 and 15 m. By contrast, catches of Culex and Anopheles males were no higher at 3 m than at greater distances. It is concluded that Mansonia males, but not males of the other genera studied, are attracted to mammals from at least 3 m. Catches of Mansonia females were greater at 3 and 7 m than at 15 m, indicating that they are attracted to hosts from a greater distance than the males. This behaviour facilitates mate-finding by bringing the sexes together in the vicinity of the host.

Examples of the persistence of adult infestations of Chortoicetes terminifera (Wlk.) in Australia were contrasted with ones where mass displacement took place. Migration occurred if sufficient rain had fallen at the nymphal stage to produce green pasture; persistence was associated with drought.

Coptotermes acinaciformis (Frogg.) was collected from three different mound colonies and placed in holding jars in a matrix of mound material from an alien colony. After transportation and maintenance in a controlled insectary for 28 days, they were separated from the holding jars and pooled according to colony origin. They were then used in mixed groups of various combinations in a bioassay test of their feeding capacity and survival. Termites from a fourth colony were used to determine whether pooling of individuals originating from the same colony but maintained in different holding jars had any effect on their feeding and survival in the laboratory. It was shown that, although termites from the same original colony can be re-united without detriment after transportation and maintenance, those from different colonies cannot be mixed to form reproducible bioassay groups. Although chilling before mixing produced a slight improvement, the resulting groups were still unsuitable for use in bioassays. It is noteworthy that when brought together after maintenance in the holding jars under identical conditions in an identical matrix, the termites were able to recognise and accept fellows from their own colony and to detect and reject those from other sources.

Assortative mating amongst species of the complex of Anopheles gambiae Giles that occur sympatrically in West Africa was investigated in laboratory mating-choice experiments using dieldrin resistance and hybrid sterility as genetic markers. In competition experiments involving A. gambiae and A. arabiensis Patt., mating was found to be assortative. No effect of cage volume was observed on the operation of the specific mate-recognition system. On the other hand, experiments in which A. gambiae and A. arabiensis were caged separately with A. melas Theo. failed to show the presence of mating barriers known to operate in nature. Similar cage experiments conducted with two different strains of A. gambiae showed that there was no marked mating barrier between the strains. Other experiments showed that hybrid females from the cross between A. gambiae females and A. arabiensis males and the reciprocal cross would mate with both parental types as well as their own males in cages.

In experiments at Slough, southern England, one hundred tonnes of wheat at about 14% moisture content were divided between six similar metal bins, three of which were aerated during the winter. Observations were made on the mite and fungal populations and physical conditions for an uninterrupted storage period of three years. During the winter, the wheat in the aerated bins was 2–4°C cooler than that in the unaerated bins and it always had a moisture content 0·5–1% higher, except at the surface where it was usually drier. Aeration appeared to delay the increase of Acarus siro L. and Lepidoglyphus destructor (Schr.) for 4–6 months after harvest, but few individuals survived into the second year of storage in any bin. Cheyletus eruditus (Schr.) and Tydeus interruptus Thor were present after one year and were most numerous in the aerated bins. The distribution within the bins of the different species of mites varied with season. A greater increase in storage fungi occurred in the aerated bins than the unaerated. Members of the Aspergillus glaucus and A. restrictus groups, Penicillium spp. and Wallemia sebi were the commonest fungi.

The demographic performance of a laboratory strain of Phthorimaea operculella (Zell.) was characterised by measurements of seven parameters under standard breeding conditions at six constant temperatures. The parameters were fertility, larval survival, sex ratio, weight of females, fecundity, development time and adult life-span. This information provides reference values which would be useful in experiments designed to determine the demographic effects of treatments, to identify strains and genetic populations of the species, and eventually to detect evolutionary changes in the specific properties of forms under study. The results of this investigation could be used in constructing simulation models of the species’ life system.

Diflubenzuron was applied once at 2·5–20 g a.i. in 10 litres of water to coconut palms infested with larvae of Nephantis serinopa Meyr. in Tamil Nadu, India. The entire field population of larvae was eliminated within 14 to 18 days, depending on the dose. The mortality due to moulting inhibition in larvae treated in the field and then brought into the laboratory ranged from 77·4 to 88·8%. The higher the dosage, the higher was the inhibition of transformation to the pupal and adult stages. Diflubenzuron also apparently had an antifeedant effect on the larvae. The compound directly or indirectly affected the development of Parasierola nephantidis (Mues.), a parasite of N. serinopa. The preference of female parasites for parasitising host larvae and oviposition in and the number of progency produced from a single host larva that had been treated with diflubenzuron in the field were significantly reduced. The percentage of normal adults produced from treated parasite larvae ranged from 17·3 to 43·0% as against 99·1% from untreated larvae. Treatment of mature parasite larvae directly with diflubenzuron in the laboratory affected development and caused morphological deformities in the adults.

The physiological age of female Stomoxys calcitrans (L.) caught biting horses during seven all-day catches and 20 catches in the morning or afternoon during the rainy season (January-July) in Manaus, Amazonas, Brazil, was determined by examination of their ovaries. Males and unmated females with undeveloped ovaries had similar biting patterns, with peaks of activity in the early morning and late afternoon, when the relative humidity was between 50 and 80%. Nulliparous inseminated females with ovaries at Stages II to V attacked throughout the day, with no pronounced peaks, whereas parous females showed a peak of biting in the late morning and early afternoon. The majority of parous flies had oviposited less than four times and had distended overiolar sacs, indicative of recent oviposition.

The cossid moth Azygophleps albovittata Bethune-Baker is recorded for the first time as a pest of groundnuts in northern Nigeria. This is the first food-plant record for the species and, as groundnuts were only introduced into Africa 400 to 500 years ago, there must be at least one indigenous host-plant. The larval, pupal and imaginal stages are described and figured. Attacks by larvae of this moth appear to be confined to crops on sandy and gravelly soils, as groundnuts grown on lateritic soils at Samaru are not affected. Larvae cause massive damage to the crown of the plant, but attacks are highly localised and never affect more than 20% of plants. As larvae diapause throughout the dry season, crop rotation may prove to be an effective means of control.

A single male and female were removed from a well-established laboratory colony of Glossina morsitans morsitans Westw. and became the parents of an inbred stock. In general, each subsequent generation comprised ten randomly selected females mated to one of three randomly selected males, both sexes being offspring of the preceding generation. The inbred stock was fed on the ears of rabbits for 40 generations, over a period of almost eight years. Performance, in terms of length of female life, female fecundity, number and weight of puparia produced, effective emergence rate from puparia and sex ratio of emerged flies showed little variation between generations. By generation 40, the inbreeding coefficient was 0·9347; over the same eight years, the inbreeding coefficient of the parent colony of G. m. morsitans was less than 0·0303. It is concluded that the risks of inbreeding having deleterious effects on laboratory colonies of Glossina are slight.

Sixty-seven per cent of parasitoid mummies which developed from Metopolophium dirhodum (Wlk.) collected in wheat fields at Rothamsted, southern England, in 1979 were of Toxares deltiger (Hal.), a species previously unrecorded from cereal aphids. T. deltiger formed only 1% of samples when parasitoid mummies were collected directly from cereals in the field. Laboratory observations of the parasitoid indicate that affected aphids probably leave the host-plant prior to death and mummy formation.

A key is provided to the ten genera of Anomaloninae occurring in sub-Saharan Africa. The numbers of African species in the various genera are discussed with particular reference to those having potential economic importance as parasites of Lepidoptera. Parania Morley is recorded for the first time from Africa, and two new species P. prima sp. n. and P. secunda sp. n. are described. A number of new host records are given.

The dynamics of Bemisia tabaci (Gennadius) were followed during two years in treated and untreated cotton fields in three locations in Israel. Two parasite species, Encarsia lutea (Masi) and Eretmocerus mundus Merc., were the only important natural enemies, but percentage parasitism did not rise with increase in the host population. The whiteflies reached peak populations at the end of the summer. Their distribution upon the plants was not uniform, rather, they tended to concentrate on a few leaves. The leaf bearing the maximal population was the sixth or seventh until mid-July. From then on, its location was variable according to the growth pattern of the foliage. Insecticide treatments, in particular with aldicarb, resulted in depression of both whitefly and parasite populations, but neither was exterminated.