A comparison is made of the distribution, breeding, migration and population dynamics of Schistocerca cancellata (Serville) in South America and S. gregaria flaviventris (Burmeister) in southern Africa. The annual patterns of breeding and migration are strongly influenced by the weather and its seasonal variations. Breeding is confined to the summer rains, and outbreak regions lie in the driest parts of the distribution areas, where habitats are unstable but where high reproductive capacity allows the occasionally abundant rains to lead to plagues. The long dry season is passed in the mobile, downwind-displacing adult stage, survival being assisted by flexibility of rates of sexual maturation and of egg development. Some comparisons are made with S. gregaria gregaria (Forskål).

A description is given of the phlebotomine faunas of forests in north Pará State, Amazonian Brazil, that are endemic for ‘pian bois’-type dermal leishmaniasis of man caused by Leishmania braziliensis guyanensis. As judged by collections from human baits, mammal-baited traps, CDC miniature light traps and from various resting sites, only the females of Lutzomyia umbratilis Ward & Fraiha have the habits (both arboreal and terrestrial) and abundance (periodic, seasonal and spatial) consistent with being a major vector to man of Leishmania b. guyanensis. Man is at risk of infection by the bite of Lutzomyia umbratilis at any time of the year if he disturbs the females from their daytime resting sites (on and around the bases of the larger forest trees) or if he remains in the forest between late afternoon and dawn (1700–0700 h).

The identity and scientific name of the cocoa moth or cocoa pod borer, Conopomorpha cramerella (Snellen), the major pest of cocoa in South-East Asia and generally recorded in the literature as Acrocercops cramerella, are clarified. Three previously unrecognized congeneric species are described and differentiated, viz. C. oceanica sp. n., C. sinensis sp. n. and C. litchiella sp. n. Wing pattern, male and female genitalia are figured for each species.

Between 1980 and 1984, a total of 2710 individuals of Myzus persicae (Sulzer) collected in England and Wales was tested by electrophoresis and classified as being susceptible (S), moderately resistant (R1) or strongly resistant (R2) to insecticides. Aphids sampled from oilseed rape from the Midlands and western and eastern England had the lowest frequencies of S and the highest frequencies of R1 aphids. Over all crops, eastern England had a low frequency of S and a high frequency of R1 aphids. R2 aphids were more common in northern England than in other areas of England and Wales but only on potatoes. There was no evidence of any increase in the incidence of resistant aphids (both R1 and R2) since a previous survey in 1976. Possible reasons for the distribution patterns of the three aphid types are discussed.

Survival of Musca vetustissima Walker from egg to adult in nutritious cattle dung from pasture irrigated during the dry south-western Australian summer was measured in the field. When drowning was prevented by placing dung on a low embankment, survival was high for only the first two months of the fly season, which included the first month of the five-month irrigation period. Substantial emergence of wild M. vetustissima adults from naturally- infested dung occurred only around that time. Survival was so low during the last four months of irrigation, even in the absence of mortality caused by drowning, that irrigated pasture areas in south-western Australia are unlikely to have significantly greater potential for breeding of M. vetustissima than non-irrigated pastures during most of the summer.

Egg production by two scarabaeine dung beetles, Onthophagus binodis (Thunberg) and Onitis alexis Klug, was measured in the laboratory in relation to seasonal changes in the characteristics of the cattle dung on which they fed. Dung was collected in two areas of south-western Australia monthly between September and May. Egg production was high on dung from green annual pasture from September to November and on green irrigated perennial pasture from December to May and low on dung from dead annual pasture from December to May. O. alexis was somewhat less affected by these seasonal changes in dung characteristics than Onthophagus binodis.

Isolates of Serratia marinorubra and S. liquefaciens pathogenic for Costelytra zealandica (White) were artificially cultured and applied to field populations of larvae of C. zealandica in New Zealand in the late summer and autumn of 1984. In four trials, when bacteria were applied from February to late March, high levels of disease transmission were recorded. Three months after application, significant (P<0·05) reductions of 30–59% in the larval populations were obtained, and 47% of the remaining larvae in the treated plots were diseased, suggesting the long-term effect would be greater. Treatment resulted in a 30% increase in dry matter production in the pastures. There was no consistent difference between the bacterial isolates tested. Application of the bacteria in May had no effect on the larvae, suggesting that they were no longer susceptible. It is concluded that these pathogenic isolates should be developed further as microbial insecticides for control of C. zealandica.

Some flightworthy alate exules of Aphis fabae Scopoli reproduce before taking off while others do not. This difference in behaviour is influenced by crowding and has previously been taken as an indication of the urge to migrate, although it has never been conclusively demonstrated. In this study, the flight performance of those aphids depositing some nymphs before take-off (‘flyers’) was compared with those which did not (‘migrants’). In fact, no significant difference was found between migrants and flyers in any of the aspects of post-take-off flight or settling behaviour tested. In tethered flight, large alatae flew for longer than small ones, irrespective of their pre-flight reproductive behaviour. In free flight, however, large alatae flew for a shorter period before actively landing on a plant. Large alatae were also subsequently more reluctant to leave the plant than small alatae, spending more time in sedentary activities such as probing and less time preparing to take off. It is concluded, therefore, that migratory urge is related more to aphid size, a product of plant nutritive quality, than to take-off urge, as measured by pre-flight reproductive behaviour. However, as high population densities tend to occur when the nutritional quality of the host is declining, take-off urge and migratory urge are likely to be synchronized in the field.

A deterministic simulation model for Glossina spp. based upon a simple life-history analysis was used to test a variety of effects designed to cause a decline in population numbers. Average daily survival values for pupae were varied to make populations grow at different rates. All age classes were then updated for all life stages each day for a 12-month period. As expected, the population remained stable when Ro = 1·0, and the population doubled in 105 days when Ro = 2·0. Sub-routines were added to test the effects of trapping 0·5 to 2·5% of the population per day and killing both sexes, sterilizing and releasing both sexes or sterilizing and releasing males only, the females not being trapped. Results suggest that killing or sterilizing both sexes is always superior to sterilizing males only and leaving the females unharmed but that this superiority is diminished when either population growth rates are low (<1·0) or trapping rates are high (>2·0% per day). As population growth rate increases or trapping rates decline, there is a proportionately greater advantage to be gained by sterilizing both sexes than by adopting either of the other two strategies. A situation is illustrated where for a trapping rate of 1% per day within a population that is doubling at close to its optimal rate (Ro = 2·0) sterilization of both sexes is the only strategy which will cause a population decline. Results are discussed in terms of development of low technology, cost-effective methods of tsetse control which are non-polluting and therefore environmentally acceptable.

An antiserum was prepared against carboxylesterase E4, the enzyme conferring resistance in Myzus persicae (Sulzer) to a wide range of insecticides, and the immunoglobulin G (IgG) fraction was purified from it by affinity chromotography. Interactions of the antiserum and IgG with aphid homogenates and the purified esterase proteins were studied by immune diffusion, immunoelectrophoresis and enzyme-linked immunosorbent assay (ELISA). In M. persicae, the interactions were specific for E4 and its closely-related mutant form, FE4, and except for Phorodon humuli (Schrank), there was no cross-reaction with homogenates of the nine other aphid species examined. These studies confirmed the quantitative changes in E4 protein previously reported and established that the increased esterase activity in P. humuli also arises from the production of more protein, or proteins, homologous to E4. Resistance of M. persicae could be characterized by immunoelectrophoresis even after preservation of the insects in 30% ethanol. Although ELISA could also be used to identify resistance, a simpler immunoplate assay was developed based on measuring the esterase activity of E4 retained when the enzyme bound to IgG. This assay discriminates well between the three resistant M. persicae variants common in the field in the UK, and its simplicity allows the study of large numbers of insects.

The development of Onitis caffer Boheman in cattle dung was studied in the laboratory. The larvae feed on the dung in which the eggs are laid. Egg to adult development at 25°C was completed in 24·7 weeks by a strain from a winter rainfall (WR) area of South Africa and 29·4 weeks by a strain from a summer rainfall (SR) area, and occurred without diapause. Maximum larval dry weight was achieved mid-way through the third larval instar, after which the larva emptied much of its gut to form a protective faecal shell, in which pupation occurred. At 20°C, 20% of WR larvae developed without diapause and the adults emerged after 33·5 weeks, whereas the remaining 80% of adults emerged after 80·1 weeks. In the SR strain, 70% emerged after 37·1 weeks without having entered diapause, while the remaining 30% emerged after 83·8 weeks. Thus, the period of diapause for both strains was 47 weeks and occurred in the third larval instar. At 15°C, 74% of WR larvae had pupated by 153 weeks, with a mean development time of 121·8 weeks. Zero development temperatures were 10·4°C (WR) and 10·1°C (SR), and day-degree requirements for development without diapause at 20°C were 2251 (WR) and 2571 (SR).

The status and taxonomy of the west Palaearctic Pyrus-feeding psyllids are reviewed, and keys for the identification of adults and larvae are given. The species, now referred to the genus Cacopsylla, have been much confused. They are shown to comprise seven distinct species: C. pyrisuga (Förster), C. pyri (L.) (summer form pyrarboris, winter form pyri), C. pyricola (Förster) (summer form pyricola, winter form simulans), C. bidens (Šulc) (summer form vasilevi syn. n., winter form bidens), C. notata (Flor) sp. rev., C. permixta sp. n. (= simulans sensu Loginova and Gegechkori nec Förster) and C. fera (Baeva). Psylla horvathii Šulc and P. vicina Šulc are synonymized with C. pyricola; P. picta is regarded as a nomen dubium. Information is given on the host-plants and distribution of each species.

Six hundred and twelve anthropods from 11 families collected in and around cattle dung in south-western Australia were screened using a general antiserum against all developmental stages of Musca vetustissima Walker with gel precipitin and immunoelectroosmophoresis (IEO) tests. Positive results were found in Staphylinidae (65%), Histeridae (64%), Carabidae (12%), Dermaptera (21%) and Lycosidae (27%). The relative proportions of predator species varied in different sites, but three staphylinids (Leptacinus socius (Fauvel), Philonthus longicornis Stephens and P. subcingulatus MacLeay) and one histerid (Saprinus sp.) were widespread and numerous and consistently had a high proportion of positive results. Compared to precipitin tests, IEO was found to extend detection times for a single meal from two to five hours for small staphylinids and from 24 to 36 hours for larger carabids. In subsamples of P. subcingulatus and Saprinus sp. collected on the same day at one site, the relative proportions of positive results using IEO and gel precipitation, respectively, were 74 and 23% for P. subcingulatus and 95 and 53% for Saprinus sp.

A radioimmunoassay (RIA) was developed that utilizes 125I-linked Protein A as a tracer to detect the presence of antibodies to an antigen of Mansonia larvae. Antiserum was made by periodic injections of ground gut of fourth-instar larvae of M. dyari Belkin, Heinemann & Page into a rabbit, bleeding the rabbit by cardiac puncture and separating the serum. Using the rabbit antiserum at various dilutions, the specificity of the antibody to Mansonia was examined in tests with seven other mosquito species of different genera. Although there was low-level cross-reactivity with all the other species, the differences in reactivity between those and Mansonia larvae ranged between 2·5 and 8·4-fold; therefore, positive identification was possible. Furthermore, one fourth-instar Mansonia larva could be detected within a predator (fourth-instar larvae of Toxorhynchites rutilus rutilus (Coquillett) 48 h after consumption using the RIA.

Spodoptera exempta (Walker) occurs very widely in Africa south of the Sahara and in south-western Arabia, and more intermittently in the eastern Indian Ocean and Pacific areas. Throughout its range, the extent and frequency of its attacks have increased markedly, especially in the last 10–15 years. In parts of Africa and in south-western Arabia it is now regularly a seasonally important pest; examples are given of monthly distribution maps of the frequency of its attacks in this region. Maps such as these provide a useful and wide-based perspective for those concerned with prediction, survey and control of S. exempta in a more limited area and with little or no access to information from other territories. Year to year variations within the general patterns derived from many years' records are illustrated by the distribution of outbreaks in three recent seasons, in all of which there were outbreaks in at least seven countries of central and eastern Africa, in two years in Arabia, and in one year also in southern and western Africa.

From previous studies in Garki, Nigeria, it was deduced that the population of Anopheles gambiae Giles s.l. there includes a proportion of individuals which consistently rest out of doors and are therefore not vulnerable to insecticide residues inside houses, but may still be able to maintain malaria transmission. A direct test for the existence of such individuals in A. gambiae s.l. and A. funestus Giles in a village in Tanzania was made by catching resting mosquitoes indoors and in outdoor pits, differentially marking them according to their site of capture and releasing them from a single site. Recaptures indoors and in the pits showed no significant association between the sites of capture and recapture among the females of either species, i.e. no evidence for an invariably outdoor-resting type of female. It is concluded that behavioural polymorphism is unlikely to interfere with the successful use of house spraying for malaria control in this area. From data on the proportion of the captures found to be marked and on the parity rate, estimates were calculated of the total mosquito population available for sampling in the village.