Field populations of Musca vetustissima Walker were sampled in a region of New South Wales at 2-h intervals on 35 occasions between spring 1984 and autumn 1985 using wind-oriented fly traps. Ambient temperature, solar radiation, relative humidity and wind speed explained 84·3% of the within-day deviance of total catches (both sexes combined). Temperature and solar radiation jointly explained 82·6% of this deviance (71·1 and 11·5%, respectively), indicating that the other variables, although significant, did not greatly affect trap catches. As air temperature increased, log catch rates increased non-linearly up to a maximum at 27·5°C and declined thereafter. Log catch rates increased linearly as solar radiation increased and declined linearly as relative humidity and wind speed increased. Changes in log catch rates with time of day were explained almost entirely by the four weather variables, i.e. when weather effects were removed, time of day effects were no longer significant. These weather variables also accounted for 79·9% of the between-day variation in logarithms of trap catches. Relative responses of males and females to traps differed significantly with respect to relative humidity, wind speed and time of day. Male catches tended to increase relative to female catches between 1200 h and 1800 h and also declined more slowly with increases in relative humidity and wind speed. Separate models are presented for standardization of male and female catch rates; the estimates differ from those obtained from observed sex ratios and total catch rates, but the differences are small compared to the observed day-to-day variation in catch rates.

Preparations made from the Australian acridine grasshopper Caledia captiva (F.) that contained a recently discovered cytoplasmic polyhedrosis virus (CPV) were used to treat Locusta migratoria (L.). Feeding of the locusts with the preparations caused a significant increase in mortality. Although these deaths were associated with the viral treatment, their ultimate cause appeared to be uncontrolled proliferation of a bacterium, which is probably a strain of Enterobacter cloacae and which is usually found in locusts without ill effect. Four areas are identified where further work is necessary before the potential of the C. captiva CPV as an agent for the biological control of L. migratoria can be assessed.

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).

An island of 4·5 km2 in Lake Kariba, Zimbabwe, was stocked with cattle and infested with Glossina morsitans morsitans Westwood and G. pallidipes Austen in 1979. From February 1980 to April 1981, the tsetse populations, estimated by mark, release and recapture, increased about ten times, to contain about 3000 males of G. m. morsitans and 2000 males of G. pallidipes. From May 1981 to May 1983, six traps, with carbon dioxide and acetone as odour attractants, were used to capture 0·1–0·3% per day of the G. m. morsitans population and 1–4% per day of the G. pallidipes population. Captured flies were retained and killed, or were automatically sterilized with metepa and released. In May 1983, when the populations of G. m. morsitans and G. pallidipes had declined by about 90 and 99%, respectively, the traps were replaced by 20 targets with acetone and 1-octen-3-ol as attractants. The targets were coated with dieldrin or, later, deltamethrin and killed about 2% per day of G. m. morsitans and 5% per day of G. pallidipes. Both populations then declined rapidly, G. pallidipes disappearing in 11 weeks and G. m. morsitans in nine months. Targets offer a cheap, simple and effective means of eliminating isolated populations of tsetse.

In Tanzania, residual populations of Spodoptera exempta (Walker) may persist in highlands and river valleys, giving rise to the first outbreaks in the rainy season. To examine whether parasitoids could be a key factor in maintaining these populations at low density, samples were taken during outbreaks in eastern and north-eastern Tanzania from 1980 to 1984. Parasitism was high (around 50%) in the low density samples (below 25 larvae/m2) and low (below 17%) in the highest density ones (about 250–1200 larvae/m2). The number of outbreaks reported from the same administrative district as the sample site, and concurrent with it, was inversely related to parasitism level. The directly density dependent relationship between percentage parasitism and host density at lower densities, and the inversely density dependent one at higher densities, is similar to that found in parasitoid complexes of other Lepidoptera. Parasitoids in the rare braconid genus Meteoridea were recorded attacking S. exempta; this is the first published record from mainland Africa.

The cold hardiness of Aphis fabae Scopoli was assessed by determining the ability of individual aphids to supercool. All stages of A. fabae maintained parthenogenetically at 20°C on broad bean (Vicia faba) were capable of extensive supercooling ability to below −20°C; first- and secondinstar nymphs were the most cold hardy individuals. First instars and adult apterae of A. fabae collected from natural summer populations on broad bean and sugarbeet in England showed levels of supercooling similar to that of laboratory-maintained aphids. Compared to aphids on herbaceous hosts, all those associated with the woody host, spindle (Euonymus europaeus), showed a substantially poorer ability to supercool, often to less than −15°C, both in the autumn (oviparae) and spring (fundatrices and fundatrigeniae). All samples of eggs supercooled to below −30°C, becoming fully acclimatized in mid-winter, and lost supercooling potential prior to hatching in spring. The influence of feeding on woody and herbaceous plants on the cold hardiness of A. fabae was confirmed in a series of host-plant transfer experiments in which aphids that were transferred to bean from spindle acquired good levels of supercooling and then lost over 10°C of supercooling potential when transferred back to spindle. The shift from poor (spindle-associated) to good (bean-associated) supercooling was more difficult to achieve and suggested the presence of a nucleator in the spindle sap.

Chilozela trapeziana (Sepp) comb. n. is the senior name for the pyralid whose larvae damage cassava leaves in South America, and Botys jatrophalis Walker syn. n. and Phlyctaenodes bifilalis Hampson syn. n. are junior synonyms.

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).

Field studies of Mythimna convecta (Walker), Persectania ewingii (Westwood) and P. dyscrita Common, and their associated parasitoids, were conducted in cereals and pastures in Victoria, Australia, in 1980–83. The study included a survey of the armyworm fauna in the major agricultural districts, detailed phenological studies within five oat crops, and ultraviolet-light trapping of adults. M. convecta was the most abundant species in cereals and was found more commonly in the warmer months of spring and summer in all districts. Larval development in oat crops during spring was preceded by little moth activity in light traps. P. ewingii was common in the southern districts and in the cooler months from May to September. It was the most prevalent armyworm species in pastures and rarely occurred in barley. P. dyscrita was the least abundant species and occurred mostly in the drier inland areas, particularly in the west. Light-trap catches of P. ewingii and P. dyscrita suggested there were two generations, one in spring and one in the autumn. Regular sampling in oat crops showed that M. convecta developed faster and was usually more abundant than P. ewingii during seed development and ripening, and hence had the potential to inflict more crop damage. Of the 17 species of parasitoids reared from field-collected larvae, the wasp Campoletis sp. was the most abundant. In 1980–82, average parasitism ranged from 13 to 16% but fell to 2% after the drought of 1982.

In the province of Hälsingland in central Sweden, mosquitoes were sampled in 1983 with rabbit-, guineapig-, hen- and dove-baited and unbaited suction traps and similarly baited net traps. Blood-meals were identified by the precipitin test. Aedes cantans (Meigen), Ae. cinereus Meigen, Ae. communis (De Geer), Ae. diantaeus Howard, Dyar & Knab, Ae. excrucians (Walker) s.l. and Ae. intrudens Dyar were mainly attracted to the mammals, and Culex pipiens pipiens L., Culiseta morsitans (Theobald) and Cs. ochroptera (Peus) mainly to the birds. Significantly larger numbers of Cx. p. pipiens and Cs. morsitans were caught in dove- than in hen-baited traps. Of all identified feeds of engorged Aedes females, 95% were from mammals and 5% from birds. Only feeds from birds were found in engorged Cs. morsitans females. Movement of engorged females between the traps was demonstrated. Some Aedes females entered baited traps shortly after having fed on cervids and/or cattle. In the study area, suspected vectors between birds of Sindbis virus, the causative agent of Ockelbo disease, are Cx. p. pipiens, Cx. torrentium Martini and Cs. ochroptera in late spring and summer and Cs. morsitans in late summer. The isolation of this virus from Cx. p. pipiens and Cs. morsitans females captured in this area supports their role as suspected primary vectors. Ae. communis and other abundant Aedes species are suspected vectors of this virus from birds to man. Ae. cinereus may be a vector of tularaemia (caused by Francisella tularensis) in this area.

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.

The ecology of Aedes albopictus (Skuse) was studied in a rubber estate near Kuala Lumpur, Malaysia, in 1982–84. The rainfall fluctuated from month to month and year to year. However, there was close correspondence between rainfall and the numbers of eggs, larvae and pupae, and females throughout the two years. The mortalities of larvae and pupae observed were 87·5% in 1983 and 73·5% in 1984. Larvae of the dytiscid Lacconectus punctipennis Zimmermann were the major predators of the mosquito larvae, and the spider Heteropoda venatoria (L.) was the main predator of the adults. A species of Coelomomyces was found infecting the ovaries and an unidentified species of neogregarine was seen in the Malpighian tubules. The presence of Dirofilaria immitis larvae in the proboscis of A. albopictus was an indication that it is a potential vector of diseases of veterinary importance in Malaysia.

Five capture-recapture experiments with three species of the group of Anopheles punctulatus Dönitz were undertaken in four villages in Madang Province, Papua New Guinea. Females were collected in landing catches, blood-fed, marked with fluorescent powder according to time and location of capture, and released. Recaptures took place for 4–13 nights after release. A proportion of the recaptured mosquitoes was dissected for evidence of recent oviposition and gonotrophic age determination. Two models were developed to test a number of the assumptions that underlie the analysis of capture-recapture data from mosquitoes. Species abundance and numbers collected varied within and between villages, but marked mosquitoes dispersed at random within the mosquito population. No heterogeneity was found between indoor and outdoor biters of any of the three species. Survival rates were similar in all species. Significant differences were found in the duration of the oviposition cycle between species and village. This was 2·7–3·7 days for A. punctulatus, 2·4–3·2 days for A. koliensis Owen and 2·1–3·0 days for A. farauti Laveran. No differences were found in the duration of the oviposition cycle of nulliparous and parous females of A. farauti. Thus temporary pool breeders had a longer cycle than permanent pool breeders. This tended to be due to a delay in returning to feed rather than a delay in oviposition. It is concluded that differences between local environments exert a greater influence on the duration of the oviposition cycle than do species specific differences.

Tambinia verticalis Distant, an Indian tropiduchid planthopper, has been found breeding on coconut in Zanzibar, Tanzania, and also in low numbers in mainland Africa. No Tambinia species has hitherto been recorded in Africa. A lectotype is designated for T. verticalis, and the species is redescribed and figured.

A simple field method for direct detection of an altered acetylcholinesterase (AChE)-type organophosphate and carbamate resistance mechanism in individual insects was developed. The test will allow accurate differentiation by eye, on the basis of a colour change, of homozygous-susceptible and heterozygous or homozygous-resistant individuals. In initial field trials of this test in Sri Lanka, Anopheles nigerrimus Giles and Culex tritaeniorhynchus Giles were shown to contain this type of resistance gene, while a further nine species of mosquito had no evidence of it. Frequencies of the altered AChE gene in A. nigerrimus were estimated to be higher than those of C. tritaeniorhynchus, where the gene was found in only one of three localities in the island. The implication of the increase in prevalence of the AChE resistance gene in mosquito populations is discussed.

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.

Mangoma spinidorsum gen. et sp. n. reared from the galls of Procontarinia matteiana Kieffer & Cecconi at Bangalore, Karnataka, India, on mango leaves is described.

Four geographical strains of Ceratitis capitata (Wiedemann) were subjected as third-instar larvae to mass selection with dieldrin. Two strains, SOUTH and COSRIC, responded well but continued to show substantial heterogeneity in tolerance to the insecticide after 21 and 25 generations of selection, respectively. The technique was altered to single family sib selection, resulting in the isolation from the SOUTH strain of a dieldrinresistant strain (73) showing a more homogeneous response to the insecticide. By the same technique, a dieldrin susceptible strain (72/3) was isolated from the COSRIC strain. A decline in resistance was observed in the 73 strain between generations three and four, but the level subsequently increased again, without selection, reaching 68-fold in generation seven. It remained high for the next two years. No significant change was observed in susceptibility to dieldrin of strain 72/3; it remained highly susceptible. Resistance to solutions of technical dieldrin (96%) was shown to be mainly under the control of a single major autosomal gene, intermediate in dominance but with a modifying effect of the genetic background on the expression of the resistance gene. The resistance heterozygotes, segregating in backcrosses to susceptible individuals, were shown to be more resistant than expected, while in backcrosses to resistant ones they were more susceptible. A dose of 11 p.p.m. dieldrin was found to discriminate almost completely between heterozygous and homozygous-susceptible individuals among backcross progeny. In tests using a purer form of the insecticide (99·7%), a similar pattern of resistance was observed. The implications for genetic sexing in C. capitata 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.

Ticks were regularly collected from cattle along transects in Sukumaland and the Southern Highlands, Tanzania, and from locations near Tabora, Mbeya, Arusha and Dar es Salaam from 1973 to 1976. Marked seasonal variation in abundance occurred in Rhipicephalus appendiculatus Neumann in the Southern Highlands (but not in Sukumaland) and in Amblyomma variegatum (F.) near Tabora. It was possible to detect Theileria parva antibodies in cattle sera from the Southern Highlands only during the season of R. appendiculatus adult abundance. Despite this there was no evidence of enzootic instability of the disease. The results demonstrate that the behaviour and distributions of these and the other species of ticks found are not fixed and constant but vary according to a complicated interplay of factors as yet imperfectly understood, such as climate and vegetation and host density, susceptibility and grazing habits.