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.

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.

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.

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.

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

The chalcidoid parasites associated with galls on mango leaves and branches caused by Cecidomyiidae (mainly Procontarinia spp. in India) are taxonomically treated and keyed out. They include ten species belonging to five families (plus one treated elsewhere). The following taxa are described as new: in Torymidae, Mangostigmus gen. n. for Neomegastigmus amraeus Kurian; in Ormyridae, Ormyrulus gibbus gen. et sp. n.; in Pteromalidae, Gastrancistrus (Mangistrus subgen. n.) cherryi sp. n.; and in Eulophidae, Aprostocetus sankarani sp. n., Mangocharis longiscapus gen. et sp. n. and Chrysonotomyia obesula sp. n. The name Gastrancistrus mangiferae Subba Rao is placed in synonymy under G. muneswari Yadav. Two probable new synonymies are suggested under Chrysonotomyia.

F2 traps of 53 different colours, selected from measurements of spectral reflectivities in the colour range visible to Glossina, were tested in a field study against G. morsitans morsitans Westwood and G. pallidipes Austen in Zimbabwe. Trap effectiveness depended mainly on reflectivity in four different wavelength bands, two of which, blue-green and red, were positively correlated with trap score; and two of which, ultraviolet and green-yellow-orange, were negatively correlated with trap score, the most important effects coming from the blue-green and green-yellow-orange bands. The ‘best’ trap material was a royal blue cotton, which reflected blue-green strongly but very little ultraviolet or green-yellow-orange. This material together with the lowest-scoring colours (green and yellow) gave results outside the range of a set of grey traps, indicating that the flies employ colour information and not intensity-contrast information alone in trap- orientated behaviour. No significant differences in colour preferences were found between sexes or species.

Ultraviolet-light and fermentation trap catches of adults of Mythimna convecta (Walker) in Victoria, Australia, could be related to the times of various stages of larval development in oat crops by means of a day-degree accumulation model. Mated females were more attracted to fermentation than ultraviolet-light traps, and predicted oviposition times closely coincided with fermentation trap catches. The phenological model successfully mimicked the observed larval instar development in the field. Peak moth flights occurred within three periods. The first peak period (October to mid-November) usually contained mated moths which generated larval populations in maturing oat crops; in 1983, these moths probably occurred in late August. The second (mid-November to December) contained unmated females; in 1983–84, moth flights during this period could be related to the emergence of moths from crops 70–130 km north of the trap site. The third peak period (January to February) also comprised unmated moths which had usually emerged locally and were probably emigrating.

The biology and development of immature stages of summer (SR) and winter rainfall (WR) strains of Onitis caffer Boheman were studied in South Africa in a summer rainfall area (Pretoria). A pair of adult beetles buried up to 650 ml of dung from one dung pad, and females laid an average of 1 egg for every 62 ml of dung buried. Broods were buried at an average depth of 50 cm in watered soil and 24 cm in unwatered soil. Eggs laid in June (winter) hatched 10 weeks later. The third instar was reached by late October. WR larvae suffered higher mortality (82%) with the onset of summer rains than did SR larvae (53%). By the following June, 6% of surviving WR individuals had emerged as adults, 12% were adults in faecal shells and 82% were diapausing third-instar larvae. Of the SR individuals, 67% emerged by June and 33% were diapausing third-instar larvae. In a second experiment, two groups of broods of the SR strain of O. caffer of different ages were set out in the field in June. One group, equivalent to broods produced early in the season (March), entered diapause as third-instar larvae, and adults emerged the following autumn. The second group represented broods produced later in the season (May); the majority did not diapause, but adults also emerged the following autumn. A field population of SR adults of O. caffer was sampled for two years. Adults were first recorded at the end of February (late summer), and newly-emerged specimens were caught up until the end of April. Maximum numbers were recorded in late March to early April (autumn), and activity ceased in June-July (winter).

A chalcidoid wasp, Torymus apiomyiae sp. n., is described from material reared in southern Yugoslavia. The host is Apiomyia bergenstammi (Wachtl), a gall midge galling young fruit-bearing twigs of pear trees, which is locally a serious pest.

In order to understand how the malaria vector Anopheles arabiensis Patton exists in the extremely hot and arid environment (mean annual rainfall 21 mm) in Northern Province, Sudan, regular sampling from breeding places and resting sites was undertaken during 1978 and 1979 at four villages along the River Nile downstream (i.e. northwards) from Dongola. The population density of A. arabiensis was lowest during the flood season (July—October) and increased as the river flow decreased during November—June. Thus there was an inverse relationship between the Nile water level and A. arabiensis production. Prolific breeding in riverside pools was the main source of A. arabiensis as the river receded. During the annual flood, when riverside pools were all inundated, A. arabiensis continued breeding at low densities in sheltered sites such as wells and pits. Breeding also occurred in all months in association with the weed Potamogeton crispus in slow reaches of the river. Adult females fed regularly on blood, with gonotrophic concordance in all months, and there was no evidence of aestivation. Outdoor biting activity occurred throughout the night, with a peak between 2100 and 0500 h. Daytime searches indoors and outdoors indicated that resting females A. arabiensis are almost entirely endophilic in the study area.

A malathion-resistant strain of Oryzaephilus surinamensis (L.) was subjected to selection with malathion for ten generations at three doses, 65, 260 and 390 mg/m2. The relative fitness of the resistant homozygote, the heterozygote and the susceptible homozygote were estimated at each dose and in an untreated control population by comparing the change in frequency of the susceptible homozygote from generation to generation. In the absence of the insecticide, the resistant genotypes had a fitness coefficient of 0·82 compared to the susceptibles, whereas following selection at the highest dose of malathion, the fitness coefficient of the susceptible homozygote was 0 and that of the heterozygote 0·4, compared to the resistant homozygote. With selection at the highest dose of malathion, the frequency of the resistance gene rose from 0·5 to around 1·0 during the experiment, and this was accompanied by a 2·3-fold increase in the resistance factor at the ED50. A model is provided to show how the data collected in these experiments can be used to predict the increase in resistance under various treatment regimes. The model shows that although resistance would be delayed longest at the lowest dose, such a dose would fail to control the pest population. Using the data from these experiments, the model predicts that the best combination of control and delay of the spread of resistance would be achieved by using the highest dose of malathion while allowing the maximum acceptable proportion of beetles to remain untreated.

A key is provided to distinguish the three species of Planococcus occurring in the Mediterranean Basin, P. citri (Risso), P. ficus (Signoret) and P. vovae (Nasonov), and their nomenclatural histories are reviewed. Notes on economic importance, host preferences, distribution and taxonomy are given for each species. Pseudococcus citrioides Ferris is synonymized with Planococcus ficus (Signoret), Pseudococcus lindingeri Bodenheimer is transferred to Planococcoides, Pseudococcus inamabilis Hambleton is synonymized with Planococcus vovae, and Allococcus Ezzat & McConnell is regarded as a subjective junior synonym of Planococcus Ferris. A new genus, Delottococcus, is erected to contain a group of species previously placed in Allococcus.

Indirect and direct measures of parasitoid activity were taken in grassland and autumn-sown cereals in southern England between 1979 and 1981. Studies of anholocyclic aphid populations in the winter months were followed through to parasitism of the main pest species, Sitobion avenae (F.), during the period of population increase in April and May. Aphidius spp. parasitized artificially-established colonies of cereal aphids in ryegrass in every month between December and May of both seasons, but there was no Aphidius activity until March-April in winter cereals sown early enough to receive an autumn input of aphids and parasitoids, apparently due to the small amount of physiological time that accumulates before temperatures drop in the winter months. A. rhopalosiphi De Stefani Perez and A. picipes (Nees) were completely dominant over other parasitoid species in the winter and spring period. Natural populations of Aphidius adults and parasitized aphids were low (<2/m2) in both winters, and percentage parasitism of S. avenae measured by dissection in March and April did not exceed 11·7%. Rates of S. avenae parasitism in many winter wheat fields peaked in May, before the peak and rapid decline in aphid populations. The significance of winter and spring parasitoid activity to the survival of the parasitoid and effects on pest aphid peaks are discussed.

Five strains of Culex pipiens L. (four resistant and one susceptible) were compared at the fourth larval instar for tolerance to organophosphate, carbamate and pyrethroid insecticides, with and without the addition of three synergists (piperonyl butoxide, triphenyl phosphate (TPP) and S, S, S-tributyl phosphorotrithiote (TBPT)). The DAR/D strain from Tanzania showed the highest levels and broadest range of resistance (temephos 37 ×, malathion 579×, propoxur 3032× and permethrin 100×). A strain from Rangoon and two from France (S54, BLEUET) showed lower resistance, restricted to organophosphates. Temephos and malathion resistance in the RANGOON strain was strongly inhibited by TBPT but not by TPP or piperonyl butoxide. Temephos and permethrin resistance in the DAR/D strain was slightly inhibited by TBPT and permethrin resistance by piperonyl butoxide. The DAR/D, RANGOON and CfCA (susceptible) strains were also compared for general esterase activity and phosphatase activity, both of which were higher in the resistant strains. It is concluded that resistance in RANGOON is associated with high production of an esterase sensitive to inhibition by TBPT but with little or no sensitivity to TPP, resembling but not identical in properties with the enzyme in strain S54 investigated earlier. Resistance in DAR/D was also associated with some increase in esterase activity, but the basis of resistance was different from that in S54 and RANGOON, having a much lower sensitivity to inhibition by TBPT.

The influence of ageing, larval dietary nitrogen and adult carbohydrate diets on development of the male and female reproductive systems of Samea multiplicalis Guenée are described. Mature oocytes appeared in the ovarioles of one-day-old females and remained constant in number from one to three days after eclosion. Females from larvae that fed on plants of Salvinia molesta matured fewer oocytes (65 vs. 138) when the plants had lower (0·94% vs. 2·74%) levels of nitrogen. Resorbing oocytes were identified in the ovarioles of females 1–3 days old. The proportion of females with resorbing oocytes increased with age but not with larval dietary nutrition. Following high levels of larval dietary nitrogen, the seminal vesicles in males increased in length, while their width increased with age but not with diet. High levels of larval dietary nitrogen and an intake of adult dietary carbohydrate were both necessary for maximum fecundity. Higher levels of larval dietary nitrogen resulted in greater adult size, as measured by forewing length.

An investigation into the possible development of insecticide resistance in Glossina was carried out by comparing the susceptibility to topical applications of endosulfan and dieldrin between two populations of G. pallidipes Austen in Kenya, one from the Lambwe Valley, where there has been a long history of spraying operations, and the other from Nkruman which has never been sprayed. Dosage-mortality regression lines and LD50 and LD95 data showed that wild-caught, non-teneral males and females from Lambwe were significantly more tolerant of both insecticides than their counterparts from Nkruman, with the exception of males treated with dieldrin. The differences were insufficiently great, however, to be incontestable evidence for the development of resistance in the Lambwe strain, although there were no other obvious sources of variability between strains adequate to account for the differences in susceptibility.

Cuticular wax was extracted from adult females of Anopheles culicifacies Giles and analysed by gas liquid chromatography. The flies were taken from pure cage stocks of three sibling species: 56 individuals of species A, 43 of species B and 51 of species C. The three cytospecies were found to be significantly different in their cuticular hydrocarbon composition by a multivariate analysis of variance. Using discriminant analysis, each cytospecies was characterized by the amounts of C25-C33 hydrocarbons extracted from the cuticle, allowing criteria to be established for the identification of flies. By these criteria, specimens from stocks of known identity were allocated to the correct group with a high success rate. These results may reflect ecological differences among the sibling species.