The biology and pest status of Rhopalosiphum padi (L.) in Europe are critically reviewed. New data are presented and the temporal occurrence of the aphid and its host-plants considered. In Britain, R. padi is a pest mainly because of its ability to transmit virus diseases, in particular barley yellow dwarf virus. In other European countries, especially in Scandinavia, R. padi is a pest in its own right. Predator and parasite complexes in Britain and Finland are compared and contrasted. The occurrence of R. padi as a pest of cereals in Europe is compared with that of Sitobion avenae (F.) and Metopolophium dirhodum (Walker). It is postulated that the great abundance of the primary host of R. padi, bird cherry (Prunus padus), and the spring planting of cereals in colder climates such as in Finland are major factors contributing to the differences in pest status of this aphid between Britain and in Scandinavia.

High levels (>1000-fold) of resistance to DDT, permethrin and deltamethrin were detected in Culex quinquefasciatus Say from Saudi Arabia. Biochemical enzyme and metabolic studies indicated that there is evidence for a metabolic basis to both the organochlorine and pyrethroid resistances. Electrophysiological studies indicated that there is no kdr-type mechanism conferring resistance to the pyrethroid lambda-cyhalothrin neurophysiologically, although there is evidence of cross-resistance between DDT and the pyrethroids by bioassays. There was a change in the oxidase system in both the DDT- and permethrin-selected strains and an increase in glutathione transferase activity in the DDT-selected line. Metabolic studies indicated that both oxidases and glutathione transferases are involved with DDT resistance as DDA and DDE were the predominant metabolites after a 5-h in-vitro incubation period. Permethrin resistance is likely to involve an increase in oxidative degradation, but further metabolic studies are needed to confirm this.

Copidosoma graminis sp. n., a polyembryonic encyrtid parasitoid of armyworm pests of gramineous crops and pasture in Australia, is described and compared with related species. The parasitoid plays an important role in the natural control of these pests in Australia.

Metopolophium dirhodum (Walker) is occasionally a pest of cereals in the UK. A simulation model was developed to study its population dynamics and damage potential. The model was initiated by the aphid immigration as measured by 12·2-m suction trap samples and with temperature as the major driving variable. It was validated with field observations from three contrasting years, 1979, 1985 and 1986. The model accurately predicted aphid populations and yield loss in a major outbreak year (1979) but was less accurate when densities were lower (1985 & 1986). Possible reasons for these discrepancies are discussed.

Pelidnoptera nigripennis (F.) is a parasitoid of the millipedes Ommatoiulus spp. in Portugal. It is univoltine. The adults lay eggs on their hosts during the spring in southern Portugal, and the first-instar larva penetrates through the soft tissue of the millipede. The parasitoid spends the summer as a firstinstar larva, kills the host during the autumn when in the third instar and overwinters in the pupal stage. P. nigripennis occurs in habitats of low bushes, but not in open grasslands. The female searches for prey by day. The maximum rate of parasitism recorded in this study was 20%. In laboratory specificity studies, 15 species of millipedes from five families were exposed to P. nigripennis, but only julid millipedes were successfully parasitized. Synchronization of the life-cycle in the laboratory with the seasons of the southern hemisphere was achieved by inducing pupation five months prematurely after cooling to 10°C.

The use of six cowpea varieties highly resistant to Aphis craccivora Koch in grafts (as resistant scion and rootstock) with the susceptible variety Prima indicated the presence of a graft-transmissible chemical involved in the resistance. Wrapping the resistant part in light-proof foil indicated that photosynthesis is involved in the production of the chemical. In a third test, intergrafting is involved in the production of the chemical. In a third test, intergrafting the resistant part with and without leaves confirmed the importance of photosynthesis in the transfer of resistance. Finally, covering the resistance intergrafts with foil showed that the accumulation of the chemical in the stem before the foil was applied was the major source of the graft-transmissible resistance.

Digonogastra kimballi sp. n. and D. solitaria Wharton & Quicke sp. n. are described from Texas and Mexico. They attack stalk-boring pyralids in a variety of gramineous plants, including maize, sorghum and sugarcane. Known hosts are Eoreuma loftini (Dyar) and five species of Diatraea.

Hypatima mangiferae Sattler sp. n. is described from Kenya, where its larva is injurious to commercial mango trees. A description of its life-history, based on extensive field observations and laboratory studies, is also provided. The moth, its male and female genitalia and the damage caused by the larva are illustrated.

Three carbon-dioxide-baited silhouette traps of different shape were used to investigate aspects of trap-finding by Austrosimulium bancrofti (Taylor) in the Australian Capital Territory. Highly significant effects were included in a model which generated fitted estimates of the number of flies captured under defined conditions. Fitted captures indicated higher numbers were collected on two of the 15 trapping days. Low wind and high cloud cover increased trap catches. Temperature and solar flux had a quadratic effect, with fitted catches indicating that the highest numbers were captured at 19°C and 620·6 W/m2. The results were compared with trap captures of A. bancrofti 1300 km north in Queensland.

Attempts to establish a laboratory colony of Glossina pallidipes Austen from adults and puparia of Uganda origin (Lugala) sent from a colony previously established in Amsterdam have been highly successful. Flies are maintained at 25 ± 0·5°C, L:D 12:12 and 85% RH. They are fed six days per week on whole defibrinated pig blood collected aseptically and irradiated at 1·5 kGy before storage at 4°C. The blood is presented through silicon rubber membranes at 37°C. Virgin female flies are mated when 7–9 days old with equal numbers of 9–12-day-old males in a 30 × 30 × 10-cm cage covered with white Terylene netting and illuminated with a fluorescent light from above, providing 300–500 lux on the cage bottom. The sexes are left together for 40–48 h, during which time they are offered food twice. After separation of the sexes, 30 females are housed in a cage 15 cm in diameter and two males are added. Flies are kept for 90 days before discarding. The establishment of this colony is discussed in terms of the mating behaviour of the species, highlighting differences in the laboratory between G. pallidipes from Uganda and Zimbabwe and between G. pallidipes and G. morsitans morsitans Westwood.

The population dynamics of three vectors of rice tungro viruses (RTV), Nephotettix virescens (Distant), N. nigropictus (Stål) and Recilia dorsalis (Motschulsky), were investigated in farmers' fields in the Philippines from 1979 to 1984. R. dorsalis was the most abundant vector species on the rice seedbeds and weed covered levees between rice-growing seasons, whereas N. virescens was the most abundant on the rice crop. Population curves for the three species were similar in the same season, suggesting common population-regulating processes. Adults and nymphs of all three species were present at the sampling site during a four-month fallow period between crops.

Chaetorellia acrolophi sp. n. is associated with some European species of the subgenus Acrolophus of Centaurea. It is a potential biocontrol agent of some Acrolophus species that are adventive noxious weeds in North America. Ch. acrolophi sp. n. is described, and a key is provided to all nine species. The confirmed host-plants, knapweed, starthistles and related plants, belong to the genera Centaurea, Carthamus and Chartolepis (Asteraceae), and these are listed. Available biological data are reviewed, and some details of egg, larval and pupal morphology are described. Host-plant choice tests and canonical variates analysis were used to justify the separation of some species and to help identify some populations. The following nomenclatural changes are made (junior synonyms in brackets): Chaetorellia conjuncta (Becker) is removed from synonymy with Ch. succinea (Costa); Ch. hexachaeta australis Hering is raised to specific status; Ch. hestia Hering (=Ch. nigropicta Hering); Ch. loricata (Rondani) (= Ch. mara Hering and Ch. loricata septentrionalis Hering). Questionable synonyms include: Ch. australis Hering (?=Trypeta hexachaeta Loew); Ch. hestia (?= T. vittata Rondani); Chaetostomella cylindrica (Robineau-Desvoidy) (?= Tephritis algira Macquart, which is removed from Chaetorellia).

Infestations of Eldana saccharina Walker in South Africa are higher in intensively-grown than in peasant-grown sugarcane, and are worse in water-stressed plants. Although field trials showed negligible increases in the incidence of the pest with applied nitrogen, the degree in which the degree of water stress could not be controlled. Pot-plant trials, in which the degree of water stress was controlled as well as the amount of fertilizer, showed that the combination of nitrogen with stress resulted in increased survival of larvae and greatly increased biomass with shortened development times. Adults did not appear to choose stressed or fertilized plants in preference to normal or unfertilized ones. In every case, whether in the field or in insectary trials, increased infestation levels were associated with increased stalk total nitrogen. Amino acid determinations showed that the balance of individual acids did not appear to alter but that the balance of individual acids did not appear to alter but that glyphosate ripener had a similar effect to water stress, increasing all amino acids together. Infestations in older cane were disproportionately higher than in younger cane, weight for weight, despite reduced levels of stalk nitrogen. This anomaly may be due to the presence of phenolic compounds in younger cane, or in cane tops. Levels of nitrogen are much higher in the feeding sites of the insect in natural host-plants than in cane stalks, and the fecundity of feral moths natural hosts appeared to be higher than that of moths from sugarcane. The insect appears to have invaded sugarcane when stalk nitrogen levels reached sufficiently high levels for its survival as a result of intensive cultivation.

A commercial trial of different strategies for suppressing damage by Cryptophlebia leucotreta (Meyrick) to citrus was made in the Transvaal lowveld, South Africa. Different regimes tested were applications of the chitin synthesis inhibitor teflubenzuron at 60 mg a.i./litre and ca 30 litres/tree, inundative releases of the egg parasitoid Trichogrammatoidea cryptophlebiae Nagaraja, and a combination of the two. One objective was to examine whether application of the insecticide earlier in the season than usually recommended would enhance the subsequent impact of parasitoids, native or released. It was found that parasitoid releases throughout the season (1.3 million/ha in total) produced the best overall reduction in damage by C. leucotreta. This was due largely to their better performance than that of any other strategy early in the season. Their impact in the later part of the season was not significantly different from that of release programmes which had begun at a later stage (0·6 million/ha). Very early applications of the teflubenzuron had no apparent impact on crop losses and did not enhance the impact of subsequent parasitoid releases to a significant degree. Teflubenzuron application at a recommended time later in the season was the most successful short-term approach, but its overall impact on crop loss was diminished by damage during the unprotected period before its application. A more appropriate management programme against C. leucotreta might therefore be to combine inundative releases of parasitoids early in the season with later applications of teflubenzuron if economic thresholds show they are required. The two approaches should not be concurrent since parasitoid activity was suppressed by the chitin synthesis inhibitor.

Landing site preferences of fed males of Glossina morsitans morsitans Westwood were measured in ca 50-cm-wide arenas in the laboratory. Flies were presented with simple black shapes of 225 cm2 against a white back-ground. Preference ran in the order: circle < square < triangle (whether the targets were black shapes on white or white on black). However, the triangle on its side (i.e. rotated through 90°) or the square presented as a diamond (i. e. rotated 45°) were both greatly preferred over their original orientations, whereas inverting the triangle (by rotating it 180°) greatly decreased its attractiveness. These preferences were retained whether the targets were compared paired or singly. The most obvious correlation was between preference and the relative lack of horizontal features in the target. When the diamond (the most attractive target) was split horizontally by a narrow white band, its attractiveness was reduced by ca 60%, whereas when split by a vertical band the attractiveness was reduced by only ca 25%. Similarly, when an additional narrow black bar was placed horizontally beneath the diamond its attractiveness was cut by 47%, whereas when the bar was placed vertically beside it the attractiveness was cut by only 28%. These reductions occurred even though the targets should have been more attractive because of their greater edge length and area. When the effect was tested with a series of rectangles, the greater the ratio of the vertical:horizontal edge length, the greater the attractiveness. The relative inhibition of landing by the presence of horizontal features in a laboratory-tested landing site thus seems clear, notwithstanding that horizontal resting sites in nature are the most preferred.