The effects of vegetative cover and soil type on the abundance and distribution of 50 species of scarabaeine dung beetle were examined during three successive days in January 1979 in Hluhluwe Game Reserve, South Africa. Pitfall traps baited with bovine dung were set at intervals of 20 m in a transect across a 20–ha patch of grassveld surrounded by Acacia bushveld. One end of the transect was on clay–loam soil and the other on sandy loam. In all, 32 936 specimens were caught, representing 71 species from 22 genera. Thirty–two species were diurnal and 18 were crepuscular or nocturnal. Twenty–six species were more abundant in bushveld than in grassveld, and eight species were more abundant in grassveld than in bushveld. Soil type influenced the relative abundance of 23 species. The degree of habitat specificity varied widely between species. During overcast weather, both bushveld and grassveld species became abundant in the transitional zone between bushveld and grassveld where the light intensity was similar to that in bushveld on a clear day. It is suggested that light intensity is one characteristic by which beetles recognise bushveld and grassveld.

Detailed data from a preselected release site in Tanzania were collected preparatory to testing the insect sterility concept against Glossina morsitans morsitans Westw. The site was at Mkwaja Ranch, a north-eastern coastal cattle-ranching enterprise, in which about 195 km2 was encompassed by a 1-km-wide fly barrier constructed at an average cost of $37/ha. Weekly surveys of flyround transects spaced 1 km apart were conducted over a 14-month period. The estimated male density of G. m. morsitans in the release site was about 630/km2 and for G. pallidipes Aust., 255/km2. The only other species of tsetse found was G. brevipalpis Newst., which was restricted to drainage areas during periods of low rainfall.

As part of a programme to test the sterile insect technique against Glossina morsitans morsitans Westw. in Tanzania, two aerial applications of endosulfan were applied to a 195-km2 test area. The applications were made with a 28-day interval to provide an initial reduction in the target species prior to the release of sterile males. A Cessna 310 aircraft equipped with a rotary atomiser and operating at night was used to apply the insecticide at a dosage of about 20 g/ha. Flyround surveys within 48 h following the spraying operations indicated that a 100% reduction of G. m. morsitans adults was achieved in both applications, while G. pallidipes Aust. was reduced by 91 5% in the first and 100% in the second.

A field trial of the sterile insect technique was conducted in Tanzania using males of Glossina morsitans morsitans Westw. that were reared, irradiated and packaged at Tanga. The experimental site was a 195–km2 area 110 km to the south. Following two applications of endosulfan as an aerosol at an interval of 28 days, irradiated puparia of G. m. morsitans were released twice weekly at stations distributed throughout the experimental site. Each of the 120 release stations was serviced every 14 days with puparia which produced sterile adults synchronously within 30 min after placement. Over the 15–month experimental period, an average of 81% control of G. m. morsitans was obtained, whereas G. pallidipes Aust., against which no releases were carried out, recovered to prespray levels within five months. The released sterile insects were found to be highly competitive and to survive well in the field. Immigration of indigenous flies from outside the perimeter barrier surrounding the experimental plot provided a continuous influx of fertile flies that provided the nucleus of the 19% residual population. Under operational conditions, the prevention of migration should result in the elimination of an indigenous G. m. morsitans population subjected to the combined stress of population reduction by two applications of endosulfan aerosols and sequential releases of sterile males.

Males of Phthorimaea operculella (Zell.) less than 24 h old were sterilised with thiotepa by circulatory fumigation in the laboratory and then released in cages in a potato field in New Zealand. Laboratory-reared sterile males, normal males and females were released in different ratios. Sterile males competed successfully in mating to suppress reproduction between laboratory-reared normal males and females. Laboratory-reared sterile males were also released in different numbers into field cages containing the resident population and additional field-collected males and females. The results showed that the sterile males were slightly less competitive than normal ones, but they were effective in suppressing the population in the cages.

Extracts from unsterile sheep fleeces seeded with Pseudomonas aeruginosa, Proteus mirabilis, Enterobacter cloacae or Bacillus subtilis equally stimulated oviposition by females of Lucilia cuprina (Wied.). However, with increasing length of incubation, significant differences emerged, the cultures of P. mirabilis, E. cloacae and B. subtilis becoming contaminated with increasing numbers of Pseudomonas aeruginosa and the responses of the flies to the culture extracts becoming greater. The maximum number of eggs was laid over four–g day–old cultures. The response was highly significant for Proteus mirabilis and E. cloacae but not significant for B. subtilis. Although contamination with Pseudomonas aeruginosa appeared to be the cause of the increased oviposition, pure P. aeruginosa cultures did not elicit high responses. The response to cultures of P. aeruginosa was apparently enhanced by interactions with other bacteria.

Natural enemies of Aonidiella aurantü (Mask.) were counted in suction-machine samples taken fortnightly over 41 months from an orchard of orange trees in the Swaziland lowlands, a region where biological control of the scale is difficult. Changes in the log population intensity/‘twig’ (Δ log N) of four species were, in each case, calculated over four thermal constants of 5000, 10 000, 15 000 and 20 000 hour– degrees above 12°C (h°>12C). The middle two constants were assumed to approximate to the thermal constants of the generation times of the natural enemies. For each natural enemy, Δ log N measured over each thermal constant was related by regression analysis to climatic and biotic indices to see how the interval over which population change was measured affected the conclusions. The longer the interval, the greater was the percentage of the explained variation in Δ log N, and the greater the number of indices that became significant. However at 20 000 h°>12°C, population change was measured over rather long intervals for short–lived species like Aphytis. At both 10 000 and 15 000 h°>12°C, the number and the identity of the significant indices in the regression tended to be the same. Consequently, conclusions about the factors affecting the natural enemies were based on these regression results. A. africanus Qued–nau, Comperiella bifasciata How. and Rhyzobius lophanthae (Blaisd.) responded directly to changes in their host's numbers, but Habrolepis rouxi Comp. responded inversely and was unlikely to have been effective. Furthermore, it was sensitive to high summer temperatures, as was A. africanus and possibly R. lophanthae. C. bifasciata was not sensitive to high summer temperatures but was adversely affected by the hyperparasitoid Marietta javensis (How.). None of the natural enemies was affected by prevailing saturation deficits.

A new species in the genus Phycita, the larva of which is a pest of eggplant in Nigeria and Senegal, is described and named P. melongenae sp.n. Notes on its biology and illustrations of the adult insect and genitalia of both sexes are given

The two weevils Ceutorhynchus geographicus (Goeze) and C. larvatus Schultze, which live and develop on Echium plantagineum (Boraginaceae) in the western Mediterranean regions, are potential biological control agents for this plant, which is an important weed in Australia. Adults bite holes in the leaves and petioles, but this damage is not great in comparison with that caused by their larvae, which mine the collar and root, causing massive necrosis and often the death of the plant. C. larvatus larvae are found especially in the aerial parts of the collar of the plant, while those of C. geographicus attack principally the rootstocks. Quarantine safety testing was based on plants selected by the criteria already used for the Echium leaf–miner Dialectica scalariella (Zell.), and it was confirmed that the two weevils would be safe and effective agents for the biological control of E. plantagineum in Australia.

A fast and simple method of preparing virgin females of Spodoptera littoralis (Boisd.) for exposure in the field is described. Low predation rates were achieved by tethering the moths on a short (20 cm) piece of cotton thread directly to the plants and by keeping unnecessary daytime exposure to a minimum. Consistently high levels of successful mating were recorded in both berseem and cotton fields in Egypt, suggesting the suitability of the tethering technique for measuring reduction of mating levels in pheromone control trials.

Illustrated descriptions of galls, larvae, pupae and adults, with a diagnostic key, are given for five species of Psectrosema Kieffer (= Amblardiella Kieffer = Isosandalum Kieffer) collected from various species of Tamarix during field surveys of potential biocontrol agents undertaken by the Commonwealth Institute of Biological Control in Pakistan. The genus Psectrosema is re-defined and the eleven species previously described from Europe, North Africa, India and Kazakhastan, USSR, are listed, mostly as new combinations. The five species recorded from Pakistan are P. manü nom. nov., stat. rev., comb. n. (= tamaricis Mani) from T. dioica; P. indicum sp.n. from T. indica; P. reticulatum sp.n. from T. hispida, T. androssowii and T. arceuthoides; P. unicornis sp.n. from T. dioica; and P. parvum sp.n. from T. indica.

The galls induced on Tamarix spp. in Pakistan by six species of Psectrosema are described, and the known host ranges and geographical distributions of these species are given, together with information on seasonal biology and adult behaviour based on field surveys and laboratory observations. Parasitic Hymenoptera and other insects associated with the galls are listed.

The occurrence of the African ichneumonine Ctenochares bicolorus (L.) in Australia and New Zealand as a parasite of the crop pest Chrysodeixis chalcites (Esp.)/C. eriosoma (Dbd.) is reported. The advent of the species to Australasia is discussed in relation to the known distribution and host associations of the genus.

Studies in southern England on aphids in cereals and adjacent wasteland included observations on the survival of aphid-specific predators (Coccinel-lidae and Syrphidae) and the more polyphagous Chrysoperla carnea (Steph.), with particular reference to their parasites. Counts were made of all the predator stages found on samples of shoots in each plot and, in wheat only, collected with a vacuum sampler. All stages of predators seen were collected and reared in the laboratory to estimate mortality and parasitism rates. Overwintering survival outdoors of Coccinella septempunctata L. was studied in partly sheltered and exposed netting cages over dense ground cover. At least 90% of predator eggs hatched in the laboratory, and no parasites were reared from them or from larvae. In cereals, there were significantly fewer larvae than eggs of Coccinellidae, probably because of cannibalism, whereas eggs and larvae of Chrysoperla carnea and Syrphidae (mainly Episyrphus balteatus Deg.) occurred in similar numbers. Unlike Coccinellidae, however, there were fewer cocoons of C. carnea and syrphid pupae on the shoots than expected. Since larval mortality was apparently small, it is suggested that many larvae pupate in the soil. Two parasite species emerged from coccinellid pupae and one from the adults, compared with two species from C. carnea cocoons and nine species from syrphid pupae. Parasitism rates were usually small (25%). More individuals of Coccinella septempunctata survived overwinter in partly sheltered than in exposed cages.

The assumption that by minimising contact with pyrethroids, satisfactory control of Musca domestica L. could be retained without eliciting resistance was tested on a pig farm in southern England where permethrin had failed through rapid development of resistance. Flies were satisfactorily controlled in enclosed buildings for 12 months by space spraying bioresmethrin (2 mg a.i./m3) at approximately fortnightly intervals when numbers reached an arbitrary nuisance level. Throughout this period, bioassays revealed no increase in tolerance of pyrethroids, although selection experiments in the laboratory confirmed the strong pyrethroid-resistance potential of the fly population. Thus effective control can be retained in spite of strong resistance potential when non-persistent insecticides are used intermittently. The results are discussed in the light of a published theoretical study of the influence of pesticide persistence on the evolution of resistance.

The survivors of field treatments of Blattella germanica (L.) with ben-diocarb (strain D) and malathion (strain H) in the UK were bred in the laboratory. The resistance of these two strains to commercial formulations of bendiocarb, dioxacarb, propoxur, lindane, dieldrin, malathion, diazinon, fenitrothion, pirimiphos-methyl and permethrin was assessed in 24-h exposures on treated glass plates. Resistance in terms of knockdown or mortality was demonstrated for bendiocarb, dioxacarb and dieldrin in both strains, for malathion in strain H and, marginally, for permethrin in strain D. Selection with bendiocarb in strain D produced a x4 and x3 increase in resistance to bendiocarb at the LC50 and KD50 levels, respectively. There was no significant cross-resistance to propoxur, but cross-resistance to dioxacarb was evident at the LC50 and KD50 but not the 95 % levels. There was little or no cross-resistance in strain D to diazinon, pirimiphos-methyl or fenitrothion. In strain H, malathion selection increased resistance to malathion at the 50% but not the 95% levels, and there was no evidence of cross-resistance to diazinon, pirimiphos-methyl or fenitrothion. Some cockroaches from strains D and H were able to recover from knockdown during and after exposure to the carbamates and permethrin. There was no recovery from the organophosphorus or organochlorine insecticides.

A preliminary investigation to find an easily assayable biochemical character, varying reproducibly with age which would give a more accurate assessment of insect age than the best methods then available, had revealed the fluorescent eye pigments, the pteridines, as a promising candidate. Stomoxys calcitrans (L.) was chosen as a model. Double-blind laboratory experiments in which the age post-eclosion of females was predicted from a standard laboratory curve of pteridine accumulation with age post-eclosion, showed the method to be accurate on average to ±1·49 days. Further laboratory experiments defined the relationships between temperature and pteridine accumulation in males and females of S. calcitrans such that the method could be modified for field use. Field observations in the UK indicated that the temperature of adults in the wild is determined by ambient temperature, the number of sunlight hours and the flies' own physiological and/or behavioural capabilities. From this information, equations for the accumulation of pteridines with temperature and age post-eclosion in males and females of S. calcitrans were constructed. To test the accuracy of these equations, approximately 19 600 marked flies of known age were released in a farmyard; 126 females were recaptured over 22 days and 90 males over 19 days. The average errors of predicted age using the pteridine accumulation method were ±190 days for females and ±137 days for males over the life-span of the recaptured insects.

Manitoba traps were used in a pasture field in northern England between June and October in 1980 and 1981.Samples of Diptera were also collected from cattle, cow dung, the field surface and from flowers in the hedges. A comparison of these samples, using multivariate similarity coefficients, showed that the Manitoba trap and cattle samples were most similar. There were 12 weeks in the two years during which both Manitoba trap and cattle samples were obtained, and the accumulated catches for this period were compared. They consisted mainly of cattle-visiting species, the proportion being greatest in the Manitoba trap samples (97%). Non-cattle-visiting species in the cattle sample (25%) consisted mainly of dung flies and species associated with the field surface. It is suggested that these were taken accidentally in proportion to their abundance around the cattle. There were some differences in the proportions of various species between the samples from cattle and the Manitoba trap, and the sex ratio of the three most abundant species was significantly higher in the traps. An experiment in which a large electrocuting grid was used to intercept flies travelling towards artificial bait as used in Manitoba traps, showed that the proportion of the two most abundant species differed significantly from a sample obtained from a nearby Manitoba trap. No such difference was observed in the sex ratios of these species.