The molecular detection of predation is a fast growing field, allowing highly specific and sensitive detection of prey DNA within the gut contents or faeces of a predator. Like all molecular methods, this technique is prone to potential sources of error that can result in both false positive and false negative results. Here, we test the hypothesis that the use of suction samplers to collect predators from the field for later molecular analysis of predation will lead to high numbers of false positive results. We show that, contrary to previous published work, the use of suction samplers resulted in previously starved predators testing positive for aphid and collembolan DNA, either as a results of ectopic contamination or active predation in the collecting cup/bag. The contradictory evidence for false positive results, across different sampling protocols, sampling devices and different predator-prey systems, highlights the need for experimentation prior to mass field collections of predators to find techniques that minimise the risk of false positives.

Potency in the male Culicoides melleus (Coq.) has been investigated by direct counts of spermatozoa liberated from spermatophores removed forcibly during copulation. At the first copulation, virgin males 12–24 h old transferred a mean (± s.d.) of 1156±210 sperm to the females. In a series of copulations in immediate succession (with a fresh virgin female at each mating in the series), the numbers of sperm transferred declined progressively to a mean of 72±88 at the seventh copulation. The percentage fertility was recorded in first egg batches oviposited naturally by females that partnered individual males at one of the copulations in an immediately successive series. Fertility remained essentially unchanged at its highest level (62–66%) for the first three copulations. It then declined through copulations 4, 5 and 6, and reached zero at the seventh copulation and beyond. The minimum number of sperm required to ensure full fertility in the first egg batch appeared to be about 600. Limited recovery of potency was exhibited by males mated three times in immediate succession, then kept 24 h and mated again.

A series of forty 24-hour catches was carried out at seven levels (20-ft. intervals from 0 to 120 ft.) on a steel tower in Zika Forest by means of unbaited and unlighted suction traps that acted simply as air samplers. The object was to study the general flight activity of mosquitos in a tropical forest environment from samples that would not be subject to the selective effects exercised by bait-traps and light-traps.

Altogether, 4,151 mosquitos belonging to thirty-four species or species-groups were taken. Eight species, Aedes (Stegomyia) apicoargenteus (Theo.), Mansonia (Coquillettidia) aurites (Theo.), M. (C.) fuscopennata (Theo.), M. (C.) maculipennis (Theo.), M. (C.) metallica (Theo.), M. (C.) pseudoconopas (Theo.), M. (Mansonioides) africana (Theo.) and M. (M.) uniformis (Theo.), were taken in numbers sufficient for detailed analysis. By far the most abundant of these was M. aurites, comprising 55·7 per cent, of the total sample. The remaining twenty-six species together constituted only 7·6 per cent.

Only 144 or 3·5 per cent, of the mosquitos taken were males; and of the females, only 19 or 0.5 per cent. were blood-fed and only 11 or 0·3 per cent, were gravid. Thus, catches in the suction traps consisted almost entirely of unfed non-gravid females. It is tentatively concluded that male mosquitos in the forest are generally very inactive in the absence of stimuli such as lights or baits. The paucity of engorged and gravid females was expected; few of these would come within range of the unlighted unbaited suction traps.

Dissection of 3,072 females belonging to the eight most numerous species showed all to be inseminated. Age-composition was determined in species of Mansonia only; the majority of females in the subgenus Coquillettidia were nulliparous, whereas in the Mansonioides, nulliparous and parous females occurred in roughly equal proportions.

The unlighted, unbaited suction traps caught far fewer mosquitos than did light- and bait-traps under similar conditions.

In general, the vertical distributions and flight-activity cycles of the various species as indicated by the suction-trap catches differed distinctly from those indicated by bait- and light-trap catches reported by other workers. Very little activity was recorded above the forest. Although, in general, activity was irregular, three main patterns could be distinguished: largely nocturnal activity continuing up to about midday but almost completely suppressed in the afternoon, as in M. aurites, M. fuscopennata, M. maculipennis, M. metallica and M. pseudoconopas; activity spread throughout the entire 24-hour period, as in M. africana and M. uniformis; and mainly diurnal activity, as in A. apicoargenteus.

Decorticated groundnuts (Arachis) are stored in bags in pyramid-shaped stacks in Northern Nigeria over the period November to October. In Kano the dry season extends from October until March and is followed by a short hot season preceding the rainy season, which usually commences during May.

The seasonal distribution within such pyramids of the various insect species infesting groundnuts is considered in some detail, with particular reference to the primary pest Tribolium castaneum (Hbst.). This distribution is discussed in relation to temperature and moisture content of the kernels and to the effect on the environment of covering pyramids with tarpaulins, the normal practice for protection during the rainy season. T. castaneum is the only species present on groundnuts initially and throughout the storage season. It is concluded that the elimination, during storage, of other species also present initially, i.e., Cadra cautella (Wlk.), Plodia interpunctella (Hb.), Corcyra cephalonica (Stnt.) and Oryzaephihis mercator (Fauv.), and the ultimate concentration of infestation by T. castaneum within peripheral bags is the result of changes in physical conditions. It would appear that Cryptolestes ferrugineus (Steph.), which was not found until late in the storage season, is a pest of secondary importance.

The significance of the results obtained in relation to control measures is discussed, bearing in mind that all but one of the pests considered were found to be present on groundnuts when received at the Kano central storage area from buying stations. It is concluded that a programme of surface spraying of pyramids with insecticides is of little value and recommendations for the introduction of initial fumigation of pyramids have been put forward.

Major potential sources of variation in the feeding of Nilaparvata lugens (Stål) which are not host-dependant are those related to time, i.e. the age of the insect, the length of time the insect is in association with the plant and the time of day. These parameters were investigated with a susceptible, a moderately resistant and a resistant rice variety using honeydew clocks for the collection of honeydew excretion data. It is concluded that there are non-circadian patterns of honeydew excretion which are related to the degree of resistance of the variety and that such feeding and excretion patterns can be used to characterize the relationship between insect populations and rice varieties.

Data from surveys in 1951, 1972, 1973 and 1978–79 showed that tick numbers are generally low on the miniature breed of cattle in the Yemen Arab Republic and tick-borne diseases have not been recognised as a serious problem. This breed should be investigated for properties of resistance to tick bite. Each tick species commonly infesting livestock has been recorded as transmitting viruses (and some also rickettsiae) causing human illness in Africa and/or Eurasia. Between 1300 and 2000 m in altitude, Amblyomma variegatum (F.) is more abundant on camels than on cattle and Boophilus annulatus (Say) infests cattle. Below 1500 m, B. kohlsi Hoogst. & Kaiser is more abundant on goats than on sheep. Haemaphysails sulcata C. & F. infests sheep in certain highland areas. Hyalomma dromedarii Koch is the most prevalent and abundant tick of livestock. H. anatolicum excavatum Koch is next in abundance on camels. The numbers of H. anatolicum anatolicum Koch vary greatly in collections from different years. Few examples of H. erythraeum Tonelli-Rondelli were taken. H. impeltatum Schultze & Schlottke and H. marginatum rufipes Koch are widely distributed; the former is most abundant in coastal lowlands, the latter in humid habitats. H. arabica Pegram, Hoogst. & Wassef is recorded from goats, and also sheep, in southern hills. Immature examples of Hyalomma spp. are especially abundant on camels and hares. Rhipicephalus evertsi evertsi Neum. is common in the highlands, as is R. simus Koch below 2000 m. Species of the R. sanguineus (Latr.) group occur on some livestock.

Descriptions are given of the larval stages of the 15 most damaging African stemborer species, belonging to the genera Chilo Zincken, Coniesta Hampson, Eldana Walker, Maliarpha Ragonot, Scirpophaga Treitschke (Pyralidae), Sesamia Guenée and Busseola Thurau. Chaetotaxy of the larvae has been studied. Previously published studies on the same subject are discussed. A key is provided for the identification of the genera, and where possible, the species.

A population of Myzus persicae (Sulz.) that apparently showed resistance to organophosphorus insecticides was found on plants growing in glasshouses at the Plant Breeding Institute, Cambridge, in 1963. Experiments were conducted to compare the resistance to dimethoate and demeton-methyl of this population with that of another population, which had never been treated with insecticides. The resistant aphids were killed much more slowly than were susceptible aphids on plants sprayed with organophosphates, and they were able to transmit beet yellows virus (BYV) and beet mild yellowing virus (BMYV) to the treated plants. Under similar conditions, susceptible aphids were able to transmit BYV, a semi-persistent virus, but less efficiently than the resistant aphids, and were not able to transmit BMYV, a persistent virus, at all.

It is not known how common these organophosphorus-resistant populations of M. persicae are, at present, in the field in Britain. Under normal field conditions, control of such resistant aphids would be difficult, and virus yellows might, in consequence, become widespread even in crops that had been treated with organophosphorus chemicals.

A study was made at Hurley in southern England of the hymenopterous parasitoids of the stem-boring larvae of Oscinella spp. and Geomyza tripunctata Fall, in perennial ryegrass plants {Lolium perenne) taken from swards managed in different ways. Six species of parasitoids were identified after their emergence from stem-borer pupae; four of these were also identified in the parasitoid larval form parasitising stem-borer larvae. Parasitism exceeded 45% during 1980 but was only about 20% in 1981. Of the species of Oscinella, larvae of O. frit (L.) were always the most highly parasitised and those of O. vastator (Curt.) the least, irrespective of their frequency of occurrence. G. tripunctata also showed less parasitism than O. frit. The braconid Chasmodon apterus (Nees) was responsible for 95 % of the parasitism in 1980 and 85% in 1981. The higher parasitism in 1980 probably resulted from greater synchrony between the populations of the adults of C. apterus and those of the stem-boring larvae. Samples from eight other sites in the UK gave results similar to those obtained from Hurley.

Sixty-seven per cent of parasitoid mummies which developed from Metopolophium dirhodum (Wlk.) collected in wheat fields at Rothamsted, southern England, in 1979 were of Toxares deltiger (Hal.), a species previously unrecorded from cereal aphids. T. deltiger formed only 1% of samples when parasitoid mummies were collected directly from cereals in the field. Laboratory observations of the parasitoid indicate that affected aphids probably leave the host-plant prior to death and mummy formation.

The following notes deal with a collection of sandflies from Africa sent for identification by Sir Guy Marshall, C.M.G., F.R.S., of the Imperial Institute of Entomology, by Dr. Pontes from Mozambique, by Major W. F. M. Loughnan, R.A.M.C., Mauritius, and with a number of specimens lent to Prof. Adler by the London School of Tropical Medicine. I am indebted to Prof. Adler for placing this material at my disposal.

Trials for the control of soil pests, particularly of termites (Isoptera: Termiti-dae), in groundnuts (Arachis hypogaea) in India and Sudan used chlorpyrifos and isofenphos granules, chlorpyrifos, phorate, carbosulfan and carbofuran in controlled release formulations, and chlorpyrifos seed dressing. Their effects on foliar pests were also noted. Chlorpyrifos controlled release pellets were as effective as aldrin, used as a standard, in reducing root and pod attack and, like aldrin, doubled yields. Isofenphos and chlorpyrifos granules increased yields and reduced pod damage, but to a lesser extent. Other treatments were less effective. Carbosulfan and phorate controlled release and isofenphos granules reduced leaf miner attack. These trials establish the efficacy of controlling termites and other soil pests with controlled release formulations of otherwise non-persistent insecticides. However, the expensive formulation is unlikely to be cost-effective for rural farmers in developing countries and, in the case of chlorpyrifos, residue levels in kernels may be unacceptable. Future work should investigate other insecticides in the formulation and development of cheaper controlled release matrices.

A number of leaf-eating insects have been studied with the object of selecting species suitable for rearing in the laboratory.

Four species have proved satisfactory for large-scale rearing throughout the year. These are Plutella maculipennis, Plusia gamma, Diataraxia oleracea and Phaedon cochleariae. A number of species possess certain disadvantages : (1) apparently obligate diapause (Mamestra brassicae, Sphinx ligustri). (2) The same as (1) with the additional disadvantage of lack of food-plant in winter (Lymantria dispar). (3) Uncertain copulation and oviposition (Pieris brassicae). When available, these species may be reared satisfactorily in large numbers.

Mesographe forficalis, Xanthorhoë fluctuata, Lema melanopa and Crioceris asparagi have been reared in relatively small numbers. They possess certain disadvantages but should be satisfactory for large scale rearing at any rate during some part of the year.

At present laboratory rearing of Phlogophora meticulosa, Agrotis segetum, Triphaena pronuba, Aclypea opaca and Athalia colibri is considered impracticable. A number of leaf-eating species, particularly Hymenoptera, which appear to possess suitable qualities for laboratory rearing, have not yet been obtained and studied in the laboratory.

Particular attention has been paid to factors influencing development of leaffeeding insects with the object of determining the conditions under which healthy stocks of uniform resistance can be maintained. The results of experiments on the effect of food-plant, temperature, humidity and illumination are described. Studies on the factors influencing diapause in the various species are mentioned. Descriptions, are given of the rearing techniques that have been developed.

Helicoverpa armigera (Hübner) exhibits a facultative pupal diapause, which depends on temperature and photoperiod. Pupal diapause is induced at 20°C by short photoperiods and inhibited by long photoperiods during the larval stage. However, in some pupae (35% of males and 57% of females) of a non-selected field population from Okayama Prefecture (34.6°N), diapause is not induced by short photoperiods. In the present experiment, the importance of temperature for diapause induction was studied in the non-diapausing strain, which was selected from such individuals reared at 20°C under a short photoperiod of 10L:14D. Furthermore, the sensitive stage for thermal determination of pupal diapause was determined by transferring larvae of various instars and pupae between 20°C and 15°C. Diapause was induced by 15°C without respect to photoperiod. When larvae or pupae reared from eggs at 20°C under a short or a long photoperiod were transferred to 15°C in the periods of the middle fifth instar to the first three days after pupation, the diapause induction rate was significantly reduced in both males and females, especially in females. In contrast, when larvae or pupae reared at 15°C were transferred to 20°C in the same periods, diapause was induced in males, but not in females. However, the diapause induction rate of pupae transferred to 20°C on the fourth day after pupation was significantly increased in females. The results show that temperature is the major diapause cue in the photoperiod-insensitive strain and the periods of middle fifth larval instar to early pupal stage are the thermal sensitive stages for pupal diapause induction with some different responses to temperatures between males and females in H. armigera.

Cryptolestes ferrugineus (Stephens) and C. pusillus (Schönherr) were reared separately at initial densities of 20 or 40 adults each and together at an initial density of 20 adults/100 g cracked wheat or cracked maize at 35, 30, 25, and 20°C and 70% r.h. for developmental periods of 10, 11, 16, or 40 weeks, respectively. Intraspecific competition in the 40-adult treatments restricted population growth to levels similar to 20-adult treatments for each species; impact was greatest for C. pusillus on maize at 30°, where the population of the 40-adult treatment was less than half that of the 20-adult treatment. Both species produced larger populations on wheat than on maize, except for C. pusillus at 35°C; mortality for both species was high on wheat at 35°C. Interspecific competition resulted in significantly reduced populations relative to single species populations for both C. ferrugineus at 30, 25, and 20°C and C. pusillus at 35, 30, and 25°C on wheat and for C. ferrugineus at 25 and 20°C and C. pusillus at 35, 30, and 25°C on maize. During interspecific competition, C. ferrugineus was more successful in multiplying at 35 and 30°C on wheat and 35°C on maize; both species multiplied equally well at 25°C on wheat or 30 and 25°C on maize; C. pusillus multiplied best at 20°C on both wheat and maize. Cryptolestes pusillus reproduces more effectively alone or in interspecific competition under cool conditions, although C. ferrugineus occurs with much greater frequency in cool Canadian stored grain, probably because of cold-hardiness and winter survival

Female tsetse flies (Glossina morsitans Westw.) were more active in an experimental chamber in the laboratory: (a) at high than at low temperatures, (b) in high than in low humidities, and except at high temperatures, (c) when hungry than when replete. Flies were also more active in the chamber when a small area of black surface (1·6%) was present than when a larger black surface (12·8% or 50%) was available. Both black and white surfaces were provided in all experiments, and over the temperature range 25–40°C flies settled on black more frequently than would be expected by chance. This preference for a black resting surface was most marked when the flies were most active: (a) above 35°C in all experiments, (b) at high humidities with teneral flies, and (c) when the flies had not fed. Flies settling on black usually rested longer than those settling on a white surface.

The coccinellid biocontrol agent Chilocorus nigritus (Fabricius) can be established on the non-target scale Asterolecanium sp. (Hemiptera: Asterolecaniidae) on giant bamboo Dendrocalamus giganteus. When these sites are adjacent to citrus orchards, the coccinellid readily moves across to reduce population levels of the target prey, red scale Aonidiella aurantii (Maskell) (Hemiptera: Diaspididae). C. bipustulatus (Linnaeus) and C. infernalis Mulsant are potential new biocontrol agents against A. aurantii in South Africa. Each life stage of C. nigritus, C. bipustulatus and C. infernalis has advantages and disadvantages for field introductions. This paper investigates different methods of introduction of the different life stages for field establishment. A number of synthetic materials were tested as egg pads for C. infernalis without success. Introduction of eggs adhering to stiff paper cards was unsuccessful and impractical for all species. Eggs, young larvae (first and second instars), older larvae (third and fourth instars) and adult C. nigritus were introduced into stands of bamboo. The adult was the most suitable life stage for establishment followed by older larvae, then younger larvae, with the least suitable being the egg stage. Adults of the three species were released on to scale-infested bamboo at two sites to evaluate the viability of such introductions and to compare their persistence at these sites. C. nigritus and C. infernalis persisted at one release site through the winter and the hottest period of the summer.

Until about ten years ago Australia was considered to be free from the haematophagous Diptera of the genus Phlebotomus, which are found abundantly in all other regions of the earth, over one hundred species having been recorded. Mr. G. F. Hill was the first entomologist to discover in Australia a species of the minutus group, which he described under the name of P. queenslandi. This species was found in Townsville, North Queensland, in a bath-room, and nine flies were secured. It has not been found again since, either there or lower down the Australian east coast, where such experienced entomologists as Drs. Bancroft, Ferguson and Mackerras, have kept a special look-out for these flies.