During 1966 a Rothamsted and a New Jersey light-trap were operated at two coastal sites in Dorset, southern England. They collected fifteen species of Culicoides but did not give an accurate estimate of the relative importance of the anthropophilic species in the areas as shown by human-bait catches. Although unfed females predominated, gravid individuals formed a substantial part of the catch. Few males were caught. The seasonal incidence of the commoner species at the two sites were compared. Fecundity, as estimated by dissection, was higher than previously recorded for Ceratopogonidae, reaching a mean of 153/female in C. maritimus Kieff. A few females of several species had well developed fat reserves indicating the possibility of autogeny, hibernation or a migratory phase.

Copris diversus Waterh. is a brood-caring dung beetle from Africa, the females remaining in the nest with their brood balls until the young emerge. A technique was developed which allowed access to the nest without interrupting nesting behaviour, so that beetles and nest contents could be observed and dung could be added into or removed from the nest at specific times. At 27°C, if more dung was added to the nest in the first three days after the start of brood care, most beetles continued oviposition. Resorption of the terminal follicle started some time between the third and twelfth days of brood care, and while the terminal follicle was resorbing the beetles did not revert to breeding if supplied with additional dung. Subsequent follicles were also resorbed if brood care was allowed to continue beyond ten days, but their resorption did not impose a lengthy delay in breeding. Oviposition resumed 17 to 21 days after the start of brood care, irrespective of when the dung was added. Development of new follicles following follicle resorption took three to seven days, and thus the resorption of the terminal follicle must have taken about seven to fifteen days.

Two weevil species, Ceutorhynchus geographicus (Goeze) and C. larvatus Schultze, feed on Echium plantagineum (Boraginaceae) in southern France. This paper shows that they do not compete for resources in the host's native environment. Niche overlaps of the two weevils were measured using the proportional overlap measure and Morisita's original index. The two species showed significant overlap in niche requirements during the egg and early larval stage. During the final two larval instars, larvae feed on different parts of the plant, C. geographicus in the tap root and C. larvatus in the root crown. Spatial separation in niche requirements is augmented by a temporal separation, C. larvatus emerging in the field about one month earlier than C. geographicus. In Europe and in Australia, to which E. plantagineum has been introduced and has become a serious weed, the host-plant has an extended germination period during the autumn. The differences in emergence times of the two species mean that their niches are separated both in time and in space. Should the two species be released into Australia they would not compete for resources. They may, however, be able to displace other species of the stemfeeding guild that are also proposed as candidates for the biological control of E. plantagineum.

The lesser date moth (LDM) Batrachedra amydraula is a significant pest of date palm fruits. Previously, detection and monitoring of the pest was inaccurate due to high costs of sampling with lifting machines. We report a practical system for detection and monitoring of LDM based on pheromone traps and relevant models. Dose–response experiments with LDM pheromone traps indicated a 1 mg lure is optimal for monitoring. Delta traps with adhesive covering their entire inner surface gave the highest captures while trap colour was unimportant. Sampling pheromone traps throughout the night indicated male flight began at 1:00–2:00 and reached a peak 2 h before sunrise. Monitoring traps exposed all year long in Israel revealed three generations with different abundance. Trapping transects in a date plantation indicated interference from a monitoring trap became minimal at distances >27 m away. Inter-trap distances closer than this may lower efficiency of monitoring and mass trapping in control programs. Our estimate of the circular effective attraction radius (EARc) of a 1 mg delta trap for LDM (3.43 m) shows this bait is among the most attractive compared with baits for other insects. We developed encounter-rate equations with the pheromone trap EARc to model the interplay between population levels, trap density and captures that are useful for detection of invasive LDM and its control by mass trapping. The integrated methodologies are applicable to many pest species.

Although the effects of nutrient enhancement on aquatic systems are well documented, the consequences of nutritional supplements on soil food webs are poorly understood, and results of past research examining bottom-up effects are often conflicting. In addition, many studies have failed to separate the effects of nutrient enrichment and the physical effects of adding organic matter. In this field study, we hypothesised that the addition of nitrogen to soil would result in a trophic cascade, through detritivores (Collembola) to predators (spiders), increasing invertebrate numbers and diversity.

Nitrogen and lime were added to plots in an upland grassland in a randomised block design. Populations of Collembola and spiders were sampled by means of pitfall traps and identified to species.

Seventeen species of Collembola were identified from the nitrogen plus lime (N+L) and control plots. Species assemblage, diversity, richness, evenness and total number were not affected by nutrient additions. However, there was an increase in the number of Isotomidae juveniles and Parisotoma anglicana trapped in the N+L plots.

Of the 44 spider species identified, over 80% were Linyphiidae. An effect on species assemblage from the addition of N+L to the plots was observed on two of the four sampling dates (July 2002 and June 2003). The linyphiid, Oedothorax retusus, was the only species significantly affected by the treatments and was more likely to be trapped in the control plots.

The increased number of juvenile Collembola, and change in community composition of spiders, were consequences of the bottom-up effect caused by nutrient inputs. However, despite efforts to eliminate the indirect effects of nutrient inputs, a reduction in soil moisture in the N+L plots cannot be eliminated as a cause of the invertebrate population changes observed. Even so, this experiment was not confounded by the physical effects of habitat structure reported in most previous studies. It provides evidence of moderate bottom-up influences of epigeic soil invertebrate food webs and distinguishes between nutrient addition and plant physical structure effects. It also emphasises the importance of understanding the effects of soil management practices on soil biodiversity, which is under increasing pressure from land development and food production.

The effects of Bt transgenic cottons (Bt-I expressing cry1Ac and Bt-II expressing cry1Ab and cry2Ab or cry1Ab and cry1Fa) and non-Bt cottons on feeding, oviposition and longevity of adults, and development and survival of Liriomyza trifolii larvae were studied under laboratory conditions; and infestation on four Bt and two non-Bt cotton traits were investigated under field conditions. Laboratory choice and no-choice tests showed that L. trifolii adults were capable of distinguishing between Bt cottons and non-Bt cottons. In a choice test on younger plants (4–5 leaves), the adults were found more often and made more feeding punctures (FP) on non-Bt cottons than on Bt cottons. On older plants (8–9 leaves), adults made the most FP on non-Bt cotton followed by those on Bt-II cottons and the least on Bt-I cotton. The females oviposited more eggs (6.7 eggs per leaf) on non-Bt cotton than on Bt-I (1.7 eggs per leaf) and Bt-II (0.8 eggs per leaf) cottons on younger plants and oviposited similar numbers of eggs (0.7–1.3 eggs per leaf) on non-Bt and Bt cottons on older plants. In a no-choice test, the females also fed more FP on non-Bt cottons than on Bt cottons on both younger and older plants. The females oviposited more eggs (15.6 eggs per leaf) on non-Bt cotton than on Bt-I (8.2 eggs per leaf) and Bt-II (6.5 eggs per leaf) cottons on younger plants and similar numbers of eggs (2.5–3.3 eggs per leaf) on non-Bt and Bt cottons on older plants. Larval and puparial survivals were not different among Bt and non-Bt cottons. The occurrence and damage of leafminers on cottons in the field showed that L. trifolii infested more plants and leaves and had more mines on non-Bt cotton than on Bt cottons.

The biology of Anopheles claviger (Mg.) was studied for a varying number of years in three localities in southern England. The fluctuations in the proportions of the larval instars and pupae were studied by weekly sampling throughout the year. The population overwintered from October to April as pre-adults, and in mid-winter larval development was arrested, but was resumed in March. The construction of a simple life-table showed the existence of a large mortality of immature stages during the overwintering period. Females were sampled at two localities by human bait catches, and at one also by insect suction traps. There was an interval of 1–2 weeks between adult emergences in April and blood-feeding, during which time females apparently fed on sugar solutions. Maximum biting densities of nullipars in May and September showed that A. claviger was bivoltine. The physiological age structure of the population showed that most parous adults at bait had oviposited only once or twice, but a few females had laid four batches. Live Hygrobatid-type mites proved reliable in indicating nulliparity. Mature larvae developed in the eggs 5–7 days after oviposition and while most eggs hatched within the next three days, a few remained unhatched until the 30th day. Females of the second generation (September) laid fewer eggs than those of the first generation (May). About six days were required for blood digestion, and females supplied with sugar were able to live 46 days. The marked delays between successive gonotrophic cycles in natural populations would make parous rates unreliable for the estimation of daily mortalities.

Between January 1965 and August 1967 49 species of biting flies were caught in Langridge and Fredeen traps and from bait animals in western Uganda. Catches were recorded daily, and monthly catches (geometricmeans) of the species most frequent on bullocks were plotted as percentages of the year's catch. Haematobia minuta (Bez.) was the only species to show a unimodal peak; this is attributed to maintenance of soil conditions suitable for the larvae during the short rains (September-November). Bimodal peaks are shown by Haematopota brunnescens Ric, H. patellicorne (End.),Tabanus par Wlk., Stomoxys inornata Grünb., S. nigra nigra Macq. and Haematobosca squalida (Grünb.) (adversely affected by severe dry conditions), by T. taeniola P. de B. and T. thoracinus P. de B. (emergence from pupae coincides with the beginning of the rainy seasons (March-May and September-November)), by Stomoxys omega Newst. and Haematobiaspinigera Mall, (minimum numbers in the wet months September-October), and by species of Haematopota, Tabanus, Chrysops, Stomoxys and Haematobosca(breeding occurs in the rainy seasons). Ill defined cycles are shown by Chrysops distinctipennis Aust, C. longicornis Macq., S.ochrosoma Speiser and females of S. calcitrans (L.) ; Glossina fuscipesNewst., G. fuscipleuris Aust. and G. pallidipes Aust. showed minimum numbers in September-October.

Cephalonomia stephanoderis and Prorops nasuta are two bethylid wasps released into several Latin American countries for classical biological control of coffee berry borer, Hypothenemus hampei, the most serious insect pest of coffee worldwide. Recent studies on the host location behaviour of these parasitoids have shown that females of both species are attracted to volatile compounds released by immature stages and dust and frass of H. hampei. In this study, we investigated the role of the contact chemicals present in dust and frass of H. hampei on the behaviour of P. nasuta and C. stephanoderis females. Parasitoids remained longer on patches treated with methanol extracts than on acetone and hexane extracts. Females spent more time on the patch treated with the methanol extract of dust and frass than on the patches treated with the methanol extract of dry coffee and methanol control. The concentration of the methanol extracts from dust and frass influenced the locomotory activity of parasitoids of both species. The time that females spent in the patch tended to increase as the concentration of the methanol extracts increased. A further experiment aimed to identify other behavioural descriptors and gain a deeper understanding of the mechanisms underlying the response of parasitoids to methanol extracts was performed. Females of both species spent more time, covered more distance, turned more (per unit time and per unit distance), and decreased their speed when they contacted patches treated with methanol extracts in comparison to patches treated with methanol control.

The reproductive phenology of Listronotus bonariensis (Kuschel) in the north of North Island, New Zealand, was studied by dissection of adults collected at intervals from several sites. First-generation adults exhibited reproductive development and activity, followed by gonad atrophication and death. Most second-generation adults entered directly into oligopause in the autumn. Some early emergent weevils of this generation oviposited before onset of winter and reproductive dormancy. Oligopause was not intense, and reproductive maturity was gradually attained over the winter, with resumption of egg laying in early spring. These results are discussed in relation to population reproductive biology and survival.

Reports of the presence and absence of biting by Simulium damnosum Theo. in the Volta River Basin in 1962, 1966 and 1975 were used to identify occasions when sites were invaded by parous and nulliparous females. Circumstantial evidence suggests that this insect is a wind-borne migrant, and the weather before and during some of these invasions was examined. Although most invasions studied took place south of the Inter-tropical Convergence Zone, for the first time evidence is presented suggesting that migration also takes place to the north of this zone. Immigrants were captured at the invaded sites only when light winds or calms were present. This cannot, however, be used as proof that S. damnosum migrates and lands only where winds are light or it is calm because host-seeking is inhibited by high winds and the time of arrival, as opposed to capture on a host, is unknown. Until the factors initiating emigration, as well as the height, duration and number of flights in each gonotrophic cycle and the time of immigration are known, the present findings cannot be tested rigorously nor can wind records be used to trace the source of immigrants.

Crosses were made between the three subspecies of the complex of Glossina morsitans Westwood and the hybrid females backcrossed. Hybrid female fecundity was highly ‘reactive’ to foreign male genes when the mother was G. morsitans centralis Machado compared with the reciprocal crosses and backcrosses. Hybrid F1 males were unable to inseminate females successfully, and although in nearly a quarter of the dissections sperm was transferred to the uterus, it did not migrate to the spermathecae. Heterozygosity between the X- and Y-chromosomes and most of the autosomes led to high frequencies of sterile males, but homozygosity between the X- and Y-chromosomes could still yield 30–50% sterility. Successive backcrosses of hybrid females between G. m. morsitans and G. m. centralis to the latter subspecies continued to increase the frequency of fertile males. Interactions between X-chromosome and autosomal gene seemed to be responsible for hybrid male sterility, and the number of sterility genes involved appeared to be very few. Crosses involving G. morsitans submorsitans Newstead generally agreed with those between the other two subspecies, but the distortion in the sex ratio of emergent adults limited the application of the data to this subspecies. Competition experiments using sterile hybrid males and fertile males in population cages (30 cm cube) showed that suppression was possible, especially when the ratio of sterile:fertile males was 2:1. The value of stetile hybrid males in tsetse control programmes and the evolution of reproductive isolation in the complex is discussed.

With the aid of reflective patches fixed to flies, nocturnal resting sites of Glossina morsitans Westw. released in teak woodland near the Mashi River in Zambia were detected by torchlight. Within this habitat, sites on the margins of woody vegetation were chosen for the tests, so as to slow up fly dispersal and raise the chances of seeing the marked flies. Over 500 flies were marked and released, and of these 82 (16%) were subsequently seen resting, the maximum height recorded being 20 ft. above ground-level. The distribution of resting heights is shown in tables. Leaves and small twigs comprised 77 per cent, of the nocturnal resting sites. In one series of tests, the proportion of marked flies detected was considerably lower than in other tests, and an environmenal factor is thought to be the cause.

Records of stainer infestation in cotton have been taken at the Cotton Experiment Station, Barberton, South Africa, since 1931, and in 1933 a uniform system of recording stainer populations in cotton by sampling 10-acre blocks was extended to four farms in the Barberton district, three farms in Swaziland and the Cotton Experiment Station at Magut, Natal.

The records so obtained show that stainers normally appear in plant cotton in late February or early March. D. intermedium, Dist., is present in comparatively small numbers throughout the season; D. nigrofasciatus, Stål, and D.fasciatus, Sign., are very variable in relative abundance. In 1933 the latter species was practically absent from cotton at all points save those in the vicinity of ratoon or standover cotton, but in 1931 and 1932 it appeared in numbers equal to those of D. nigrofasciatus and bred up a very much larger population in the crop.

Where normal migration occurs, all three species of stainers pass through two and a partial third generation in the crop; at the end of the season part of the adults migrate from the crop and the remainder, together with the bulk of the nymphs, may be destroyed by appropriate clean-up measures.

Extensive surveys of the Transvaal Low Veld and rapid tours of portions of Swaziland, Zululand and Portuguese East Africa, indicate that the principal wild food-plants of stainers in these regions comprise the genera Abutilon, Gossypium, Hibiscus and Sida in the Malvaceae, Melhania and Sterculia in the Sterculiaceae and Adansonia in the Bombaceae.

The Malvaceous host plants and Melhania are all herbaceous or shrubby species and upon these D. nigrofasciatus is frequently found. It is possible that colonies of these plants existing in sheltered situations may provide overwintering grounds for this species.

Two species of Sterculia are known, S. rogersii and S. murex. The former is wide-spread and abundant throughout the Low Veld and probably constitutes the main breeding-ground of all species in the early summer. The latter species is rarer, and its status as a food-plant is not yet fully investigated.

The Baobab occurs in large numbers in the Northern Transvaal, but it has not yet been proved to be a winter food-plant. The latest information shows that during the summer it may commonly be infested with D. fasciatus.

In conjunction with stainer population records in the crop, weekly systematic records of damage to the crop have been obtained from samples of bolls which have been examined for puncturing and graded for degree of staining. The number of punctures per boll and the percentage staining are strongly correlated, but it has proved difficult to correlate these with stainer population, except where young bolls are examined.

Internal boll disease, particularly early in the season, may be due to bacterial organisms transmitted by species of Hemiptera other than stainers. Later in the season the infection of the crop is more definitely due to Nematospora spp., of which N. gossypii is commoner than N. coryli.

All species of stainers collected on cotton have been found to transmit Nematospora, though they are not efficient vectors until the fourth instar is reached. Adult stainers collected on wild food-plants (Gossypium herbaceum var. africanum, Hibiscus spp., and Sterculia rogersii) have been shown to be infected with N. gossypii.

The etiology of the disease produced by both species of Nematospora has been followed in inoculation experiments, using pure cultures. The rate of spread of the disease varies with the age of the boll at the time of inoculation, being slower when the boll has passed middle age. In neither species does staining extend beyond the foculus in which infection starts, nor does the fungus occur within the seed except lollowing direct puncturing of the seed.

The fact that the staining is not co-extensive with the region occupied by the fungus, but goes far beyond it, and that a pathological condition indistinguishable from that due to the living organism may be produced by injecting a sterilised suspension of the fungus, suggests that the death of the lint hairs, producing staining, is due to a toxic substance liberated by the developing fungus.

A molecular tool, focused on the mitochondrial Control Region (CR), was developed to discriminate the two hawthorn-feeding psyllid species, Cacopsylla melanoneura (Förster) and C. affinis (Löw), and to estimate their frequencies in mixed populations. The test was carried out in paired and single-tube amplifications and validated analysing 52 male specimens previously determined by morphological analysis. The frequencies of the two species in mixed populations in the Aosta Valley (northwestern Italy) were analysed. The presence and type of 16SrX-group phytoplasmas was detected by nested PCR and RFLP tests in both species. C. melanoneura was the predominant species (86.5%; 80.4–91.2 CI); of these, 0.9% of the samples were positive for ‘Ca. Phytoplasma mali’ and 1.8% for ‘Ca. Phytoplasma pyri’. One of 21 specimens of C. affinis was positive for ‘Ca. Phytoplasma pyri’. The test also allowed us to identify two genetic variants of C. melanoneura, depending on the presence or absence of a 56 bp indel; these were named WI (with indel) and WOI (without indel), respectively. Further analyses were carried out on C. melanoneura specimens collected in apple orchards at six different locations in northern Italy where different levels of transmission efficiency have been described. Our preliminary observations suggest that some differences might exist between the two genetic variants in their ability to transmit phytoplasmas and to colonise different host plants.

This paper describes the method used to produce maps of the incubation and hopper development periods of the desert locust Schistocerca gregaria (Forsk.). From these maps it is possible to calculate the likely development periods of eggs and hoppers for, respectively, laying and hatching on any date and at any place within the invasion area of the species. Maps could not be based on actual observations of development periods because such observations are few in number, irregular in distribution and are not for standard dates. Instead, expected mean development periods for laying and hatching on the first of each month were calculated for a large number of meteorological stations for which long-term mean temperatures were available, using relationships between the rates of development and mean daily screen temperatures. These relationships were, in the main, derived from earlier work by one of the authors (K.G.W.) and his associates. Some assessment has been made of the accuracy of development periods derived from the maps.

Alate exules of Rhopalosiphum padi (L.) were flown in a flight chamber for three different flight times: 1 min, 5 min and 25 min. The rate of climb was recorded continuously during flight. Afterwards, the aphids were forced to land on either wheat or potato and settling behaviour was recorded. The settling response was strengthened with increasing flight time on both plants. The aphids spent more time walking and made more probes on potato than on wheat after 25 min of flight. The rate of climb was the same immediately before landing as immediately after a spontaneous re-take-off, except after a 25-min flight and landing on potato when the rate of climb was significantly higher after re-take-off. Comparison with Aphis fabae Scop. from other investigations showed that the change in settling response with flight time was similar for the two species. R. padi seemed less able to discriminate rapidly between host and non-host plants than A. fabae. It is concluded that its behaviour does not hinder R. padi from being a vector of stylet-borne potato viruses.

Hollow-fibre, microencapsulated and twist-tie formulations of the pheromone of the pink bollworm Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae) were used in trials conducted in Pakistan from 1985–1988. Early season control of this pest by mating disruption, permitted an average reduction of two applications, of conventional insecticides otherwise required to control the cotton pest complex, particularly at the time of flower and fruit setting when beneficial insects are most numerous. The pheromone formulations, together with a mixture of selective and broad-spectrum insecticides in plots of 5 or 10 ha of cotton were compared with plots of cotton, of similar size in the same locality treated with a conventional insecticide spray programme and in plots where no insecticide applications were made for the control of bollworms. Comparisons of numbers of infested bolls and estimated yields showed that levels of control achieved using the pheromone/insecticide combinations were equal in effect to conventional programmes of insecticide sprays, whereas in plots where no bollworm control measures were taken, significantly higher bollworm infestations and reduced yield estimates were recorded.

An account is given of work carried out during the third year to eradicate Glossina morsitans submorsitans Newst. and G. tachinoides Westw. from an elongated fly-belt situated in the Sudan savannah vegetational zone of Northern Nigeria, which is an important cattle-raising area.

The total area of the fly-belt, which is isolated as far as G. morsitans is concerned, measures about 120 miles in length and extends, in places, up to almost 10 miles in width. The country involved forms the flood plains and adjacent uplands of the Komadugu Gana river.

Sixty-nine sq. miles were sprayed with DDT during the 1957–58 dry season(between end of January and end of April 1958), and 18 months after completion of work no tsetse has been found in the treated area. These 69 sq. miles formed the dry-season habitat of the fly on this section of the river, and the cost of insecticide and labour involved amounted to approximately £86 per sq. mile. As the zone infested in the wet season greatly exceeded this dry-season concentration area, reclamation costs per sq. mile, when applied to the amount of grazing land made safe for cattle, amounted to much less than the figure quoted.

Successful continuation of this project is ascribed to three salient features of the technique employed: —

(a) A single application only, of a 3·75 per cent, aqueous suspension of DDT from a wettable powder, is sufficient for complete eradication.

(b) A high degree of discriminative or selective spraying is possible: for the elimination of G. morsitans, spraying can be mostly confined to larger tree trunks, in shade, up to a hei ght of about 5 ft.

(c) Artificial or natural barriers to isolate each season's work, and so prevent re-invasion, are not necessary where the fly-belt is of a comparatively narrow and elongated nature. Spraying the re-infested area during the following season is more economical.

Bruchid pests such as Callosobruchus chinensis (Linnaeus) endanger stored legume seeds throughout the tropical belt. The chemical composition of the headspace volatiles from healthy and fourth instar larvae-infested cowpea seeds were identified, characterized, and compared using gas chromatography–mass spectrometry. Y-tube olfactometer bioassays were performed to evaluate the effect of these chemicals on the orientation of conspecific adult females. Analysis of volatiles released from healthy and infested seeds revealed qualitative differences for three out of the 17 compounds identified. Dimethyl disulphide, isobutenyl methyl ketone and methyl trisulphide were found only in the blend emitted from infested but not from healthy seeds. Quantitative differences were apparent for tridecane which was released in larger amounts from infested seeds. While volatiles collected from healthy seeds were attractive to female bruchids, volatiles collected from infested seeds were repellent. To test the hypothesis that the qualitative differences in the chemical composition found may be due to insect-derived components, the volatiles from frass and fourth instar larvae combined were analysed. These volatiles contained both of the sulphides emitted from infested seed but not from healthy seeds. Although a limited induction of volatiles from cowpea seeds cannot be excluded, it is postulated that behavioural differences of the female weevils are largely due to insect-derived semiochemicals. The potential use of such semiochemicals as part of an integrated pest management strategy is discussed.