Experiments were carried out to determine the effects of the insect growth regulators (IGRs), diflubenzuron and two of its analogues, on adult female Glossina morsitans morsitans Westw. The most effective method of dosing was by topical application, and less pronounced effects followed tarsal contact with treated surfaces and contact during mating with treated males. The compounds had no effect on female length of life or the number of offspring produced, but following topical application at 0·5 μg/female or above, most offspring produced throughout reproductive life (more than 100 days) failed to pupariate. Little difference was detected between the effects of the three IGRs tested. Following the application of diflubenzuron to oviparous insects, egg hatch is inhibited; it is suggested that in the larviparous tsetse fly such compounds act by inhibiting the biosynthesis of chitin at the time of pupariation. IGRs show promise as potential agents for the control of Glossina in the field, and the quantities required would probably not exceed the quantities of insecticides used in current operations against tsetse flies.

Oviposition site selection in insects is essential in terms of low egg mortality, high offspring survival and therefore a high reproductive output. Although oviposition height could be a crucial factor for the fitness of overwintering eggs, it has rarely been investigated. In this study the oviposition height of a polyphagous leaf beetle, Galeruca tanaceti Linnaeus in different habitats and at different times of the season was examined and its effect on egg clutch mortality was recorded. The leaf beetle occurs as an occasional pest on several agricultural plants. It deposits its eggs within herbaceous vegetation in autumn. Eggs are exposed to numerous biotic and abiotic mortality factors summarized as egg parasitism and winter mortality. Oviposition height of the leaf beetle was not uniform, but changed significantly with the structure of the habitat and during the season. Mean oviposition height per site (70.2±4.9 cm) was significantly higher than mean vegetation height (28.4±2.4 cm). Height of plants with egg clutches attached and oviposition height were significantly positively correlated. The results suggest that females try to oviposit as high as possible in the vegetation and on the plants selected. In accordance with this, the probability of egg parasitism and of winter egg clutch mortality significantly declined with increasing oviposition height. A preference of G. tanaceti for oviposition sites high up in the vegetation might therefore have evolved due to selection pressures by parasitoids and winter mortality.

Two techniques have been developed to investigate the incidence of multiple feeding by mosquitoes. One system detects the ABO blood group substances and can be used up to 24 h after feeding in the case of Anopheles stephensi List. and 30 h for Aedes aegypti (L.). It is limited by cross-reactions which develop between blood group substances as digestion occurs in the stomach of the mosquito. The second system detects the serum protein haptoglobins (Hp) and it is possible to detect the Hp type of blood in single feeds 20 h after feeding for Ae. aegypti and 16 h for A. stephensi. Multiple feeds taken within a short time of each other can be identified up to 16 h after completion of the meal. The minimum amount of blood necessary to effect an identification in a fresh two-part meal is 0·1 mg, which is approximately one-tenth of the total amount of blood taken. It is now therefore possible to measure multiple ‘cryptic meals’ taken from man, if they are of different Hp types. Identification of Hp from A. gambiae sp. A blood-meals has been successfully carried out using material sent from the tropics. Limitations of the techniques as applied to field collections are discussed.

The ecology of Aedes albopictus (Skuse) was studied in a rubber estate near Kuala Lumpur, Malaysia, in 1982–84. The rainfall fluctuated from month to month and year to year. However, there was close correspondence between rainfall and the numbers of eggs, larvae and pupae, and females throughout the two years. The mortalities of larvae and pupae observed were 87·5% in 1983 and 73·5% in 1984. Larvae of the dytiscid Lacconectus punctipennis Zimmermann were the major predators of the mosquito larvae, and the spider Heteropoda venatoria (L.) was the main predator of the adults. A species of Coelomomyces was found infecting the ovaries and an unidentified species of neogregarine was seen in the Malpighian tubules. The presence of Dirofilaria immitis larvae in the proboscis of A. albopictus was an indication that it is a potential vector of diseases of veterinary importance in Malaysia.

Observations on Aphis craccivora Koch at Serere, Uganda, in 1964–68 showed that dry season carry-over of aphids could occur on the common weeds Euphorbia hirta and E. prostrata; at other times aphids were seen on Gliricidia sepium, Cassia tora, Centrosema pubescens and Macroptilium atropurpureum, the last two being increasingly used as pasture legumes. In pot tests, attempts to transfer the virus through G. sepium, Cassia tora, Stylosanthes guianensis and Centrosema pubescens were unsuccessful. Volunteer groundnuts growing in open situations were an important source of virus and vector. Field studies on menazon-sprayed and unsprayed plants closely or widely spaced showed that aphid numbers increased rapidly on the groundnut crop 31–45 days from emergence but declined rapidly as the plants matured. Superficially the plants appeared to be free of aphids but large populations were often found on hypanthia, flowers and gynophores. Coccinellids, especially Cheilomenes sulphurea (Ol), were important predators. Aphid numbers were far higher on groundnuts with low plant densities, possibly because the number of favoured feeding sites is increased, but the number of plants infested was not significantly different at high and low densities. Yellow panels had little effect on aphid numbers. Spraying with menazon (294 g active ingredient/ha, 5 times) prevented breeding by incoming alates.

Two previous lists of Parasitic Hymenoptera of economic importance have been prepared and published by the writer—one in 1919 and another in 1921 ; these included some of the more important of the economic forms then noted. During the last two or three years further work in this line was continued and additional data have been collected. In this paper an attempt is made to bring together in one incorporated list all the forms hitherto recorded from South India, at the same time revising the previous lists wherever necessary and adding recently collected data or data omitted from the two previous lists. It is believed that this revised list, with the available bionomical and synonymical notes, may be of some use for purposes of reference to those interested in this line of work. The writer takes this opportunity of expressing his thanks to the authorities of the Imperial Bureau of Entomology, London, and of the United States National Museum, Washington, for the help received from them in identifying some of the forms submitted to them, and confirming or correcting some of the identifications made at Coimbatore.

The occurrence and causes of plagues of tropical Locusta spp. are compared for the three major outbreak areas, Middle Niger of Mali (L. migratoria migratorioides (R. & F.)), south-west Madagascar (L. m. capito (Sauss.)), and Mindanao (Philippines) (L. m. manilensis (Meyen)). Multiplication and concentration are the two most important processes involved and may occur concurrently or sequentially depending on the outbreak area. In the Middle Niger and Madagascar heavy rainfall, through its effect of increasing multiplication, is the key density-disturbing factor, whereas on Mindanao the factor is drought leading to concentration of locusts. Variations in multiplication rates are determined by the response of eggs and hoppers to desiccation and by the density-dependent effects of fecundity and natural enemies. Concentration is caused by the restriction of favourable breeding habitats in relation to the seasonal population displacements and, because it occurs at different seasons in the three outbreak areas owing to their differing climates and geographies, profoundly modifies the timing of outbreaks. Man's modification of the environment, particularly in relation to the dry season survival of Locusta, has caused outbreaks to occur in new areas. Long-term solutions to the problem of controlling such outbreaks lie in the field of management rather than in the continued use of insecticides because of the continued reinfestation from surrounding populations. The use of natural enemies does not as yet show any promise as a means of controlling outbreaks of tropical Locusta.

The control of stored-product moths in bagged commodities is difficult because the developmental stages of the moths are protected by the bagging material from control measures such as the application of contact insecticides. Studies were carried out to assess the ability of Hymenopteran parasitoids to locate their hosts inside jute bags in the laboratory. The ability of different parasitoids to penetrate jute bags containing rice was investigated in a controlled climate chamber. Few Habrobracon hebetor (Say) (Hymenoptera: Braconidae) passed through the jute material while a high percentage of Lariophagus distinguendus (Förster), Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae), Theocolax elegans (Westwood) (Hymenoptera: Pteromalidae) and Trichogramma evanescens Westwood (Hymenoptera: Trichogrammatidae) were able to enter the Petri-dishes. Significantly more L. distinguendus and T. elegans entered compared to H. hebetor. There was significant difference in the mean percentage parasitoids invading depending on species. Head capsules and/or thorax widths were measured in order to determine whether the opening in the jute material would be large enough for entry of the parasitoids. These morphometric data differed depending on parasitoid species and sex. The parasitoid Venturia canescens (Gravenhorst) (Hymenoptera: Ichneumonidae) did not enter the bags, but located host larvae inside the jute bags and parasitized rice moths Corcyra cephalonica larvae by stinging through the jute material. Venturia canescens significantly reduced the number of C. cephalonica adults emerging from the bagged rice; therefore, it could be released in storage rooms containing bagged rice for biological control of C. cephalonica. The use of parasitoids to suppress stored-product insect pests in bagged commodities could become a valuable supplement to the use of synthetic pesticides.

Protease inhibitors cause mortality in a range of insects, and transgenic plants expressing protease inhibitors have been protected against pest attack, particularly internal feeders that are not amenable to control by conventional means. A study of luminal proteases in Conogethes punctiferalis Guenée was performed to identify potential targets for proteinaceous biopesticides, such as protease inhibitors. The midgut protease profile of the gut lumen from C. punctiferalis was studied to determine the conditions for optimal protein hydrolysis. Optimum conditions for peptidase activity were found to be in 50 mm Tris-HCl, pH 10 containing 20 mm CaCl2; incubation for 30 min at 40°C. Four synthetic substrates, i.e. benzoyl-arg-p-nitroanilide, benzoyl-tyr-p-nitroanilide, succinyl-ala-ala-pro-leu-p-nitroanilide (SAAPLpNA) and leu-p-nitroanilide were hydrolysed by C. punctiferalis gut proteases in Tris-HCl buffer pH 10. Trypsin and elastase-like chymotrypsin were the prominent digestive proteases, and age-related modulation of midgut proteases existed for trypsin, chymotrypsin, elastase-like chymotrypsin and leucine aminopeptidase. Serine protease inhibitors such as aprotinin, soybean trypsin inhibitor and phenylmethanesulfonyl fluoride inhibited peptidase activity. Some metal ions such as Ca2+, Mg2+, Pb2+ and Co2+ enhanced BApNA-ase activity whereas others like Mn2+, Zn2+, Cu2+, Fe2+ and Hg2+ were inhibitory at 6 mm concentration. Trypsin and elastase-like chymotrypsin were significantly inhibited by 94% and 29%, respectively, by aprotinin (150 nm) under in vitro conditions. A possible incorporation of protease inhibitors into transgenic plants is discussed.

Codling moth Cydia pomonella L. (Lepidoptera: Tortricidae) is the most important insect pest of apple production in Europe. Despite the economic importance of this pest, there is not information about the genetic structure of its population in Greece and the patterns of gene-flow which might affect the success of control programs. In this study, we analysed nine samples from apple, pear and walnut from various regions of mainland Greece using 11 microsatellite loci. Six samples from the aforementioned hosts from southern France were also examined for comparison. Bayesian clustering and genetic distance analyses separated the codling moth samples in two genetic clusters. The first cluster consisted mainly of the individuals from Greece, and the second of those from France, although admixture and miss-classified individuals were also observed. The low genetic differentiation among samples within each country was also revealed by FST statistics (0.009 among Greek samples and 0.0150 among French samples compared to 0.050 global value among all samples and 0.032 the mean of the pair-wise values between the two countries). These FST values suggest little structuring at large geographical scales in agreement with previous published studies. The host species and local factors (climatic conditions, topography, pest control programs) did not affect the genetic structure of codling moth populations within each country. The results are discussed in relation to human-made activities that promote gene-flow even at large geographic distances. Possible factors for the genetic differentiation between the two genetic clusters are also discussed.

Glyphodes pyloalis Walker (Lepidoptera: Pyralididae) is a common pest in sericulture and has developed resistance to different insecticides. However, the mechanisms involved in insecticide resistance of G. pyloalis are poorly understood. Here, we present the first whole-transcriptome analysis of differential expression genes in insecticide-resistant and susceptible G. pyloalis. Clustering and enrichment analysis of DEGs revealed several biological pathways and enriched Gene Ontology terms were related to detoxification or insecticide resistance. Genes involved in insecticide metabolic processes, including cytochrome P450, glutathione S-transferases and carboxylesterase, were identified in the larval midgut of G. pyloalis. Among them, CYP324A19, CYP304F17, CYP6AW1, CYP6AB10, GSTs5, and AChE-like were significantly increased after propoxur treatment, while CYP324A19, CCE001c, and AChE-like were significantly induced by phoxim, suggesting that these genes were involved in insecticide metabolism. Furthermore, the sequence variation analysis identified 21 single nucleotide polymorphisms within CYP9A20, CYP6AB47, and CYP6AW1. Our findings reveal many candidate genes related to insecticide resistance of G. pyloalis. These results provide novel insights into insecticide resistance and facilitate the development of insecticides with greater specificity to G. pyloalis.

Information volunteered by Salim, the native headman of Basheshi, near Maswa, drew attention to the outbreak of sleeping sickness here described late in February 1922.

Experimental evidence is given to show that only two larval instars occur during the development of Meligethes aeneus (F.) (Coleoptera, Nitidulidae) under laboratory conditions in Scotland, based on the facts that there is only one moult and only one increase in head-capsule width. The egg, first- and second-instar larvae, prepupa and pupa of M. aeneus are described and compared with the corresponding stages of M. viridescens (F.). The larvae of the two species are differentiated for the first time by the arrangement of dorsal cuticular tubercles, the size and form of the urogomphi and the width of the head capsules.

Species of the genus Pnigalio Schrank are ectoparasitoids on several pest insects. Most species are polyphagous parasitoids of lepidopteran and dipteran leafminers. Despite their potential economic importance, information on intraspecific phenotypic variability is insufficient. Pnigalio soemius (Walker) was reared at five different temperatures (10, 15, 20, 25, 30°C) on mature larvae of one of its natural hosts, Cosmopterix pulchrimella Chambers (Lepidoptera: Cosmopterigidae), to investigate the influence of temperature on size, colour and other morphological traits, and to measure the range of variation of several characters. Thermal developmental reaction norms, which represent the effect of temperature during growth and development on the value of some adult traits, were produced. The results confirmed the influence of temperature on numerous characters and that these characters had a larger range of variation than realized previously in the construction of taxonomic keys to species. In particular, the number and position of the costulae on the propodeum and colour of the gaster were affected by rearing temperature.

In a previous publication (1919), I brought our knowledge of the Ithonidae up to date, so far as the perfect insects were concerned, and gave a short account of the work which had been done by Mr. Luke Gallard and myself in discovering the habitats and dates of appearance of the commonest species, Ithone fusca, Newman. This paper also recorded our success, in November 1918, in obtaining numbers of fertile eggs, larvae and pupae. I promised then to give a full account of the life-history in a later paper, and that promise is now being fulfilled.

Data on the populations of the Pea Aphid, Acyrthosiphon pisum (Harris), have been accumulated over four years on several leguminous crops in East Anglia. The populations on lucerne have provided the most extensive studies.

Considerable annual variation was shown by the populations, but in spring the development of a peak in the numbers of Aphids occurred on lucerne, hop trefoil and sainfoin. On lucerne, which was periodically cut, the Aphids persisted throughout the growing season and a tendency towards the development of a peak in numbers in the autumn was also recorded.

All the factors which affected the number of Aphids varied considerably in the influence they exerted. The probable reason for the more obvious trends in the populations have been given in fairly broad outline, but how the effect of these factors had been altered or predisposed by less apparent factors has been speculated upon only in certain instances.

A light-weight spear has been developed to take samples of unlimited size from bulks of cereal grains. The spear is screwed on to lengths of narrow metal pipe, which are used to insert it into a bulk of grain. The sample is sucked out of the bulk through the pipe by the air stream of a domestic vacuum cleaner. This method largely overcomes the disadvantages inherent in other types of spear. The spear can be inserted into a bulk in any direction, even upwards. When sampling downwards, samples can be obtained from as deep as 9 m. Samples can be taken from directly against the walls of a store and as close as 1 cm. to the floor.

Thrips, the sole vector of plant Tospovirus, are major pests of many agricultural crops throughout the world. Molecular approaches have been applied in recent decades to identify these minute and morphologically difficult to distinguish insects. In this study, sequences of internal transcribed spacer 1 (ITS1) region of 15 agronomically important thrips, including several virus transmission species, have been analyzed in order to design species-specific primers for multiplex PCR and probes for microarray assay. That the ITS1 sequence distances within species were smaller than those among species suggests that the ITS1 fragment can be used for thrips species identification. The specificity and stability of these primers, combined with universal paired primers, were tested and verified in multiplex PCR. Using these specific primers as probes, microarray assay showed that PCR products of all thrips species hybridized consistently to their corresponding probes, though some signals were weak. We have demonstrated that multiplex PCR using specific primers based on ITS1 sequences is a simple, reliable, and cost-effective diagnostic tool for thrips species identification. Moreover, the DNA microarray assay is expected to extend into a reliable high-throughput screening tool for the vast numbers of thrips.

Alatae of Aphis fabae Scop. which reproduced before their first flight (flyers) were compared in the laboratory with those which did not (migrants) in order to test whether this difference in behaviour could be taken as an expression of migratory urge. No difference in live weight or dry weight could be found between the two groups. Flyers, however had a higher wingloading than migrants after the final moult but not after pre-flight reproduction. Flyers also had a lower fat/dry weight ratio than migrants and appeared to have more embryos, including a greater number in an advanced state of development. The significance of these observations is discussed in relation to two hypotheses which could account for the different behaviour of migrants and flyers. The results support the hypothesis that migrants have an innately greater urge to take off than flyers, mediated by their crowding experience during development, and that this is likely to result in migratory as opposed to trivial flight.

Populations of the soil insects African black beetle, Heteronychus arator (Fabricius), and whitefringed weevil, Graphognathus leucoloma (Boheman), and the damage caused to potato crops in south-western Australia were measured with and without the insecticide chlorpyrifos incorporated into the soil prior to planting. Low populations of both insects were highly damaging. Destruction of stems by H. arator reduced tuber yield and both species damaged tubers from the time of their formation. Tuber damage increased with time because both insect species on average damaged multiple tubers and caused multiple attacks on tubers. Growth of G. leucoloma larvae caused increased abundance of the more damaging later instars in spring. The insecticide reduced resident H. arator abundance and hence damage to newly-emerging potato stems in summer, but had less effect on reducing attacks on tubers in summer crops because adult beetles flew into some crops during growth. Exceptionally high tuber damage per H. arator adult in winter crops was ascribed to enhanced activity during its spring breeding season. The insecticide was inconsistent in reducing the abundance of G. leucoloma larvae. Insecticidal effects were greatest near the soil surface, resulting in an increase in the relative proportion of both insects deeper in the soil. Since a greater proportion of the tubers occurred there, the resulting greater potential for the insects to cause tuber damage tended to outweigh reduction in their abundance.