First instars of the soil-inhabiting whitefringed weevil, Naupactus leucoloma(Boheman), are a particularly good bioassay model for assessing volatile soil fumigants and biofumigants. Eggs are readily obtained and can be stored for long periods with larvae hatched on demand and the first instar is non-feeding, surviving without food or shelter. Longevity varies with temperature, but readily accommodates the period required to conduct bioassays without appreciable mortality of untreated controls. In vitro bioassays of pure methyl isothiocyanate, the active ingredient from metham sodium soil fumigant, and the less volatile 2-phenylethyl isothiocyanate, sensitively detected differences in toxicity and effects of temperature. Bioassay of volatiles emitted from hydrolysed tissue of various isothiocyanate-producing Brassicaplants revealed widely varying toxicity effects, indicating that bioassays with N. leucoloma are a sensitive and relevant indicator of the potential of different plants for biofumigation of soil-borne pest organisms.

An account is given of observations made in two rooms of a warehouse during 1945 and 1946. In 1945 fortified flour was stored in a single tier of upright sacks, whilst in 1946 the rooms were empty except for 50 small experimental bags of wheatfeed.

Before the flour arrived in 1945, no insects were found except a few larval Ptinids in a bag of sweepings. Adult Ptinus tectus soon appeared on the sacks of flour and, in one room, the numbers on the sacks increased steadily to 6,000 by the time the flour was removed in November. In the other room, where the ecological conditions were obviously variable, the increase was erratic, but there were 4,500 adult Ptinus on the sacks by the time the flour was removed. The numbers on the experimental bags in 1946 rose from zero to 5,000 by the end of September. The weekly figures varied with temperature, falls in numbers coinciding with colder weather. In both years a steady 30–40 per cent, of the total Ptinus on the sacks or bags were fcund at the bottom except for the early months of 1946 when 80 per cent, were at the base of the bags until April.

In empty premises it was obvious that many adult beetles hid in the fabric of the building, a rough estimate of 150,000 being obtained following the use of traps and marked beetles. There were indications that the main hiding place in this building was at the junction of walls and floor. After the sacks of flour had been removed in 1945, it was estimated that the flour covering the floor of Room 70 contained about 7,000 larvae. These would normally be removed by sweeping and vacuum cleaning, but this treatment left behind about a further 10,000 larvae in the floor cracks of each room. No estimate of larvae inside the sacks was possible, but in eight months in 1946, about 1,500 eggs were laid in each small bag of wheatfeed. An average of at least 300 eggs per day were laid in the room in 1946.

Ptinus tectus has two complete generations a year. All stages may survive the winter so that overlap of generations is complete.

In a stack of sacks of flour, adults are most abundant on the sacks at the edge of the stack especially on those near the corners. Draughts, wetness and sunshine caused local changes of distribution. There was some suggestion that Ptinus preferred to rest upon cotton sacks rather than on jute. Larvae are normally present only in the outer layers of flour in a sack and spin cocoons on the inside surface of the sacking. The adults emerge through the sacking to the outside.

The activity of Ptinus in a warehouse is greatest during darkness. Hence it is fairly continuous in dark premises and periodic in light places. In the latter, beetles emerge from their hiding places at dark and return at dawn. If dark crevices are provided artificially they act as traps, for some of the beetles will use them as daytime hiding places. Activity is reduced by low temperatures but does not stop altogether until it is as low as 2°C.

Two methods are suggested for actual estimation of insect numbers without too much labour. One for estimating the numbers on the sacks is based on the fact that most of the insects are found on outside sacks, and involves the counting of the insects on several representative groups of contiguous sacks. Over half of the estimates made by applying this method to the data from one of the rooms in 1945 were within 20 per cent, of the correct values as indicated by total counts of the population. The combination of traps with the release of marked beetles is suggested for estimating the resident population of empty premises.

Insects and mites associated with each species in the Salvinia auriculata complex were recorded in Trinidad, Venezuela, Guyana, Brazil, Uruguay, Paraguay and Argentina. There was a consistent pattern of herbivore-plant association throughout the range of the complex. Field studies showed that three insects, the curculionid Cyrtobagous sp., the pyralid Samea multiplicalis Gn. and the pauliniid Paulinia acuminata (Deg.), together contained Salvinia molesta at a density slightly below the carrying capacity of the environment in coastal areas of Brazil.

Catches of Musca vetustissima Wlk. in West Australian blowfly traps containing week-old baits were consistently greater (4·5–24·1 times higher) than in traps with fresh baits. Recovery of marked flies within 26·5h of release showed mean dispersal distances of 1·5 ± 0·7 km for males and 1·6 ± 0·6 km for females under favourable weather conditions (mean air temperature 28·8°C and mean wind speed 5·5 m/s). The recovery rate of males (1·3%) and females (1·0%) over this period indicates the feasibility of using single mark-release experiments to estimate absolute fly densities. It is shown that estimates having a 95% probability of being within ± 10% of the true population density could be achieved by the release of 39 000 marked flies.

Contarinia sorghicola was discovered in Uganda in 1951, the only previous African record being from the Sudan. The infestation started in September in early varieties of sorghum grown in observation plots and reached a peak onlate varieties and ratoons in early March, thereafter declining as parasitism, chiefly by Tetrastichus sp. and Aprostocetus sp., increased to reach 100 per cent. in April.

The life-cycle was normally 19–25 days, but between December and April diapause larvae were found; these all produced adults in early August, following a period of high humidity.

Midges morphologically indistinguishable from C. sorghicola have been bred from Eleusine coracana and from wild Sorghum verticilliflorum in Uganda, and the midge may well be endemic wherever wild sorghums grow. Enquiries show that midge damage to sorghum occurs in Kenya, Tanganyika and Nyasaland, and it is likely that all the mainsorghum growing areas of Africa will prove to be infested.

The possible occurrence of resistance is discussed.

Various aspects were studied of the brood size and sex allocation strategies, and of size-fitness relationships in Parallorhogas pyralophagus (Marsh), a gregarious ectoparasitoid of Eoreuma loftini Dyar. Brood size was significantly correlated with host size; larger hosts were allocated larger broods. Brood sex ratios were fixed precisely at 1 male per 4 females, and eggs were likely to be deposited in that order; differential mortality did not contribute to this precise sex ratio. The sex allocation strategy of P. pyralophagus is likely to conform to strict, i.e. single foundress, local mate competition. Adoption of this strategy is probably influenced by a limited insemination capacity of males; a smaller proportion of females (0.09 vs. 0.21) remained virgin in broods with precise or higher sex ratios (≥0.20 males) relative to broods with lower than precise sex ratios (< 0.20 males). Moreover, all females were inseminated in most broods (60%) with precise or higher sex ratios, whereas this did not occur in broods with lower than precise sex ratios. The hypothesized occurrence of strict local mate competition in P. pyralophagus was supported also by observations that: (i) offspring brood sex ratios were independent of maternal brood sex ratios and number of parental females concurrently allocating offspring to a group of hosts, and; (ii) the rate of superparasitism under no-choice conditions was low (~20%), suggesting that rates of outbreeding in the field are low. Other results suggested that fitness in P. pyralophaguswas correlated with adult size; longevity and reproductive capacity both increased with adult size in males and females. However, adult size may be more important for females than for males because the differences in reproductive capacity between the largest and smallest individuals was up to 7.3 times greater in females versus <2 times in males.

The effects of avermectin exposure on natural populations of the yellow dung fly, Scathophaga stercoraria Linnaeus, were investigated at the field scale on farms in south-west Scotland. Pastures forming the focus of the study were grazed with either untreated cattle or cattle receiving standard, manufacturer-recommended treatment regimes of an avermectin product. Flies were sampled between April and July in 2002 and 2003 using dung-baited pitfall traps. Abundance and wing asymmetry in S. stercoraria populations were examined in relation to a range of environmental and management variables (including avermectin exposure, pasture management intensity, weather and season). Data used for abundance analyses were collected in fields where treated cattle had been dosed with either doramectin or ivermectin, while the data for the asymmetry analyses were from a subset of fields where treated cattle had been dosed with doramectin only. While abundance of S. stercoraria varied significantly between years and with season, there was no difference in their abundance between fields grazed by avermectin-treated or untreated cattle. Asymmetry was significantly higher in fly populations in fields grazed by doramectin-treated cattle, suggesting that exposure to doramectin during development could have imposed some degree of environmental stress. While these results suggest that exposure to doramectin residues in dung on grazed pastures may have sublethal effects on the insects developing in that dung, there was no evident avermectin effect on the abundance of adult S. stercoraria occurring in the pastures.

Infection of the commercially important silkworm, Bombyx mori by a tachnid parasitoid, Exorista bombycis induced activation of genes and cellular responses associated with apoptosis in integumental epithelial cells. Composite cellular profile showed initial autophagy, intermediate endoplasmic reticulum degranulation and deformed nucleus as well as later DNA fragmentation indicating apoptosis. Two cell death-associated proteins, autophagy 5-like (Atg5L) and apoptosis-inducing factor (AIF), in addition to caspase, are identified from the infected integumental epithelium through mass spectrometric analysis. Genes encoding these proteins showed age-dependent activation after the infection as revealed by quantitative expression analysis. Atg5 showed early upregulation in association with signs of autophagy whereas AIF showed late upregulation in association with DNA condensation and fragmentation. Expression of AIF showed negative correlation with that of Atg5 after the infection. On the other hand, in control, caspase expression showed positive correlation with AIF expression indicative of regulated expression in normal larval epithelium, which was absent after infection. Activation of Atg5, AIF and caspase genes in close association with different cell death events revealed the synchronized differential expression of apoptosis-associated genes in response to the macroparasitism. Enhanced expression of Atg5, AIF and caspase genes coupled with the appearance of cell death symptoms indicate parasitism-induced activation of genetic machinery to modulate cell death events in the epithelium, which was hither to unknown in invertebrate systems.

Infestations of the sugarcane pest Eldana saccharina Walker have been consistently serious in one part of the cane-growing belt of Natal, South Africa. Mortality in this region over seven years was estimated from moth catches in light traps, checked against population change measured from extensive larval counts, and plotted against climatic indices. The object was to construct a predictive model to illustrate mortality in other regions of the cane belt, to which infestations have spread in recent years. The spread southwards along the coast did not seem to have resulted from a decrease in natural mortality, but the spread to higher altitudes appeared to be due to lower mortality associated with warmer and drier years. The phenology of the insect and the effect of the annual harvesting cycle on phenology are discussed.

The four commonest species of Sitona injuring leguminous crops in Israel were found during a survey in 1957–62 to be S. lividipes Fhs., S. hispidulus (F.), S. crinitus (Hbst.) and S. lineatus (L.). Adults of all four were collected in the field in December-January each year, at the termination of diapause, and kept in the laboratory for observations on their bionomics. Larvae and pupae did not survive in the laboratory, and therefore these stages were reared in the soil outside (where suitable food-plants had been grown) from eggs laid by the adults in the laboratory and kept at known temperatures until they were about to hatch. The soil was later examined daily for pupae.

Egg-laying began in December, larvae were found in January–March, pupae in March–April, and adults of the new generation in April–May. These adults fed freely but did not oviposit, and in June–July they sought shelter and entered diapause, which lasted until the close of the year. Feeding was then resumed, oviposition began shortly afterwards, and death occurred up to 250–300 days later.

The eggs of all four species are creamy or yellowish white when laid but soon become glistening black. High humidity was necessary for hatching; no eggs of S. lividipes or S. hispidulus hatched at relative humidities of 76 per cent., or less, and virtually none of S. crinitus or S. lineatus at 56 per cent, or less. In favourable humidities, the percentage hatching was reduced at constant temperatures exceeding 25°C., except in S. lineatus, in which it was not affected up to 29°C. The threshold temperatures for development of eggs of S. lividipes, S. hispidulus, S. crinitus and S. lineatus were 4·8, 4·6, 5·8 and 6·5°C., respectively, and the thermal constants were 180, 211, 166 and 145 day-degrees C. The mean larval and (in brackets) pupal periods outdoors were 52 (23), 58 (34), 36 (25) and 38 (21) days, respectively. The average numbers of eggs laid were 843, 719, 519 and 1,113 per female, and the mean numbers laid per day were 10·2, 8·5, 9·6 and 17·5. These data were obtained by feeding adults on a variety of food-plants throughout their life in the laboratory. In another series of observations, adults were fed on the same type of food-plant throughout. Egg production of S. lividipes and S. hispidulus was greatest on clover (Trifolium alexandrinum) and least on broad bean (Vicia faba) and pea, respectively; that of S. crinitus and S. lineatus was greatest on pea and least on broad bean and clover, respectively.

Thirty Reticulitermes flavipes (Kollar) colonies established by alates collected from two separate field sites were raised in the laboratory for eight years. Twenty-one of the colonies were founded by alates from one field source and nine from another, providing demographic data from two unrelated parental lineages. Colony totals ranged from 3620 to 11641 individuals, with no significant difference in size between lineages. Soldier caste proportion of the colony total and mean wet weights for workers, soldiers and kings were significantly different between the two lineages. This suggests that at least a portion of the variability observed in caste ratios and body size may be heritable. One founding reproductive had died in five of the colonies (17%); none lost both parents. The queenless colonies contained exclusively female replacement reproductives (neotenics); the kingless colony contained a female-skewed mixture of male and female neotenics. All the nests that lost a founding parent contained significantly more pre-alate nymphs than the nests with both a king and a queen. Comparisons with published reports of ontogenetic patterns in other termites and social insects are discussed.

A total of 4418 mosquitoes caught by three collection methods at two levels in the forest near Belém, Brazil, were dissected to determine the proportion of parous individuals. About two-thirds of the mosquitoes belonged to Culex (Melanoconion) portesi Senevet & Abonnenc and C. (M.) taeniopus D. & K. The dissection technique entailed dissecting out the ovaries for examination of the tracheoles, whilst preserving the rest of the mosquito for later processing for virus recovery. Analysis of the results showed that, although significant differences were found in the parous rates from samples caught off human bait, and from mouse-baited Trinidad no. 17 and blower traps, these differences were unlikely to be of practical value when compared to differences in catching ability and ease of operation of the methods. In all, 2771 mosquitoes were classed as parous, and these when inoculated into baby mice in 142 pools yielded 14 isolations. It was concluded that the technique used did not reduce the likelihood of isolating viruses from the dissected mosquitoes.

The Sugar Industry of Mauritius is suffering heavily from damage by stem-borers, especially the “Spotted Borer,” Diatraea mauriciella, Wlk. It has been estimated (Moutia, 1934) that this species alone is responsible for an average reduction of 15 per cent, in the field, per arpent, and that the loss in sugar averages 2-3 per cent., i.e. 16 per cent, of the sugar in cane. This means a gross loss of about 1£ million rupees per annum for the whole island, or a net loss of approximately 125,000 rupees.

The majority of sorghum in Northern Nigeria is stored unthreshed in farmers' granaries made of dried mud or plant materials such as grass matting and cereal stems. During the course of survey work and insecticide trials in 1959–61 it was possible to examine many samples of unthreshed sorghum from granaries throughout Northern Nigeria. It was found that the distribution of insect species within the Region is not uniform. Sitophilus oryzae (L.) and Sitotroga cerealella (Ol.) are the major pests. Sitophilus zeamais Motsch. was found only in the southernmost area. Heavy infestations of Rhyzopertha dominica (F.), Lasioderma serricorne (F.), Cryptolestes ugandae Steel & Howe, Oryzaephilus mercator (Fauv.), Tribolium castaneum (Hbst.) and T. confusum Duv. usually occur. Attagenus gloriosae (F.), Ahasverus advena (Waltl), Palorus ficicola (Woll.), P. ratzeburgi (Wissm.) and P. subdcpressus (Woll.) are occasionally important.

R. dominica, Bruchidius sp., G. ugandae, Planolestes cornutus (Grouv.), S. oryzae, Brachypeplus sp., T. castaneum, Sitotroga cerealella (all of which occurred on the standing crop), L. serricorne, Typhaea stercorea (L.), O. mercator, Palorus spp. and Tribolium confusum were found in sorghum sampled before storage. Insects from infested stores were found to infest sorghum growing nearby. Prestorage infestation alone can result in subsequent heavy populations of insects in the store. Cross-infestation between granaries almost certainly occurs.

Under Samaru conditions, where sorghum is harvested in November–December, insect populations remain at a low level in granary-stored unthreshed sorghum until after June, when the moisture content rises in the rainy season. In sorghum stored for nine months in provincial trials, more damage occurred during the last three months than during the previous six months of storage.

Sorghum heads stored in granaries made of plant materials such as grass matting and cereal stems are more severely damaged by insects than those stored in dried-mud granaries. This is probably due to a higher rate of immigration in the former.

In threshed grain stored in a mud granary, moisture content and damage by the most abundant insect, Sitophilus oryzae, decreased with depth. The insect population rose to a peak in November, two months after the maximum moisture content. The numbers fell rapidly during the following dry season. The annual cycle of insect damage was also assessed by taking fortnightly samples of threshed grain from a local market. S. oryzae was the most numerous insect, but even this species was uncommon from December to May, during the dry season.

In populations of overwintering pupae of Delia radicum (L.) collected from ten sites in England and Wales, parasitism varied from 0% at Newcastle to 42% at Evesham. Unlike their hosts, few of the parasites were in extended diapause. Irrespective of when collected at Wellesbourne, emergence of 50% of the ichneumonid parasite Phygadeuon trichops Thoms., the eucoilid parasite Trybliographa rapae (Westw.) and the staphylinid parasite Aleochara bilineata Gylh. occurred after 14, 21 and 28 days, respectively, at 20°C. Early-emerging populations of D. radicum were more heavily parasitised than intermediate- or late-emerging populations. During the winters of 1979–80, 1980–81 and 1981–82, T. rapae and A. bilineata emerged in similar numbers from 37% of the field-collected pupae from Wellesbourne. Less than 1% of the pupae were parasitised by P. trichops. D. radicum adults emerged from a further 25% of the pupae, and the remainder, approximately 38%, were dead. Most dead pupae were recovered from heavily parasitised populations. When parasites were present in high numbers, many of their progeny probably died from multiple parasitism and superparasitism. Comparison with earlier studies indicated that parasitism should be expressed as a percentage of the total pupae, and not just as a percentage of the living insects, if the data are subsequently to be of use for studies on the population dynamics of this pest.

A novel type of emergence trap capable of capturing and separating ‘live’insect catches is described. The trap was shown to be 96% efficient at capturing newly emergent adult Hylobius abietis Linnaeus on bare ground and at least 82% efficient over stumps on a weedy Sitka spruce clearfell. The trap was more than 80% efficient at capturing Bracon hylobii Ratzeburg, the most commonly found parasite of H. abietis. It was also shown to be effective at capturing adult H. abietis of unknown age (98%), indicating that it could also be used to trap out H. abietis from known areas to estimate on-site overwintering densities. Fifty-four percent of newly emergent weevils were captured within 12 h of release on bare mineral soils. Forty-two percent of unknown age weevils and 52% of parasites were captured within 1 h of their release within the trap. The rapid rates of capture mean that when traps are checked frequently they can be used to reflect accurately temporal patterns of emergence. Its potential for use in control programmes and ecological studies is discussed.

Infestations of Dermestes maculatus Deg. in dried fish at Dugbe market, Ibadan, are favoured by traditional packaging and display methods. In laboratory experiments last-instar larvae and adults showed low thigmokinesis and a bias towards the dry end of a 50–100% r.h. gradient; in alternative humidities between 40% and 100% last-instar larvae and adults selected 60–80% r.h., adults having a stronger preference than the larvae for the higher humidity; in a temperature gradient last-instar larvae and adults avoided the 30–45° C zone and showed low thigmokinesis and immobilisation at 19° C. These findings were generally consistent with observations in the market. Heating dried fish in an oven at 60° C for 30 min killed all larvae and adults of D. maculatus present. Two 30-min heat treatments at four-day intervals in a simple charcoal-fired oven and storage in metal containers would control the pest.

The effects of intraplant variation of nitrogen, phosphorus, potassium and wafer content within maize plants on fitness of the African armyworm, Spodoptera exempta (Walker), were studied in three experiments by using an excised leaf system. Maize plants were phosphorus deficient in one of the experiments. Various leaf categories were distinguished differing in age and position on the plants. Leaf sections on which caterpillars fed were daily refreshed. Changes in the four plant variables measured, due to the excision and subsequent placement of the leaf sections in the excised leaf system for one day, were small and mostly insignificant. Highly significant differences were found between the composition of the various leaf categories in all three experiments. In all experiments, the nitrogen concentrations ranged from 2.4 to 4.5%, phosphorus from 0.1 to 1.3%, and potassium from 1.4 to 4.8% dry weight, while water content varied from 83 to 90% fresh weight. Of all insect fitness parameters observed, only larval growth rate was consistently and significantly affected by leaf category. Fecundity was strongly correlated with pharate adult weight. Only phosphorus was significantly and positively correlated with larval fresh weight, especially in the experiment with phosphorus deficient plants. Multiple regression models revealed that in all experiments a significant proportion of variation in larval fresh weight between leaf categories could be explained by the four plant variables. However, only phosphorus was included in all models. When all leaf categories used in the three experiments were considered simultaneously, the importance of phosphorus for larval growth rate in these experiments was again evident. The variation in nitrogen, potassium and water appeared to be of little or no significance. The consequences of these findings for outbreak development of S. exempta are discussed.

Primers for DNA amplification using the polymerase chain reaction (PCR) were synthesized for a microsatellite locus isolated from a partial genomic library of the aphid parasitoid Aphelinus abdominalis (Dalman). Screening for genetic polymorphism at this locus in two laboratory strains of this wasp revealed the presence of two alleles different in the number of (GT) and (GGC) repeats. The relative frequencies of the two alleles were not significantly different between the two strains or between diploid females and haploid males. Heterozygosity at this microsatellite locus was estimated to be 0.40 which is within the range in other hymenopterous species. Given that A. abdominalis is a good candidate for augmentative release programmes in greenhouses against aphids, we suggest that microsatellite markers may have application in discriminating among aphelinid sibling species and strains. The markers provide a means for studying the performance and impact of selected parasitoid lines on pest dynamics in field release experiments.

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.