Argas persicus (Oken) fed readily on avian hosts and consumed more blood and produced more eggs than on mammalian hosts. Ornithodoros tholozani (Lab. & Mégn.) fed equally well on chicken and various laboratory animals and converted the blood of all hosts into eggs at equal rates. O. moubata (Murr.) was intermediate, feeding more readily on chicken, rabbit and guineapig than on mouse, rat or hamster, and showing greater utilisation of blood of chicken and rabbit than of the other hosts. The relation of these phenomena to the natural host spectra of the 3 tick species is discussed.

Seeing that Glossina morsitans, the typical “tsetse” fly of writers on South Africa, has been well known for perhaps a longer period than any other member of the genus, it is a matter for great surprise that much of its life history is yet entirely unknown. A large mass of literature, dealing with its general habits, is extant, but the breeding habits and the larva have not been described. It is noteworthy that only last year a single specimen of the puparium was discovered for the first time, and when the wide distribution, the great plentitude, and the economic importance of the fly are considered, this becomes all the more remarkable.

Aspidoproctus armatus, Newst.

PortugueseCongo: San Salvador; on tree of unknown species (Dr. Mercier Gamble).

Aspidoproctus ? glaber, Lind.

Nyasaland: Mlanje; on “ mwanga ” tree, x. 1913 (S. A. Neave).

A small undersized female, unfortunately imperfect. I have placed it here, as it agrees, apart from its size, with Lindinger's description.

Fourteen species of SIMULIIDAE (of which one occurs in two forms) are recorded from Northern Nigeria. Localities for each species are given on distribution maps. Most of the species are of fairly general occurrence in the Ethiopian Region, although Simulium kenyae De Meillon is recorded for the first time from West Africa. No new species was found in an extensive survey of about 200,000 square miles.

Some notes are included on the breeding habits of the species, particularly the type of breeding site preferred, the altitudes at which breeding occurs, and the months in which immature stages have been found.

Some discussion is given of the distribution of SIMULIIDAE in Northern Nigeria and the factors which appear to influence it, partly illustrated by maps. The most important factor is thought to be the geology of the country, which determines the areas of rivers suitable for breeding. Other factors such as climate, altitude, or vegetation zones, seem to play little part, except in the far north.

In certain areas of the Kenya coast, Culex quinquefasciatus Say is unable to maintain itself in breeding sites (flooded pit latrines) which it has to share with C. cinereus Theo. The pattern of settlement of the two species and the replacement of C. quinquefasciatus by C. cinereus were studied from May to November 1980 by monitoring newly emerged males as they departed from two breeding sites located in a small village near Mombasa. C. quinquefasciatus was the first species to be recorded from both sites, soon after they were flooded by the early rains. C. cinereus came later and did not increase markedly until after the late rains. The pattern of replacement of C. quinquefasciatus by C. cinereus was similar in the two breeding sites; the former species was unable to maintain itself once C. cinereus started to increase. Studies in another village showed that, after displacement, egg laying by C. quinquefasciatus continued but at a much reduced level. It is suggested that this is an example of competition-mediated succession occurring annually, with C. quinquefasciatus being better adapted to exploit rapidly the newly flooded sites but unable to sustain later competition from C. cinereus.

The effectiveness of ten acaricides against Boophilus microplus (Can.) on cattle in southern Queensland, Australia, was investigated in 1960–63. Of infested cattle dipped in or sprayed with each acaricide, some were kept in stalls so that observations on ticks that survived treatment could be made, and others were grazed in tick-infested pastures in order to find the period of protection against reinvasion by larvae. Untreated cattle were also kept in the stalls to indicate the numbers of ticks occurring in the absence of treatment. The reproductive capacity, in terms of eggs and larvae produced, of ticks surviving treatment was compared with that of untreated ticks, and, for aldrin, dieldrin and the last four compounds mentioned below, the protective period in the field was compared with deposits of acaricide on the hair of the cattle as indicated by chemical and biological tests. For the last four acaricides, the effect on toxicity of artificially fouling the dip fluid was investigated, and also the relative toxicity of clean and artificially fouled fluids to ticks dipped in them under laboratory conditions.

The acaricides tested, and (in brackets) the concentrations used, were aldrin (0·05 & 0·1%), dieldrin (0·1%), carbaryl (0·2%), Boots' ED 12308 (0·2%), ethion (0·1%), Ciodrin (0·1%), coumaphos (0·02%), diazinon (0·05%), carbophenothion (0·086%) and dioxathion (0·075%). All were emulsion formulations except carbaryl and diazinon, which were used in wettable-powder form.

Daily collections of engorged adult ticks that fell from the stalled cattle provided clear-cut, though not quantitative, assessments of the effects of the acaricides. All the compounds tested gave a very high level of control, the only exception being the lower concentration of aldrin, and the reproductive capacity of ticks that survived treatment was negligible. With some of the acaricides, large numbers of surviving ticks fell in the first day or two after treatment, and some laid eggs; but the viability of the latter was invariably low. These observations emphasise the need to consider the reproductive capacity as well as the direct kill of parasitic ticks when assessing the value of acaricides. At the concentrations tested, nearly all the compounds allowed a few ticks to survive that were in the engorged-nymph stage at the time of treatment; these dropped off the cattle from the tenth day onwards and laid viable eggs.

The mean protective periods of the chlorinated hydrocarbons and organophosphorus compounds ranged from three to six days, but on individual animals periods from three to eight days were recorded. Amongst the carbamates, a mean protective period of seven days was recorded for carbaryl in summer, whereas the mean protective period of RD12308 in winter, when such periods are longer, was 12 days. In come cases, protection appeared to continue when deposits of the original acaricide could no longer be detected on hair samples, and reasons for this are discussed.

The influence of various factors, other than concentration, on the effectiveness of acaricidal fluids and on the results of tests was examined. Chemical and biological tests of hair samples showed that the acaricides persisted longer on stalled than on pastured cattle. Formulations affected the amount of toxicant deposited on the hair, and there was an indication that fouling of the dip fluid with soil and dung may, under certain circumstances, increase the amount of toxicant deposited.

Threshold temperatures, growth rates and physiological development times were calculated for the egg, larval and pupal stages of the groundnut leaf-miner, Aproaerema modicella (Deventer), a key pest of groundnut (Arachis hypogaea) and soyabean (Glycine max) in India. The life cycle of Aproaerema modicella required 660 degree-days (DD) above threshold temperatures (12.4°C for eggs, 11.3° for larvae and 14.7° for pupae). A function fitted to the adult longevity and fecundity data describes the effect of temperature and female age on fecundity. Egg production was greatest at 30°C and declined at lower and higher temperatures. Head capsule width measurements indicated that five larval instars are typical in India. The results obtained are discussed in the context of earlier work.

Observations were made on the bionomics of Spodoptera mauritia acronyctoides Gn. in Malaysian Borneo (Sarawak) during an outbreak in 1967. The outbreak was discontinuous over about 6 000 sq. miles, affecting 25 000 acres of lowland and upland rice. In the insectary the durations of the various stages were: egg 2·9 days, first- to seventh-instar larvae respectively 3·1, 1·8, 2·2, 2·1, 2·2, 2·3 and 4·9 days, and pupa 8·4 days. Larval instars could usually be distinguished on head width and the width of the faecal pellets. Food consumption of the larvae was greatest during the final instar. During the outbreak the larvae were found mainly on young rice, and also on young maize; wild host-plants included grasses and sedges, but dicotyledonous plants were not attacked.

Females generally mated on the night following emergence, and the pre-oviposition period averaged 2·9 days. Fertilised females laid an average of 1 749 eggs, 80% of the potential total. Virgin females laid only 22% of the potential, and resorbed some of their oocytes. The mean longevity of fertilised females was 5·5 days. Fecundity was directly correlated with pupal weight or length, and the weights of pupae produced in wet-rice fields were significantly heavier than those from dry hill-rice sites. There was a significant correlation between the weight of frass produced (hence food consumed) by the seventh-instar larva and the weight of the pupal stage. Pupae from larvae in crowded cultures were significantly lighter than those reared singly.

Observations on the sexual behaviour, oviposition and responses to insect prey of the predatory Reduviid Vestula lineaticeps (Sign.) were made in the laboratory. Experiments with cardboard models indicated the importance of moving visual stimuli in eliciting predatory responses, but provided no evidence that olfactory stimuli play any such role. The responses of adult females towards other adults were apparently purely predatory. Males did not visibly discriminate between living females and other specimens (dead females, living or dead males) until they had seized them, when they displayed sexual responses with the living females and usually purely predatory behaviour with the remainder.

In this study, we present the first characterization of herbivore-induced plant volatiles (HIPVs) released from infested olive leaves. The gall midge Dasineura oleae is a specific pest of Olea europaea and endemic of the Mediterranean Basin, an area in which severe outbreaks currently occurred. Little is known about the damage caused by the pest and the relationship with its host. Since gall formation and larval feeding activity may lead to the release of specific plant volatile compounds, we investigated the volatile profiles emitted from infested plants compared with healthy plants under both laboratory and field conditions. Additionally, the volatiles emitted from mechanically damaged plants were considered. A blend of 12 volatiles was emitted from olive trees infested by D. oleae. Of these, β-copaene, β-ocimene, cosmene, unknown 1 and unknown 3 were found to be exclusively emitted in infested plants. The emission of germacrene-D, (E,E)-α-farnesene, and (Z,E)-α-farnesene, α-copaene, (E)-4,8-dimethylnona-1,3,7-triene, (E)-β-guaiene and heptadecane significantly increased in infested trees. Linalool, β-copaen-4-α-ol, β-bourbonene, β-cubebene, β-elemene, β-copaene and δ-amorphene were found only in the field trial and showed differences depending on the level of infestation and the plant stage. (Z)-3-Hexenol, (E)-4-oxohen-2-enal, and 2-(2-butoxyethoxy)-ethanol, were exclusively emitted from the leaves after mechanical damage. In a field trial in Italy, we also demonstrated spring synchronization between adults of D. oleae and O. europaea trees. Analyses of morphoanatomical malformations of gall leaves showed that tissue alterations occur at the spongy parenchyma causing an increase of the leaf blade thickness. We speculate that tissue alterations may lead to HIPV release, in turn potentially attracting D. oleae natural enemies.

Larvae of the southern African geometrid moth Comostolopsis germana Prout feed on the shoot apices and axillary buds of Chrysanthemoides monilifera, a serious alien weed of native vegetation in Australia. The insect was found in low abundance throughout the distribution of its hosts, C. incana and C. monilifera, in southern Africa. Larvae were present throughout the year in subtropical Natal, but were absent in winter in the cooler, Mediterranean type climate of Cape Province. In host-specificity tests using 65 plant species from 26 families, Comostolopsis germana completed development only on Chrysanthemoides monilifera monilifera and C. monilifera rotundata. Insignificant, exploratory feeding occurred on Olearia axillaris (Compositae) and pea, Pisum sativum (Leguminosae). In multiple-choice oviposition tests eggs were laid on 41 species, but a strong preference was shown for the foliage and stems of C. monilifera. Larvae grazing the flower buds, pedicels and peduncles of C. monilifera may reduce the reproductive capacity of their host and contribute to its control. Comostolopsis germana has been approved for release as a biological control agent of Chrysanthemoides monilifera in Australia.

Uscana lariophaga Steffan is an egg parasitoid of the bruchid species Callosobruchus maculatus (Fabricius) and Bruchidius atrolineatus Pic in West Africa, which cause damage in stored cowpea (Vigna unguiculata (Leguminosae)). In a no-choice situation, the attractiveness of some odour sources to the parasitoid was studied in a simple diffusion olfactometer. Cox's proportional hazards model was used for data analysis. The results showed that cowpea beans were more attractive to naive U. lariophaga females than glass beads. Baits with host eggs were more attractive than baits without eggs. Experienced females did not perform any better than naive ones. The relationship between the inclination to fly of the parasitoids, and the baits used, was difficult to interpret. Changes in searching activity between the different weeks of experimentation were observed. Only a small part of this variation could be explained by (absolute) changes in barometric pressure.

The numbers of adults of Hydrotaea irritans (Fall.) caught in Manitoba traps in north-eastern England varied greatly between successive 30-min periods. Weather variables accounted for 49·4% of this variation, but only wind speed and sunshine showed significant simple correlations with fly catch. Using principal component analysis of weather data, three principal components accounted for 67·3% of the variation in catch. The two components most highly correlated with catch were composed mainly of wind speed, sunshine, shade temperature and radiant temperature. These two principal components were used as covariates in an analysis of the effects of a heated target and carbon dioxide on trap effectiveness. Heating the target to blood temperature increased the catch of females 1·8-fold but had only a slight effect on the catch of males. The presence of CO2 increased the female catch nearly fivefold and the male catch more than fourfold. There was no interaction between the two stimuli of heat and CO2. A separate experiment showed no significant difference in catch between CO2-baited traps using spheres 0·6 or 0·3 m in diameter as the target.

The quantification of host–parasite associations from field data is a fundamental step towards understanding host–parasite and host-parasite–pathogen dynamics. For parasites that are not rigid host specialists, exemplified in this paper by ticks, the interpretation of host–parasite association data is difficult. Interpretations of tick collection records have largely assumed that off-host collection records offer a valid basis from which to make claims about the host specificity or generality of tick species. A simple simulation analysis of rudimentary tick–host interactions in a hypothetical 50 × 50-cell habitat demonstrates that perceptions of tick–host relationships can be strongly biased by spatial patterns. Regardless of their true level of host specificity or generality, it seems that: (i) more abundant ticks will be perceived as generalists, while rarer species will be considered specialists; and (ii) tick species that have patchy, strongly aggregated distributions will be more likely to be perceived as host specialists than species that have more dispersed or uniform distributions. Since all available evidence suggests that abundances and spatial patterns vary between tick species, there is no way of assessing the true validity of claims about host specificity without first undertaking detailed research on the relative abundances and spatial and temporal patterns of both tick and host distributions.

The within-plant dispersion characteristics of Megalurothrips sjostedti (Trybom) on cowpeas were determined in studies in Nigeria. Iwao's regression procedure and Taylor's power law analysis were used to determine the relationship between the mean and variance of thrips counts. Both methods showed that adult thrips were randomly distributed within cowpea plants at initial low populations. At later high densities, Iwao's method provided a better fit of the population dispersion of larvae and adults and showed that both were aggregated. The negative binomial best described this aggregation at high population densities. Sequential count plans suitable for pest management surveys were developed using critical stop lines derived from Iwao's regression procedure and Taylor's power law, but the latter was found to require less effort to achieve the same level of precision. There was a functional relationship between the variance and mean of untransformed population counts, and the suitability of transformation functions is discussed.

Following the global uptake of transgenic cotton several Hemipteran pests have emerged as primary targets for pesticide control. Previous research on one such emergent pest: the green mirid, Creontiades dilutus, indicated differential use of two crop hosts, cotton (Gossypium hirsutum, Malvaceae) and lucerne (alfalfa) (Medicago sativa, Fabaceae). We tested the hypothesis that this apparent demographic independence of lucerne and cotton inhabiting mirids is the result of cryptic species being associated with these two crops. We assessed gene flow using microsatellite markers across adjacent cotton and lucerne crops at three geographically separated sites (up to 900 km apart). We also analysed the recent feeding behaviour of these insects by amplifying chloroplast markers from their gut contents. We find high gene flow between these two crops (mean pair wise FST between host plants=0.0141 within localities), and no evidence of cryptic species. Furthermore, the gut analyses revealed evidence of substantial recent movement between these two crops. We discuss the implications of these results for interpreting multiple host use in this species and setting future research priorities for this economically important pest.

Nesidiocoris tenuis (Reuter) (Heteroptera: Miridae) is an omnivorous insect used for biological control. Augmentative release and conservation of N. tenuis have been used for pest control in tomato crops. Intracellular bacterial symbionts of arthropods are common in nature and have diverse effects on their hosts; in some cases they can dramatically affect biological control. Fingerprinting methods showed that the symbiotic complex associated with N. tenuis includes Wolbachia and Rickettsia. Rickettsia of N. tenuis was further characterized by sequencing the 16S rRNA and gltA bacterial genes, measuring its amount in different developmental stages of the insect by real-time polymerase chain reaction, and localizing the bacteria in the insect's body by fluorescence in situ hybridization. The Rickettsia in N. tenuis exhibited 99 and 96% similarity of both sequenced genes to Rickettsia bellii and Rickettsia reported from Bemisia tabaci, respectively. The highest amount of Rickettsia was measured in the 5th instar and adult, and the symbionts could be detected in the host gut and ovaries. Although the role played by Rickettsia in the biology of N. tenuis is currently unknown, their high amount in the adults and localization in the gut suggest that they may have a nutritional role in this insect.

Anthropogenic range expansion and cultural practices have modified the distribution, abundance and genetic diversity of domesticated organisms, thereby altering multitrophic assemblages through space and time. The putative Mesoamerican domestication centre of the common bean, Phaseolus vulgaris L., in Mexico allows investigating the effects of plant domestication on the genetic structure of members of a multitrophic system. The aim of this study was to compare the evolutionary history of Horismenus parasitoids (Hymenoptera: Eulophidae) to those of their bruchid beetle hosts (Coleoptera: Bruchidae) and their domesticated host plant (P. vulgaris), in the context of traditional agriculture in Mexico. We analyzed the population genetic structure of four Horismenus species in Mexico using mitochondrial COI haplotype data. The two most abundant parasitoid species were Horismenus depressus and Horismenus missouriensis. Horismenus missouriensis were infected by Wolbachia endosymbionts and had little to no population differentiation (FST = 0.06). We suspect the mitochondrial history of H. missouriensis to be blurred by Wolbachia, because differentiation among infected vs. non-infected individuals exists (FST = 0.11). Populations of H. depressus were found to be highly differentiated (FST = 0.34), but the genetic structuring could not be explained by tested spatial components. We then compared the genetic structure observed in this parasitoid species to previously published studies on bruchid beetles and their host plants. Despite extensive human-mediated migration and likely population homogenization of its two Acanthoscelides bruchid beetle hosts, H. depressus populations are structured like its host plant, by a recent dispersal from a diverse ancestral gene pool. Distinct evolutionary dynamics may explain inconsistent patterns among trophic levels. Parasitoids likely migrate from wild bean populations and are poorly adapted to bean storage conditions similar to their bruchid beetle hosts. Integrating several trophic levels to the study of evolutionary history has proven to be fruitful in detecting different ecological responses to human-mediated disturbances and host parasite interactions.

Previous attempts to control Woolly Apple Aphid (Eriosoma lanigerum (Hsm.)) in Rhodesia are briefly reviewed. By the application of dimethoate at a rate of more than 5.0 grams a.i. or of vamidothion at more than 6.0 grams a.i. to the soil in the drip area of the tree, it was found that good control of both the foliar and root populations of the insect could be obtained on three-year-old apple trees 10 feet high. and the treatment appeared to remain effective for three seasons. It is considered that the timing of the application, the soil temperature, and the amount of wead cover are all important factors in affecting the amount of insecticide taken up by the apple trees.

Studies were carried out in Jamaica on the larval biology of Leptoconops becquaerti (Kieff.) in 1962–63.

Larvae were reared on natural breeding sites in chambers constructed from large tins, by methods that are described in detail. The features of the breeding sites are illustrated and briefly discussed.

The developmental period from egg hatching to adult emergence probably occupies four to eight weeks, depending to a certain extent upon temperature and hence on time of year. It is unlikely that the adult stage is ever reached in much less than three weeks under natural conditions. Under experimental conditions, overall survival to the adult stage was frequently greater than 20 per cent., and occasionally over 50 per cent. It is considered that survival in natural populations is probably also quite high.

Larval mortality in the experimental chambers apparently occurred maintly in the first instar, and this probably happens in nature. The results showed a relationship between percentage survival and egg number such that proportionately fewer adults were obtained from chambers with greater numbers of eggs. This was interpreted as being due to progressively more severe starvation of very young larvae in the more crowded chambers.

There was no marked tendency for adults of the more same sex to emerge first in the chambers. The sex ratio among the total of 1,039 adults obtained was 1:1.

In an experiment to investigate the diel rhythm of adult emergence, 71 per cent. of adults of L. becquaerti emerged in the four-hour period of 0300–0700 hr., and a further 27 per cent. appered between 0700–1100 hr. This is earlier than found in Culicoides furcns (Poey) in a previous experiment.