1. The male of Pseudococcus is co-equal in importance with the female for the propagation of the species. Virgin females of P. citri, Risso (both aerial and root forms), P. maritimus, Ehr., P. gahani, Green, P. longispinus, Targ., and T. peregrinus, Green, are incapable of producing offspring. No form of parthenogenesis occurs in these five species. Only fertilised eggs develop.

2. The relative abundance of the male sex varies greatly from species to species. The specific sex ratio of citri is 101·62± 1·54 ♂♂ per 100 ♀♀, estimated from 11,413 progeny from 47 females; that of maritimus is 59·65± 9·39 ♂♂ per 100 ♀♀, estimated from 4,630 progeny from 42 females; that of gahani is 43·025± 2·28 ♂♂ per 100 ♀♀ estimated from 12,092 progeny from 61 females; that of longispinus (for bisexual families only) is 19·28± 2·27 ♂♂ per 100 ♀♀, estimated from 4,084 progeny from 19 females; and that of peregrinus 37·01± 7·906 ♂♂ per 100 ♀♀, estimated from 3,946 progeny from 24 females.

In the introduction to the first part of this paper* it was remarked that very little exact work had been published on the adult European SIMULIDAE. This is equally true of the larvae and pupae ; in fact no one has attempted to describe the early stages of more than two or three of the common species. Moreover, in spite of their great interest, and the ease with which they can be collected and reared, they have apparently been almost entirely ignored by collectors, so that whereas in publishing my previous work I was able to acknowledge valuable assistance from a number of fellow entomologists, the results given in the following pages are, unless otherwise stated, due to my own observations. I wish especially to thank Mr. M. E. Mosely for the early stages of S. subornatum, the last species to come under my notice in the pupal stage. While there are still many important gaps in our knowledge which remain to be filled, it has been thought worth while to state without further delay the results that have been obtained so far.

The importance of colour in the attraction of Glossina palpalis palpalis (Robineau-Desvoidy) to trapping devices was investigated in the Ivory Coast. Biconical traps were tested with the normally royal blue lower cone replaced with one of 25 differently coloured cloths. Royal blues were consistently the best colours for traps; yellow and orange were the worst, catching less than 1% as many as the best royal blue. Modelling trap data from the spectral reflectivities of the colours used showed that blue wavelengths contributed positively, and ultraviolet and green-yellow-red negatively, to trap performance. The responses to screens were studied using electric nets, deployed to catch flies both circling around and landing on the screen. The overall catch (of circling and landing flies) was greatest for royal blue screens, intermediate for yellow and green ones, and lowest for screens highly reflective of ultraviolet light; the total range of variation between colours was much smaller than was the case with traps. The relationship of catch to spectral reflectivity was similar to that described for trap score. An achromatic series of screens (black, white and greys) all attracted significantly fewer females than did royal blue screens, implying that attraction to blue depends on colour discrimination and not on intensity contrasts alone. For most colours, the majority of flies circled the screen without landing; with materials strongly reflecting ultraviolet, however, a high proportion of flies (especially females) landed.

The common green lacewing Chrysoperla carnea is a key biological control agent employed in integrated pest management (IPM) programs for managing various insect pests. Spinosad is used for the management of pests in ornamental plants, fruit trees, vegetable and field crops all over the world, including Pakistan. A field-collected population of C. carnea was selected with spinosad and fitness costs and realized heritability were investigated. After selection for five generations, C. carnea developed 12.65- and 73.37-fold resistance to spinosad compared to the field and UNSEL populations. The resistant population had a relative fitness of 1.47, with substantially higher emergence rate of healthy adults, fecundity and hatchability and shorter larval duration, pupal duration, and development time as compared to a susceptible laboratory population. Mean relative growth rate of larvae, intrinsic rate of natural population increase and biotic potential was higher for the spinosad-selected population compared to the susceptible laboratory population. Chrysoperla species are known to show resistance to insecticides which makes the predator compatible with most IPM systems. The realized heritability (h2) value of spinosad resistance was 0.37 in spinosad-selected population of C. carnea.

To improve the precision of understanding of the phenology of Listronotus bonariensis (Kuschel), samples were collected at regular intervals near Canterbury, New Zealand, and the seasonal changes in their reproductive morphology monitored by regular dissection. It was demonstrated that the adult weevils enter hibernatory reproductive diapause in early March and remain in this state until late July when reproductive activity resumes. Adults emerging in February may enter diapause immediately. The existence of diapause was further supported by its associated cessation of mating, increase in body fat and apparent drop in the haemolymph titre of juvenile hormone. Laboratory experiments indicated that a critical photoperiod induces diapause and an eventual reduction in sensitivity to photoperiod allows reproductive activity to resume.

Massive mosquito nuisance problems, caused by the flood-water mosquito Aedes sticticus, occur after floods in the flood plains of the River Dalälven, central Sweden. Since 2002, the biological mosquito larvicide Bacillus thuringiensis var. israelensis (Bti) has been used to control these mosquitoes. Here, we report results from the first six years of monitoring Chironomidae, the most susceptible non-target organisms, in three wetlands with Bti-treatment against mosquitoes and in three wetlands without treatment. Emergence traps were used for continuous insect sampling from May to September each year, 2002–2007, and were emptied once a week. A total of 21,394 chironomids of 135 species were collected, and the subfamily Orthocladiinae dominated the fauna followed by Chironominae and Tanypodinae. The annual chironomid production in the wetlands was low, with an average of 1917 individuals per m2, and 42 g ash-free dry weight per m2. We found no reduced production of chironomids at neither family, nor subfamily level, in Bti-treated as compared to untreated wetlands. This is the first long-term follow-up study of the possible effects of Bti-based mosquito larval control on chironomid species production. In the short-term view, one species had higher production in treated areas. In the long-term view, four species had higher and one species had lower production in treated areas. We conclude that the Bti-based control of flood-water mosquitoes does not cause any major direct negative effects on chironomid production, and therefore does not seem to induce any risk for indirect negative effects on birds, bats or any other predators feeding on chironomids.

The life-history and seasonal cycle of the Lepidopterous borer, Busseola fusca (Fuller), the most serious pest of maize in Southern Rhodesia, have been studied there.

There are two generations in the year, the majority of the full-grown larvae of the second entering diapause, in which condition the dry season is passed in the maize stem, but a proportion of the second-generation consists of short-cycle individuals that give rise to moths irregularly during the dry season.

In the field, the egg stage lasts about 7–11 days, according to the time of year. In the laboratory, there are six, very occasionally seven, larval instars in the first generation, occupying about 37 days, and the pupal stage lasts about 17 days. In the second (diapausing) generation there may be one or two additional moults without appreciable change in size, and there is considerable variation in the length of instars and in the date of entry into diapause, but by mid-June the bulk of the larvae that will survive are in diapause. The majority of diapause larvae pupate in early November, the pupal stage lasting about 23 days.

The feeding habits of the larvae are described and reference is made to other food-plants.

The length of life of the adult, in cage conditions, averages 6–7 days, but there is great variation. When provided with diluted honey, adults were not observed to feed, and absence of such food did not appear to impair egg-laying. The sex ratio was 1:1, but in catches at a light-trap the ratio of males to females was 5:1. Copulation takes place shortly after emergence, and oviposition may begin within 24 hours of emergence.

The average number of eggs laid per female in cages was 360 over an average of four days, one female laying 1,032. Several batches of eggs may be laid in one night. A single mating appears to be sufficient, but males may copulate with more than one female. Eggs laid by virgin females do not hatch.

Diapause is thought to be induced by larval feeding on drying food. Continuous rearing of non-diapause generations can be achieved by feeding the larvae on fresh, green maize. Similarly, in the field, irrigated out-of-season maize will support non-diapause generations and constitute a source of infestation that may render ineffectual the normal routine destruction of all plants of the previous dry-land farming season.

The main parasite is the Tachinid, Sturmiopsis parasitica (Curr.), which may destroy more than 33 per cent, of the larvae in either generation.

The aim of this study was to evaluate the effects of silicon application and administration of the phytohormone gibberellic acid on resistance of the corn plants to the fall armyworm (FAW), Spodoptera frugiperda, and their vegetative characteristics. We evaluated larval and pupal duration, survival and biomass, and adult longevity, malformation and fecundity of S. frugiperda after feeding on plant matter treated with silicon and/or gibberellic acid. The feeding preference of FAW first-instar larvae, the total leaf area consumed by the insects, and the vegetative parameters of corn plants were also evaluated. No significant differences were observed in the measured parameters of larval and pupal stages of S. frugiperda in response to silicon or gibberellic acid. In adult stage insects, the number of eggs per female was significantly reduced in insects derived from larvae fed plants treated with silicon or gibberellic acid. In a non-preference test, 48 h after release, caterpillars preferred control untreated plants and consumed less matter from plants that had received hormonal treatment (gibberellic acid). Gibberellic acid also altered the vegetative characteristics of plants, by increasing their height, shoot fresh and dry mass, and silicon content. We conclude that gibberellic acid can alter the vegetative characteristics and silicon uptake of corn plants, leading to a reduction in their consumption by S. frugiperda larvae and a decrease in female insect oviposition.

Competitive displacement of fruit fly parasitoids has been a serious issue in the history of fruit fly biological control in Hawaii. This concern regarding competitive risk of new parasitoids has led to an overall tightening of regulations against the use of classical biological control to manage fruit flies. Fopius arisanus (Sonan), an egg–larval parasitoid, is the most effective natural enemy of tephritid fruit flies in Hawaii. This study evaluated the competitive risk of two recently introduced larval parasitoids, Diachasmimorpha kraussii Fullaway and Psyttalia concolor (Szépligeti), to F. arisanus attacking the Mediterranean fruit fly, Ceratitis capitata (Wiedemann). Fopius arisanus won almost all intrinsic competitions against both larval parasitoids through physiological suppression of egg development. 83.3% of D. kraussii eggs and 80.2% of P. concolor eggs were killed within three days in the presence of F. arisanus larvae within the bodies of multi-parasitized hosts. The mechanism that F. arisanus employs to eliminate both larval parasitoids is similar to that it uses against three other early established larval fruit fly parasitoids: F. vandenboschi (Fullaway), D. longicaudata (Ashmead) and D. tryoni (Cameron). It suggests that introduction of these larval parasitoids poses minimal competitive risk to F. arisanus in Hawaii.

Two field-collected strains of Culex quinquefasciatus Say, collected 50 km apart in Havana City, Cuba, were both resistant to malathion and propoxur, while one population also showed low level resistance to temephos. Laboratory selection of the latter population with malathion for 22 generations increased the malathion resistance 1050-fold, temephos resistance 24-fold and propoxur resistance 453-fold compared to the standard laboratory susceptible strain. Synergist studies and biochemical tests indicated that two mechanisms, an elevated esterase and an insensitive acetylcholinesterase, were operative in these strains. The esterase mechanism conferred resistance to malathion, but not to temephos or propoxur. The acetylcholinesterase mechanism increased the level of malathion resistance and extended the cross-resistance spectrum to temephos and propoxur.

Sizes of young field-collected males of Glossina morsitans morsitans Westw. were compared with those of teneral males emerging in the laboratory from field-collected puparia. Based on the mean size, indications were that smaller flies in field populations were selected against for about seven months in the year. A method is described for estimating the proportion of flies lost in the field population, and for the calculation of standard deviations for the estimates. Estimates of the extent of elimination showed that up to 35·2% of the total fly population in the field was eliminated in the cool months and up to 75·5% in the hot dry months.

The four components of the synthesised sex pheromone of Spodoptera littoralis (Boisd.) are tetradecan-1-yl acetate (I); cis-9-tetradecen-1-yl acetate (IIA); trans-11-tetradecen-1-yl acetate (IIB); and cis-9, trans-11-tetradecadien-1-yl acetate (III). Dissolved in hexane they were dispensed in small polythene containers either singly or in combination over water-trough (WT) traps located in the potato-growing region of south-east Cyprus. Only III was necessary to attract male moths. Increased loadings of III resulted in an increased catch during the 20-day test periods; at a loading of 500 μg per dispenser the material was attractive for approximately 20 days, and at 5000 μg for up to 40 days. IIA combined with III in WT traps or with virgin females in the vane traps markedly reduced the catch of male moths. The level of inhibition induced by IIA on the attraction of female moths was related to the loading of this substance in the dispensers. An inhibitory effect on the attraction of female moths in vane traps was also shown for cis-11-tetradecen-1-yl acetate, although this substance was less active compared with IIA at the same loading. No marked attraction or inhibition was shown for I or IIB, neither was any synergistic action demonstrated for these substances when in combination with III. When 200 polythene dispensers each containing 500 μg of III were evenly distributed throughout a potato field of 2000 m2 during the test period of 19 days virtually no males were caught in a trap baited with virgin females located in the centre of the field. Using only 100 point sources of III at twice the loading, only a slight reduction in catch compared with control catches was noted.

1. 97 per cent, of the ♀ A. gambiae, A. funestus and A. melas remained until after dawn in the huts in which they had fed.

2. ♀ A. melas seldom left suitable huts in the daytime.

3. There was a high positive correlation between the time at which ♀ A. funestus entered huts and the time of moonlight. The maximum correlation coefficient was between the size of the catch at 8 p.m. and the duration of moonlight after this period, and its value was –0·783±0·068.

4. During moonless periods, the flighting of ♀ A. funestus was partially inhibited, and when the moon came out, the waiting mosquitos entered the huts in greatest numbers. The average proportion caught when the moon rose during catching periods ending 10 p.m., midnight and 7 a.m. was approximately 50 per cent., 100 per cent. and 400 per cent. greater, respectively, than the proportion caught during these periods on moonless nights. On moonless nights many mosquitos waited until twilight of the following evening before entering the huts, and in consequence the average proportion caught in the period ending 8 p.m. was six times greater on moonless nights than on the nights after full moon.

5. The records for ♀ A. melas are less complete, and the correlation coefficient for the relation between time of entry and time of moonlight has the value 0·421±0·184, a result which is barely significant. In view of the highly significant correlations found in the case of A. funestus it is unlikely that this correlation is fortuitous.

6. The average rate of entry of ♀ A. funestus throughout one complete lunar cycle at Krabonekrom, Gold Coast, was 27 per cent. before 8 p.m., 22 between 8 p.m. and 10 p.m., 21 between 10 p.m. and midnight and 30 after midnight. The similar rates for A. gambiae (based on very few records), were 10, 20, 30 and 40 per cent. respectively. Comparable rates for A. melas in Sierra Leone are not available, but at least 45 per cent. entered before 10 p.m. (= 11 p.m. Gold Coast time).

7. The essential difference between the behaviour of ♀ A. funestus and that of A. gambiae is that the former flight earlier than the latter. A. funestus also seem to be more active at dawn, so that they are more crepuscular in their habits than A. gambiae.

8. 58 per cent, of the Anophelines caught at 8 p.m. were unfed. This indicates that early entrants usually rest after entry and before feeding, and average time of biting is later than average time of entry. Gravid or half-gravid mosquitos and those containing partly-digested blood, did not enter the huts; there was evidence that Anophelines usually became fully gorged at one feed. Of the Anophelines caught in huts after dawn 95 per cent, were fully fed.

The spotted stemborer, Chilo partellus (Swinhoe) (Lepidoptera: Crambidae), is one of the most important insect pests attacking maize and sorghum in Ethiopia. Recent studies have indicated that the pest is spreading to new locations where it was not reported before. In the current study, laboratory investigations were carried out to determine the combined effect of different levels of relative humidity and temperature regimes on the development and fecundity of C. partellus, as these physical factors are known to play an important role in the life cycle of insects and adaptability to local climate. Developmental time, longevity, potential fecundity and realized fecundity of C. partellus were measured under controlled conditions. Three temperature regimes (22°C, 26°C and 30°C) and three relative humidity levels (40%, 60% and 80%) were tested. It was found that temperature, relative humidity (RH) and their interaction significantly affected the developmental time, adult longevity, potential fecundity and realized fecundity of the pest. Developmental time was inversely related to temperature. Mean duration of C. partellus life cycle was 70.2 days at 22°C and 80% RH, whereas it took only 26.5 days to complete its life cycle at 30°C and 40% RH. Male and female longevity were similar in most cases. The adult life span ranged between 6.9–11.1 days at 22°C and 3.1–7.2 days at 30°C for different levels of relative humidity. The most suitable conditions for C. partellus development and fecundity were 26–30°C temperatures regimes and 60–80% RH levels.

Intensive chemical treatments have led to the development of a number of insecticide resistance mechanisms in the peach–potato aphid Myzus persicae (Sulzer). Some of these mechanisms are known to be associated with negative pleiotropic effects (resistance costs). Molecular and biochemical methods were used to determine the genotypes or phenotypes associated with four insecticide resistance mechanisms in single aphids from sexually-reproducing populations in southern France. The mechanisms considered were E4 and FE4 carboxylesterase overproduction, modified acetycholinesterase, and kdr and rdl resistance-associated mutations. A new method for determining individual kdr genotypes is presented. Almost all resistant individuals overproduced FE4 carboxylesterase, whereas modified acetylcholinesterase was rare. Both the kdr and rdl resistance mutations were present at high frequencies in French sexually-reproducing populations. The frequencies of insecticide resistance genes were compared before and after sexual reproduction in one peach orchard at Avignon to evaluate the potential impact of selection on the persistence of resistance alleles in the over-wintering phase. The frequencies of the kdr and rdl mutations varied significantly between autumn and spring sampling periods. The frequency of the kdr mutation increased, probably due to pyrethroid treatments at the end of the winter. Conversely, the frequency of the rdl mutation decreased significantly during winter, probably because of a fitness cost associated with this mutation.

The eggs, three larval instars and puparia of Chrysomya bezziana Villeneuve are described and illustrated in detail by scanning electron micrographs. Particular attention is paid to the extent and nature of the median strip in the eggs and the spine bands and spiracular structures in the larvae and puparia.

Eggs and third-instar larvae of five other species of Chrysomya, C. nigripes Aubertin, C. varipes (Macquart), C. rufifacies (Macquart), C. saffranea (Bigot) and C. megacephala (F.), are illustrated, described and compared with C. bezziana and each other by means of keys, which also permit their identification. In addition, notes on the puparia of these species are provided.

Night migrations of insects above the surface boundary layer were studied by direct observations with an entomological radar, and by direct aerial sampling with a kite-borne net, in an area in New South Wales inhabited by large fledging populations of Chortoicetes terminifera (Wlk.). The aerial catches and radar echo-modulation observations suggested that the majority of migrants detected by the radar were locusts, and this conclusion was supported indirectly by light-trap catches and by observations of take–off at dusk. Night flights of locusts began at dusk with a mass take-off and continued on a diminishing scale until about midnight. Displacements were all approximately downwind and to the north, under the influence of a southerly airflow which prevailed throughout the six-day study period. A quantitative radar observation procedure was used to estimate locust aerial densities and migration rates, and to observe the variations of these quantities with height and time; typical and extreme values for all the principal migration quantities are presented. The flight paths of the locusts were estimated from radar observations of target tracks, and probable source areas at distances of up to 200 km to the south were identified; a major overflight which probably originated 150 km away was detected on one occasion. Northward movements of C. terminifera during anticyclonic conditions may help to explain how populations are redistributed in the periods between the long-range southward invasion movements for which this species is well-known.

The length of the intergenic spacer in the rRNA cistron varied within and among individuals of Schizaphis graminum (Rondani). Spacer lengths did not vary among offspring of a single maternal lineage (clone). The intergenic spacer was used as a molecular fingerprinting probe on individual aphids and to study spatial and temporal distributions of clones. A spatially nested sampling design was used in wheat and sorghum to estimate numbers of clones among aphids on leaves, among leaves on plants, among plants in fields, among fields in counties, among counties, and among dates. Each level of nesting added a level of clonal diversity to the entire population. 82.3% of the total population diversity was found among aphids on one sorghum leaf. Sampling additional leaves increased diversity slightly (5.4%), whereas plants (0.9%), fields (0.6% to 3.6%), and counties (1.2%) added very little. Sample dates contributed the highest increase in diversity (11%). Diversity rose and fell in wheat along with aphid numbers but remained constant in sorghum. Little variation in Mahalanobis distances could be explained by geographic distances. No genotypes were unique to any field, county, crop, or year. Kansas populations are made up of a large mixture of genetically diverse clones that recolonize wheat and sorghum each year. Sampling many plants, fields, or counties is an ineffective way to increase clonal diversity. Plant breeders developing crop resistance to S. graminum can expect plant entries to be exposed to most of the genetic diversity present in Kansas populations regardless of location.

The eggs of A. gambiae var. melas are distinctly different from those of typical gambiae, and it is now regarded as a distinct species, A. melas. Other workers have found that the larvae also differ, physiologically and structurally. All adults with an extra dark band on the palps—4-banded forms— are known to be melas, but those adults with normal 3-banded palps can so far only be distinguished from typical gambiae by egg characters.

A. melas is now known to be an important vector of malaria in coastal districts in West Africa. In some estuarine and mangrove swamp areas it may be even more important than typical gambiae. In melas caught in Freetown estuary (mostly from Wellington village), 42 out of 1,000 glands dissected were positive, giving a sporozoite rate of 4·2 per cent. for all months of the year. The oocyst rate was 4·7 per cent., and the total infection rate was 7·8 per cent.

In Freetown estuary melas is rare in Freetown itself, and in the adjoining village of Kissy, but in all other parts of the estuary is at least as important as typical gambiae. In many places it is the dominant vector. In Wellington to the east of Kissy, and on the Bullom shore which forms the north shore of the estuary, melas forms about 90 per cent. of Anophelines caught in houses.

Bactrocera zonata (Saunders) is one of the most harmful species of Tephritidae. It causes extensive damage in Asia and threatens many countries located along or near the Mediterranean Sea. The climate mapping program, CLIMEX 3.0, and the GIS software, ArcGIS 9.3, were used to model the current and future potential geographical distribution of B. zonata. The model predicts that, under current climatic conditions, B. zonata will be able to establish itself throughout much of the tropics and subtropics, including some parts of the USA, southern China, southeastern Australia and northern New Zealand. Climate change scenarios for the 2070s indicate that the potential distribution of B. zonata will expand poleward into areas which are currently too cold. The main factors limiting the pest's range expansion are cold, hot and dry stress. The model's predictions of the numbers of generations produced annually by B. zonata were consistent with values previously recorded for the pest's occurrence in Egypt. The ROC curve and the AUC (an AUC of 0.912) were obtained to evaluate the performance of the CLIMEX model in this study. The analysis of this information indicated a high degree of accuracy for the CLIMEX model. The significant increases in the potential distribution of B. zonata projected under the climate change scenarios considered in this study suggest that biosecurity authorities should consider the effects of climate change when undertaking pest risk assessments. To prevent the introduction and spread of B. zonata, enhanced quarantine and monitoring measures should be implemented in areas that are projected to be suitable for the establishment of the pest under current and future climatic conditions.