The method and evaluation of a field application of rubidium chloride for the purpose of a mark-and-recapture experiment are described. In the Philippines, populations of the rice pests Nilaparvata lugens (Stål) and Sogatella furcifera (Horv.) were successfully marked by a foliar spray of rubidium chloride plus surfactant applied to a rice field at 1·03 g/hill. Individual insects marked with rubidium, which were easily distinguishable from unmarked individuals for at least seven weeks, were generated at this dose level, and even after one year elevated rubidium levels could be detected in pooled samples. Other phytophagous and entomophagous insects also became marked.

Investigations into some possible attractants of Glossina morsitans Westw. and G. pallidipes Aust. have been described. In small cages (8x8x11 in.) under laboratory conditions, flies with painted eyes survived longer than those that were untreated, whilst removing the antennae decreased longevity. Olfactory stimuli were probably more important than vision in orientating a fly towards a static guinea-pig used as a host in a moulded mesh insert into the cage. Field observations indicated that tsetse flies were orientated towards an ox at a distance mainly by vision and few flies found oxen concealed by screens. Olfaction may be used at relatively short distances to find hidden host animals, and G. pallidipes may respond to smell more readily than G. morsitans.

Tests in the laboratory and small field cages (6 ft3) indicated that tsetse were not attracted to any particular colour (red, yellow, blue) or shade (white, grey, black). However, in the field more flies were caught off a dark ox than a white ox. In the laboratory > 80% of male G. pallidipes responded to black light within four hours while with G. morsitans a similar proportion was attracted only after six hours. Responses by both species decreased with blue, red and white light and were least with yellow. In small field cages attraction to black light was reduced and only 20–38·6% of either species were caught by a “flap trap” in 6–13½-h test periods. Tests with either blue or red lights in these field cages trapped less than 9% of the released tsetse flies in similar periods. Field trials with black light indicated that this attractant was ineffective as a sampling technique since very few of a natural population were trapped.

Antibiosis of resistant melon lines to the carmine spider mite, Tetranychus cinnabarinus (Boisduval), was evaluated in the laboratory. Significant differences among lines were observed seven days after the inoculation of detached leaf disks. The most resistant lines, namely CHI-8, BUS-7 and BUS-3, reduced the average mite daily fecundity by 49%, 40% and 33%, respectively, as compared to the susceptible NY line. Resistance did not appear to be related to the growth habit. Selfing resistant melon parents resulted in a significant increase in the number of plants on which female mites produced less than one egg per day.

The following paper gives a list of those insects of economic importance which have been collected or bred from various crops in Nyasaland during the first three months of the planting season 1911–12 and the whole of the season 1912–13. No attempt has been made to describe the various species mentioned, but their actual economic importance is stated in each case, so far a3 it has been possible to ascertain it during so short a period. All insects have been included as pests which have been found to feed en any particular crop in sufficient numbers to justify their inclusion in that, category. In many cases the actual damage done may be slight, but at any time one or all of those species which feed regularly on crops may assume the position of dangerous pests, and so insects of apparently minor importance are included with those of definite and proved powers of destruction. The insects of first-class importance, which annually inflict heavy losses on the planters, are ten in number. These ten are confined to cotton, tobacco and maize, of which cotton is the worst sufferer, since it is attacked by a greater variety of insects than any other crop that has come under the writer's notice. Except where the contrary is specially mentioned, insects included in this paper are from the Shire Highlands.

A comparison is made of the populations of mealybugs, ants, predators and parasites on cacao growing in dense secondary bush and under well-cultivated conditions in Ghana, West Africa. The percentage of cacao trees infested (termed the infestation rate), the number of colonies and the populations of the vectors were similar under the two cultural conditions. Populations of ants of the genus Crematogaster and of COCCINELLIDAE were higher in bush areas than in cultivated ones. Populations of ants of the genus Pheidole, though smaller than those of Crematogaster, were greater in areas of well-maintained cacao.

Correlations of infestation rates and populations were compared under the two cultural conditions for mealybugs, ants, predators and parasites. The field data showed an exponential relationship between these factors, which was rendered linear by suitable transformations. The correlation of mealybug populations with infestation rate and with populations of parasites and predators was equally high in both habitats. The correlation of mealybug populations with those of Crematogaster was closer in the bush than in well-maintained cacao, but the implications of this are not fully understood.

There was a higher infestation rate of cacao during the first three months of the year. In contrast with previous work, the present survey has demonstrated significant changes in the vector population during the year, of a five- or six-fold order. These seasonal changes are based on mean mealybug populations per infested tree, and were largely the result of changes in the numbers of colonies; populations showed a decline during the first six months of the year and then rose to a maximum during October–November. The data suggest that these trends may be brought about largely by changes in the abundance of predators and parasites.

In considering the methods of coping with any group of injurious insects, the study of natural enemies must occupy an important place in any laboratory or field investigations that are carried out in connection with such pests.

This part of the study of the garden chafer, Phyllopertha horticola (L) in the English Lake District deals with the reproductive state of the females during the flight season. Total egg-production depends entirely on stores (fat-body) accumulated in the final larval instar. On the average, the fat-body enables about 16 or 17 mature eggs to be manufactured per female, the usual range being 9–32. Rate of reproductive development is the same in the largest and smallest female adults. The outstanding mass features of the flight season are the two roughly equal and half-overlapping Phases: Phase 1, swarming over the grass sward, followed by Phase 2, swarming on the surrounding bracken, hedges and trees. Mass aspects of the female reproductive state throughout the two Phases are as follows.

At primary emergence on the grass sward, females always contain some fat-body together with some fully developed and/or immature eggs. On the average they have about one-third of their full complement of eggs matured, the range being from none (with about 50% of the original fat-body still remaining) up to four-fifths (with about 10% of the fat-body). Since primary emergences in a homogeneous population extend over about a fortnight, females taken from the grass sward throughout Phase 1 are in various reproductive states. Thus after the first few days of the Phase and until the last individual makes its primary emergence, sample females may have half their fat-body and no eggs yet fully matured or no fat-body and all their eggs actually laid, or any intergrade between these extreme states. Towards the end of Phase 1 (which finishes about a week after the last primary emergence), females have no fat-body remaining and have already laid most or all of their eggs; and a small proportion of them now has food in the gut.

In Phase 2, about 99 per cent, of females on bracken, hedges and trees contain no fat-body and therefore cannot manufacture any more eggs. On the average they have two mature or very nearly mature eggs left (range 0–26). This egg content is much the same as at death. The remaining 1 per cent, of females are aberrants with some fat-body still unconsumed. ‘ Bee-liners ’, the females which shoot out bullet-like from the bracken, hedges or trees to alight comparatively far afield, either have some fat-body remaining, or, if not, considerable numbers of eggs (mean about 9 as compared with the general mean of 2). Thus bee-liners are the phase-2 individuals with most eggs still unlaid. Obviously they are a minority.

Deductions as to individual behaviour are made from the mass aspects of the reproductive state and are to be examined in the next paper of this series.

Since females of the garden chafer have already laid all or most of their eggs before appearing on hedges and trees, gardeners will not control this pest by killing all they find on their hedges and trees.

Three species of Pediobius Walker associated with the oil palm Hispid beetle are studied. One is identified as P. coffeicola (Ferrière), comb.n. The other two are described as new, and a key separating one of them from P. nigripes (Waterston), comb.n., and P. amaurocoelus (Waterston), comb.n., is given. Two new species of Achrysocharis Girault are described, one a parasite of Dipterous leaf-miners in coffee, one reared from galls on mango.

Staphylinid beetles are recommended bioindicators for the pre-market environmental risk assessment of genetically modified (GM) insect protected maize expressing the Cry3Bb1 toxin. Our multiannual study is a unique European analysis of a staphylinid community within a 14 ha maize field. GM maize, its near-isogenic hybrid (with or without insecticide treatment), and two other reference hybrids were each grown in five 0.5 ha plots. The opportunity for exposure to Cry toxin from plant residues ploughed into the soil was shown by the presence of saprophagous dipteran larvae that are common prey of predatory staphylinid species and hosts of the parasitoid species. 2587 individuals belonging to 77 staphylinid species were sampled using pitfall traps. Lesteva longoelytrata (31%), Oxypoda acuminata (12%), Aloconota sulcifrons (8%) and Anotylus rugosus (7%) were the most abundant beetles in the field. Bionomics, food specialization, temperature requirements and size group were assigned for 25 most common species. These traits determine the occurrence of staphylinid beetles in the field, the food sources they could utilize and thus also their likely contact with the Cry3Bb1 toxin. Statistical analysis of activity abundance, Rao indices and multivariate analysis of distribution of particular categories of functional traits in the field showed negligible effects of the experimental treatments, including the GM maize, upon the staphylinid community. Staphylinid beetles represent a considerably diverse part of epigeic field fauna with wide food specialization; these features render them suitable for the assessment of environmental safety of GM insect protected maize. However, the availability of prey and the presence of particular staphylinid species and their abundance are highly variable; this complicates the interpretation of the results.

When non-teneral male flies of Glossina pallidipes Aust. were caught concurrently on oxen and in Morris traps in two experiments in south-eastern Uganda and classified, within 1½ hr. of capture, according to a modification of the hunger-stage categories described by Jackson, individual recorders were found to differ markedly in their assessments. No conclusions regarding the hunger stage of flies taken by different attractants could therefore be drawn from the first experiment, but in the second, which was so designed as to discount possible bias amongst recorders, the proportions of ‘hungry ’ (stage III + IV) flies in catches of males were similar on variously coloured individual oxen, and generally higher than in trap catches, in which the proportions varied widely. As all the traps appeared identical, no generalisation is possible about the mechanism by which non-teneral male flies are attracted to and induced to enter such traps.

Adults, larvae and pupae of the type material of Simulium (Edwardsellum) kilibanumGouteux from Zaïre, the important onchocerciasis vector Simulium (E.) damnosumcytoform ‘Nyamagasani’ from western Uganda and Malawi, and the closely related forms ‘Nkusi’ and ‘Sebwe’ from western Uganda were compared using morphological and molecular methods. Results support the assumption of synonymy of S. kilibanum and the cytoform ‘Nyamagasani’, which hitherto was based on weak evidence. The description of S. kilibanumis supplemented and detailed descriptive data are given of ‘Nyamagasani’and the cytoforms ‘Nkusi’ and ‘Sebwe’ all of which are taxa of the ‘Sanje’ group of the S. damnosum complex.

The paper is an accouunt of a year's work on the bionomics of Glossina morsitans in the Koalib Hills, Nuba Mountains Province, Sudan, a small area which lies 200 to 300 miles north of any other locality where G. morsitans occurs.

The fly is restricted at all times of the year to the hills, where it was found to breed in rock-shade, and is always closely associated with the Nuba inhabitants and their animals, even frequenting villages and their environs. The cattle, goats and sheep are resistant to trypanosomiasis, but all have been proved to be carriers of the disease.

Wild fauna is scarce in and near the area, and the fly is probably entirely dependent for food on the Nubas and their animals.

An experiment in direct control in a small group of hills is described. It was found impossible to reduce the fly beyond a very low minimum, but the method would be of use as a routine control in small hills.

Experiment with fly lime indicated that the shiny appearance of the lime deterred the majority of flies from alighting upon it.

Marked flies remained in the bush for ten to fifteen days during the rains, but eventually returned to the hills. Given a constant food supply there seems no reason why many parts of the bush, otherwise suitable, should not harbour fly during the rains and early dry season.

The author is indebted to Major R. G. Archibald, C.M.G., D.S.O., M.D., Director of Wellcome Tropical Research Laboratories, and to Mr. H. H. King, Government Entomologist, for much assistance and advice, also to the Provincial and District Officials for help in many ways.

1. Measurements of the spiracles and the tracheae of 5th instar hoppers and adults of Locusta and adults of Schistocerca have been made (see Tables I, II and IV). These measurements show that particles of dust which had passed a 300 B.S. Sieve (i.e., under 0·053 mm. in diameter) are small enough to enter all the spiracles and that the particles which had passed a 150 B.S. Sieve (i.e., under 0·104 mm. in diameter) could enter spiracles 1 to 4 and 10.

2. It has been proved by the presence of particles of dust in the respective spiracles, that spiracles 1 to 4 are inspiratory in function and spiracles 5 to 9 expiratory under all conditions, while the function of spiracle 10 is expiratory when the locust is flying and inspiratory when it is motionless.

3. The quantity of dust present in the tracheae increases with the length of exposure to the cloud of dust ; the quantity present after 10 seconds exposure is not regarded as sufficient to kill the locust.

4. The action of external poisons is thought to be by direct penetration of the integument or through the nerve endings or both.

5. The results given in this paper suggest that further work on the action of poison dusts should be concentrated on the investigation of direct penetration of the integument and of the nerve action, rather than poisoning through the respiratory system.

1. The removal of the thicket windbreak from around a residual forest island considerably alters its climate and intensifies the rigours of the dry season. The evaporation rate becomes much higher; appreciable increases are caused in the atmospheric diurnal temperature, but are more pronounced in the soil temperature. The island becomes slightly colder at night.

Knowledge on colonization modes and interplant movement of Nasonovia ribisnigri can contribute to the development of optimal control of this pest. The aim of this study was to determine the spatio-temporal distribution and the mode of spread between adult morphs of Nasonovia ribisnigri, comparing spring and autumn lettuce protected crops. The spatial and temporal pattern was analyzed using the spatial analysis by distance indices (SADIE) methodology and other related displacement indices.

The population size of N. ribisnigri was greater in the autumn than in the spring growing seasons due to milder temperatures. The percentage of plants colonized by aphids was higher in spring than in autumn, showing the great dispersal potential of this aphid species independent of their population size. Differential propensity for initial displacement from the central plant was observed between adult morphs in spring, resulting in a greater ability of apterous than alate aphids to spread far away from the source plant. In autumn, both adult morphs showed an initial reduced displacement; however, the number of plants infested (≈20%) with at least one aphid at this initial time (seven days) was similar for both adult morphs and both growing seasons. Analysis of the spatial pattern of both adult morphs revealed a predominantly random distribution for both spring and autumn trials. This pattern was achieved by a prevalent random movement over the area (γ≈0.5). These results highlight the ability of the apterous N. ribisnigri to spread within greenhouse lettuce crops early in the spring, suggesting that detection of the pest by deep visual inspection is required after lettuce emergence.

Forest fragmentation and climate change are among the most severe and pervasive forms of human impact. Yet, their combined effects on plant–insect herbivore interaction networks, essential components of forest ecosystems with respect to biodiversity and functioning, are still poorly investigated, particularly in temperate forests. We addressed this issue by analysing plant-insect herbivore networks (PIHNs) from understories of three managed beech forest habitats: small forest fragments (2.2–145 ha), forest edges and forest interior areas within three continuous control forests (1050–5600 ha) in an old hyper-fragmented forest landscape in SW Germany. We assessed the impact of forest fragmentation, particularly edge effects, on PIHNs and the resulting differences in robustness against climate change by habitat-wise comparison of network topology and biologically realistic extinction cascades of networks following scores of vulnerability to climate change for the food plant species involved. Both the topological network metrics (complexity, nestedness, trophic niche redundancy) and robustness to climate change strongly increased in forest edges and fragments as opposed to the managed forest interior. The nature of the changes indicates that human impacts modify network structure mainly via host plant availability to insect herbivores. Improved robustness of PIHNs in forest edges/small fragments to climate-driven extinction cascades was attributable to an overall higher thermotolerance across plant communities, along with positive effects of network structure. The impoverishment of PIHNs in managed forest interiors and the suggested loss of insect diversity from climate-induced co-extinction highlight the need for further research efforts focusing on adequate silvicultural and conservation approaches.

The mango blossom gall midge, Procontarinia mangiferae, is a multivoltine species that induces galls in inflorescences and leaves of the mango tree, Mangifera indica. In subtropical Reunion Island, populations of P. mangiferae are observed all-year round, but the pattern and the role of dormancy in their life cycle have never been documented. We performed field and laboratory experiments using more than 15,000 larvae. We demonstrated that a larval diapause may affect a part of the midge population, regardless of the season. The total duration of the diapause varied from 6 weeks to more than 1 year. One year of field monitoring showed that the highest incidence of diapause was observed in larvae collected during the summer from mango leaves, where it affected approximately one-third of the individuals. This facultative diapause allows the permanent presence of P. mangiferae in the orchards. By recording diapause duration during 22 weeks under controlled conditions, we showed that high temperatures (26 °C) increased diapause duration and extended the range of the dates of diapause emergence, whereas cool temperatures (20 °C) shortened diapause duration and shortened the range of the dates of emergence from diapause. A temperature decrease from 26 to 20 °C triggered the emergence of diapausing individuals. These mechanisms ensure the synchronization of the emergence of diapausing individuals with the appearance of mango inflorescences, which is also induced by cool winter temperatures.

Inbreeding costs can be high in haplodiploid hymenopterans due to their particular mechanism of sex determination (i.e., single-locus complementary sex-determination system, sl-CSD), as it can lead to the production of sterile males. Therefore, mechanisms contributing to reduced inbred matings can be beneficial. In this sense, asynchronous nest departure of sibling drones and gynes could reduce kin encounters in social hymenopterans. Using six observation colonies, we determined under field conditions the nest departure behaviour of sibling reproductives of the social wasp Vespula germanica (Hymenoptera: Vespidae). We determined that sexuals leave the nests definitively and detected asynchronous departure not fixed to a particular caste at a seasonal scale in some colonies, as gynes or drones delayed their departure as a function of the departure of the opposite sex, depending on the colony. At a higher temporal resolution (i.e., within a day), we discovered that drones consistently began to leave nests 1 h before gynes and this difference was driven by those individuals that left on the same day as did the opposite-sex kin. Even though other mechanisms such as polyandry and differential dispersal could also be important at reducing inbred matings in the species, the observed departure patterns (i.e., in some colonies actually leave together with the opposite caste, while in others temporal segregation seems to occur) from nests could be complementary to the former and be important at reducing the negative effects of inbreeding in this invasive species.

Information on the dispersal ability of invertebrate species associated with woodland habitats is severely lacking. Therefore, a study was conducted examining the movement patterns of wood cricket (Nemobius sylvestris) (Orthoptera: Gryllidae) on the Isle of Wight, UK. Juvenile (i.e. nymphs) and adult wood crickets were released and observed over time within different ground surface substrates. Their movement paths were recorded and subsequently analysed using random walk models. Nymphs were found to move more slowly than adults did; and, when given a choice, both nymphs and adults showed a preference for moving through or over leaf litter compared to bare soil or grass. A correlated random walk (CRW) model accurately described the movement pattern of adult wood crickets through leaf litter, indicating a level of directional persistence in their movements. The estimated population spread through leaf litter for adults was 17.9 cm min−1. Movements of nymphs through leaf litter could not accurately be described by a random walk model, showing a change in their movement pattern over time from directed to more random movements. The estimated population spread through leaf litter for nymphs was 10.1 cm min−1. The results indicate that wood cricket adults can be considered as more powerful dispersers than nymphs; however, further analysis of how the insects move through natural heterogeneous environments at a range of spatio-temporal scales needs to be performed to provide a complete understanding of the dispersal ability of the species.

Mortality responses of adult New Zealand flower thrips, Thrips obscuratus (Crawford) to controlled atmospheres were assessed. Temperature (0–48°C) and time (1–24 h) had major effects on mortality. There were approximately two-fold increases in thrips mortality between atmospheres with 40 and 60% CO2, when there was 0 or 2% O2 present in treatments of 0°C for 4 h and 24 h; 12°C for all exposure times; 24°C for 1 h. Thrips mortality was significantly greater when there was no O2 in the test atmosphere, than when there was 0.25, 8 or 12 or 20% O2. The results show that there are a variety of ways produce infested with New Zealand flower thrips could be treated with controlled atmospheres to achieve high mortality. These data can be used as the basis of potential quarantine treatments depending on the produce being exported.