An experiment is described in which G. tachinoides in an isolated secondary focus was marked with distinct colours during thirteen successive weeks and the fate of the groups studied by recaptures. The population was known to be declining from moderate density to great scarcity through the dry season and the wastage in the colour groups on the average proved to be 11½ per cent, per diem, rather more, probably, than the wastage in unmarked flies. Following Jackson's method of assessment the population is shown to fall from 6,000 at the end of October to 400 by mid-January. The ratio of the boy-hour rate to these numbers is worked out for each collection and it is found that when the boy-hour rate is above 50 it is not relative to population, but below 50 the rate falls as the population, allowing for the influence of weather on rate of catching.

It is shown that under the conditions of the experiment there is an almost complete change of fly population each 5 or 6 weeks, though an occasional fly may survive 11 weeks. The proportion of male flies in the catches fell with increasing age from an initial 57 per cent, to 23 per cent, in the 6th week and no male fly surviving this period was caught.

Through the kindness of Dr. G. A. K. Marshall, of the Imperial Bureau of Entomology, and Mr. F. W. Edwards, of the British Museum, we have been enabled to examine the two small but interesting collections of African Ceratopogoninae which form the basis of this paper. We have attempted to determine or describe the majority of the specimens, but those belonging to the genus Forcipomyia we hope to deal with at some future time. Several species were represented by single or but few specimens, some of them damaged; further material is therefore much to be desired not only to confirm and complete the descriptions given, but also to determine the ranges of variation.

Wavelength dispersive X-ray fluorescence spectrometry was used to make quantitative determinations of the elemental composition of adults of Agrotis segetum (Denis & Schiffermüller) that had been reared on one of eight soil-plant combinations or a semi-synthetic diet. Robust-means principal components analysis (RMPCA) of the data for eight elements and all treatments (except for the semi-synthetic diet) separated the means of the groups by soil type, irrespective of host-plant. However, individuals could not be separated until the data were grouped into the two host-plant sub-sets. The main discriminant, Al, was of doubtful validity and was therefore excluded from the data which were reanalysed by RMPCA. This failed to discriminate either group means or individuals until each host-plant sub-set was analysed separately; then, individuals could be differentiated by soil type although not as distinctly as when Al was included in the data. There was, however, a clear separation of the sexes because of a higher content of K and lower content of Ca in females; these two elements, together with S and Cl, were the main discriminants of soil type. It is concluded that larval host-plant is a significant factor in the elemental composition of adults of A. segetum but limiting and confounding in respect of identification of soil type and, therefore, geographical source. This conclusion probably applies also to other similar polyphagous species, but specific differences in biology and behaviour may influence the applicability of the technique to field studies.

During the course of three years' estate medical work in British North Borneo, ample opportunity was found for studying the local mosquitos, and I publish the few following notes in the hope that they may be of use to other workers in Borneo.

The pineapple is a plant indigenous to Central America and, it is believed, Trinidad also. In this part of the world its cultivation has developed on commercial lines only in Cuba and Porto Rico, and to a lesser extent in Jamaica, with small areas in other islands, particularly Martinique.

There have been of late indications of an increased interest in the possibilities of fruit production on a large scale in Trinidad, the pineapple being among the favoured fruits. For this reason the pest dealt with below assumes a greater importance than it otherwise would, though the usual freedom of this plant from pests focuses attention on any new one found.

In October 1926, young fruit on the plots of the St. Augustine Experiment Station of the local Department of Agriculture were found to be exuding gum and showing signs of insect attack. Though at the time there was few fruits, it being too early for the main crop, a high proportion of these was found to be damaged. It was reported that many fruits had been rendered unsaleable during the previous season by a similar attack.

In 1909, the writer collected egg-masses of the seroot Tabanus taeniola, P. de B., and reared some of the resulting larvae to approaching maturity, but failed to obtain the pupa. The following year he took a number of immature larvae of Tabanus ditaeniatus, Macq., and reared them to the adult stage. The various stages in the life-cycles of these two Tabanids, with the exception of the pupa of the former and the egg-mass of the latter species, were figured and described in this Bulletin. The puparium of T. taeniola and egg-masses of T. ditaeniatus which are here figured and described were obtained during the summer of 1913.

In a collection of larvae of Culcine mosquitos made in northern Iraq in 1952–56 during the course of a survey of potential Amopheline breeding places in the area, the folowing genera and species were represented: Uranoaenia unguiculata Edw., Aedes caspius (Pall.) Culiseta longiareolata (Macq.), C. subochrea (Edq.), Culex theileri Theo., C.tritaeniorhynchus Giles, C. pusillus Macq., C. hortensis Fic. and C. mimeticus Noé. The last two species are reported here for the first time from Iraq. The records of Culiseta suochrea and Culec pusillus are based on a single larva of each.

An account is given of Corioxenos raoi, a new Stylopoid species that parasitizes Antestiopsis cruciata (F.) (Pentatomidae), a pest of jasmine in South India. The new species is distinguished from Corioxenos antestiae Blair, the only other known representative of the genus.

Fourth- and fifth-instar hoppers and adults of Locusta migratoria migratorioides (R. & F.) were expected to three fluctuating remperature regimes in Weyco climatic cabinets and weighed daily. The regimes were 30 ± 0.25, 30 ± 10 and 30 ± 15°C., the change from one extreme to the other in the last two being made every two hours. Temperatures were accurately determined, by plantinum-resistance thermometers whose dimensions approximated to those of adult locusts, and were automatically recorded. The three thermorhythms were analysed by methods based on Fourier’s theorem, whereby a given wave form can be described in terms of a basic sine weve and a series of superimposed harmonics.

The rates of growth (weight increase) in the 4th-instar and adult at 30 ± 10°C/ were higher than at 30 ± 0.25°C. and were within 10 per cent. of the means of the rates at constant temperatures of 20 and 40°C., whereas the frowth rate in the 5th instar, and the pre-copulation and pre-oviposition periods of adults and their rate of weight loss when starved, were the same under both regime. At 30 ± 15°C., 5th-instar hoppers did not survive and, in comparison with the other regimes, the growth rates of 4th-instar hoppers and adults were very much lower, the pre-copulation period of adults was the same but the pre-oviposition period was much longer and their rate of weight loss when starved was doubled. Adults locusts were also tested at 30 ± 17.5°C., but most of them died within 24 hours and all within three days.

Biological and morphological plasticity in polyphagous insect herbivores allow them to exploit diverse host plant species. Geographical differences in resource availability can lead to preferential host exploitation and result in inconsistent host specialization. Biological and molecular data provide insights into specialization and plasticity of such herbivore populations. In agricultural landscapes, Aphis gossypii encounters several crop and non-crop hosts, which exist in temporal and spatial proximity. We investigated the host-specialization of two A. gossypii host-associated populations (HAPs), which were field collected from cotton and squash (cotton-associated population and melon-associated population), and later maintained separately in the greenhouse. The two aphid populations were exposed to seven plant species (cotton, okra, watermelon, squash, cucumber, pigweed, and morning glory), and evaluated for their host utilization plasticity by estimating aphid's fitness parameters (nymphal period, adult period, fecundity, and intrinsic rate of increase). Four phenotypical characters (body length, head capsule width, hind tibia length and cornicle length) were also measured from the resulting 14 different HAP × host plant combinations. Phylogenetic analysis of mitochondrial COI sequences showed no genetic variation between the two HAPs. Fitness parameters indicated a significant variation between the two aphid populations, and the variation was influenced by host plants. The performance of melon-aphids was poor (up to 89% reduction in fecundity) on malvaceous hosts, cotton and okra. However, cotton-aphids performed better on cucurbitaceous hosts, squash and watermelon (up to 66% increased fecundity) compared with the natal host, cotton. Both HAPs were able to reproduce on two weed hosts. Cotton-aphids were smaller than melon-aphids irrespective of their host plants. Results from this study suggest that the two HAPs in the study area do not have strict host specialization; rather they exhibit plasticity in utilizing several hosts. In this scenario, it is unlikely that host-associated A. gossypii populations would evolve into host-specific biotypes.

Locusts and other Orthoptera have been reared free from Gregarine parasites in culture jars made from jam jars. Food can be added easily without the escape of insects. A special feature of the jars is the removable base in which faeces accumulate and from which they can be taken at intervals without exposing the insects to the infective stages of Gregarine parasites.

In insects, two types of the immune responses, cellular and humoral, constitute a defensive barrier against various parasites and pathogens. In response to pathogens, insects produce a wide range of immune agents that act on pathogens directly, such as cecropins or lysozyme, or indirectly by the stimulation of hemocyte migration or by increasing phenoloxidase (PO) activity. Recently, many new immunologically active substances from insects, such as peptides and polypeptides, have been identified. Nevertheless, in the most cases, their physiological functions are not fully known. One such substance is yamamarin – a pentapeptide isolated from the silk moth Antheraea yamamai. This yamamarin possesses strong antiproliferative properties and is probably involved in diapause regulation. Here, we examined the immunotropic activity of yamamarin by testing its impact on selected functions of the immune system in heterologous bioassays with the beetle Tenebrio molitor, commonly known as a stored grains pest. Our results indicate that the pentapeptide affects the activity of immune processes in the beetle. We show that yamamarin induces changes in both humoral and cellular responses. The yamamarin increases the activity of PO, as well as causes changes in the hemocyte cytoskeleton and stimulates phagocytic activity. We detected an increased number of apoptotic hemocytes, however after the yamamarin injection, no significant variations in the antibacterial activity in the hemolymph were observed. The obtained data suggest that yamamarin could be an important controller of the immune system in T. molitor.

In 1930 the available information regarding gall midges as enemies of the Coccidae was summarised in a paper published in the Bull. Ent. Res. (21, 1930, pp. 319–329). Since that time there have been several additions to our knowledge concerning such midges. Some of this knowledge was cited as an addendum in a later paper on gall midges as enemies of mites (Bull. Ent. Res. 24, 1933, pp. 215–228). It is proposed in this paper to bring this subject up to date by referring to published work and by describing some new forms that have been received for identification in the immediate past.

Tympanal hearing organs are widely used by insects to detect sound pressure. Such ears are relatively uncommon in the order Diptera, having only been reported in two families thus far. This study describes the general anatomical organization and experimentally examines the mechanical resonant properties of an unusual membranous structure situated on the ventral prothorax of the tsetse fly, Glossina morsitans (Diptera: Glossinidae). Anatomically, the prosternal membrane is backed by an air filled chamber and attaches to a pair of sensory chordotonal organs. Mechanically, the membrane shows a broad resonance around 5.3–7.2 kHz. Unlike previously reported dipteran tympana, a directional response to sound was not found in G. morsitans. Collectively, the morphology, the resonant properties and acoustic sensitivity of the tsetse prothorax are consistent with those of the tympanal hearing organs in Ormia sp. and Emblemasoma sp. (Tachinidae and Sarcophagidae). The production of sound by several species of tsetse flies has been repeatedly documented. Yet, clear behavioural evidence for acoustic behaviour is sparse and inconclusive. Together with sound production, the presence of an ear-like structure raises the enticing possibility of auditory communication in tsetse flies and renews interest in the sensory biology of these medically important insects.

Control of yellow stem borer, Scirpophaga incertulas (Walker), in rice was attempted by mating disruption using the natural ratio of pheromone components, a 1:3 blend of (Z)-9- and (Z)-11-hexadecenal, in replicated trials at three locations in Andhra Pradesh, India, during the 1994 and 1995 dry seasons. The pheromone was formulated in SelibateR and applied by hand at a rate of 40 g a.i./ha. In Medchal and Nellore, pheromone-mediated communication was reduced by at least 94% for the first 50 and 64 days after application respectively, as measured by pheromone trap catch suppression. Compared with adjacent farmers' practice plots, subsequent dead heart and white head damage were reduced by 74 and 63% and 83 and 40% in Medchal and Nellore, respectively. In Medchal, average rice yields were increased compared to the farmers' practice plots, 4108 and 3835 kg/ha respectively, but in Nellore, they were the same as those obtained in the farmers' practice plots, 6400 and 6733 kg/ha respectively. In Warangal, the level of communication disruption over the first 70 nights after pheromone application was less than obtained in either Medchal or Nellore and averaged between 50 and 87%. The maximum dead heart and white head damage recorded in the pheromone-treated plots in Warangal were 2.8 and 15.7% respectively compared to 7.0 and 20.9% respectively in the farmers' practice plots. Differences in S. incertulas larval damage estimates obtained from the pheromone-treated and farmers' practice plots in Warangal were reflected in grain yields, 4036 and 3715 kg'ha respectively. Surveys of insecticide use indicated that 92% of smallholders in Medchal applied insecticide at least once per season while in Warangal over 60% applied insecticide on two or more occasions. The data show that season-long control of S. incertulas comparable to that obtained with conventional insecticides can be achieved by mating disruption in smallholder rice fields in India.

The effective sampling area of a monitoring station, α, was calculated for several Coptotermes formosanus Shiraki colonies in Broward County, Florida, USA. A simple mark–recapture protocol provided data on termite station catch within a foraging range of a colony. Average recapture probability was 0.005 close to the releae point (< 5 m) and declined to 0.0008 at a distance of 51 to 60 m. The relation between the log % termites recaptured was fitted with log distance, to determine P(x), the average proportion of captured termites that started at distance x from the release point. The effective sampling area was estimated by using P(x) and the equation, α 2 π∫{ x P(x)} dx. Integrating this equation, an average estimate α that ranged from 0.607 to 14.5 m2 was obtained. Factors influencing the variation of α among the colonies are discussed. The effective sampling area estimated should be taken as a reliable estimator that translates subterranean termite catches into termite population density.

Athetis lepigone (Möschler) (Lepidoptera: Noctuidae) is a new outbreak pest in China. Consequently, it is unclear whether the emergence and spread of the outbreak of this pest are triggered by rapid in situ population size increases in each outbreak area, or by immigrants from a potential source area in China. In order to explore the outbreak process of this pest through a population genetics approach, we developed ten novel polymorphic expressed sequence tags (EST)-derived microsatellites. These new microsatellites had moderately high levels of polymorphism in the tested population. The number of alleles per locus ranged from 3 to 19, with an average of 8.6, and the expected heterozygosity ranged from 0.269 to 0.783. A preliminary population genetic analysis using these new microsatellites revealed a lack of population genetic structure in natural populations of A. lepigone. The estimates of recent migration rate revealed strong gene flow among populations. In conclusion, our study developed the first set of EST-microsatellite markers and shed a new light on the population genetic structure of this pest in China.

Adult olive fruit flies Bactrocera (Dacus) oleae Gmelin were exposed for 24 h to 25 × 10 cm polyester target devices, impregnated with 3% a.i. triflumuron (2-chloro-n-[[[trifluromethoxy]phenyl]amino]carbonyl]benzamide), a chitin synthesis inhibitor, formulated in 10% w/v sugar solution and air-dried. Treated insects were tested for egg hatch inhibition and larval mortality. Inhibition of egg hatch and F1 larval mortality depended on the sex exposed and the elapsed time after exposure. Egg hatch was reduced to 37.6% and F1 larval mortality reached 100% when both exposed sexes were mated. Exposure of one sex prior to mating resulted in a lower level of egg inhibition and larval mortality; but exposure of females was more effective at inhibiting egg hatch and larval survival than exposure of males in these crosses. In flies exposed once, the residual activity of triflumuron decreased gradually, fifteen days post-exposure egg hatch and larval mortality reached 62% and 44% respectively. Target devices aged under natural conditions reduced egg hatch to an average of 39% and inhibited completely larval development for a period of four months.

Diverse agroecosystems offer phytophagous insects a wide choice of host plants. Myzus persicae is a polyphagous aphid common in moderate climates. During its life cycle it alternates between primary and secondary hosts. A spatial genetic population structure may arise due to environmental factors and reproduction modes. The aim of this work was to determine the spatial and temporal genetic population structure of M. persicae in relation to host plants and climatic conditions. For this, 923 individuals of M. persicae collected from six plant families between 2005 and 2008 in south-eastern Spain were genotyped for eight microsatellite loci. The population structure was inferred by neighbour-joining, analysis of molecular variance (AMOVA) and Bayesian analyses. Moderate polymorphism was observed for the eight loci in almost all the samples. No differences in the number of alleles were observed between primary and secondary hosts or between geographical areas. The proportion of unique genotypes found in the primary host was similar in the north (0.961 ± 0.036) and the south (0.987 ± 0.013), while in the secondary host it was higher in the north (0.801 ± 0.159) than in the south (0.318 ± 0.063). Heterozygosity excess and linkage disequilibrium suggest a high representation of obligate parthenogens in areas with warmer climate and in the secondary hosts. The FST-values pointed to no genetic differentiation of M. persicae on the different plant families. FST-values, AMOVA and Bayesian model-based cluster analyses pointed to a significant population structure that was related to primary and secondary hosts. Differences between primary and secondary hosts could be due to the overrepresentation of parthenogens on herbaceous plants.

Faecal pellet production by Tetranychus cinnabarinus (Boisd.) was recorded at different temperatures (19, 24, 30, 35°C) and relative humidities (0% to 100%); at all temperatures pellet production was greater under dry than under wet conditions. A feeding index based on faecal pellet production and the proportion of adults surviving each day showed that the optimal conditions for the mite were 24°C and 38% r.h. Pellet production increased under continuous light and, under any particular set of conditions, was closely correlated with the numbers of eggs laid. It is concluded that faecal pellet production can be used as a measure of feeding within a given set of conditions provided it is supplemented and checked by other data.