The responses of adult Glossina morsitans Westw. to large slowly moving visual stimuli were tested in the laboratory. The standard stimulus, lasting 60 s, consisted of a vertical black stripe (5° wide) on a white background moved 12 times past a window (25° wide) at 13·5°/s. The kinetic responses (take-off), but not orientation towards the stripe, went through a daily cycle with morning and evening maxima some 500% greater than the mid-day response. Kinetic responsiveness in both sexes and all ages of fly increased in an overall linear manner during five days' starvation, though pregnant females were about half as responsive as mature males. The intensity of orientation also increased with starvation, at least in males. For take-off, the minimum stripe width eliciting responses subtended ca 0·6° to the flies, and the optimum angular velocity was 3–7°/s, for orientation, 2–20°/s; the distance of the stripe appeared unimportant. Human odour elicited take-offs in the absence of the visual stimulus, and enhanced the visual responses if these were tested within three minutes of the start of odour stimulation; these effects were much greater in teneral than in mature males. It is concluded that the differences between the sexes and physiological stages of fly are mainly quantitative, and that the accepted view of four physiologically distinguishable phases of behaviour is therefore unsatisfactory. Instead, it is proposed that tsetse behaviour is the outcome of continuously variable responsiveness to visual host stimuli, and not a succession of behavioural entities.

The autumn return migration of the beet armyworm Spodoptera exigua Hübner and other insects in northern China was observed with radar and with a simultaneously-operated searchlight trap and ground light-trap at a site in Langfang, near Beijing. The searchlight trap was found to be an efficient tool for trapping migrants and, operated alongside a ground light-trap, could distinguish migrant from locally-flying species. It was confirmed that S. exigua and some other species were high-altitude nocturnal windborne migrants during September and October in northern China. Maximum density of moths typically occurred below 500 m, and strong layering was often observed at about 200 m above ground level in airflows that would carry the moths towards the south. Descent of S. exigua in the vicinity of the radar site in late September was often associated with rain.

Generalist predators contribute to pest suppression in agroecosystems. Spider communities, which form a substantial fraction of the generalist predator fauna in arable land, are characterized by two functional groups: web-building and cursorial (non-web-building) species. We investigated the relative impact of these two functional groups on a common pest (Sitobion avenae, Aphididae) in wheat by combining a molecular technique that revealed species-specific aphid consumption rates with a factorial field experiment that analyzed the impact, separately and together, of equal densities of these two spider functional groups on aphid population growth. Only cursorial spiders retarded aphid population growth in our cage experiment, but this effect was limited to the initial aphid-population growth period and low-to-intermediate aphid densities. The molecular analysis, which used aphid-specific primers to detect aphid DNA in predator species, detected the highest proportion of aphid-consuming individuals in two cursorial spiders: the foliage-dwelling Xysticus cristatus (Thomisidae) and the ground-active Pardosa palustris (Lycosidae). The results suggest that manipulating the community composition in favour of pest-consuming functional groups may be more important for improving biological control than fostering predator biodiversity per se. Agricultural management practices that specifically foster effective species or functional groups (e.g. mulching for cursorial spiders) should receive more attention in low-pesticide farming systems.

Following the first detection of tomato yellow leaf curl virus (TYLCV) from R=union (700 km east of Madagascar) in 1997 and the upsurge of Bemisia tabaci (Gennadius) on vegetable crops, two genetic types of B. tabaci were distinguished using RAPD–PCR and cytochrome oxidase I (COI) gene sequence comparisons. One type was assigned to biotype B and the other was genetically dissimilar to the populations described elsewhere and was named Ms, after the Mascarenes Archipelago. This new genetic type forms a distinct group that is sister to two other groups, one to which the B biotype is a member and one to which the Q biotype belongs. The Ms biotype is thought to be indigenous to the region as it was also detected in Mauritius, the Seychelles and Madagascar. Both B and Ms populations of B. tabaci induced silverleaf symptoms on Cucurbita sp., and were able to acquire and transmit TYLCV. Taken together these results indicate that the Ms genetic type should be considered a new biotype of B. tabaci.

1. For the purposes of this paper a suitable host is defined as one on which the parasitoid can generally reproduce fertile offspring.

2. To be suitable for Trichogramma, a host must satisfy conditions required by two generations of the parasite: it must be such that it can be actually parasitized by the adult parasitoid; and it must provide an environment in which the parasite offspring can develop.

3. Some hosts prevent the attack of Trichogramma leading to parasitization by the physical resistance of their chorion; others by inhibiting the impulse to oviposition.

4. Five physical characteristics of the hosts of Trichogramma are investigated: the permeability, rigidity, and hardness of the egg-shell; and the fluidity and quantity of the egg-contents (pp. 226 to 231).

5. Eggs of Sialis lutaria, Tenebrio molitor, and Bruchus obtectus are chemically unsuitable for Trichogramma evanescens as food.

6. Two biological characteristics of the host, its viability and its age, do not directly affect its suitability for Trichogramma; a third, the ability of the embryo to move, is of some importance.

7. The various known factors of host unsuitability are given in tabular form (p. 239).

8. In spite of numerous attempts during several years it has not been possible to develop a strain of Trichogramma evanescens which could use Bruchus obtectus as a host.

9. The host list of most groups of parasites is greatly limited by the inaccessibility of many species; it is further restricted in some groups (e.g., the parasitoid Hymenoptera) by the selection exercised by the parasite; it is finally limited in all groups (and especially the parasitoid Diptera) by the unsuitability of many infected animals.

10. The division of the problem of host specificity into the three parts, host finding, host selection, and host suitability, is fundamental.

The autumn migration of the rice leaf roller moth, Cnaphalocrocis medinalis Guenée, in eastern China was studied at two sites (one in southern Jiangsu Province and one in northern Jiangxi Province), using radar and aerial netting. It was confirmed that C. medinalis is a high-altitude nocturnal windborne migrant, with large numbers of moths taking-off at dusk and flying continuously for several hours. Migration was post-teneral and the females had immature ovaries. Maximum densities of the moths typically occurred between 250 and 550 m above ground, and layering was intense on some nights. Moth layers often occurred at an altitude where there was a wind-speed maximum. In early September, migrant C. medinalis from southern Jiangsu Province were carried on the winds in an approximately westward direction. However, the winds prevailing in late September and October took migrants from both sites towards the south-west or south. Forward trajectories for C. medinalis and other insects emigrating from northern Jiangxi during October indicated that they were able to reach the tropical rice-growing areas near the south China coast, where year-round breeding would be possible. Incidental observations on the migratory flight of other lepidopteran pests, including Mythimna separata (Walker), Spodoptera litura (Fabricius), Ctenoplusia agnata (Staudinger) and Agrotis ipsilon (Hufnagel) (all Nocturidae), Spoladea recurvalis (Fabricius) and particularly Omiodes indicata (Fabricius) (both Pyralidae) are presented.

(1) The salivary glands of Glossina contain a powerful anticoagulin, which delays the clotting of blood of mammals, birds, reptiles and batrachians. It was found that when the salivary glands are removed from the living fly, it can still draw blood normally and may live long, but sooner or later large clots form in the narrow anterior portions of the alimentary tract, so that the fly can no longer feed and dies of starvation. The purpose of the anticoagulin is to prevent such clotting and blood coagulation in the crop.

(2) The proventriculus and first third of the mesenteron are themselves inert in relation to coagulation of blood, but as removed from the normal fly they contain the anticoagulin which is derived from the salivary secretion.

(3) The hinder part of the mesenteron contains a powerful coagulin, the purpose of which is to neutralise the anticoagulin and cause a rapid clotting, in order to retain the fluid meal in the proper region while draining and assimilation take place, probably also to save strain on the sphincter mesenteri and prevent the occasional loss of food through the anus.

Observations were made chiefly in the southern Sudan, particularly at Mvolo where human onchocerciasis is common. The country and climate are briefly described.

Methods are described at some length.

The distribution of S. damnosum and places where it is known to be abundant are shown on a map. It does not appear to exist at the Fola Rapids.

Changes in certain organs were studied, chiefly in relation to the approximate estimation of age and (particularly in the case of the mid-gut and peritrophic membrane) to the movements of microfilariae. Recently emerged flies can frequently be readily detected by the clarity of the halteres (in which glycogen has not yet been stored) and the presence of abundant fat body, and by less conspicuous features such as the absence of an old peritrophic membrane. The oesophageal diverticulum often contains plant sugars and particles of grit but never blood.

The peritrophic membrane is formed at the time of a blood meal by the epithelium of the expanding part of the mid-gut. It is a laminated chitinous envelope completely surrounding the blood and remains unbroken for 24 hours or more. When very large numbers of microfilariae are ingested they appear to prevent the completion of the membrane so that blood quickly passes to the hind-gut.

Transgenic maize, Zea maize L., expressing the Cry1F protein from Bacillus thuringiensis has been registered for Spodoptera frugiperda (J. E. Smith) control since 2003. Unexpected damage to Cry1F maize was reported in 2006 in Puerto Rico and Cry1F resistance in S. frugiperda was documented. The inheritance of Cry1F resistance was characterized in a S. frugiperda resistant strain originating from Puerto Rico, which displayed >289-fold resistance to purified Cry1F. Concentration–response bioassays of reciprocal crosses of resistant and susceptible parental populations indicated that resistance is recessive and autosomal. Bioassays of the backcross of the F1 generation crossed with the resistant parental strain suggest that a single locus is responsible for resistance. In addition, cross-resistance to Cry1Aa, Cry1Ab, Cry1Ac, Cry1Ba, Cry2Aa and Vip3Aa was assessed in the Cry1F-resistant strain. There was no significant cross-resistance to Cry1Aa, Cry1Ba and Cry2Aa, although only limited effects were observed in the susceptible strain. Vip3Aa was highly effective against susceptible and resistant insects indicating no cross-resistance with Cry1F. In contrast, low levels of cross-resistance were observed for both Cry1Ab and Cry1Ac. Because the resistance is recessive and conferred by a single locus, an F1 screening assay was used to measure the frequency of Cry1F-resistant alleles from populations of Florida and Texas in 2010 and 2011. A total frequency of resistant alleles of 0.13 and 0.02 was found for Florida and Texas populations, respectively, indicating resistant alleles could be found in US populations, although there have been no reports of reduced efficacy of Cry1F-expressing plants.

1. During the past eight years field investigations on the epidemiology of yellow fever have been carried out in Bwamba County, a small heavily-forested area in the extreme west of Uganda.

During the course of this work yellow fever virus has been isolated from a human case, from Aëdes (Stegomyia) simpsoni, Theo., and from a mixed lot of Aëdes spp. taken in uninhabited rain-forest.

As it is known that yellow fever is endemic among the monkeys of the Bwamba forests and that a high rate of immunity is shown by certain species that rarely descend to the ground, it was concluded that an arboreal mosquito was the most likely transmitter of yellow fever among monkeys, and an investigation of the arboreal mosquito fauna was begun.

The biology and pest status of Rhopalosiphum padi (L.) in Europe are critically reviewed. New data are presented and the temporal occurrence of the aphid and its host-plants considered. In Britain, R. padi is a pest mainly because of its ability to transmit virus diseases, in particular barley yellow dwarf virus. In other European countries, especially in Scandinavia, R. padi is a pest in its own right. Predator and parasite complexes in Britain and Finland are compared and contrasted. The occurrence of R. padi as a pest of cereals in Europe is compared with that of Sitobion avenae (F.) and Metopolophium dirhodum (Walker). It is postulated that the great abundance of the primary host of R. padi, bird cherry (Prunus padus), and the spring planting of cereals in colder climates such as in Finland are major factors contributing to the differences in pest status of this aphid between Britain and in Scandinavia.

The bioactivity of materials from the leaves of Ocimum kilimandscharicum was tested against Sitophilus zeamais Mots chulsky (Coleoptera: Curculionidae), Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae) and Sitotroga cerealella (Olivier) (Lepidoptera: Gelechiidae) in maize and sorghum grains in the laboratory. Exposure of adults of the three insect species to dried ground leaves and essential oil extract of O. kilimandscharicum induced 100% mortality after 48 h. Fresh and dried whole leaves were not toxic to Sitophilus zeamais or R. dominica. Grains treated with dried ground leaves and essential oil extract caused significant reductions in the number of progeny and survival rate of all three pest species tested. There was no adult survival or progeny production in grains treated separately with each of the two materials at doses of 25.0 g (dried ground leaves) and 0.3 g (essential oil) per 250 g of grain, respectively. Unlike R. dominica and Sitotroga cerealella, grains treated with fresh leaves enhanced the feeding activity of Sitophilus zeamais. Ground leaves and the essential oil, however, protected the grains against feeding by all three species, resulting in lower weight loss and number of damaged seeds compared with untreated grains. All the plant materials were repellent to S. zeamais with the essential oil extract applied at 0.3 g/250 g of grain evoking the highest repellent action. There was, however, considerable variation in the repellency of the materials against R. dominica and Sitotroga cerealella. The results are discussed in terms of the efficacy of O. kilimandscharicum for protection against loss due to insects in traditional grain storage in developing countries.

Because insects are ectotherms, their physiology, behaviour and fitness are influenced by the ambient temperature. Any changes in environmental temperatures may impact the fitness and life history traits of insects and, thus, affect population dynamics. Here, we experimentally tested the impact of heat shock on the fitness and life history traits of adults of the aphid parasitoid Aphidius avenae and on the later repercussions for their progeny. Our results show that short exposure (1 h) to an elevated temperature (36°C), which is frequently experienced by parasitoids during the summer, resulted in high mortality rates in a parasitoid population and strongly affected the fitness of survivors by drastically reducing reproductive output and triggering a sex-dependent effect on lifespan. Heat stress resulted in greater longevity in surviving females and in shorter longevity in surviving males in comparison with untreated individuals. Viability and the developmental rates of progeny were also affected in a sex-dependent manner. These results underline the ecological importance of the thermal stress response of parasitoid species, not only for survival, but also for maintaining reproductive activities.

In Cameroun, about a dozen species of insects were associated with oil palm inflorescences. All except Prosoestus spp. visited female inflorescences after visiting male inflorescences during anthesis and transported pollen to the receptive female flowers. At a rough estimate, about 20 000 individuals visited each female inflorescence during the period of receptivity, and about 70% of the pollen transported was viable. In Peninsular Malaysia, Thrips hawaiiensis (Morg.) is almost certainly the main pollinating agent. Some 200 000 individuals were estimated to visit a single male inflorescence. They also visited female inflorescences, Where up to 7.3 thrips per flower were estimated to be present at any one time, each carrying 4–5 pollen grains, of which 76% were viable. In Peninsular Malaysia and Sabah, a momphid moth. Pyroderces sp., may contribute to oil palm pollination. As natural pollination of all oil palms in Cameroun and taller palms in Peninsular Malaysia is considered adequate while in most areas of Sabah where few insects visit the flowers it is inadequate, it is concluded that the insects observed achieve pollination so the oil palm should be considered an entomophilous rather than an anemophilous plant.

The competitive abilities of seven calliphorid and one sarcophagid species were examined by investigation of various Characteristics of their larval growth curves. The relative success of each species is thought to depend to a great extent on the ability of the larvae to attain quickly the minimum weight for viable pupation. The ovoviviparous species (Calliphora nociva Hardy, C. augur (F.) and Parasarcophaga crassipalpis (Macq.)) were found to have the most rapid growth and Chrysomya megacephala (F.), Calliphora nociva and C. augur the highest assimilatory rate during the period of most rapid growth. Further, C. nociva, C. augur, Ch. megacephala and Ch. rufifacies (Macq.) were the species best adapted to pupation at low larval weight, which suggests that their food requirements for successful pupation were less (relative to maximum larval weight) than those of the other species. In this respect, Lucilia cuprina (Wied.) was also well–adapted and Ch. varipes (Macq.) was the least successful species.

The attractiveness of cattle urine to Glossina morsitans morsitans Westwood and G. pallidipes Austen was shown to be entirely attributable to the phenolic components which it contains. Four of the eight naturally occurring phenol derivatives (3- and 4-methylphenol, 3-ethylphenol and 3-n-propylphenol) were electroantennographically active, induced upwind flight in wind-tunnel bioassays and increased trap catches in field tests in Zimbabwe. One of the minor components, 2-methoxyphenol, had little antennographic activity but induced upwind flight in the wind-tunnel and appeared to be repellent in field tests.

Ingestion of radiolabelled plant juices from cut surfaces of leaves during foraging and during substrate preparation for the fungus garden was demonstrated for laboratory colonies of the leaf-cutting ants Atta cephalotes (L.) and Acromyrmex octospinosus (Reich). Using P32 isotope, up to one-third of the radioactivity in the leaves was taken in directly by the colony as a whole, but this was much less when C14 was used. Additional plant material was taken in by the ants via the fungus garden. Large numbers of ants spend time in investigating cut surfaces of leaves and also in cutting and crimping leaves. Ingestion of plant material during these processes could play an important nutritional role in the colony and this may explain why many ants return from foraging apparently unladen. Large ants obtained most of their plant juice intake during foraging and the medium and small ants took much of theirs during substrate preparation. Inhibitory chemicals did not affect cutting but they reduced drinking and also reduced the intake of P32 from leaves during substrate preparation. The ants also ingested different amounts of P32 from leaves of different acceptability. It is suggested that leaf-cutting ants use fungus culture as a means of ‘sidestepping’ plant inhibitors. Nutrients are ingested directly from leaves when these are palatable, and the less palatable components are made available to the ants via the fungus.

Mating behaviour of Scaphoideus titanus Ball, the vector of the grapevine disease Flavescence dorée, was investigated in order to determine the role of substrate-borne vibrational signals in intra-specific communication and pair formation. Vibrational signals were recorded from grapevine leaves with a laser vibrometer. Signalling activity of single males changed throughout the day and the peak in activity was associated with twilight and early night when ‘call and fly’ behaviour was observed. Pair formation began with the spontaneous emission of male signals. The male calling signal consisted of a single series of pulses, partially accompanied with a ‘rumble’. The male courtship phrase consisted of four consecutive sections characterized by two sound elements, pulse and ‘buzz’. Female vibrational signals were emitted only in response to male signals. The female response was a single pulse that closely resembled male pulses and was inserted between pulses within the male signals. All recorded vibrational signals of S. titanus have a dominant frequency below 900 Hz. A unique feature of vibrational communication in S. titanus is well-developed intrasexual competition; males may use alternative tactics, in the form of disturbance signals, or silently approach duetting females (satellite behaviour). While the male-female duet appears to be essential for successful localization of females and copulation, it is also vulnerable to, and easily disrupted by, alternative tactics like masking.

Determining insect parasitism rates is problematic due to the small size and lack of useful distinguishing morphological characters of many parasitoid taxa. To solve this problem, entomologists have employed one of four general methods to detect parasitoid protein or nucleic acid markers: serological assay; random amplified polymorphic DNA–polymerase chain reaction “RAPD-PCR” allozyme electrophoresis; or specific PCR. Serological methods, especially with monoclonal antibodies, are unrivalled for specificity, enabling discrimination at the stage as well as species level. However, they have not found favour with many workers, possibly due to complexity and expense. RAPD–PCR has been widely used, but can only be recommended for restricted applications because of its poor reproducibility. Allozyme electrophoresis provides reproducible detection and discrimination of closely related species. Specific-PCR is highly specific and reproducible, and also has the shortest latency for detection, usually 24 h or less after parasitization. The substantial existing literature on allozyme electrophoresis and specific PCR is used to support recommendations on what are apt to be fruitful enzyme systems or genomic regions for detecting and discriminating parasitoids in untried parasitoid–host assemblages.

RNA interference (RNAi) is a powerful tool for rapidly analyzing gene functions. However, little is known about the possible use of dsRNA/siRNA as a pest control method. Here, we demonstrate that dsRNA/siRNA can induce the silence of chitin synthase gene A (CHSA), which is an important gene for the growth and development of cuticles and trachea in beet armyworm, Spodoptera exigua. Based on the in vitro RNAi experiments in an insect cell line (Trichoplusia ni High 5), in vivo RNAi was performed by injecting synthesized dsRNA/siRNA into the 4th instar larvae of S. exigua. Significantly lower levels of CHSA transcripts were detected. In addition, the cuticle of these insects was disordered and the epithelial walls of larval trachea did not expand uniformly in injected individuals. Moreover, Injections significantly increased abnormalities relative to control larvae. These results highlighted the possibility of dsRNA/siRNA for gene function studies in lepidopteran insects and future pest control.