Soil samples were taken from two transects (total 63 sampling points; 25 cm quadrats) representing the Betula pubescens (Betulaceae) woodland, rush-pasture and peat-based mire vegetation of the west coast and Highlands of Scotland, in an attempt to relate soil and vegetation features to the occurrence of Culicoides impunctatus Goetghebuer larvae. The covers of vegetation groups were recorded at each sample site and soil wetness was assessed on an arbitrary scale. Culicoides spp. larvae were extracted from half of each sample and stored for subsequent identification of C. impunctatus larvae, while the remaining half was used for analysis of soil pH and organic content (loss on ignition, LOI). Correspondence analysis (using DECORANA) separated the sample sites and vegetation groups and the ordination axes were significantly correlated with the density of C. impunctatus larvae, soil organic content and soil wetness index. Simple regression analyses revealed that the density of Juncus acutiflorus/J. articulatus (Juncaceae) and soil wetness index were positively related to the overall variation in C. impunctatus larval density. The wetness index had the strongest relationship and this remained the case in step-wise multiple regression. There was no relationship between larval density and soil pH. This information on the specific microhabitat preferences of the larvae could aid colonization attempts of this dominantly important species of biting midge in the UK.

Female Aphidius rhopalosiphi De Stefani Perez reared on Rhopalosiphum padi (Linnaeus) made equal numbers of encounters with another suitable host aphid (Sitobion avenae (Fabricius (both Homoptera: Aphididae))) in arenas where the aphids were on either pieces of wheat leaf or moist filter paper. However, the number of oviposition stabs made in arenas with wheat was far higher than with filter paper, demonstrating the importance of host-plant cues in the acceptance of the aphids by the parasitoid. Diet reared aphids (even if subsequently fed on wheat) appeared to be accepted more readily than totally wheat reared individuals. In another arena experiment, there were more encounters with and more stabs made into both S. avenae and a non-host aphid (Myzus persicae (Sulzer)) on wheat than on Brussels sprouts (a host plant of M. persicae), again showing the over-riding importance of host-plant cues.

Leuronota calycophylli sp. n. attacks experimental plantations of the high-quality timber Calycophyllum spruceanum in Peru. Adults, larvae and the damage on the host are described and illustrated. Adults differ from other congeners in the absence of genal processes and in the structure of the genitalia. The host of L. calycophylli is unusual for psylloids: rubiacious hosts are otherwise known only from the four members of the Palaearctic Trioza galii Förster group and the Taiwanese Synpsylla wendlandiae Yang.

Population densities of honeydew-producing Homoptera were assessed on mature upper-Amazon cocoa (Theobroma cacao) (Sterculiaceae) trees with combinations of the ants Crematogaster clariventris Mayr, Pheidole megacephala (Fabricius) and Tetramorium aculeatum (Mayr). Interactions were found between combinations of the three ant species and the abundance of Homoptera attended for honeydew. Crematogaster clariventris primarily attended Stictococcus sjostedti Cockerell (Stictococcidae), and less frequently Waxiella sp. nr zonata (Newstead) (Coccidae). Pheidole megacephala attended mealybugs, mainly Planococcoides njalensis (Laing), and Planococcus citri (Risso) (both Pseudococcidae). Tetramorium aculeatum was negatively associated with honeydew-producing Homoptera only when it was the sole dominant ant. Where T. aculeatum co-existed with either one, or both, of the other ant species, it had little influence on the abundance of the honeydew-producing Homoptera they attended, including the mealybug vectors of cocoa swollen shoot virus. Ant-attended Homoptera were more numerous on trees solely dominated by their attendant ants than on trees where two or all three ant species co-occurred. By contrast, the non-ant-attended psyllid Mesohomotoma tessmanni (Aulmann) was least common on trees with a single dominant ant species, and was most abundant on trees foraged by all three ant species.

CDC (Communicable Disease Center) light-traps were compared with human-bait collections as an alternative method for sampling malaria vectors in two villages of western Kenya. The numbers of Anopheles funestus Giles and Anopheles gambiae sensu lato Giles in CDC light-trap collections were significantly correlated to the numbers caught in human-bait collections, but in Anopheles arabiensis Patton the two collections were not significantly correlated. Most of the female vectors collected in the traps were unfed. Parity of A. arabiensis collected in CDC light-traps (44.3%) was significantly lower than the rate obtained from females caught on human-bait (54.5%). Although CDC light-traps provide a cheap and convenient method for collecting vectors, further studies should nevertheless be undertaken to determine the influence of species-specific variation in the sizes and age-structure of collections because such variations can affect the epidemiological interpretation of the data.

The efficiency of electrocuting devices currently used for sampling tsetse flies (Glossina spp.) and similar insects, was studied in Zimbabwe by recording approaches, kills, and escapes, with video. The kill rate of an electrified netting screen increased with the discharge frequency of the device up to 200 Hz (ca the highest practicable frequency) reaching ca 90% at best. The same kill rate was achieved by an electrified black cloth target. However, ‘two-choice’ comparisons of electric nets and their components showed avoidance by the tsetse of the black mosquito netting between the electric wires, and even of the electric wires on their own, though probably not of the black metal frame that supported them. The proportion of tsetse avoiding a standard electric net was ca 27% in full sun, ca 40% in shade, implying an overall sampling efficiency of, at best, ca 65% at the optimum 200 Hz discharge rate in sunshine, and ca 40–50% with the 67 Hz nets used currently in Africa. Potential for improvements therefore lies mainly in reducing the visibility of the nets; suggestions are offered.

This paper presents a thorough review and a complete amalgamation, with some modification, of the internal classification of the genus Anopheles. Both formal and informal taxa are included. The classification is intended to aid researchers and students who are interested in analysing species relationships, making group comparisons and testing phylogenetic hypotheses. The genus includes 458 formally named and provisionally designated species divided among six subgenera. The largest subgenera, Anopheles, Cellia and Nyssorhynchus, are further divided into various descending informal groupings down to species level. These groupings include Sections, Series, Groups, Subgroups and Complexes. Other terms applied by some authors to levels of classification represented by these categories have been changed in order to establish a degree of uniformity in the application of informal group names within the genus. A few changes involving groups and species assignments have been made to eliminate duplicity or clarify concepts.

The number of wind-borne female Simulium damnosum Theobald sensu lato migrating across territory devoid of breeding populations (the Onchocerciasis Control Programme, OCP) were monitored daily at widely separated sites downwind. The seasonal curves of numbers recorded each day were remarkably similar in pattern at each site with little blurring (although numbers lessened as distance from source increased). The uniformity suggests that each daily batch of S. damnosum moved downwind en bloc with but a small proportion of laggards. To test this hypothesis, model curves were generated, with different proportions of daily laggards, from the data at each sampling site and compared by chi-squared tests with the observed curve at the next site downwind. It was found that, in general, those models that most closely resembled the downwind curves were those with the smallest proportion of laggards. Other aspects of the migration were also considered, notably the factors affecting loss of numbers as distance increased and the interaction between laggards and loss where it was shown that the greater the proportion of laggards the greater will be the daily loss.

Cross-resistance spectra were determined in strains of the Australian sheep blowfly, Lucilia cuprina (Wiedemann), which had been pressured for several years in the laboratory with diflubenzuron, butacarb or deltamethrin. Each strain was highly resistant to its selecting chemical (resistance factors > 1000-fold), however, cross-resistance levels were variable and often low. In particular, strains selected with diflubenzuron and butacarb showed very little resistance to deltamethrin (resistance factors <7-fold). Each strain showed resistance levels to diazinon only slightly higher than the highest levels currently detected in field strain larvae. Piperonyl butoxide and triphenyl phosphate significantly synergized each pressured strain with its selecting chemical, suggesting the involvement of both monooxygenases and esterases in the observed resistances. Synergism ratios in each case were greater with piperonyl butoxide. The lack of any alteration in in vitro acetylcholinesterase sensitivity to butacarb inhibition in the butacarb-selected strain, and only low level resistance to DDT in the deltamethrin-selected strain, provided no evidence for target-site insensitivities in these strains. The low-moderate levels of cross-resistance therefore imply the existence of qualitative differences in the detoxification systems in each strain.

The primary coffee of commerce, Coffea arabica, has well-developed pit domatia in the primary vein axils on the undersurfaces of the leaves. In plantations near Mareeba and Daintree in far north Queensland, Australia, these morphogenetic structures are commonly occupied by mites. Mites used domatia on over 80% of all leaves examined, and 41% of all domatia had been occupied by mites (15–28% on young leaves and 54–59% on older leaves at Mareeba, and 58% overall at Daintree). At Mareeba, domatia use by mites did not differ among plants or shoots within plants but did vary significantly with leaf position within shoots, a reflection of leaf age. Domatia were important sites for mite reproduction and development; 93% of the eggs and all moulting mites on leaves were in domatia. Seven mite taxa were identified on leaves at Mareeba and nine were present at Daintree. With the exception of Fungitarsonemus sp. and Brevipalpus obovatus Donnadieu at Mareeba, all were concentrated in leaf domatia. Almost all mites in domatia were from groups in which arboreal representatives are primarily predatory (e.g., Stigmaeidae, Phytoseiidae, and Bdellidae), fungivorous (e.g., Winterschmidtiidae, Oribatida and Acaridae), or both (Tydeidae and Tarsonemidae). The data suggest that domatia influence the distribution and abundance of predatory and fungivorous mites that have the potential to affect fungal pathogens and some arthropod pests on coffee leaves.

The seasonal occurrence and spatial distribution of the crambine stem borer, Chilo partellus (Swinhoe) were investigated in maize, Zea mays, and sorghum, Sorghum bicolor, fields at the Kenya coast. During the vegetative growth stage, small-sized larvae were typically found behind leaf sheaths and in whorls in maize and sorghum. In reproductive and senescent maize, small-sized larvae were also found feeding in ears. Later immature life stages were located predominantly in stems in sorghum, and in the stems and ears in maize. Density and variance estimates of small, medium-, and large-sized larvae and pupae in maize and sorghum were fitted to Taylor's power law which provided significant regressions in all cases. The between-plant distribution was aggregated in all life stages. In maize, the distribution remained aggregated through the larval and pupal life stages, but in sorghum the distribution became progressively less aggregated as insects aged. The relationship of C. partellus density to the proportion of plants infested also suggested aggregation. Optimal sample sizes were determined for both binomial and enumerative sampling plans at two levels of precision, and a discussion is included on the relationship of optimal sample sizes to economic injury levels. Additionally, a presence/absence sequential sampling plan is proposed.

Lutzomyia longipalpis (Lutz & Neiva), the vector of American visceral leishmaniasis (AVL), is much more abundant in animal sheds than in houses on Marajó Island, Pará State, Brazil. This difference in abundance is known not to reflect host preference. We show here that it also cannot be explained in terms of variable trapping efficiency, or insecticide application, and we exclude animal sheds as important daytime resting sites. In experimental sheds, the number of L. longipalpis increased markedly with the openness of the walls, though artificially large aggregations of flies could be generated in closed houses by using caged flies and hosts as attractants. We conclude that L. longipalpis tend to congregate at sites outdoors, including animal sheds, because these are the places where leks can most easily form on abundant, stationary (sleeping) and accessible hosts. These results help to explain why the seroprevalence of Leishmania chagasi infection is generally much higher among dogs than humans. They also indicate that human exposure to sandfly bites varies with the quality of house construction.

Detailed studies on the immature stages of the sorghum head bugs, Eurystylus immaculatus Odhiambo and Creontiades pallidus Rambur, were carried out in the laboratory at Samanko, Mali, during November 1991 to March 1992, and January to April 1993, and in the field in October 1993. Eggs of both species were laid in maturing sorghum (Sorghum bicolor) grains. The egg incubation period was 4–7 days in E. immaculatus, and 5–7 days in C. pallidus. There were five nymphal instars in both species. The total nymphal period was 6–11 days in E. immaculatus and 8–14 days in C. pallidus. The durations of first, second, third, fourth and fifth nymphal instars were 1–3, 1–2, 1–2, 1–3 and 1–3 days, respectively, in E. immaculatus, and 1–3, 1–2, 1–3, 2–3 and 2–4 days, respectively, in C. pallidus. All the immature stages of E. immaculatus are described and sketched.

Radar, aerial netting and ground sampling were used to study the autumn migration of Nilaparvata lugens (Stål) in Jiangsu Province in east central China. Emigration of macropterous adults increased from late August until late September as the main rice crop matured and was harvested. In early and mid September, the resulting windborne migrations carried the planthoppers mainly towards the west, although the migration directions ranged (within the western sector) from south to north. By late September, however, displacements were predominantly to the south-west on the then prevailing north-east monsoon winds: migration was particularly rapid when the north-easterlies were reinforced by typhoons. Although in late September such movements to more southerly latitudes are essential for the survival of the planthoppers' progeny, we found no definite evidence for preferential emigration on winds blowing towards the south. There were, however, indications that when winds towards the north occurred, the duration of migratory flight was curtailed. Irrespective of any possible preference for migration on northerlies, a large proportion of the N. lugens population would normally be carried in an adaptive southwards direction, because the advent of the north-east monsoon occurs at a time when the number of flight-ready planthoppers approaches its peak.

The numbers of insects colonizing the dung of cattle injected with the anthelmintics ivermectin or moxidectin were compared with the colonization of the dung from control animals given no treatment, in a blind field trial. Dung was collected 2, 7, 14, and 21 days after dosing and set out in a randomized grid of standard 2 kg pats. Pats were retrieved from each of the three groups group after 7, 14, 21 and 42 days in the field for analysis of insect fauna. There were no significant differences in the number of adult Aphodius spp. (Coleoptera: Scarabaeidae) found in the dung from the three treatment groups with either time of exposure in the field or time after treatment, showing that adult beetles were attracted to all pats equally. However, dung from animals treated with ivermectin prevented the development of larval Aphodius spp. for at least 7 days after treatment. In contrast, the dung from animals treated with moxidectin supported the development of Aphodius spp. at all stages after dosing, as did dung from control animals. There were no significant differences in the number of cyclorrhaphous Diptera larvae in dung from control or moxidectin-treated animals. In contrast, such larvae were largely absent from the dung collected from ivermectin-treated cattle for up to 14 days after dosing. The results show that moxidectin is less toxic to dung-inhabiting insects than ivermectin following standard injection treatment. The results are discussed in relation to the effects of anthelmintics on non-target pastureland insects.

In Zimbabwe, living and stuffed warthogs (Phacochoerus aethiopicus Pallas) were placed within an incomplete ring of electric nets and observations were made of the numbers of Glossina pallidipes Austen and G. morsitans morsitans Westwood attracted to the hogs, the alighting position and feeding responses of tsetse, and the grooming behaviour of the warthogs. Between 26 and 31% of tsetse landed on the head region of an adult live warthog compared to 8% for a juvenile and 4% for a stuffed warthog. The number of tsetse alighting adjacent to the eye of a stuffed warthog increased 20 times if dark patches were fixed there. The percentage of tsetse alighting on the head region of the adult warthog increased from 25% to 50% as the number of tsetse caught on the ring of nets increased from <100 to > 800. There was a concurrent increase in the rate of skin twitches and ear flicks by the warthog. For an adult warthog, 26% of tsetse leaving the vicinity had fed compared to only 1% for a juvenile. It is suggested that the concentration of tsetse on the head of adult warthogs is a visual response to the dark patch produced by the pre-orbital glands of a mature warthog and to density-dependent changes in the grooming responses of warthogs.

The taxonomy of 10 species of Braconidae (Microgastrinae) which are parasitoids of cereal stem borers in Africa is revised. Dolichogenidea cameroonensis, D. fuscivora, D. oryzae and D. polaszeki, are described as new, Apanteles procerae Risbec is synonymized with Dolichogenidea aethiopica (Cameron) comb. n., syn. n. A key is given and host associations are listed. A summary table of the species mentioned in the text together with their hosts is also provided.