The effects of host and non-host plant odours on the foraging responses of the banana weevil, Cosmopolites sordidus (Germar), were investigated in the laboratory through arena and olfactometer bioassays. Contrary to previous reports that banana rhizome and pseudostem were the most attractive parts to the weevil, dead leaves were most preferred. Comparison of dead banana leaves with dead leaves of other plants showed that attractant odours were present in yam, cocoyam and dead grasses but absent in cocoa and soybean leaves. Complete leaf senescence while the leaf was attached to the mother plant proved necessary for the development of the dead-leaf-based odours but the involvement of microbial organisms could not be demonstrated. It is possible that dead-leaf-based attractants could be used in combination with microbials such as entomogenous fungi and nematodes in integrated management of C. sordidus.

Calyptrate fly populations were monitored with sticky traps at the following sites in Hampshire, UK during August to November 1998: a landfill and composting site (Paulsgrove), a site adjacent to this landfill (Port Solent), a site with no landfill nearby (Gosport), and a composting site with no landfill nearby. Overall, house flies Musca domestica(Linnaeus) and lesser house flies Fannia spp. were not important constituents of the dipteran catch, while bluebottles (Calliphora spp.) and greenbottles (Lucilia spp.) comprised approximately 12% of the total. Very large fly populations were found at the two composting sites, and it seems likely that these provide ideal breeding grounds for a range of fly species since they offer an abundance of warm decaying organic matter. Large fly populations were also evident at the landfill site. The suitability of household waste for the development of calyptrate Diptera was confirmed in a controlled trial: a mean of 0.43 adults emerged per kilo of one-week-old waste. Since many hundreds of tonnes of waste are delivered to the landfill daily, it is clear that the landfill is likely to substantially increase the local population of calyptrate flies. However, the data suggest that there was little movement of Diptera from the landfill to Port Solent situated approximately 500 m away. The most important calyptrate flies at this site were the cluster flies Pollenia rudis (Fabricius) and P. amentaria (Scopoli); the landfill site is unlikely to provide a suitable breeding site for these flies, as the larvae develop as parasites of earthworms. Significantly more flies emerged from one-week-old than from two-week-old household waste. A comparison of different barriers to the emergence of adult house flies from waste demonstrated that sacking provided an effective barrier to fly emergence, but that soil did not differ significantly from control treatments. If managed appropriately, it seems that the use of sacking over landfill waste could substantially reduce associated fly populations.

The within-field spatial distribution of some common farmland arthropods from the Carabidae, Araneae and Collembola was assessed using two-dimensional grids of pitfall traps distributed across whole winter wheat fields. In the first year, the extent to which arthropod capture was influenced by location within the field and sampling intensity was examined using a nested grid design (1.5 m, 7.5 m and 30 m spacings). In the second year, distributions within two different-sized winter wheat fields were compared. Spatial pattern and association between arthropods and weed cover were analysed using SADIE and trend surfaces were used to visualize distributions. Many of these arthropod groups exhibited aggregated distributions within the fields in clusters larger than 30 m across, demonstrating that the numbers captured will vary depending on the location of sampling within a field. Amara species, Bembidion lampros Herbst, Carabidae and Lycosidae were predominantly found within 60 m of the field edge. Nebria brevicollis Fabricius and Pterostichus madidus Illiger were found within the field in patches of one and two hectares, respectively. Linyphiidae were relatively homogeneously distributed across the fields. There was some evidence of clustering by Collembola. The spermophagous Carabidae and Lycosidae were positively associated with the degree of weed cover. SADIE analytical techniques were useful for identifying the importance and location of patches with greater and less than average numbers, although a minimum of 36 sample points is recommended.

Existing attempts to estimate the survival rate of tsetse flies from ovarian age distributions generally assume that the population is stationary. The fact that the survival rate cannot be dissociated from the growth rate by these methods poses a problem. Under the assumption of a stable age distribution, we propose a maximum likelihood method to estimate the ‘apparent survival rate’ for three categories of females: nulliparous (β0), young parous (β1) and old parous flies (β2). The rate depends both on ‘real survival rates’ a0, a1 and a2, and a growth rate λ: β0 = a0/λ, β1 = a1/λ, and β2= a2/λ. We used a matrix model, which can be parameterized if the pupal survival rate and the pupal period are known. Replacing a0, a1 and a2 by β0,λ, β1λ, and β2λin the projection matrix, the problem amounts to calculating its dominant eigen-value λ, and hence a0, a1 and a2. The application to a field population of Glossina palpalis gambiensis Vanderplank in Burkina Faso showed there was a marked difference in survival rate according to age category. The average survival rate increased with age with decreasing variability. The results suggested that sampling (by trapping) may have had an effect on the dynamics of this tsetse population by ageing it artificially. This method may be a useful tool for monitoring tsetse control.

In the fragmented landscape of arable farmland, hedgerows and other non-crop habitats provide refuges of food and shelter for invertebrates, and corridors through which they can move to other habitats. Their role as corridors is likely to depend on their connectivity, both to each other and to other patches of suitable habitat. The effects of connectivity on the carabid beetle Nebria brevicollis (Fabricius) were analysed by observing movement between hedgerow intersections (nodes) and the linear section of the hedgerow, and across gaps in the hedgerow. Capture–mark–recapture of N. brevicollis revealed a uniformly higher activity at hedgerow nodes than at mid-section strips of comparable area. This is consistent with previous studies of hedgerow fauna including butterflies, plants and birds. Gaps in the hedgerows typically measured 7–9 m and functioned as a passage between fields for farm machinery. These were readily crossed by N. brevicollis as was the hedge bottom. Some movement along the hedgerow was found indicating their use as a corridor.

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.

Cattle were treated with cypermethrin and flumethrin pour-ons to determine possible adverse effects of residues in dung on the survival, fecundity and fertility of Euoniticellus intermedius (Reiche). Dung from both cypermethrin- and flumethrin-treated cattle was collected 1, 2, 3, 5, 7, 14, 21 and 28 days after treatment, with an untreated control for each. Mortality of adult E. intermedius exposed to dung collected from cypermethrin-treated cattle two to seven days after treatment ranged between 80% and 100%. Cypermethrin had no effect on adult and immature survival or on fecundity and fertility of E. intermediusexposed to dung collected 1, 14, 21 and 28 days after treatment. Dung collected from flumethrin-treated cattle had no apparent effect on adult survival, egg production, immature survival, adult emergence, fecundity and fertility of E. intermedius, except at seven days after treatment, when fewer brood balls were produced and consequently fewer adults emerged from dung from treated animals compared with the control.

The effect of vine phenological stage during larval feeding on the reproductive output of Lobesia botrana (Denis & Schiffermüller) adults was assessed. Larvae were reared under field conditions on vine inflorescences, unripe or ripe berries simulating the first, second and third insect generations respectively. The resulting adults showed significant differences in body weight, longevity and reproductive output as measured by oviposition period, total fecundity and reproductive efficiency (viable eggs/body weight) for females, and spermatophore number and volume of the first spermatophore for males. Viable egg number was positively correlated with female body weight for all treatments but male reproductive efficiency (spermatophores/body weight) was not. The reproductive output of females from larvae reared on a standard semisynthetic diet was comparable to that of females reared on ripe berries whereas males showed a higher reproductive output when reared on semisynthetic diet. These results clearly show that data obtained from insects reared on artificial diet cannot be extrapolated to ‘field-derived’ adults. The results suggest that the variation in L. botrana reproductive output due to the larval food source should be taken into account as a potential factor affecting insect population dynamics. It is suggested that different intervention thresholds, such as those based on pheromone catches, may be needed for each of the three moth generations, to compensate for the increased fecundity and potential to cause larger amounts of crop damage of later generations.

This paper reports on the performance of an atmospheric numerical model called BLAYER which has been adapted to forecast the movement of migrant brown planthopper Nilaparvata lugens (Stål) and white-backed planthopper Sogatella furcifera (Horvarth) populations from China to Korea. Comparison of model forecasts with trapping data for the 1987 and 1988 migration seasons indicated: (i) that the model is capable of successfully simulating the movement of planthoppers to Korea; (ii) that the model has sufficient detail to simulate insect movement into different regions of Korea; (iii) the source region for early season migrants is most likely to be south-eastern China (i.e. south of 25°N and east of 115°E); (iv) later season migrants may not necessarily always originate from an expanded northward region (south of 30°N); (v) the flight level of migrants may vary from about 500 to 2000 m altitude from one migration episode to another; and (vi) flight times ranging between 24 and 45 h are required to explain the migratory influxes. The results reported here have led to BLAYER forecasts of planthopper migration being produced on an operational basis within Korea.

Bioassays in Zimbabwe with wild-caught Glossina pallidipes Austen and G. morsitans morsitans Westwood showed that formulations of deltamethrin (Decatix, SpotOn and an experimental variant of SpotOn), alphacypermethrin (Renegade) and cyfluthrin (Cylence) applied to oxen at the manufacturers' recommended doses gave knockdowns above 50% for 5–24 days in hot months and 24–55 days at cooler seasons. Within these periods, the average knockdowns were 77–86% with deltamethrin, 74% with alphacypermethrin and 59% with cyfluthrin. None of the insecticides affected the numbers of tsetse attracted to oxen from a distance, the proportion of tsetse that engorged, and the alighting responses on cloth screens. In the hot season most tsetse engorged on the belly. At other times the front legs were preferred, especially in the wet season and for a few months after. Chemical assays indicated that insecticide persisted at greatest concentration on the backs of oxen and least on the legs. Modelling the experimental data suggested that 4–21 annual applications of insecticide in areas >1000 km2 would give good control at least 10 km from the invasion source if the treated cattle contributed at least 50% of tsetse diet. No treatment regime under any diet conditions would give good control near an invasion front. Insecticide at concentrations up to 0.15 ppm occurred in dung from treated oxen for up 12 days post-treatment. Dead beetles occurred in and near fresh dung.

Fourteen populations of the western flower thrips Frankliniella occidentalis Pergande, originating from different hosts and countries in Asia, Europe, North America and New Zealand, were analysed for their competency and efficiency to transmit tomato spotted wilt virus (TSWV). All populations acquired and subsequently transmitted the virus, and were thus competent to transmit. They show marked differences in their efficiency, expressed as the percentage of transmitting adults. Efficiencies varied from 18% for a F. occidentalis population from the USA (US2) to 75% for a population from Israel (IS2). The differences between populations were not affected by the amount of virus ingested or by the host plant used. However, the tospovirus species studied and age at which the larvae acquired the virus affected the efficiency to transmit. First instar larvae of the NL3 population from The Netherlands were able to acquire tomato spotted wilt virus, whereas second instar larvae failed to do so. However, both instars of this population acquired impatiens necrotic spot virus (INSV), another tospovirus. This and tomato spotted wilt virus were both acquired by both larval stages of the populations IS2 and US2, although their ability to acquire virus decreased with their age. Hence, it is likely that, in general, both instar larvae of most F. occidentalis populations are competent to acquire both tospoviruses. These results show that large differences exist in the efficiency by which tomato spotted wilt is transmitted by the various F. occidentalis populations and that the ability to acquire tospovirus decreases with the age of the larvae

Host range experiments and field sampling in Nigeria produced no evidence that African rice gall midge, Orseolia oryzivora Harris – Gagné, can develop on plants other than Oryza species. Sampling in three outbreak areas during 1994 showed that the insect's annual cycle varied according to the agroecological zone and rice cropping pattern. In the humid forest zone, Orseolia oryzivora persisted through the short dry season on ratoons of cultivated rice Oryza sativa at a rainfed site and on dry season rice crops at an irrigated one. In contrast, at rainfed sites in the moist savannah zone the pest survived the longer dry season on the perennial wild rice O. longistaminata, while ratoons and volunteers of O. sativa provided 'bridges' between the wild host and wet season rice crops. Early in the wet season at rainfed sites, galls of Orseolia oryzivora were not found at high density on wild rice, ratoons or volunteers. The heavy infestations which developed by October resulted primarily from rapid multiplication on rice crops themselves during the wet season. At all 13 sites sampled, the large majority of galls were found on fallow or cropped rice fields, rather than in ditches, bunds or uncultivated wetland, irrespective of the time of year or the hosts involved. From gall dissections, the parasitoids Aprostocetus procerae (Risbec) and Platygaster diplosisae Risbec caused over 30% mortality at some sites by October but generally increased too late to prevent crop damage. Implications of the results for the management of Orseolia oryzivora are discussed.