The term ‘dead-end trap cropping’ has recently been proposed to identify a plant that is highly attractive for oviposition by an insect pest, but on which offspring of the pest cannot survive. The potential of the wild crucifer Barbarea vulgaris R. Br. to allure and serve as a dead-end trap crop for the diamondback moth Plutella xylostella (L.), an important pest of cruciferous crops worldwide, was examined in laboratory experiments. When P. xylostella adults were provided with a dual-choice of plants of B. vulgaris, and Chinese cabbage Brassica campestris (L.), in one arena, adult moths laid 2.5–6.8 times more eggs on the former than on the latter. When P. xylostella adults were provided with a dual-choice of plants of B. vulgaris and common cabbage Brassica oleracea L., adult moths laid virtually all their eggs on the former and ignored the latter. Nearly all P. xylostella eggs laid on the three species of plants hatched successfully, but nearly all individuals on plants of B. vulgaris died as neonates or early instar larvae, while 87–100% of the larvae on Chinese cabbage and common cabbage survived to pupation. Dual choice tests with a Y-tube olfactometer showed that volatiles from B. vulgaris were much more attractive to P. xylostella adults than those from common cabbage. The results demonstrate that B. vulgaris has a great potential as a dead-end trap crop for improving management of P. xylostella. Factors that may influence the feasibility of using B. vulgaris as a trap crop in the field are discussed, and ways to utilize this plant are proposed.

The distribution of aphid predators within arable fields has been previously examined using pitfall traps. With this technique predominantly larger invertebrate species are captured, especially Carabidae, but the technique provides no estimate of density unless mark–recapture is used. However, many other numerically important aphid predators occur in arable fields and relatively little is known about their distribution patterns nor whether they exhibit a density-dependent response to patches of cereal aphids. Identification of the most effective predators can allow management practices to be developed accordingly. In this study, the distribution of cereal aphids and their predators was examined by suction sampling within a field of winter wheat in Devon, UK, along with visual estimates of weed patchiness. Sampling was conducted on four occasions in 1999 across a grid of 128 sample locations. The distribution of 11 predatory taxa from the Carabidae, Staphylinidae and Linyphiidae was examined. Additionally, the total number of aphid predators and a predation index were used in these analyses. Carabid adults and larvae, along with staphylinid larvae showed the strongest aggregation into patches and the most temporal stability in their distribution. Other taxa had more ephemeral distributions as did the cereal aphids. The distribution of carabid larvae was disassociated from the distribution of cereal aphids for the first two sampling occasions indicating biocontrol was occurring. Other predatory groups showed both association and disassociation. Carabid larvae, Bathyphantes and total numbers of Linyphiidae showed a strong correlation with weed cover for two of the sample dates. Cereal aphids were disassociated from weed cover on three sampling occasions.

Independent studies were performed in Canada and in Denmark to assess the survival of parasitic wasps (Hymenoptera: Pteromalidae) wintering in puparia of house fly, Musca domestica Linnaeus (Diptera: Muscidae). Data in Canada were collected for Muscidifurax raptorGirault & Saunders, M. raptorellus Kogan & Legner, M. zaraptor Kogan & Legner, Nasonia vitripennis(Walker), Spalangia cameroniPerkins, Trichomalopsis sarcophagae (Gahan) and Urolepis rufipes (Ashmead) in three microsites at an outdoor cattle facility in southern Alberta. Survival was highest for N. vitripennis, T. sarcophagaeand U. rufipes, ranging from near zero to c. 7%. No survival was observed for S. cameroni. Daily mean values for ambient air temperature (DMAT) averaged about −3.5°C during exposure periods. Data for Denmark were collected for M. raptor, S. cameroniand U. rufipes in a dairy barn and in a swine barn. Survival of M. raptorand U. rufipes was higher than that of S. cameroniin the dairy barn (DMAT = 8.6°C), with the three species having similar survival in the swine barn (DMAT = 15.4°C). In both studies, parasitoids in egg stages were least likely to survive. These results identify the potential for T. sarcophagae and U. rufipes to be commercialized for use in northern climates as biocontrol agents for nuisance flies, compare directly the cold-hardiness of commercialized species (i.e. all of the above species excluding T. sarcophagae and U. rufipes), and document the importance of microsite on winter survival.

A two-choice bioassay was developed to evaluate the role of host-plant berry compounds on the oviposition site acceptance of the generalist moth Lobesia botrana (Denis & Shiffermüller). A key feature was the lining of the bioassay arena with felt which focused oviposition on the test substrates. Initial experiments comparing substrates with different physical features indicated that smooth textures and spherical shapes with interstices favour oviposition. Artificial oviposition substrates were thus constructed with glass spheres in order to test the behavioural activity of grapevine berry extracts. Only polar extracts obtained by soaking berries in methanol or water stimulated oviposition (more eggs were laid on the extract-treated substrate than on the control substrate), whereas more apolar ones obtained with chloroform or hexane had no significant effect. The prior removal of epicuticular waxes from grape berries before extraction did not enhance the stimulatory activity of the methanol extract. The oviposition response to this extract was dose-dependent. It is concluded that polar compounds present on grape berries act as oviposition stimulants for L. botrana.

A significant reduction in age of mating occurred during the first four generations (G1–G4) of laboratory adaptation of wild Bactrocera tryoni (Froggatt) and this was associated with the earlier attainment of peak egg load although no significant differences were detected in the peak egg load itself. A long term laboratory (LTL) strain had a significantly earlier mating age and higher peak egg load than flies of wild origin or those from the first four laboratory generations. The amount of protein consumed by females in the first week of adult life was significantly higher in the LTL strain than in flies of wild origin or G1–G4 but there were no significant changes (or only slight changes) with laboratory adaptation in the amounts of protein consumed up to the ages of mating and peak egg load. Laboratory adaptation resulted in no significant changes in egg size, egg dry weight, puparial fresh weight and the dry weight of newly emerged females. The large increase in fecundity with laboratory adaptation is associated with a 4- to 5-fold increase in the rate of conversion of dietary protein to eggs (i.e. eggs produced per mg of protein consumed).

The basic reproductive biology of two ectoparasitoids developing on the late larval instars of the scolytid Ips typographus Linnaeus, a pest of spruce forests in Eurasia, was studied with the purpose of explaining which biological features allow the two species to share the same host. The anautogenous braconid Coeloides bostrichorum Giraud had a longer pre-oviposition period (5.1 vs. 3.3 days), a greater egg load (8.1 vs. 6.1 eggs), survived longer and emerged later than the pteromalid Rhopalicus tutela (Walker). In contrast, R. tutela was autogenous and tended to be more fecund under constrained conditions (9.7 vs. 5.1 total offspring per female). The longer pre-oviposition period of the specialist C. bostrichorum, coupled with its greater longevity, afforded the opportunity of better synchronization of ovipositing females with late instar larvae of I. typographus. By contrast, the polyphagous R. tutela matured rapidly, allowing parasitism of both younger and older larval instars of I. typographus in addition to other species. These small differences favoured the co-occurrence of the two parasitoid species on the same attacked trees.

The thelytokous parasitoid, Microctonus hyperodae Loan, was collected from eight South American locations and introduced to New Zealand in 1991 for biological control of Argentine stem weevil, Listronotus bonariensis (Kuschel) (Coleoptera: Curculionidae). Parasitoids from each population were released in equal numbers at each New Zealand site to give them the same opportunities to establish. Population markers have been sought to identify the South American geographic populations that have become most successful in New Zealand. These would assist in determining the importance of concepts such as climate matching and host–parasitoid coevolution to the establishment of natural enemies in new regions for biological control. Vertical polyacrylamide electrophoresis was used to survey 16 enzymes and ten calcium binding proteins, and this paper reports variation at three putative loci. Malate dehydrogenase, a dihydrolipoamide dehydrogenase isozyme and a calcium binding protein exhibited clear genetic variation, each with two alleles. All M. hyperodae isofemale lines from east of the Andes mountains shared one genotype, all but one from west of the Andes shared another, while a population from within the Andes contained both genotypes. This variation was highly congruent with previously described morphometric variation. At two loci, the maintenance of heterozygotes, and the absence of homozygotes, within isofemale lines suggested M. hyperodae thelytoky is apomictic.

Cereal aphids are important pests of wheat, Triticum aestivum L. and Triticum durum Desf. Crop resistance is a desirable method for managing cereal aphids in central North America, where the dominant crop, spring-sown wheat, has a low value per unit area. A diploid ancestor of wheat, Triticum monococcum L., is reported to be partially resistant to Sitobion avenae (Fabricius), the most damaging cereal aphid in the region. To identify potential sources of resistance, 42 accessions of T. monococcum and three cultivated wheats were infested with aphids, seedlings for six days and adult plants for 21 days. Overall resistance was estimated by the biomass loss of foliage and spikes in relation to uninfested control plants. Antibiosis was estimated by the gain in biomass of aphids during infestation, and tolerance was estimated as a biomass conversion ratio, overall resistance divided by antibiosis. A few T. monococcum accessions exhibited partial resistance. No relationship was found between seedling and adult plant resistance: the former exhibited primarily antibiosis and the latter primarily tolerance. Two accessions with antibiosis reduced aphid biomass by 60% compared with commercial wheats. Tolerance was correlated with growth potential, and was useful only in accessions with high growth potential. Four accessions exhibited tolerance levels at least 30% greater than commercial wheats. Highly susceptible accessions also were identified, which would be useful for investigating the inheritance of antibiosis and tolerance.

The close association of Anopheles gambiae Giles with humans and its females’ ability to live on human blood alone suggest that females may ignore sources of sugar in favour of human blood as a source of energy. They have limited energy reserves at emergence, and at 27°C both sexes generally die if they do not feed during night 1, 24–36 h after emergence. Food preferences during this critical period were tested by measuring responses to volatiles from honey and soiled socks, which served as surrogates for nectar-related and human-related volatiles in a wind-tunnel olfactometer. Both sexes responded more strongly to honey than to human volatiles, and given a choice, preferred honey over human volatiles. After 5 days of sugar access and maturation, males continued to prefer honey volatiles, whereas females changed behaviour, responding almost exclusively to human volatiles. Night 1 experiments also demonstrated that: (i) females previously having had sugar during the night of emergence responded more strongly to human volatiles; (ii) large-bodied mosquitoes of both sexes responded more strongly to honey than small-bodied ones; and (iii) females were equally responsive to honey in both early and late scotophase but were slightly more responsive to human volatiles in late scotophase. These results indicate that for a female’s first meal, sugar is a viable option and is preferred when nectar-related stimuli are strong. This supports field evidence that sugar-feeding is a significant component of A. gambiae female behaviour.

This study investigated the ability of neonatal larvae of the root-feeding weevil, Sitona lepidus Gyllenhal, to locate white clover Trifolium repens L. (Fabaceae) roots growing in soil and to distinguish them from the roots of other species of clover and a co-occurring grass species. Choice experiments used a combination of invasive techniques and the novel technique of high resolution X-ray microtomography to non-invasively track larval movement in the soil towards plant roots. Burrowing distances towards roots of different plant species were also examined. Newly hatched S. lepidus recognized T. repens roots and moved preferentially towards them when given a choice of roots of subterranean clover, Trifolium subterraneum L. (Fabaceae), strawberry clover Trifolium fragiferum L. (Fabaceae), or perennial ryegrass Lolium perenneL. (Poaceae). Larvae recognized T. repens roots, whether released in groups of five or singly, when released 25 mm (meso-scale recognition) or 60 mm (macro-scale recognition) away from plant roots. There was no statistically significant difference in movement rates of larvae.

In small-scale experiments, the predatory mites, Hypoaspis aculeifer (Canestrini) and H. miles Berlese, applied at 700 mites m−2, and the entomopathogenic nematode, Steinernema feltiae (Filipjev) applied at 3 × 10−6 nematodes m−2 controlled sciarids and phorids in mushroom compost and casing substrates. For both mite species, earliest application to the growing substrate following sciarid infestation reduced sciarid emergence. In contrast, later application of each biological control agent provided more effective control of phorid emergence. The behaviour of adult mites suggested that H. aculeifer were more positively geotactic than H. miles although both species could penetrate compost and casing substrates to a depth of 2–12 cm. A majority of S. feltiae nematodes resided at a depth of 2–4 cm in both substrate types. Independent application of H. aculeifer provided more comprehensive control of sciarids and phorids than the other biological agents studied, owing to its better dispersal within compost and casing, and ability to attack larvae of differing ages.

It is well known that amongst the sibling species of the Anopheles gambiae complex, A. arabiensis Patton predominates over A. gambiae sensu stricto Giles in hotter, drier parts of Africa. Here it was investigated whether A. arabiensis is better adapted to higher temperatures than A. gambiae s.s. at the microclimatic level. Bioassays were used to assess behavioural avoidance activity of adult mosquitoes in the presence of increasing temperature. Female mosquitoes were introduced into a holding tube from which they could escape into a cage through a one-way funnel. From a starting temperature of 28°C they were exposed to a 2°C rise in temperature every 30 min until all mosquitoes had escaped or been knocked down. As temperature increased, A. arabiensis left the holding tube at higher temperatures than A. gambiae s.s. (A. arabiensis mean activation temperature = 35.7°C, 95% CIs = 35.4–36.1°C; A. gambiae s.s. = 33.0°C, 32.5–33.5°C). To determine the relative ability of both species to survive at extremely high temperatures, batches of insects were exposed to 40°C for different periods. It took considerably longer to kill 50% of A. arabiensis at 40°C than it did A. gambiae s.s. (112 min vs. 67 min). These data show that adult A. arabiensis are better adapted to hotter conditions than A. gambiae s.s., a characteristic that is reflected in their spatial and temporal distribution in Africa.

Mosquitoes of the Anopheles maculipennis group were collected in five districts of Romania (Constanta, Giurgiu, Ilfov, Mehedinti and Suceava) between March 2000 and June 2003. Two hundred and ninety-seven specimens were identified by molecular methods. Nuclear rDNA ITS2 sequences of 178 specimens were compared with GenBank sequences for nine known Palaearctic species of the group, and 119 specimens were identified using an ITS2 PCR–RFLP assay developed during the study. Five genetically distinct species of the group were identified: A. atroparvus van Thiel, A. maculipennis Meigen, A. melanoon Hackett and A. messeae Falleroni and a previously unrecognized species. The new species, herein formally described and named A. daciaesp. n., was collected in the Black Sea coastal region and plains adjacent to the Danube River in southern Romania. Anopheles daciae is most similar to and sympatric with A. messeae. It is contrasted with A. messeae and characterized on the basis of unique nuclear ITS2 and mitochondrial COI DNA sequences and morphological characters of the eggs. The larval, pupal and adults stages of the two species were also compared, but no reliable characters were found to distinguish them. It seems likely that A. daciae is more widespread in eastern Europe and the Balkan States, and could be responsible for malaria transmission in these regions that is currently attributed to A. messeae. Anopheles melanoon is reported from Romania for the first time.

Field studies suggest that the generalist carabid predator and scavenger Pterostichus melanarius Illiger aggregates to patches with a higher density of slug prey. The mechanisms behind such aggregation are unknown. Experiments were conducted to test the hypothesis that they are responding to chemical cues. Electroantennograms (EAGs) showed no response by P. melanarius antennae to live, nematode-infected, injured or freshly killed slugs, but a strong response to dead slugs that had been allowed to decay for up to 48 h. Such a response would enable the beetles to find carrion in the field and may also, as dead prey are likely to be spatially correlated with live ones, provide a mechanism by which P. melanarius finds patches with a higher density of live slugs. Subsequent video analyses of P. melanarius responses to patches of slug mucus within arenas showed that beetles with intact antennae could detect these patches because they spent more time, and moved greater distances, within them and increased their rate of turning. Thus, at close range, P. melanarius used their antennae to detect slug mucus and hence, by implication, live slugs. The apparent contradiction between EAG data and behavioural experiments is discussed. Together these result confirm that P. melanariusdoes respond to chemical cues from its slug prey in ways that could lead to aggregation in areas of higher slug density in the field.

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.

The effects of a neurohormone, [His7]-corazonin, on phase-related morphological traits (F/C and E/F ratios; F = length of the hind femur, C = maximum width of the head; E = length of fore wing) were re-examined in the desert locust, Schistocerca gregaria Forskål. The F/C ratio was significantly different between adults with five and six nymphal instars, respectively, indicating that they need to be analysed separately. Injections of the synthesized peptide (1 nmol) into individually-reared (solitary) nymphs at the second and third instars caused a shift in classical morphometric ratio towards the value typical for crowded (gregarious) individuals in both sexes. The E/F ratio, which is smaller in solitary locusts than in gregarious ones, was also influenced significantly by injections of [His7]-corazonin into individually-reared locusts. The effect of [His7]-corazonin on E/F ratios was shown more clearly when the nymphs were injected at a higher dose (2 nmol) at the beginning of the third instar. Single injections of the peptide into individually-reared nymphs at different instars revealed that the earlier the injection the larger the ‘gregarizing’ effects of the peptide on F/C and E/F ratios. The same tendency was also detected in Locusta migratoria Linnaeus. These results supported the hypothesis that [His7]-corazonin plays an important role in the control of phase polymorphism in locusts.

Gene flow based on the spatial distribution of rare alleles at 25 gene loci was estimated in 15 populations of Ceratitis capitata (Wiedemann) from different parts of the world. Estimates of Nm, the number of migrants exchanged per generation among populations in different regions of the world, appeared to be quite similar, ranging from 3.36 in tropical Africa to 2.94 in the New World and 2.72 in Mediterranean basin populations. This suggests that gene flow among neighbouring populations of medfly is quite extensive. The genetic differentiation in American, Mediterranean and African populations was related to major climatic differences between North and South. These differences arise mainly from five loci that showed gene frequency patterns suggestive of latitudinal clines in allele frequencies. The clinal variation was such that tropical-subtropical populations were more heterozygous than temperate populations. It was concluded that gene flow, counteracting the forces of natural selection and genetic drift, determines the extent to which geographical populations of C. capitata are differentiated.

The efficiency of modified CDC miniature light-traps for sampling adult mosquitoes was evaluated in comparison with indoor resting, outdoor resting, indoor man-landing and outdoor man-landing collections in the hilly district of Koraput, Orissa, India. Overall, light-traps captured 78% of adult mosquitoes collected by all methods. Of the 16 anopheline species recorded in the study area, light-traps effectively sampled 13, contributing about 72% of the total anophelines collected by all methods. Light-traps also caught a large number of female Culex vishnui Theobald (96%). As fully-fed mosquitoes were predominant (82%) and caught alive, light-traps can be used to catch large numbers of vector mosquitoes for studies on vector prevalence, distribution, vector incrimination and also for laboratory bioassays. Light-trap and indoor resting collections revealed similar seasonal trends in numbers of Anopheles culicifacies Giles, A. fluviatilis James, A. jeyporiensis James, A. vagus Doenitz, and A. splendidus Koidzumi. Age-structure of the samples did not vary significantly between the two methods. Light-traps could be used as an alternative to daytime indoor resting collections to monitor the seasonal fluctuations in the abundance and parity rates of these species. The light-trap collections correlated with indoor and outdoor man-landing collections of A. jeyporiensis and the outdoor man-landing collections of A. maculatusTheobald in measuring seasonal trends. Light-trap collections can thus be used as a substitute for man-landing collections of A. jeyporiensis and A. maculatus.

Twenty one species of ticks belonging to five genera of the family Ixodidae (Order Acari, sub-order Ixodida) – Amblyomma, Haemaphysalis, Hyalomma, Ixodes and Rhipicephalus (including the sub-genus Rhipicephalus (Boophilus)) – were collected from 1260 mammals, representing 29 species, 14 families and 6 orders, in four vegetation zones in Ghana during the period 1971–1978. Four other species were collected from humans in 1977. In all, eight species appeared to be new records for Ghana: Amblyomma tholloni Neumann; Dermacentor circumguttatus Neumann; Haemaphysalis houyi Nuttall & Warburton; Ixodes loveridgei Arthur; Ixodes oldi Nuttall; Ixodes vanidicus Schultze; Rhipicephalus complanatus Neumann; Rhipicephalus cuspidatus Neumann. The updated list of tick species in Ghana given here includes 41 species of ixodid ticks and four species of argasid ticks. Most species have been found in neighbouring regions of West Africa but 56 of the 121 different combinations of ixodid tick species and host species found in the collection described here have not apparently been reported before. The new combinations recorded here bring the total number of different combinations of ixodid tick species and mammalian host species now reported in Ghana to 151. The tick species found on wild mammals in Ghana mostly differed from those reported from domestic stock by other authors. The data showed that different tick species occurred in different vegetation zones and that most species displayed a pronounced preference for certain groups of related host species. Some tick species were found in the savanna feeding mainly on large bovids and/or suids; others were found in forests feeding mainly on small bovids, large rodents or small carnivores.

Sentinel cattle and a grid of swormlure-baited sticky traps were used to monitor a Malaysian population of the Old World screw-worm fly, Chrysomya bezziana Villeneuve. Observations were carried out on an isolated cattle station at monthly intervals during the period August 1996 to June 2000. The number of flies caught was unaffected by weather conditions at the time of trapping, but was positively correlated with the total rainfall and the average daily air temperature prevailing 15–28 days earlier, when trapped flies were still juveniles. Trap catches were biased in favour of females, but daily catch rates of both sexes increased significantly the longer traps were open, suggesting that efficacy was related to the differential volatility of the chemicals comprising swormlure. Oviposition on sentinel cattle occurred mostly in late afternoon or early evening but increased significantly as the wound aged. Oviposition rates were positively correlated with female catch rates, but the relationship was curvilinear, suggesting that fly populations may be subject to some form of density-dependent constraint. Consistent differences in oviposition rates on sentinel cattle at different localities on the cattle station suggested the existence of highly clumped, quasi-stationary populations. Differences in trap catches between traps located in pastoral areas and those sited in nearby oil palm or rubber plantations supported this interpretation of the data. These findings are discussed in relation to the use of the sterile insect technique for the control of screw-worm fly infestations.