The juvenile hormone mimic, pyriproxyfen, applied topically to female tsetse flies, Glossina morsitans morsitans Westwood and G. pallidipes Austen, effectively sterilizes them by arresting development of their offspring in the pupal stage. Between July and November 1989, 41 odour baited traps treated with pyriproxyfen were deployed near Rekomitjie Research Station, Zambezi Valley, Zimbabwe, in a 12.3 km2 block of woodland habitat of G. m. morsitans and G. pallidipes. Tsetse entering the traps brushed against material dosed with 2 mg/cm2 pyriproxyfen and were then allowed to escape. Emergence rates from pupae of the two species collected in the block fell to 30% and 2.7%, respectively, of control levels after three months. Of more than 750 pupae of each species dissected 78% and 94%, respectively, showed incomplete development. The average ovarian age category of female G. pallidipes sampled in the block doubled during the trial. This was due to immigration of older flies and the declining birth rate which, if sustained over a large area for a year, was estimated as sufficient to cause a population reduction to 10−6 of its original level.

The diamond-back moth, Plutella maculipennis, and Crocidolomia binotalis are the main pests of cabbage in Indonesia. Until 1951, good control was obtained with DDT sprays and dusts, but in that year growers near Lembang (Bandung) obtained poor results with DDT against P. maculipennis as compared with previous years. Investigations were started in Lembang, and also in Patjet (on Mt. Gedeh) where no difficulties had arisen. In laboratory experiments, a marked difference in susceptibility to DDT between a Lembang and a Patjet strain of P. maculipennis was demonstrated.

In field tests near Patjet with DDT, BHC and toxaphene, DDT gave satisfactory control and was better than the other two. At Lembang, however, where these three materials were again tested, but with derris and pyrethrum also, toxaphene was the most effective, followed by derris and BHC, while DDT, and also pyrethrum, gave almost no control.

For the time being, toxaphene and derris are recommended, the former during the growing season and the latter subsequently, but it is feared that resistance to toxaphene will develop. It may become necessary to resort to cultural and biological measures.

Data from dung-baited pitfall traps show that dung beetles (Coleoptera: Scarabaeidae) do not discriminate against dung from sheep or cattle treated with avermectin. On the contrary, for a period post-treatment, dung from animals treated with avermectin attracted more beetles than dung from untreated animals. This effect was more marked with cattle dung than with sheep dung. The period of enhanced attractiveness of sheep dung was restricted to dung produced during the first day after treatment, whereas with cattle dung, the effect was still evident in faeces produced 25 days after treatment. Cattle dung produced from 3–25 days post-treatment caused 100% mortality in newly hatched larvae of the bushfly, Musca vetustissima Walker (Diptera:Muscidae). In dung of day 35, mortality was 93.6%. Dung collected from sheep from 1–6 days after treatment also caused 100% mortality of fly larvae, but by day 28, no toxic effects were detectable. Field observations on the colonization of cattle pats confirmed the enhanced attractiveness of dung from treated animals and suggested that departure rates from treated dung were lower than those from untreated dung. Treated pats supported higher beetle populations than untreated pats and burial was more rapid. The potentially serious implications of the enhanced attractiveness of avermectincontaminated dung are discussed in relation to the survival of dung beetle communities.

Insects have evolved a variety of physiological and behavioral responses to various toxins in natural and managed ecosystems. However, insect behavior is seldom considered in insecticide studies although insects are capable of changing their behavior in response to their sensory perception of insecticides, which may compromise insecticide efficacy. This is particularly serious for insect pests that are physiologically resistant to insecticides since insecticide avoidance may further compromise their management. Locomotion plays a major role determining insecticide exposure and was, therefore, considered in investigating the behavioral responses of male and female adult insects from an insecticide-susceptible and two insecticide-resistant strains of the maize weevil Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae), a major pest of stored cereals. Different dose-dependent behavioral responses were expected among strains with behavioral resistance less likely to occur in physiologically resistant insects since they are able to withstand higher doses of insecticide. The behavioral responses to deltamethrin-sprayed surfaces differed among the maize weevil strains. Such responses were concentration-independent for all of the strains. Stimulus-independent behavioral resistance was unrelated to physiological resistance with one resistant strain exhibiting higher rates of flight take-off and the other resistant strain exhibiting lower flight take-off. Female mobility was similar for all strains, unlike male mobility. Males of each strain exhibited a pattern of mobility following the same trend of flight take-off. Behavioral patterns of response to insecticide are, therefore, variable among strains, particularly among insecticide-resistant strains, and worth considering in resistance surveys and management programs.

The effect of photoperiod and temperature on the production of the various forms of Acyrthosiphon pisum (Harris) has been studied. In this study apterous virginoparous females were exposed throughout their lifetime to two photoperiods (8 hr./24 hr. and 16 hr./24 hr.) and six different temperatures. At each of the temperatures the apterae (parent Aphids) received one of four treatments of photoperiod, i.e., (1) 8 hr./24 hr. photoperiod throughout their whole life; (2) 8 hr. /24 hr. photoperiod during the period from birth until the last (imaginal) moult (nymphal period), followed by 16 hr./24 hr. photoperiod from the last (imaginal) moult until death (the adult period); (3) 16 hr./24 hr. throughout life; (4) 16 hr./24 hr. during the nymphal period followed by 8 hr./24 hr. during the adult period. The offspring produced by the various parents were collected at successive intervals, and their form determined.

Four main forms of offspring were produced: apterous and alate virginoparae, males and oviparae. In addition, a subsidiary form of the apterous virginoparae was obtained, which had sensoria on the hind tibiae.

The factors that set broad-scale limits on the species ranges of ticks have not been clearly defined, despite their potential importance for the study and control of ticks. A database of 33,989 published collection records for African ticks is used to test the hypothesis that the outer limits to tick species ranges are determined by the distributions of their hosts. Distribution maps for many of the more economically important tick species are given. Direct comparisons of the known ranges of ticks and their hosts show that the hypothesis of a host-determined species range is supported for only one tick species, Amblyomma rhinocerotis (de Geer), which has been constrained by the near-eradication of its rhinoceros hosts. At least 97 other species are not host-limited; the quality of available host-use and distribution information is insufficient to draw strong conclusions about the (approximately) 132 remaining species. In general, the boundaries to tick species ranges are more likely to be set by factors such as vegetation and climate.

An investigation of insect parasitoids of the diamondback moth, Plutella xylostella(Linnaeus), in brassica vegetable crops in the suburbs of Hangzhou was conducted during five periods from 1989 to 1997. Eight species of primary parasitoids were recorded: Trichogramma chilonis Ishii, Cotesia plutellae Kurdjumov, Microplitis sp., Oomyzus sokolowskii Kurdjumov, Diadromus collaris(Gravenhorst), Itoplectis naranyae (Ashmead), Exochus sp. and Brachymeria excarinata Gahan. Seven species of hyperparasitoids were also collected. Rates of parasitism of eggs of P. xylostella were usually very low. However, rates of parasitism of larvae and pupae were substantial and showed two peaks each year, around June–July and September–November respectively. Rates of parasitism during peaks were usually 10–60% and reached over 80% on a few occasions. Cotesia plutellae, O. sokolowskii and D. collaris were the major larval, larval-pupal and pupal parasitoids respectively. In the field, C. plutellae was active throughout the year. Oomyzus sokolowskii was active from May to October, entered a quiescent pupal stage in October–November to overwinter and did not emerge until next April–May. Diadromus collariswas recorded from April to July and October. Rates of parasitism of P. xylostellain radish and mustard fields were usually higher than those in cabbage and Chinese cabbage fields in the same locality. Negative correlations of parasitism rates between C. plutellae and O. sokolowskii indicate a competitive relationship for host larvae between these two larval parasitoids.

Seed predation is an important component of seed mortality of weeds in agro-ecosystems, but the agronomic use and management of this natural weed suppression is hampered by a lack of insight in the underlying ecological processes. In this paper, we investigate whether and how spatial and temporal variation in activity-density of granivorous ground beetles (Coleoptera: Carabidae) results in a corresponding pattern of seed predation. Activity-density of carabids was measured by using pitfall traps in two organic winter wheat fields from March to July 2004. Predation of seeds (Capsella bursa-pastoris, Lamium amplexicaule, Poa annua and Stellaria media) was assessed using seed cards at the same sites and times. As measured by pitfall traps, carabids were the dominant group of insects that had access to the seed cards. In the field, predation of the four different species of seed was in the order: C. bursa-pastoris>P. annua>S. media>L. amplexicaule; and this order of preference was confirmed in the laboratory using the dominant species of carabid. On average, seed predation was higher in the field interior compared to the edge, whereas catches of carabids were highest near the edge. Weeks with elevated seed predation did not concur with high activity-density of carabids. Thus, patterns of spatial and temporal variation in seed predation were not matched by similar patterns in the abundance of granivorous carabid beetles. The lack of correspondence is ascribed to effects of confounding factors, such as weather, the background density of seeds, the composition of the carabid community, and the phenology and physiological state of the beetles. Our results show that differences in seed loss among weed species may be predicted from laboratory trials on preference. However, predator activity-density, as measured in pitfall traps, is an insufficient predictor of seed predation over time and space within a field.

Methodology for detailed dissections of the phylogenetically most informative structures from adult aleocharine staphylinid beetles is provided. These methods include specimen preparation, relaxation, clearing, bleaching, dehydration and full dissection. A detailed summary of mouthpart and male and female genitalic dissections is provided. Recently described character systems, including those of the mouthparts and the thoracic regions, have been successfully used in phylogenetic studies of aleocharine staphylinids. This paper provides the first thorough description of the techniques necessary to reveal these character systems.

Samples of Aedes aegypti (L.) larvae were collected in domestic, peridomestic and feral habitats in the Rabai area, Kenya, and reared in the laboratory. Newly emerged mosquitoes, 2000 from each habitat, were marked with fluorescent pigments and released in a peridomestic habitat in Shauri Moyo village. Of the 407 mosquitoes recaptured in landing-biting collections on man inside houses, 83% were domestic, 15·5% were peridomestic and 1·5% were feral. These various recapture rates indicate the existence of three behaviourally distinct populations of A. aegypti: domestic, peridomestic and feral; they also indicate that the mosquitoes' ability to enter houses is a genetically controlled behavioural trait.

The migratory flight behaviour of Nilaparvata lugens (Stål), other delphacid and cicadellid pests of rice and some of their heteropteran predators was investigated during the dry-season crop in an irrigated rice-growing area of the Philippines. A combination of radar (including an X-band and a newly-developed Q-band system (8 mm wavelength)), aerial netting, ground trapping and visual observations was used to determine diel changes in aerial density and composition of arthropods in flight over the study site. The most abundant migrant caught in the aerial nets was Cyrtorhinus lividipennis Reuter (a mirid predator of N. lugens), with Nephotettix spp. and Nilaparvata lugens the next most abundant species. Flight activity in all migrants was found to be very largely confined to periods of about 30 min at dusk and dawn, with minimal activity at other times of the day and night. Migration distance in the dusk flight was generally limited to 6–30 km, depending on wind speed, and the dawn migration covered shorter distances due to the lighter winds. Small numbers of rice cicadellids and delphacids including N. lugens were occasionally detected later in the night, and these may have had the potential to migrate longer distances.

Lactic acid, carbon dioxide and human sweat stimuli were presented singly and in combination to female Aedes aegypti (Linnaeus) within a wind-tunnel system. The take-off, flight, landing and probing responses of the mosquitoes were recorded using direct observation and video techniques. The analyses determined the nature of the response to different stimuli and the concentration ranges within which specific behaviours occurred. A threshold carbon dioxide concentration for taking-off of approximately 0.03% above ambient was detected. Lactic acid and human sweat samples did not elicit take-off when presented alone, however, when they were combined with elevated carbon dioxide, take-off rate was enhanced in most of the combinations tested. Flight activity was positively correlated with carbon dioxide level and some evidence for synergism with lactic acid was found within a narrow window of blend concentrations. The factors eliciting landing were more subtle. There was a positive correlation between landing rate and carbon dioxide concentration. At the lowest carbon dioxide concentration tested, landing occurred only in the presence of lactic acid. Within a window of low to intermediate concentrations, landing rate was enhanced by this combination. At the highest carbon dioxide concentration, landing was however inhibited by the presence of lactic acid. The sweat extract elicited landings in the absence of elevated carbon dioxide. This indicated the presence of chemical stimuli, other than lactic acid, active in the short range. Probing occurred only at low carbon dioxide concentrations and there was no probing when lactic acid alone was tested. There was however probing in the presence of combined stimuli, the level of response seemed to be positively correlated with the ratio of carbon dioxide and lactic acid concentrations.

Field trials were undertaken in Victoria and New South Wales, Australia, to discover whether synthetic sex pheromone, cis-8-dodecenyl acetate, could be used to control the oriental fruit moth, Cydia molesta (Busck), in peach orchards by the disruption technique. When pheromone was released at rates exceeding 5 mg/ha h from polyethylene capillary tubes males were generally unable to locate synthetic pheromone sources or live virgin females. By maintaining a constant rate of release per unit area it was possible to reduce the number of dispensers from one per 50 m2 to one per 400 m2. There was no significant difference in disruption when pheromone was released from tree crowns at 3·5 m or lower down at 1·5 m. Shoot and fruit damage from trials in commercial orchards suggested that pheromone treatments were as effective as a full seasonal schedule of insecticide applications in reducing damage.

Insect cytochrome P450 monooxygenases (P450s) play an important role in catalysis of many reactions leading to insecticides resistance. Our previous studies on transcriptome analysis of chlorantraniliprole-resistant development in the diamondback moth, Plutella xylostella revealed that up-regulation of cytochrome P450s are one of the main factors leading to the development of chlorantraniliprole resistance. Here, we report for the first time a novel cytochrome P450 gene CYP321E1, which belongs to the cytochrome P450 gene family CYP321. Real-time quantitative PCR (RT–qPCR) analyses indicated that CYP321E1 was expressed at all developmental stages of P. xylostella but was highest in the fourth-instar larvae; furthermore, the relatively high expression was observed in the midgut of the fourth-instar larvae, followed by fat bodies and epidermis. The expression of CYP321E1 in P. xylostella was differentially affected by three representative insecticides, including alphamethrin, abamectin and chlorantraniliprole. Among them, the exposure to chlorantraniliprole resulted in the largest transcript level of this cytochrome P450 gene. The findings suggested potential involvement of CYP321E1 in chlorantraniliprole resistance of P. xylostella. To assess the functional link of CYP321E1 to chlorantraniliprole resistance, RNA interference (RNAi)-mediated gene silencing by double stranded RNA (dsRNA) injecting was used. Results revealed that injection delivery of dsRNA can greatly reduce gene expression after 24 h. As a consequence of RNAi, a significant increment in mortality of larvae injected CYP321E1 dsRNA was observed after 24 h of exposure to chlorantraniliprole. These results strongly support our notion that this novel cytochrome P450 gene plays an important role in chlorantraniliprole detoxification in the diamondback moth and is partly responsible for its resistance.

The aim of this study was to determine which Arabidopsis thaliana (L.) genes had significantly altered expression following 2–36 h of infestation by the aphid Myzus persicae (Sulzer). Six biological replicates were performed for both control and treatment at each time point, allowing rigorous statistical analysis of any changes. Only two genes showed altered expression after 2 h (one up- and one down-regulated) while two were down-regulated and twenty three were up-regulated at 36 h. The transcript annotation allowed classification of the significantly altered genes into a number of classes, including those involved in cell wall modification, carbon metabolism and signalling. Additionally, a number of genes were implicated in oxidative stress and defence against other pathogens. Five genes could not currently be assigned any function. The changes in gene expression are discussed in relation to current models of plant-insect interactions.

1.—Encarsia formosa, Gahan, is a Chalcid wasp that parasitises the white-fly, Trialeurodes vaporariorum, Westw., a single female ovipositing in 50 or more young pupae of the host. The larvae of the parasite, on hatching from the egg, destroys the white-fly pupa, the skin of which becomes black in colour, thus distinguishing the parasitised pupa from the normal white scales and pupa of the white-fly.

2.—The parasite is parthenogenetic, males, probably impotent, only appearing when temperatures are low.

3.—The life-history of the parasite occupies at least 28 days, and adults may remain in the scales for some time before cutting their way out by a circular hole in the roof of the scale. The adult is capable of travelling over large areas in glasshouses.

4.—Low temperatures militate seriously against the increase of the parasite, which is probably a tropical insect and has possibly been imported into this country from India.

5.—Fumigation with hydrocyanic acid gas, as practised commercially for the control of white-fly, does not affect the parasites.

6.—The parasite is best distributed by detaching the black pupae of white-fly from the foliage, though 20 per cent, may be injured in this way. An almost complete emergence is obtained by cutting branches from plants and pinning them to the plants in houses where distribution is desired, but this involves risk of infecting the houses with various pests and diseases.

We investigated the resistance potential of a red-coloured Japanese strain (JR) of a tobacco feeding form of Myzus persicae (Sulzer) of the M. persicae species complex closely related to the tobacco aphid Myzus nicotianae Blackman. Bioassays were performed with a range of insecticides, imidacloprid, nicotine and cartap, thought to act on nicotinic acetylcholine receptors in vivo, as well as with two conventional insecticides, pirimicarb and oxydemeton-methyl, acting on acetylchol-inesterase (AChE). Compared to a susceptible strain, JR showed high resistance to pirimicarb and oxydemeton-methyl, but was far less resistant to nicotine, cartap and imidacloprid. Imidacloprid was, among the insecticides tested, the most active compound in contact and ingestion bioassays. Compared to the susceptible strain, JR showed four-to seven-fold resistance to imidacloprid depending on the type of bioassay. Resistance factors for other insecticides tested in an oral ingestion bioassay were: cartap five-fold, nicotine nine-fold, oxydemeton-methyl 107-fold and pirimicarb > 385-fold. JR showed high carboxylesterase activity. Polyacrylamide gel electrophoresis indicated esterase FE4 as the major carboxylesterase. As for most M. persicae strains and some Greek strains of M. nicotianae, JR was monomorphic for glutamate oxalacetate transaminase. Studies with pirimicarb showed a marked insensitivity of AChE to inhibition by this chemical, whilst such insensitivity could not be detected with the organophosphate insecticide oxydemeton-methyl. Receptor binding assays with [3H]-imidacloprid in aphid homogenates revealed I50-values of 0.4 to 0.8 nM and no statistical difference between the JR and susceptible strain.

The diversity of macromoths in the various fast-growing exotic tree plantations and natural secondary forest in Brumas, Sabah, Malaysia was assessed by means of an annual cycle of light-trap samples. The moth diversity in the forest plantations, viz. Acacia mangium, Gmelina arborea, Paraserianthes (=Albizia) falcataria, Pinus caribaea, and in particular Eucalyptus deglupta, was unexpectedly high. Eucalyptus deglupta showed moth diversity as high as that in the natural secondary forest, a finding attributed to the fact that the E. deglupta plantation had a very diverse understorey both in terms of plant species (secondary regrowth species) and architecture, and thus supported a more diverse moth fauna. Subsidiary samples showed that primary natural forest in the neighbouring Danum Valley does not show higher moth diversity compared to the disturbed forest habitats in Brumas, though moth diversity at Danum is lower than that recorded in other Bornean primary forests. The value of plantation forests for conservation of invertebrate diversity is discussed, together with the implications for plantation management strategy.