The continuous automatic monitoring of the aerial density, biomass and relative diversity of high-flying insect faunas has been made practicable by a new, vertical-looking radar. This inexpensive radar system, with its novel signal analysis capability, represents a major advance over earlier vertical-beam radars because it provides estimates of the body mass of individual overflying insects, as well as measurements of their direction and speed of movement. This paper summarizes data collected over a three-month period by the new radar in the height range from 150 m to c.1 km, over agricultural land in Worcestershire, England. The day-to-day variation in the numbers of insects and their altitudinal and diurnal patterns of flight activity are presented. Examples are also given of distributions of mass, displacement speed and direction, and orientation direction. The potential of the new radar for various research and operational monitoring tasks is briefly discussed.

The olive fruit fly, Bactrocera oleae (Rossi), is a newly invasive, significant threat to California's olive industry. As part of a classical biological control programme, Psyttalia ponerophaga (Silvestri) was imported to California from Pakistan and evaluated in quarantine. Biological parameters that would improve rearing and field-release protocols and permit comparisons to other olive fruit fly biological control agents were measured. Potential barriers to the successful establishment of P. ponerophaga, including the geographic origins of parasitoid and pest populations and constraints imposed by fruit size, were also evaluated as part of this investigation. Under insectary conditions, all larval stages except neonates were acceptable hosts. Provided a choice of host ages, the parasitoids' host-searching and oviposition preferences were a positive function of host age, with most offspring reared from hosts attacked as third instars. Immature developmental time was a negative function of tested temperatures, ranging from 25.5 to 12.4 days at 22 and 30°C, respectively. Evaluation of adult longevity, at constant temperatures ranging from 15 to 34°C, showed that P. ponerophaga had a broad tolerance of temperature, living from 3 to 34 days at 34 and 15°C, respectively. Lifetime fecundity was 18.7±2.8 adult offspring per female, with most eggs deposited within 12 days after adult eclosion. Olive size affected parasitoid performance, with lower parasitism levels on hosts feeding in larger olives. The implications of these findings are discussed with respect to field manipulation and selection of parasitoid species for olive fruit fly biological control in California and worldwide.

The importance of colour in the attraction of Glossina palpalis palpalis (Robineau-Desvoidy) to trapping devices was investigated in the Ivory Coast. Biconical traps were tested with the normally royal blue lower cone replaced with one of 25 differently coloured cloths. Royal blues were consistently the best colours for traps; yellow and orange were the worst, catching less than 1% as many as the best royal blue. Modelling trap data from the spectral reflectivities of the colours used showed that blue wavelengths contributed positively, and ultraviolet and green-yellow-red negatively, to trap performance. The responses to screens were studied using electric nets, deployed to catch flies both circling around and landing on the screen. The overall catch (of circling and landing flies) was greatest for royal blue screens, intermediate for yellow and green ones, and lowest for screens highly reflective of ultraviolet light; the total range of variation between colours was much smaller than was the case with traps. The relationship of catch to spectral reflectivity was similar to that described for trap score. An achromatic series of screens (black, white and greys) all attracted significantly fewer females than did royal blue screens, implying that attraction to blue depends on colour discrimination and not on intensity contrasts alone. For most colours, the majority of flies circled the screen without landing; with materials strongly reflecting ultraviolet, however, a high proportion of flies (especially females) landed.

DNA-based techniques have proved to be very useful methods to study trophic relationships between pests and their natural enemies. However, most predators are best defined as omnivores, and the identification of plant-specific DNA should also allow the identification of the plant species the predators have been feeding on. In this study, a PCR approach based on the development of specific primers was developed as a self-marking technique to detect plant DNA within the gut of one heteropteran omnivorous predator (Macrolophus pygmaeus) and two lepidopteran pest species (Helicoverpa armigera and Tuta absoluta). Specific tomato primers were designed from the ITS 1–2 region, which allowed the amplification of a tomato DNA fragment of 332 bp within the three insect species tested in all cases (100% of detection at t=0) and did not detect DNA of other plants nor of the starved insects. Plant DNA half-lives at 25°C ranged from 5.8 h, to 27.7 h and 28.7 h within M. pygmaeus, H. armigera and T. absoluta, respectively. Tomato DNA detection within field-collected M. pygmaeus suggests dietary mixing in this omnivorous predator and showed a higher detection of tomato DNA in females and nymphs than males. This study provides a useful tool to detect and to identify plant food sources of arthropods and to evaluate crop colonization from surrounding vegetation in conservation biological control programs.

Aphids belonging to the species Nasonovia ribis-nigri (Mosley), Aulacorthum circumflexum (Buckt.), Macrosiphum euphorbiae (Thos.), Myzus persicae (Sulz.) and A. solani (Kalt.) were exposed to attack by the parasite, Monoctonus paludum Marshall, and were sectioned and dissected at various time-intervals after attack in order to observe the developmental processes of the parasite.

The egg was always laid in the posterior mass of fused ventral nerve ganglia in the thorax of the aphid host.

The development of the parasite in N. ribis-nigri, its normal host on lettuce, is described.

In the species A. circumflexum the development of the parasite was arrested after approximately 24 hours by the secretion around it of a thin brown capsule formed by certain of the host's blood cells.

In the other three species, Macrosiphum euphorbiae, Myzus persicae and A. solani, no capsule formation occurred. The development of the parasite embryos was rather variable in these but it was common for parasites in Macrosiphum euphorbiae to reach the stage normal for 24-hour embryos and for parasites in Myzus persicae and A. solani to reach stages rather less advanced than this before degenerative changes set in.

The degenerative changes in the parasite embryos are described for each species of aphid and the nature of these changes is discussed.

Sizes of young field-collected males of Glossina morsitans morsitans Westw. were compared with those of teneral males emerging in the laboratory from field-collected puparia. Based on the mean size, indications were that smaller flies in field populations were selected against for about seven months in the year. A method is described for estimating the proportion of flies lost in the field population, and for the calculation of standard deviations for the estimates. Estimates of the extent of elimination showed that up to 35·2% of the total fly population in the field was eliminated in the cool months and up to 75·5% in the hot dry months.

The aim of this study was to evaluate the effects of silicon application and administration of the phytohormone gibberellic acid on resistance of the corn plants to the fall armyworm (FAW), Spodoptera frugiperda, and their vegetative characteristics. We evaluated larval and pupal duration, survival and biomass, and adult longevity, malformation and fecundity of S. frugiperda after feeding on plant matter treated with silicon and/or gibberellic acid. The feeding preference of FAW first-instar larvae, the total leaf area consumed by the insects, and the vegetative parameters of corn plants were also evaluated. No significant differences were observed in the measured parameters of larval and pupal stages of S. frugiperda in response to silicon or gibberellic acid. In adult stage insects, the number of eggs per female was significantly reduced in insects derived from larvae fed plants treated with silicon or gibberellic acid. In a non-preference test, 48 h after release, caterpillars preferred control untreated plants and consumed less matter from plants that had received hormonal treatment (gibberellic acid). Gibberellic acid also altered the vegetative characteristics of plants, by increasing their height, shoot fresh and dry mass, and silicon content. We conclude that gibberellic acid can alter the vegetative characteristics and silicon uptake of corn plants, leading to a reduction in their consumption by S. frugiperda larvae and a decrease in female insect oviposition.

The influence of food sources comprising the natural diet on the reproductive behaviour, fecundity and longevity of three African fruit flies Ceratitis cosyra (Walker), C. fasciventris (Bezzi) and C. capitata (Wiedemann) was investigated. Three natural food sources, varying in protein and sugar content, were evaluated. These included bird droppings (farm chicken), aphid honeydew and guava (Psidium guajava L.) juice. For C. fasciventris and C. capitata, flies fed on a protein-rich diet displayed higher frequency of calling, mating and oviposition than flies fed on a protein-poor diet, whilst for C. cosyra, quality of diet significantly influenced the mating behaviour of the flies, but not the calling and oviposition behaviour. Net fecundity rates were lowest for C. fasciventris and C. capitata when fed only on guava juice (0.1, 2.6 eggs per female, respectively), and higher for those on a diet of honeydew only (9.5, 33.8 eggs per female, respectively) and a combined diet of guava, honeydew and chicken faeces (11.8, 25.8 eggs per female, respectively). For C. cosyra, due to low numbers of eggs collected, no significant differences in fecundity between diets could be detected. All species fed only on a diet of chicken faeces since emergence died within the first three days of adult life without laying eggs, but when carbohydrates were provided by addition of guava juice and honeydew, the longevity of the flies was sustained for more than four weeks after adult emergence. The practical implications of these findings for control purposes are discussed.

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.

The oriental army worm Mythimna separata (Lepidoptera: Noctuidae) is a migratory pest in Eastern Asia and China. Seasonal high temperatures in Southern China and low temperatures in Northern China are pressures favouring the annual migration of this species, while cold tolerance determines the northern limit of its overwintering range. A number of physiological stress responses occur in insects as a result of variations in temperature. One reaction to thermal stress is the generation of reactive oxygen species (ROS), which can be harmful by causing oxidative damage. The time-related effects (durations of 1, 4 and 7 h) of thermal stress treatments of M. separata at comparatively low (5, 10, 15 and 20°C) and high (30, 35, 40 and 45°C) temperatures on the activities of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), peroxidase (POX) and glutathione S-transferases (GSTs), and total antioxidant capacity (T-AOC) were determined. Thermal stress resulted in significant elevation of the activities of SOD, CAT and GSTs, indicating that these enzymes contribute to defence mechanisms counteracting oxidative damage caused by an increase in ROS. However, at high-temperatures, POX and T-AOC were also found to contribute to scavenging ROS. Our results also indicate that extreme temperatures lead to elevated ROS production in M. separata. The present study confirms that thermal stress can be responsible for oxidative damage. To overcome such stress, antioxidant enzymes play key roles in diminishing oxidative damage in M. separata.

Growing interest in biodiversity and conservation has increased the demand for accurate and consistent identification of arthropods. Unfortunately, professional taxonomists are already overburdened and underfunded and their numbers are not increasing with significant speed to meet the demand. In an effort to bridge the gap between professional taxonomists and non-specialists by making the results of taxonomic research more accessible, we present a partially automated pattern recognition system utilizing artificial neural networks (ANNs). Various artificial neural networks were trained to identify spider species using only digital images of female genitalia, from which key shape information had been extracted by wavelet transform. Three different sized networks were evaluated based on their ability to discriminate a test set of six species to either the genus or the species level. The species represented three genera of the wolf spiders (Araneae: Lycosidae). The largest network achieved the highest accuracy, identifying specimens to the correct genus 100% of the time and to the correct species an average of 81% of the time. In addition, the networks were most accurate when identifying specimens in a hierarchical system, first to genus and then to species. This test system was surprisingly accurate considering the small size of our training set.

1. Only large game movements produce noticeable effects upon the fly community.

2. The fauna of the hills is not subjected to game concentration.

3. The country included in the N.E. Kikori round is not subjected to large game movements, as is the S.E. round.

4. A concentration of game appears to cause a considerable increase in fly density the surrounding country; when the game have dispersed the density drops.

5. In the small area of country forming the core of the concentration fly appear to be very scarce while the game are present. When the game have left the density greatly increases.

6. The arrival of much game in an area causes an increase in the activity of the females.

The question of the attractancy of water-vapour, carbon dioxide and candidate attractant compounds was investigated by the use of an olfactometer emitting freely into a 360-cu. ft. cage filled with female adult Aëdes aegypti. Moist air (85 per cent. R.H.) was found to attract 3–5 times as many mosquitos as dry air (15 per cent. R.H.). A moistened billiard-ball was found to attract about seven times as many mosquitos as a dry one, the result being similar whether black or white balls were used. The attractancy was reduced and even reversed at very high room humidities.

The addition of 10 per cent. CO2 to a dry air stream approximately doubled its ability to bring mosquitos within 0·5 inches of the olfactometer port. Its addition to a moist air-stream did not significantly increase its attractancy. Pure CO2 vapour proved to be no more attractive than dry air, and several times less attractive than moist air.

A number of chemical compounds found in body exudations, and some housefly attractants, were tested in the olfactometer for their effect on Aëdes adults. None were consistently attractive, and many were significantly repellent. However, sweat itself proved significantly attractive at a low vapour concentration, while significantly repellent at a high concentration.

Cuticular wax was extracted from adult females of Anopheles culicifacies Giles and analysed by gas liquid chromatography. The flies were taken from pure cage stocks of three sibling species: 56 individuals of species A, 43 of species B and 51 of species C. The three cytospecies were found to be significantly different in their cuticular hydrocarbon composition by a multivariate analysis of variance. Using discriminant analysis, each cytospecies was characterized by the amounts of C25-C33 hydrocarbons extracted from the cuticle, allowing criteria to be established for the identification of flies. By these criteria, specimens from stocks of known identity were allocated to the correct group with a high success rate. These results may reflect ecological differences among the sibling species.

The eggs, three larval instars and puparia of Chrysomya bezziana Villeneuve are described and illustrated in detail by scanning electron micrographs. Particular attention is paid to the extent and nature of the median strip in the eggs and the spine bands and spiracular structures in the larvae and puparia.

Eggs and third-instar larvae of five other species of Chrysomya, C. nigripes Aubertin, C. varipes (Macquart), C. rufifacies (Macquart), C. saffranea (Bigot) and C. megacephala (F.), are illustrated, described and compared with C. bezziana and each other by means of keys, which also permit their identification. In addition, notes on the puparia of these species are provided.

Counts of first-instar larvae showed that in a potato plot near Canberra, A.C.T., eggs of Phthorimaea operculella (Zell.) were more prevalent around the bases of plants than between the rows or 2 m outside the plot; the few eggs on the plants were on dead leaves. In small plots each of different plant species, with due allowance for predation, many eggs were laid around tobacco and potato, and few or none near tomato, maize, lettuce or pea. Older larvae were most numerous on tobacco plants, while adults were most numerous on potato plants. A series of laboratory experiments using different oviposition substrates showed that the factors favouring oviposition could be ranked, in descending order: coarse substrate, shade, and treatment of the substrate with juices of potato tubers or foliage; foliage of potato or tobacco was not preferred.

Several series of host-reared specimens of an Encarsia species, initially thought to be the cosmopolitan Encarsia inaron (Walker), were collected in the Azores Islands (Portugal). Subsequent morphometric analysis supported the presence of two species: E. inaron and a new species, described herein as Encarsia estrellae Manzari & Polaszek sp. n.Encarsia estrellae was reared from Aleyrodes singularis Danzig, A. ?singularis, and Bemisia sp. afer-group on several host plants. In addition, the D2 region of the 28S rDNA gene was sequenced in eight individuals belonging to these species, as well as single representatives of two closely related and one distantly related species. Phylogenetic analysis of these DNA sequences, together with 23 additional Encarsia sequences retrieved from the European Molecular Biology Laboratory (EMBL) and GenBank databases, further supported the specific status of E. estrellae, and the placement of E. dichroa (Mercet) in the E. inaron species-group. Additionally, E. inaron is redescribed and some taxonomic problems in the E. inaron species-group are discussed.

The importance, geographical and temporal distributions of parasitoids of lepidopterous borers on maize and elephant grass, Pennisetum purpureum, were assessed during surveys in farmers’ fields in six villages and two on-station trials in the forest zone of Cameroon between 1995 and 1996. The borer species encountered were Busseola fusca (Fuller), Sesamia calamistis Hampson, Eldana saccharina Walker on both host plants, and Mussidia nigrivenella Ragonot on maize only. Busseola fusca was the predominant host accounting for 44–57% and 96% on maize and elephant grass, respectively, followed by E. saccharina on maize with 27–39%. Fifteen hymenopterous, two dipterous and one fungal species were found on these stem and cob-borers. Among those were six pupal, six larval, four egg, one larval–pupal parasitoid and four hyperparasitoids. The scelionid parasitoids Telenomus busseolae Gahan and T. isis Polaszek were found on B. fusca eggs in all locations. During the first season, mean egg parasitism was low and ranged between 3.1% and 27% versus 54–87% during the second season. Species belonging to the Tetrastichus atriclavus Waterston complex were recovered from all four borer species. The majority and most common larval and pupal parasitoid species belonged to the ingress-and-sting guild.Larval and pupal parasitism were very erratic and on more than 50% of the sampling occasions no parasitoids were recovered. Parasitoid diversity was higher on elephant grass than maize.

Archeological records attest the early association of Sitophilus with stored cereals from the beginning of agriculture on Asia. The maize weevil (Sitophilus zeamais) became particularly damaging to maize, a cereal crop domesticated on Mesoamerica. We investigated the late evolutionary history of the maize weevil to gain insights on its origin, timing of association with maize, and genealogical relationship to the almost morphologically indistinguishable rice weevil (Sitophilus oryzae). Two mitochondrial genes (cytochrome oxidase subunit I and cytochrome oxidase subunit II) and the nuclear ribosomal gene region were partially sequenced. Analyses showed that the maize weevil shared no haplotypes with the rice weevil; instead, each species exhibited distinct mitogroups and ribogroups. The two weevil species likely split about 8.7 million years ago (95% highest posterior density: 4.0–15.0). Microsatellite data analyses sorted the 309 specimens from 15 populations of the maize weevil into three genotypic groups, which displayed low genetic differentiation and widespread occurrence worldwide. The maize weevil and the rice weevil are each a distinct species; both of which emerged prior to the onset of agriculture. The maize–maize weevil association took place after maize became widespread as a global crop. The maize weevil populations lack spatial genetic structure at the regional, continental, and intercontinental scales.

Hofmannophila pseudospretella is widely distributed in this country. It is a minor pest of stored foodstuffs, clothes and furnishings, and under certain conditions may give rise to a major infestation.

The egg stage is characterised by a high sensitivity to temperature and almost complete indifference to humidity. The incubation period varied from 110 days at 10°C. (90 per cent. R.H.) to 8·5 days at 27°C. (90 per cent. R.H.) and from 9·8 days at 90 per cent. R.H. (25°C.). to 14·0 days at 8·5 per cent. R.H. (25°C.). The percentage survival was greatly reduced both at very low (<3 per cent. R.H.) and at very high (100 per cent. R.H.) humidities. The survival of eggs from a single female varied from 56 to 97 per cent. under favourable conditions.

The duration of the feeding larval stage varied between 145 days at 13°C. and 71 days at 25°C. (at 90 per cent. R.H. on middlings). Larvae failed to mature below 80 per cent. R.H. at all temperatures. Larvae were reared successfully on a wide range of diets of both animal and vegetable origin, some predominantly carbohydrate, some almost entirely protein. The most rapid development occurred on dead adults and the slowest upon leather and yeast.

Under most conditions fully grown larvae entered diapause. This was characterised by a diapause moult after which the larvae assumed a typical diapause appearance. The length of the diapause was extremely variable and was determined largely by the temperature during larval growth. Larvae grown at low temperature did not enter diapause when incubated at 25°C. as fully grown larvae. The diapausing larvae were remarkably resistant to desiccation.

The duration of the pupal stage is affected by temperature but not by humidity. It lasted 98 days at 10°C. and 13 days at 28°C.

The total length of the developmental period was highly variable because of the variability in the length of the diapause under constant conditions. When the conditions throughout were 25°C. and 90 per cent. R.H. the total developmental period varied between 152 and 266 days, and at 20°C. and 90 per cent. R.H. the figures were 192 to 440 days. The developmental period was approximately 12 months under field conditions.

Under crowded conditions, mating was observed between males of H. pseudospretella and females of Endrosis lactella but none of the eggs developed.

The weight of the female at emergence was the most important factor governing the number of eggs laid. Weight of females varied between 8·2 mg. and 43·6 mg. and the egg number between 106 and 657 at 25°C. and 70 per cent. R.H. The number laid was significantly reduced at lower temperatures (10°C.) and at lower humidities (20 per cent. R.H.).

The sex ratio was found to be approximately 1:1, with a slight predominance of females.

The longevity of the fertilised adult female depended upon its weight at emergence and upon the physical conditions. Variation in weights of males was small, and the length of life of mated males could be correlated directly with the physical conditions. The mean longevity of mated females of all weights was 11·9 days at 25°C. and 70 per cent. R.H., 19·0 days at 15°C. and 70 per cent. R.H. and 9·4 days at 25°C. and 20 per cent. R.H. At 25°C. mated males lived 7·1 days on the average, and 18·8 days at 15°C.

The only important predator was the mite, Cheyletus eruditus, which destroyed numbers of eggs and young larvae.