An Australian gall-inducing eulophid, Ophelimus eucalypti (Gahan) was first recorded on the foliage of Eucalyptus botryoides after it invaded New Zealand in 1987. It has spread throughout the eucalypt plantations in the North Island and in the northern parts of the South Island affecting several species of Eucalyptus in the section Transversaria (subgenus Symphyomyrtus). Because gall-inducing insects usually have extremely narrow host ranges, O. eucalypti that induces galls on E. saligna and E. botryoides is currently recognized as a biotype, O. eucalypti (Transversaria). Heavily galled leaves abscise from the plant. Repeated defoliation led to widespread die-back of susceptible eucalypt species in the 1990s. Female larvae of O. eucalypti induce circular, protruding galls on the leaves of E. botryoides and E. saligna, whereas the males induce pit galls on the same species. The biology of O. eucalypti females and the development of their galls are described. Adult female O. eucalypti antennate the leaf surface before inserting the ovipositor (otherwise concealed within the metasomal apex) into the young host leaf. The egg is inserted at approximately 45° and discharged between differentiating palisade cells. Callus-type cells surround the egg chamber, but cytologically specialized nutritive cells appear once the egg hatches and the larva begins to feed. The gall also differentiates a multi-layered sclerenchymatous tissue around the nutritive tissue. After feeding for many months, the larva pupates and the active nutritive tissue degenerates. The adult wasp emerges after cutting an exit hole through to the outside of the gall. Abscission of heavily galled leaves results in widespread defoliation and loss of growth and vigour in susceptible trees in New Zealand.

With the decline in production of new insecticides, the development of resistance is likely to become more of a problem than at present. Models of the spread of resistance genes may become integral parts of many management programmes. A critical examination is made of the classical theory of inheritance of resistance, i.e. the spread of a single resistance- conferring allele through a population. The theoretical considerations suggest that simple Mendelian inheritance is unable always to account for the development of resistance. It is suggested that some resistance factors may be under multigenic control and that such inheritance could account for the rate at which resistance sometimes develops. Following on from the theory, an analysis was made of time to knockdown and dry body weight in Sitophilus oryzae (L.). A half-sib experimental design was employed which enabled quantitative analyses of the characters to be made. Both characters had substantial heritabilities and were phenotypically correlated. The analysis also indicated a positive genetic correlation between the characters. The implications for the development of tolerance in the light of the genetic analysis are discussed.

These experiments with Locusta migratoria show that temperature conditions during breeding have a great influence on the normal development and general health of this insect. There is a certain limit of favourable temperature, below which the development of the genital products in the imagines ceases, and the insects easily succumb to bacterial diseases.

The distribution and trypanosome infection rates of Glossina morsitans submorsitans Newst. were studied during the wet season of 1967 along 75 miles of the main trade cattle route which passes through the savannah country between Ilorin and Oyo in south-western Nigeria.

G.m. submorsitans was found inhabiting open woodland, grassland, farmland and the environs of towns associated with the cattle route. In comparison with the types of habitat this species occupies in its zone of wide distribution in northern Nigeria, those habitats studied were considered atypical. It is suggested that the presence of G.m. submorsitans in the area investigated had resulted from a southward population advance over the last 50 years and this hypothesis is discussed in relation to existing knowledge of G.m. submorsitans advances.

The trypanosome infection rates of 61.6 and 76.6 per cent, found in 364 examples of G.m. submorsitans dissected are much higher than previously recorded for any of the subspecies of G. morsitans Westw. A steady southward increase in the trypanosome infection rates of G.m. submorsitans was demonstrated for populations inhabiting 200 miles of cattle route. Trypanosome infections in G.m. submorsitans are attributed to Trypanosoma vivax and T. congolense, and the absence of brucei-group infections is discussed in relation to the incidence of T. brucei infections in trade cattle and limitations of the technique used for demonstrating infections in tsetse flies.

It is stressed that epizootiological aspects of the present findings cannot be clarified until reliable data on trypanosome infections of trade cattle in the area studied are available.

Two species of Gryon Haliday, parasites on eggs of blood-sucking Reduviids, are described, namely G. triatomae sp.n. from Singapore and India, reared from eggs of Triatoma rubrofasciata (De Geer) and Linshcosteus sp., and G. linshcostei sp.n. from India from eggs of Linshcosteus sp. The species differ in biological attributes but are not separable by morphology; with G. insularis (Ashmead) they form the insularis-group.

Studies on the precision levels and efficiencies of available insect suction samplers (D-Vac and FARMCOP) were undertaken in the Philippines to determine the best possible sampling procedure to derive absolute population estimates of delphacids, cicadellids and their predators in flooded rice. The D–Vac suction sampler when used in conjunction with an enclosure placed over the rice hill prior to sampling was found to be the most suitable. The sampling procedure adopted is described in detail, and sampling efficiencies for the D–Vac are given for nymphs and adults of the delphacids and cicadellids and their predators. These values could be used by other workers following the sampling procedures described here on modern rice varieties grown under flooded conditions to achieve absolute population estimates.

The crops and guts of adults of Leptohylemyia coarctata (Fall.) from different parts of England and Scotland contained spores of Septomyxa affinis. This fungus is widespread on dead wheat leaves and grass in wheat fields and is an important food for the flies, especially in south and east England during July and August. Of all flies dissected in 1967, 1968 and 1969, 57%, 39% and 45%, respectively, contained Septomyxa spores. Spores of other fungi, pollen grains, bacteria and yeasts were also ingested. All solid food was ingested in water or honeydew. The weight of the newly emerged female fly almost doubled with the ripening of the first batch of eggs, whereas males remained the same weight or became lighter. Different individuals had different numbers of ovarioles, so the number of eggs ripe and ready to lay at the same time also differed between individuals. The mean numbers, 25·6 ± 0·8 in 1968 and 28·6 ± 0·4 in 1969 were fewer than the usually accepted 32. During August, before all the eggs had been laid, many flies were killed by Entomophthora muscae and Strongwellsea castrans.

The antimicrobial activity of the pygidial gland secretion released by adult individuals of the troglophilic ground beetle Laemostenus (Pristonychus) punctatus (Dejean, 1828), applying microdilution method with the aim to detect minimal inhibitory concentration, minimal bactericidal concentration and minimal fungicidal concentration, has been investigated. In addition, morphology of the pygidial glands is observed. We have tested 16 laboratory and clinical strains of human pathogens – eight bacterial both gram-positive and gram-negative species and eight fungal species. The pygidial secretion samples have showed antimicrobial properties against all strains of treated bacteria and fungi. Micrococcus flavus proved to be more resistant compared with other bacterial strains. More significant antimicrobial properties of the secretion are observed against Escherichia coli, which proved to be the most sensitive bacteria. Aspergillus fumigatus proved to be the most resistant, while Penicillium ochrochloron and Penicillium verrucosum var. cyclopium the most sensitive micromycetes. Commercial antibiotics Streptomycin and Ampicillin and antimycotics Ketoconazole and Bifonazole, applied as positive controls, showed higher antibacterial properties for all bacterial and fungal strains, except for P. ochrochloron, which proved to be more resistant on Ketoconazole compared with the pygidial gland secretion of L. (P.) punctatus. Apart from the role in ecological aspects, the antimicrobial properties of the tested secretion possibly might have medical significance in the future.

1. The female tsetse extrudes her larva on soils ranging from fairly heavy clay to coarse sand; the presence or absence of organic matter seems to be immaterial.

2. The soil temperature varies greatly in different breeding-grounds in the dry season, but little in the rains.

3. The soil water content varies greatly in different breeding-grounds in the rains, but little in the dry season.

4. The soil water content in some of the breeding-grounds falls so low in the dry season that there can be no doubt that the atmosphere in these soils is below saturation.

5. Evaporation measured at 5 inches above ground-level varies little from site to site; bigger and important differences occur at greater heights above the ground where the screening effects of thicket become operative.

6. The seasonal changes are so great at Gadau that no one breeding-ground can satisfy the female's requirements throughout the year; instead, different breeding-places are selected for different seasons.

7. The cycle for G. morsitans is as follows: In the rains breeding occurs under palm fronds and logs in the open woodland. In the early dry season breeding continues in the open woodland, but shifts from the palm and log sites to the small thickets; breeding also starts in the more open parts of the forest islands. At the beginning of the very hot weather all the thickets of the open woodland are evacuated, and breeding is confined to the densest parts of the forest islands. In the early rains the movement is reversed: breeding shifts out into the open woodland, and in the heavy rains is confined to the log and palm sites.

This cycle fits in closely with the cycle for the seasonal concentration and dispersal of the adult population (Nash 1937, pp. 85–90).

8. The major wet season breeding-ground of G. tachinoides is unknown, but the cycle is believed to be as follows: In the early dry season breeding shifts from the log, palm, and probably from the unknown site, to the small thickets and forest islands, and becomes maximal in the cold season. Breeding now decreases in all sites, suggesting that none is really suitable—a surmise which is strengthened when tremendous breeding activity starts in the river-bed, as soon as it becomes available at the beginning of the hot season. In the early rains this site is destroyed and breeding is believed to commence in the unknown site, as it certainly does under the logs and palms.

The optimal use of available host by parasitoid insects should be favoured by natural selection. For solitary parasitoids, superparasitism (i.e. the egg-laying of several eggs/host) may represent a detrimental phenomenon both in a biological and an applied sense, but under certain circumstances it may be adaptive. Here, we studied the effects of increasing levels of superparasitism (LSPs, number of parasitoid larvae/host) on fitness-related parameters of the immature and adult stages of Diachasmimorpha longicaudata, a solitary endoparasitoid parasitizing Ceratitis capitata. We investigated the moment when supernumerary parasitoid larvae are eliminated and the effects produced by this process, together with its repercussion on female fecundity, parasitism rate, sex ratio, adult survival, flight ability and body size. Complete elimination of competitors occurred soon after larval hatching, before reaching the second larval stage. Elimination process took longer at higher LSPs, although a normal developmental (egg–adult) time was achieved. For LSPs 1, 2, 3 and 5 the effects on parasitoid emergence were mild, but LSP 10 led to the death of all developing parasitoids. Aside from this, to develop in superparasitized hosts did not significantly affect any of the evaluated parameters, and only a female-biased sex ratio was observed at higher LSPs. However, the effects of superparasitism on the adults may have a different outcome under more variable conditions in the field, once they are released for biological control purposes.

1. Shinyanga is divisible into:

(a) Thorn-bush country containing plenty of tsetse but no population (Pl. x, figs. 1 and 2). This now covers far more country than it did fifty years ago, owing, first, to depopulation caused by natives wars, secondly, to depopulation caused in the past fifteen years by (chiefly) the advance of tsetse; and its distribution has also changed greatly.

(b) Open grass-land, produced in the past from the thorn bush by the settlement in it of people in sufficient numbers to clear it and keep it clear through their cutting for firewood and building and the browsing of their stock (Pl. xi, fig. 2; Pl xv, fig. 1).

2. Except in one respect the position in the open country is ideal. There is complete segregation of tsetse and people, and a situation exists in consequence amounting, for practical purposes, to control of the tsetse. All the people are able to keep cattle and all the children to get milk, tsetse are excluded, sleeping-sickness is excluded, and, owing to the compactness of settlement, mammalian pests are excluded except from the margins, and the people generally are accessible for purposes of administration, medical treatment, education, and agricultural development.

3. The exception is this. The tree roots still survive in the open country and, whenever population thins for a time, shoot up into bushes and trees. Where these are adjacent to tsetse bush, the fly is carried into them, while they are still small, on persons passing to and fro, and cattle begin to die. The people then fall back, allowing new bush to spring up and the process to be repeated. In Shinyanga this retreat and the reconquest by fly has been for some time at the rate of a mile a year, and new “fronts” have been formed, so that the cattle-areas are now nearly surrounded.

4. The position is serious and urgent. If it had not been taken in hand the cattle areas were doomed, as were the present schemes of development, and the railway now planned on the strength of the presence of population might have led ultimately to a depopulated waste.

5. The remedy is in the hands of the people themselves. They have merely each year to combine to cut back the young shoots and the bush and the tsetse cannot advance. And persons must not allow the flies to travel on them into cleared areas.

6. But the retreat, and natural increase of stock, have caused congestion of the cattle in the areas still populated, with severe shortage of grazing, and deaths; and the destruction of grass has led to erosion and serious loss of soil (Pl. ix, figs. 1 and 2). The remedy is again easy. When the people come out each year to cut back the young shoots, they should take the opportunity to clear for some little distance into the bush and so get enough grazing. Also, any new agriculture likely to demand much ground, and so still further to reduce the grazing, should be located so far as possible in the fly-bush. All this was explained to the people, and they asked us to organise an effort on their part. This we did, in May and June 1924, when about ten thousand men went into camp under their respective Sultans and headmen and cleared in the most energetic manner many square miles of tsetse bush on a great part of the Shinyanga tsetse “front.” It only remains to organise this effort as a popular annual custom and to locate the clearings knowledgeably and in conformity with a thoughtout plan in order gradually to break up and destroy the fly-belt. The lessons as to management that were learned from this year's clearing are detailed on p. 331.

7. A small, typical, infested block of the fly-bush has been cut off by clearing and an experiment initiated: (a) in-inducing natives to settle in the barrier, so as to widen it automatically and keep it clear; (b) in clearing the block itself of fly; and (c) in testing the width of barrier which, combined with such precautions as may prove of use, will prevent the block from becoming reinfested from the main bush. The initial response to the inducements offered (p. 000) has been good.

8. The first step towards breaking up the fly-belt on a greater scale has been taken by clearing, to a width of 400 yards on either side, a road traversing a point (Samuye to Kizumbi) at which the fly-belt narrows to seven miles. It is planned to make (and greatly widen) further breaks and to attack in detail the blocks broken off, should it prove difficult otherwise to prevent reinfestation of country that may be cleared of fly by grass-burning, etc.

9. Felled bush continued to harbour fly for some time, at any rate if people and game continued to wander between it and the bush as yet unfelled. Complete destruction of the timber by twice piling and burning it made it uninhabitable by fly, but if time is of no account, the bush can lie till the twigs and small branches of it are warped downwards into a closer mass by the next rains and so are destroyed by the grass fires of the following year.

10. A direct prohibition, enforced by a patrolling guard here and there, reduced nearly to nothing the carrying of flies into cleared or cattle country by man. Game wandered in and out almost entirely at night. The stationing of a pair of fly-boys on a road with nets, combined ultimately with dark shelters alongside for the attraction of the flies, was most useful during an entire year in preventing the carrying in of flies by cars and wayfarers. The attachment of brown paper smeared with “rat varnish” to the hoods of cars and the backs of natives was useful in destroying flies frequenting a road.

11. Mere cutting of tsetse bush is useless, for it springs again, so that it is futile to try to gain ground by this means faster than we can consolidate it. The following measures for the consolidation of clearing are being tested now in Shinyanga: The introduction of native settlement to keep the ground clear automatically; the special cutting down once or twice a year by each village of the new shoots for a few hundred yards round; the encouragement of the keeping of goats; the diversion of large scale agriculture by ploughing, which entails stumping, to the clearings it is wished to consolidate; the digging up of stumps by the natives for firewood; and the killing of trees by poisons and particular forms of ring-barking.

12. The annual postponement of the grass fires till October, and then lighting them on an organised plan, was advocated some years ago (Bull. Ent. Res. xi, 1921, p. 382), and was encouraged by circular in Tanganyika Territory in 1921, when also I carried out a successful experiment near Kilosa (Pl. xv, figs. 1, 2). Father Cirvegna took up the organisation of the measure over a small piece of fly-belt at Madibira, in the Iringa district, and there seems to be little doubt that he has cleared the area of fly by means of it in three burnings.

A large scale experiment by myself this year in the Nzega and Shinyanga subdistricts seemed to show: (a) that by means of native guards, each with an area, and some aid from the headmen, it is perfectly possible to preserve a great piece of country nearly unburned; (b) that the late grass fire, lighted on a broad front with a good wind and followed up by the burners, produces, when the grass growth is sufficient, a “drive” of the flies on the wing; these then become congregated in enormous numbers beyond the limits of the fire and in any appreciable patches of ground which escape it; (c) that in these places, by the prompt use of nets and bird-lime, it is possible nearly to exterminate the congregated flies. The fewer these congregations the more practicable is this measure, so that the destruction of the more extensive fire-excluding thickets by hand will be a useful preliminary measure; (d) that far more numerous breeding thickets and breeding logs are destroyed by such a fire than by an earlier or ill-organised fire, and that with the expenditure of some labour in the littering with dry grass of thickets and logs unlikely to be burned otherwise all may be burned, or many may be cleared by hand; (e) that a much larger percentage of dead pupae (52 per cent. in this case) may be found afterwards in breeding places thus burned through than in those that are not burned (9 per cent.).

13. Some of these indications merely confirm results previously obtained by me in Rhodesia and Tanganyika; others need to be confirmed by means of further experimentation. Meantime, combined with Cirvegna's result, they suggest that late organised grass burning is likely to be of value over the very considerable areas in Africa in which the grass and the dry season are long and organisation is possible. But even if this should definitely prove true, means of preventing reinfestation must be studied, for these may turn out to be a serious difficulty.

14. The relations of the fly and the game are not being ignored. They are being studied and will be the subject of special experimentation and, if necessary, of special localised measures fitted into our general scheme of control.

15. This scheme amounts to an attempt to destroy and control tsetse by means of agencies and resources already in existence and merely requiring to be diverted specially to that purpose and organised, and by enlisting the co-operation of the people themselves who are to be aided and protected. This is both the most practical way of dealing with the problem and the way that best accords with the sound policy of educating the natives to understand and attack their own problems and advance themselves through their own efforts.

Catches by gypsy moth (Lymantria dispar (Linnaeus)) ‘milk-carton’ pheromone traps with (+)-disparlure were compared with estimates of the absolute aerial density of gypsy moths obtained using a suction trap of known absolute sampling efficiency. The mean number of male L. dispar caught per pheromone trap per day was found to be proportional to the 2/3 power of the suction trap's estimate of aerial density. We infer that the efficiency of the gypsy moth milk-carton pheromone trap is density-dependent, declining as aerial density increases. The significance of the density-dependent efficiency and the mode of action of attractant traps are discussed, and the problems of designing and building suction traps to standardize pheromone traps for other species are also considered. It is concluded that standardization is only possible when some basic biology is known because pheromone trap parameters are specific to the field behaviour of the species.

Hollow-fibre, laminate-flake and microencapsulated formulations of the synthetic sex pheromone (a 1:1 mixture of (Z, Z)- and (Z, E)-7, 11-hexadecadienyl acetate) of Pectinophora gossypiella (Saunders) were compared in large-scale mating disruption trials in Egypt in 1982. Fifty-hectare blocks of cotton were treated at regular intervals throughout the season with the formulated pheromone as the sole means of controlling the pest. The pheromone treatments were compared with conventional insecticide spray treatments in other 50-ha blocks of cotton sited in the same localities. Comparisons of numbers of infested flowers and green boils, open boll counts, crop development, yield of seed cotton, lint quality and seed damage in pheromone-and insecticide-treated blocks, showed that adequate levels of control were achieved using the pheromone formulations, which were equal in effect to the insecticide sprays. Beneficial insects were found in greater numbers in the pheromone-treated areas than in areas treated with insecticides.

Currently, the systematics of the African noctuid stem borers of the subtribe Sesamiina, which include major pests of cereals, is confused. In addition, their ecology is poorly known, as are the factors influencing their evolution. In this paper, we address these shortcomings for two genera of the Sesamiina, Sciomesa Tams & Bowden and Carelis Bowden. Mixed Bayesian phylogenetic analysis, which included their host plants and two mitochondrial genes, showed the genus Sciomesa to be polyphyletic. Two new genera were created, Pirateolea and Feraxinia. The genus Carelis proved to be paraphyletic and was subdivided into two sub-genera. The genera Sciomesa, Carelis and Pirateolea (named the ‘Sciomesa genus group’) share morphological traits, and the phylogenetic analysis showed that they had a common ancestor living on Cyperaceae and that they were distant from the genus Feraxinia belonging to another clade which had an ancestor living on Poaceae. Seven new species were described: Sciomesa gnosia sp. n., Sciomesia bua sp. n., Pirateolea nola gen. n, sp. n., Feraxinia serena gen. n., sp. n., Carelis australis sp. n., Carelis transversa sp. n. and Carelis agnae sp. n. Ten species were sunk as synonyms: Sciomesa mesoscia (Hampson) syn. n., Sciomesa mirifica Laporte syn. n., Sciomesa constantini Laporte syn. n. and Sciomesa etchecopari Laporte syn. n. are synonyms of Sciomesa mesophaea (Aurivillius); Acrapex sparsipucta Laporte syn. n. is a synonym of Sciomesa excelsa (Laporte) comb. n.; Acrapex congitae Laporte syn. n., Sesamia minuta Laporte syn. n. and Sesamia minuscula Laporte syn. n. are synonyms of Sciomesa boulardi (Laporte) comb. n.; Acrapex bryae Laporte syn. n. and Acrapex fayei Laporte syn. n. are synonyms of Feraxinia jemjemensis (Laporte) comb. n. Eleven new combinations were created: Sciomesa excelsa (Laporte) comb. n., Sciomesa boulardi (Laporte) comb. n., Sciomesa punctipennis (Krüger) comb. n., Pirateolea piscator (Fletcher) comb. n., Pirateolea argocyma (Fletcher) comb. n., Pirateolea cyclophora (Fletcher) comb. n., Pirateolea ochroneura (Fletcher) comb. n., Pirateolea funebris (Krüger) comb. n., Feraxinia nyei (Fletcher) comb. n., Feraxinia jemjemensis (Laporte) comb. n. and Carelis biluma (Nye) comb. n.

Morphologically, early immature stages of the economically important pest called screwworms, Cochliomyia hominivorax (Coquerel) (Diptera: Calliphoridae), and non-pest secondary screwworms, Cochliomyia macellaria (Fabricius) (Diptera: Calliphoridae), are nearly indistinguishable. Correct identification is crucial to the ongoing eradication and exclusion program protecting the United States, Mexico and Central America from reinvasion of screwworms persistent in South America and the Caribbean. Amplified fragment length polymorphism (AFLP) polymerase chain reaction was used to differentiate populations of C. hominivorax and to discriminate them from C. macellaria. Ten primer pairs screened for interspecific discrimination of C. hominivorax from C. macellaria showed 52 discrete bands, allowing the two species to be readily distinguished; divergent branches on resulting dendrograms showed 100% bootstrap support. C. macellaria populations grouped at the 92% level; C. hominivorax populations grouped at the 68% level. Of the 52 bands, seven were monomorphic for both species, 22 were specific to C. macellaria, ten were present only in C. hominivorax and the remaining 13 bands differentiated C. hominivorax populations. Separate studies using ten strains of C. hominivorax showed a higher level of genetic similarity within than between populations. Analyses using 72 bands (19 monomorphic bands, 53 bands grouped all ten strains at the 58% similarity level) resolved seven mutant strains from Mexico (85% similarity level); all ten strains were resolved at the 72% similarity level. Diagnostic bands were identified for species and strain identification. We conclude that AFLP can be a valuable tool for studies of interspecific and intraspecific genetic variation in screwworm populations.

The Australian plague locust, Chortoicetes terminifera (Walker), is an important agricultural pest and oviposits into compacted soil across vast semi-arid and arid regions prone to irregular heavy summer rainfall. This study aimed to quantify the effects of flooding (control, 7, 14, 21, 28 and 35 days) at different temperatures (15, 20 and 25°C) and embryonic development stages (25 and 75%) on egg viability, hatchling nymph body mass and survival to second-instar. Egg viability after flooding was dependent on temperature and flood duration. Eggs inundated at 15°C showed ≥53.5% survival regardless of flood duration and development stage compared with ≤29.6% for eggs at 25°C for ≥21 days early in development and ≥14 days late in development. Hatchling nymphs did not differ in body mass relative to temperature or flood duration, but weighed more from eggs inundated early in development rather than late. Survival to second-instar was ≤55.1% at 15 and 20°C when eggs were flooded for ≥28 days late in development, ≤35.6% at 25°C when flooded for ≥28 days early in development, and zero when flooded for ≥21 days late in development. These results suggest that prolonged flooding in summer and early autumn may cause very high egg mortality and first-instar nymph mortality of any survivors, but is likely to only ever affect a small proportion of the metapopulation. More common flash flooding for ≤14 days is unlikely to cause high mortality and have any direct effect on distribution and abundance.

An account is given of observations made in two rooms of a warehouse during 1945 and 1946. In 1945 fortified flour was stored in a single tier of upright sacks, whilst in 1946 the rooms were empty except for 50 small experimental bags of wheatfeed.

Before the flour arrived in 1945, no insects were found except a few larval Ptinids in a bag of sweepings. Adult Ptinus tectus soon appeared on the sacks of flour and, in one room, the numbers on the sacks increased steadily to 6,000 by the time the flour was removed in November. In the other room, where the ecological conditions were obviously variable, the increase was erratic, but there were 4,500 adult Ptinus on the sacks by the time the flour was removed. The numbers on the experimental bags in 1946 rose from zero to 5,000 by the end of September. The weekly figures varied with temperature, falls in numbers coinciding with colder weather. In both years a steady 30–40 per cent, of the total Ptinus on the sacks or bags were fcund at the bottom except for the early months of 1946 when 80 per cent, were at the base of the bags until April.

In empty premises it was obvious that many adult beetles hid in the fabric of the building, a rough estimate of 150,000 being obtained following the use of traps and marked beetles. There were indications that the main hiding place in this building was at the junction of walls and floor. After the sacks of flour had been removed in 1945, it was estimated that the flour covering the floor of Room 70 contained about 7,000 larvae. These would normally be removed by sweeping and vacuum cleaning, but this treatment left behind about a further 10,000 larvae in the floor cracks of each room. No estimate of larvae inside the sacks was possible, but in eight months in 1946, about 1,500 eggs were laid in each small bag of wheatfeed. An average of at least 300 eggs per day were laid in the room in 1946.

Ptinus tectus has two complete generations a year. All stages may survive the winter so that overlap of generations is complete.

In a stack of sacks of flour, adults are most abundant on the sacks at the edge of the stack especially on those near the corners. Draughts, wetness and sunshine caused local changes of distribution. There was some suggestion that Ptinus preferred to rest upon cotton sacks rather than on jute. Larvae are normally present only in the outer layers of flour in a sack and spin cocoons on the inside surface of the sacking. The adults emerge through the sacking to the outside.

The activity of Ptinus in a warehouse is greatest during darkness. Hence it is fairly continuous in dark premises and periodic in light places. In the latter, beetles emerge from their hiding places at dark and return at dawn. If dark crevices are provided artificially they act as traps, for some of the beetles will use them as daytime hiding places. Activity is reduced by low temperatures but does not stop altogether until it is as low as 2°C.

Two methods are suggested for actual estimation of insect numbers without too much labour. One for estimating the numbers on the sacks is based on the fact that most of the insects are found on outside sacks, and involves the counting of the insects on several representative groups of contiguous sacks. Over half of the estimates made by applying this method to the data from one of the rooms in 1945 were within 20 per cent, of the correct values as indicated by total counts of the population. The combination of traps with the release of marked beetles is suggested for estimating the resident population of empty premises.

Primers for DNA amplification using the polymerase chain reaction (PCR) were synthesized for a microsatellite locus isolated from a partial genomic library of the aphid parasitoid Aphelinus abdominalis (Dalman). Screening for genetic polymorphism at this locus in two laboratory strains of this wasp revealed the presence of two alleles different in the number of (GT) and (GGC) repeats. The relative frequencies of the two alleles were not significantly different between the two strains or between diploid females and haploid males. Heterozygosity at this microsatellite locus was estimated to be 0.40 which is within the range in other hymenopterous species. Given that A. abdominalis is a good candidate for augmentative release programmes in greenhouses against aphids, we suggest that microsatellite markers may have application in discriminating among aphelinid sibling species and strains. The markers provide a means for studying the performance and impact of selected parasitoid lines on pest dynamics in field release experiments.

Infection of the commercially important silkworm, Bombyx mori by a tachnid parasitoid, Exorista bombycis induced activation of genes and cellular responses associated with apoptosis in integumental epithelial cells. Composite cellular profile showed initial autophagy, intermediate endoplasmic reticulum degranulation and deformed nucleus as well as later DNA fragmentation indicating apoptosis. Two cell death-associated proteins, autophagy 5-like (Atg5L) and apoptosis-inducing factor (AIF), in addition to caspase, are identified from the infected integumental epithelium through mass spectrometric analysis. Genes encoding these proteins showed age-dependent activation after the infection as revealed by quantitative expression analysis. Atg5 showed early upregulation in association with signs of autophagy whereas AIF showed late upregulation in association with DNA condensation and fragmentation. Expression of AIF showed negative correlation with that of Atg5 after the infection. On the other hand, in control, caspase expression showed positive correlation with AIF expression indicative of regulated expression in normal larval epithelium, which was absent after infection. Activation of Atg5, AIF and caspase genes in close association with different cell death events revealed the synchronized differential expression of apoptosis-associated genes in response to the macroparasitism. Enhanced expression of Atg5, AIF and caspase genes coupled with the appearance of cell death symptoms indicate parasitism-induced activation of genetic machinery to modulate cell death events in the epithelium, which was hither to unknown in invertebrate systems.

A novel type of emergence trap capable of capturing and separating ‘live’insect catches is described. The trap was shown to be 96% efficient at capturing newly emergent adult Hylobius abietis Linnaeus on bare ground and at least 82% efficient over stumps on a weedy Sitka spruce clearfell. The trap was more than 80% efficient at capturing Bracon hylobii Ratzeburg, the most commonly found parasite of H. abietis. It was also shown to be effective at capturing adult H. abietis of unknown age (98%), indicating that it could also be used to trap out H. abietis from known areas to estimate on-site overwintering densities. Fifty-four percent of newly emergent weevils were captured within 12 h of release on bare mineral soils. Forty-two percent of unknown age weevils and 52% of parasites were captured within 1 h of their release within the trap. The rapid rates of capture mean that when traps are checked frequently they can be used to reflect accurately temporal patterns of emergence. Its potential for use in control programmes and ecological studies is discussed.