The efficacy of two entomopathogenic biocontrol agents, Steinernema feltiae (Filipjev) and Verticillium lecanii (Zimmerman) Viégas (reclassified now as Lecanicillium muscarium (Petch) Zare & Gams), against Thrips palmi Karny was investigated. Assessments of the effect of temperature on the efficacy of S. feltiae indicated that higher mortality of T. palmi was recorded at 20°C compared to either 15 or 25°C, whereas significantly higher T. palmi mortality followed application of L. muscarium at 25°C. Testing the control agents efficacy on three host plants; chrysanthemum, sweet pepper and cucumber, under constant temperature and high humidity conditions produced no significant difference in the level of T. palmi larval mortality on each host plant. Incorporating the chemical insecticide imidacloprid with both biological agents in a combined control strategy increased T. palmi juvenile mortality. The potential role of S. feltiae and L. muscarium within integrated pest management programmes for the control of T. palmi is discussed.

Sex ratios of populations of the wheat midge Sitodiplosis mosellana Géhin, developing on wheat Triticum aestivum L., were determined at reproduction, adult emergence, and dispersal. The patterns of sex ratio through the life cycle of S. mosellana result from: (i) a genetic mechanism that causes all or nearly all of the progeny of individual females to be a single sex, with an overall sex ratio that is slightly biased at 54–57% females; (ii) a differential mortality during diapause that increases the sex ratio to 60–65% females; (iii) mating which occurs near the emergence site followed by female dispersal which causes the post-dispersal sex ratio to rise to nearly 100% females; and (iv) oviposition which spreads eggs among different plants and assures that the next generation has a local sex ratio close to the population average. These changes in sex ratio through the life cycle have implications for using crop resistance or pheromones to manage S. mosellana, because mating takes place quickly near emergence sites, and because mated females but not males disperse from emergence sites to oviposition sites. Crop refuges used to protect resistance genes against the evolution of virulence by S. mosellana must be interspersed to prevent assortative mating that would occur in separate blocks of resistant and susceptible plants. Monitoring or mating disruption using a pheromone would be ineffective when wheat is grown in rotation with a non-host crop.

Habrobracon hebetor (Say) is a parasitoid of various Lepidoptera including Helicoverpa armigera (Hübner), a key pest of different crops and vegetables. The development of both H. armigera and H. hebetor were simultaneously evaluated against a wide range of constant temperatures (10, 15, 17.5, 20, 25, 27.5, 30, 35, 37.5 and 40 °C). Helicoverpa armigera completed its development from egg to adult within a temperature range of 17.5–37.5 °C and H. hebetor completed its life cycle from egg to adult within a temperature range of 15–40 °C. Based on the Ikemoto and Takai model the developmental threshold (To) and thermal constant (K) to complete the immature stages, of H. armigera were calculated as 11.6 °C and 513.6 DD, respectively, and 13 °C and 148 DD, respectively, for H. hebetor. Analytis/Briere-2 and Analytis/Briere-1 were adjudged the best non-linear models for prediction of phenology of H. armigera and H. hebetor, respectively and enabled estimation of the optimum (Topt) and maximum temperature (Tmax) for development with values of 34.8, 38.7, 36.3, and 43 °C for host and the parasitoid, respectively. Parasitisation by H. hebetor was maximal at 25 °C but occurred even at 40 °C. This study suggests although high temperature is limiting to insects, our estimates of the upper thermal limits for both species are higher than previously estimated. Some biological control of H. armigera by H. hebetor may persist in tropical areas, even with increasing temperatures due to climate change.

Thiamine is a vitamin that has been shown to act as a trigger to activate plant defence and reduce pathogen and nematode infection as well as aphid settling and reproduction. We have here investigated whether thiamine treatments of seeds (i.e. seed dressing) would increase plant resistance against aphids and whether this would have different effects on a generalist than on specialist aphids. Seeds of wheat, barley, oat and pea were treated with thiamine alone or in combination with the biocontrol bacteria Pseudomonas chlororaphis MA 342 (MA 342). Plants were grown in climate chambers. The effects of seed treatment on fecundity, host acceptance and life span were studied on specialist aphids bird cherry-oat aphid (Rhopalosiphum padi L.) and pea aphid (Acyrthosiphon pisum Harris) and on the generalist green peach aphid (Myzus persicae, Sulzer). Thiamine seed treatments reduced reproduction and host acceptance of all three aphid species. The number of days to reproduction, the length of the reproductive life, the fecundity and the intrinsic rate of increase were found reduced for bird cherry-oat aphid after thiamine treatment of the cereal seeds. MA 342 did not have any effect in any of the plant-aphid combinations, except a weak decrease of pea aphid reproduction on pea. The results show that there are no differential effects of either thiamine or MA 342 seed treatments on specialist and generalist aphids and suggest that seed treatments with thiamine has a potential in aphid pest management.

The turnip sawfly, Athalia rosae Linnaeus, is a pest on cruciferous crops. Larvae sequester secondary plant compounds, namely glucosinolates, in their haemolymph. When attacked, their integument is easily disrupted and a droplet of haemolymph is exuded (‘easy bleeding’). This has been shown to be an effective, chemical-based, defence against invertebrate predators. The efficiency of this proposed defence was tested against a vertebrate predator, using groups of the iguanid lizard Anolis carolinensis Voigt as a model predator. Caterpillars of Pieris rapae Linnaeus and Pieris brassicae Linnaeus served as control prey species that do not sequester glucosinolates. Lizards attacked far fewer sawfly larvae than pierid caterpillars. Several of the sawfly larvae were rejected after an initial attack, demonstrating unpalatability to the lizards, while the Pieris larvae were not rejected. However, P. rapae larvae topically treated with extracts of haemolymph of A. rosae had no deterrent effect on the lizards and no avoidance learning occurred over a period of two weeks. Adult sawflies do not easy bleed but have glucosinolates carried over from the larval stage. Lizards attacked them at a higher rate than larvae and they were never rejected. The results suggest that for the defensive effectiveness of the pest sawfly species against vertebrates the chemical cue is not necessarily sufficient. Movement and colour may be important additional factors triggering the behaviour of vertebrate predators.

The sudden decline following the peak in population abundance of aphids on crops of small grain cereals is attributed to the joint effect of natural enemies and plant senescence. To distinguish between these causes, a four year experiment was established in which the numbers of Metopolophium dirhodum (Walker) infesting spring wheat plots sown from April to June at c. 14 day intervals were determined. Aphid abundance in replicates sown at successive dates peaked within a period of 5–9 days (106–171 day degrees above a base temperature of 0°C) although their sowing dates varied by 62–97 days (727–1106 day degrees). At the time of the aphid population peaks, plants in the different sowings differed in age (11–99 days), developmental stage (stage 15–65 on the Zadoks scale), leaf nitrogen content and shoot mass. Maximum abundance of M. dirhodum decreased with sowing date because the time available for its population increase was shorter on late than early sowings. The abundance of M. dirhodum on spring wheat was similar to its abundance on winter wheat. After reaching peak abundance, aphids declined in numbers within 3–7 days. The effect of host plant ageing on the M. dirhodumdecline thus appeared small. Natural enemies (largely mycoses), and timing of alata production may have contributed to the aphid decline.

Viviparae of Sitobion avenae (F.) in clip-cages on winter wheat in field plots in southern England were monitored throughout the 1980–81 winter to determine characteristics of development, reproduction and lifespan under winter conditions. Rate-temperature relationships for development and reproduction were well described by straight lines when temperatures were measured above 3°C. A simple thermal-time scale could therefore be used for both processes. The parental morph and the time of year modified thermal-time requirements for the production of an adult's first 20 nymphs but did not affect those for development. For both alatae and apterae, nymph production per day-degree was greater than at higher temperatures and the relationship between reproductive rate and age was different. The minimum temperature experienced by the aphids was −7°C; survival was good, with little low temperature mortality. Total fecundity of apterae was usually greater than at higher temperatures, though some apterae and alatae that were deposited in October had low fecundity, possibly because they were insufficiently acclimatized at the onset of cold winter weather. Overwintering alatae had lower development rates, reproductive rates and total fecundity than apterae and did not survive as long, but were restless as young adults and appeared ready to migrate. Oviparae were produced from late September to mid-October but not after this, suggesting that the clone used could ‘switch off’ sexual morph production in winter.

A non-technical description is given of a new, powerful, low cost field system (Infra-red Active Determination of Insect Flight Trajectories or IRADIT) for detailed and automatic remote sensing studies of natural insect flight behaviour. The special requirements and difficulties of the detection problem are defined. A series of examples of field devices and techniques are presented to illustrate the key factors of the optical sensing and tracking of insects in flight. In the finally adopted IRADIT system, flying insects are differentially illuminated, under all natural light conditions, by an intense beam of pulsed near-infra-red radiation and detected using a shuttered image intensifier linked with a video camera operating at a rate of 50 frames per second. Immediate fully-automatic determination of the flight trajectories of several simultaneously detected insects was achieved, at this same high rate and in the presence of sky background photon noise, by processing the video signals with electronic circuits and a microcomputer. Flight trajectories are influenced by the local wind, whose vector must be subtracted to study insect flight behaviour. This was achieved by the use of a specially developed sensitive three-vector vane anemometer, providing digital data to the microcomputer at a minimum rate of 5 Hz. In tests of the prototype IRADIT-anemometer system in the field, insects with wing area of only 1·5 mm2 and flying against the midday sky were readily tracked at ranges up to 15 m. A range of at least 100 m is expected for nocturnal moth tracking.

The performance of six grain storage technologies for the control of insect pests in maize was evaluated over a 36-week (9-month) storage period. The six technologies used were: two ZeroFly® hermetic bag brands (laminated and non-laminated); Purdue Improved Crop Storage (PICS) bag; non-hermetic ZeroFly® bag; woven polypropylene (PP) bag containing maize grain treated with Actellic Gold® Dust (pirimiphos-methyl 1.6% + thiamethoxam 0.3%) and woven PP bag containing untreated grain. Each bag was filled with 50 kg maize grain and four replicates of each were set up. With the exception of the non-hermetic ZeroFly® bag, 50 live adults of the larger grain borer Prostephanus truncatus and of the maize weevil Sitophilus zeamais, were introduced into all the bags. Insects were not introduced into the non-hermetic ZeroFly® bag to assess its effectiveness in repelling infestation from outside. Parameters recorded were gas composition (oxygen and carbon dioxide) levels inside the bags; weight of flour generated by insect feeding activities; grain moisture level; live adult insect counts; grain damage and weight loss; grain germination rate and aflatoxin level. At termination, the plastic liners of the hermetic bags were examined for perforations. Results show that oxygen depletion and carbon dioxide evolution were faster in ZeroFly® hermetic compared to PICS bags. Throughout the 36-week storage trial, grain damage remained below 4% and weight loss below 3% in all the treatments except in the untreated PP bags in which it increased to 81.1 and 25.5%, respectively. The hermetic PICS, ZeroFly® and Actellic Gold dust-treated PP bags maintained grain germination at 60%, which was lower than the initial 90%, while in untreated control, it reduced to 4.7%. The mean aflatoxin levels fluctuated between 0.39 and 3.56 parts per billion (ppb) during 24 weeks of storage in all the technologies tested, which is below the acceptable maximum level of 10 ppb in maize. Based on the evaluation results, it can be concluded that hermetic PICS and ZeroFly® bags and woven PP bag with Actellic Gold dust-treated grain effectively protected stored maize grain from insect attack and weight losses. Appropriate strategies and mechanisms for the effective and efficient adoption of hermetic storage bag technology at scale would contribute towards global food security.

The form of the Migratory Locust (Locusta migratoria, L.) appearing in swarms in south-eastern tropical Asia, the Malay Archipelago and the Philippine Islands, is usually referred to the subspecies migratorioides (Reiche & Fairmaire) which occurs in tropical Africa. However, even a superficial examination of series of specimens of the gregarious phase is sufficient to show that the Oriental locusts are somewhat different in their size and structure from the African ones. It was, therefore, of interest to compare the two forms biometrically and the results as described below have proved that the Oriental Migratory Locust should be regarded as a subspecies distinct from the African one, as well as from the three other subspecies of Locusta migratoria so far distinguished (Uvarov & Zolotarevsky, 1929).

In this paper four new species of Phlebotomus are described, three from Africa and one from the Malay States, and the differential characters and affinities of seven other known species are described and illustrated. Three specimens, including one of P. minutus, Rond., and two of P. papatasii (Scop.), have been observed to possess supernumerary spines on the superior claspers: a remarkable and apparently hitherto unrecorded phenomenon in this genus. In several instances fresh data are given as to the geographical distribution of these insects, and an endeavour has been made to clear up some confusion with regard to certain closely allied species.

When incorporated into an artificial diet or painted on the surface of the membrane containing the diet, solutions of the insect repellent GD 880 (2-methyl-2-(octylamino)-1-propanol) killed aphids, whilst extracts of neem seeds (Azadirachta indica) or extracts of the bodies ofMyzus persicae (Sulz.) deterred settling and larviposition of apterous adults. The deterrent effect occurred even when the painted membrane was covered by a similar but untreated membrane. When applied in culture solutions to the roots of young kale plants, GD 880 and extracts of neem influenced aphids on the foliage only at concentrations that visibly affected plant growth, but neem extract (and to a lesser extent GD 880) decreased aphid colonisation when painted on kale leaves at non-damaging concentrations.

Leek moth, Acrolepiopsis assectella (Zeller) (Lepidoptera: Acrolepiidae), is an invasive alien species in eastern Canada, the larvae of which mine the green tissues of Allium spp. This study was designed to construct and analyse life tables for leek moth within its native range. Stage-specific mortality rates were estimated for the third leek moth generation at three sites in Switzerland from 2004 to 2006 to identify some of the principle factors that inhibit leek moth population growth in areas of low pest density. The contribution of natural enemies to leek moth mortality was measured by comparing mortality on caged and uncaged leeks. Total pre-imaginal mortality on uncaged plants was 99.6%, 99.1% and 96.4% in 2004, 2005 and 2006, respectively. Variation in mortality was greater among years than among sites. Total larval mortality was greater than that in the eggs and pupae. This was due largely to the high mortality (up to 83.3%) of neonates during the brief period between egg hatch and establishment of the feeding mine. Leek moth pupal mortality was significantly greater on uncaged than on caged leeks, indicating an impact by natural enemies, and this pattern was consistent over all three years of study. In contrast, the other life stages did not show consistently higher mortality rates on uncaged plants. This observation suggests that the pupal stage may be particularly vulnerable to natural enemies and, therefore, may be the best target for classical biological control in Canada.

The physical state of deposits from various formulations of insecticides applied to different materials is considered in relation to the availability of the insecticide to insects making contact with the surface of the treated material.

Applications of oil solutions of insecticides to absorptive material result in absorption of the solution, and the insecticide is thereby rendered ineffective. On a nonabsorptive surface, oil solutions are the most efficient formulations, but only so long as the deposit remains wholly or partly liquid; if evaporation of the solvent gives a dry crystalline residue, this is much less efficient than the original solution.

On some fibrous absorptive surfaces, a solution of DDT in oil remains in a supersaturated condition in and around the fibres. If crystallisation is stimulated by mechanical means, the resulting crystals project from the treated surface and it is suggested that, in these circumstances, crystals are more readily available to insects than the oil solution from which they were derived.

DDT on compressed wall board shows the induced crystallisation to a greater degree than other insecticides. It is concluded, therefore, that wall board and similar surfaces should not be used in comparing the potencies of chlorinatedhydrocarbon insecticides applied as oil solutions, as DDT would be more available than others. Some factors that affect the degree of induced crystallisation are mentioned.

The following notes may be regarded chiefly as materials towards the study of the geographical distribution of this group of the bloodsucking midges, which are of so much interest from a medical standpoint. For the opportunity of examining the very large series of specimens (570) herein recorded, I have to thank Dr. Guy A.K. Marshall, Director of the Imperial Bureau of Entomology, who sent the collections made by Drs. A. Ingram and J.W. Scott Macfie, in the Gold Coast ; and also that formed by Capt. J. Waterston, R.A.M.C., in Macedonia. I tender my thanks also to Capt. P.A. Buxton, R.A.M.C., for the collections made by him at Amara, Mesopotama ; to Capt. H.W. Leatham, R.A.M.C., for examples from Basra ; and to Major J.A. Sinton, V.C., I.M.S., for the specimens which he collected in N.E. Persia, under exceptionally difficult circumstances, and also for the long series taken by him in the N.W. Frontier Province of India.

The populations of Nomadacris septemfasciata described in this paper were all of solitaria or neai-solitaria phase.

Sexual maturation as measured by the developing ovaries took place rapidly though irregularly through the population. Its onset coincided with an increase in the daily number of hours of relative humidity at or above 75 per cent., and abundance of green food; Copulation, which started after the first wide-spread rain, took place before the ovaries of many females were completely mature.

Caged locusts gave a mean fecundity of 183 eggs contained in 2·4 pods which is probably a minimum figure. Pods were laid at intervals of about two weeks and each was laid before the next batch had visibly developed.

The period spent in the egg was at least 39 days, at most 46 days and probably 42 days. Adults appeared 67 days after the first hatchings. Both these periods are greater than those recorded in phase transiens or gregaria.

Solitaria locusts were found to pass through seven instead of six nymphal instars as do gregaria. This difference seemed to be constant. The extra instar was probably interpolated between the second and third of gregaria but was not an exact duplicate of any other instar.

The number of vertical dark eye-stripes is a convenient and fairly constant indicator of the instar. The number of antennal segments in the later instars and in the adult, and also the number of adult eye-stripes, is greater in the solitaria phase.

Amongst the hoppers three main types of coloration were encountered and are briefly described but they could not be closely related to phase. The amount of dark pigment present in late stage nymphs was reflected in the young adult, the appearance of which is described in some detail. Subsequent changes during the dry season are briefly noted, in particular the pink of the hind wing, which becomes faintly visible within a month of the last moult.

The changes in pigmentation which take place during sexual maturation are described in detail. In addition to pronounced darkening of the tegmina which completely changes the appearance of the solitaria locust, certain bright pigments are laid down which are later obscured by a general blackening. It is unsafe to classify Nomadacris septemfasciata as to phase on colour alone unless the date of capture and its relation to the breeding season in the locality is taken into consideration. Solitaria do not normally develop the general reddening of the body which is shown by migrating swarms, even when these are only transiens in phase.

During 1919–20 an investigation into the habits of A sterochiton (Aleurodes) vaporariorum, Westw., was being carried out at the Lea Valley Experimental Station, Cheshunt, with a view to controlling its attacks on tomatoes under glass. The station exists for the study of scientific problems connected with the glasshouse industry, and as the staff is small, the work is necessarily confined to strictly economic lines. Points that appear in the course of the investigations cannot be followed to their ultimate conclusion in these earlier years of the station's existence if they seem to be of theoretical rather than of practical importance. The following notes relate to such a problem, which it has been decided to record, though in a very unfinished state.

The attack rate by the parasitoid Apanteles glomeratus (L.) on laboratory-reared larvae of Pieris rapae (L.) exposed for 3–4 day periods in a kale field in Massachusetts was greater when five larvae rather than two were placed on plants. The attack rate was greatest if host larvae were in the first instar when placed in the field, and little or no attack occurred when second- or third-instar larvae were exposed. The co-occurrence of unoccupied P. rapae larval feeding sites on plants where larvae were exposed reduced attack rates. Parasitism rates in trap-host larvae and in field-collected larvae (counting only cases in which the parasitoid was still in the egg stage) did not differ as estimators of recruitment to the population of parasitized hosts either in terms of total recruitment achieved per host generation or in the temporal pattern of the recruitment. In both simple and multiple linear regressions, the density of young P. rapae larvae (either parasitized or not) was the strongest correlate of parasitoid recruitment for the whole season, whereas average air temperature was the strongest correlate in the last month of observations (September).

Between 1987 and 1989, three predatory beetle species (Chilocorus bipustulatus (Linnaeus), C. infernalis (Linnaeus) and C. cacti (Linnaeus)) (Coleoptera: Coccinellidae) and two predatory mite species (Hemisarcoptes coccophagus Meyer and H. cooremani Thomas) were imported and released for the biological control of armoured scale insects (Hemiberlesia rapax Comstock, H. lataniae Signoret and Aspidiotus nerii Bouché) on kiwifruit and shelter trees in New Zealand. Hemisarcoptes coccophagus has established on Hemiberlesia lataniae infestations on Lombardy poplar (Populus nigra var. Italica) shelter trees at three sites. Detailed studies at one of the release sites over a period spanning nine to 24 months after release, showed that densities of Hemiberlesia lataniae in samples with mites fell to less than 20% of the level in control trees. Assessment of the dispersion characteristics of the mite suggested that the adults are repelled by the presence of other mites on a host. Hemisarcoptes coccophagus can use two species of New Zealand ladybirds (Scymnus fagus Broun and Halmus chalybeus Boisduval) for phoresy. Hemisarcoptes coccophagus spread naturally to the control trees between 20 and 24 months after release, though the means of dispersal between trees is not known.

Preliminary experiments are described of applications from aircraft of coarse sprays and coarse aerosols. The experiments were carried out over dense forest areas containing the tsetse fly G. palpalis.

At dosages of 0·2 lb. per acre of the p,p'isomer of DDT, or 0·032 lb. per acre of the γ isomer of BHC, both the sprays and the aerosols were relatively ineffective, and significant kills were obtained only with the aerosols.

The sprays were ineffective not only because they did not penetrate the canopy, but also because the nominal dosage was in any case too small to produce lethal deposits upon vegetation.

Much of the aerosol was filtered out by the upper layers of the canopy. The meteorological conditions in the area were also unsuitable for the application of aerosols, and much of the insecticide did not reach the canopy, but was blown away from the treated area.

It is concluded that aircraft applications of insecticide against G. palpalis are wasteful of insecticide, and would be very costly if substantial reductions in fly population were to be obtained. If insecticides are to be of value in such areas, ground methods of applying them would be almost certainly more effective, and less costly.