Aerial sampling for Nysius vinitor Bergroth was undertaken in the surface and upper air, at altitudes of 2 and 100-300 m, respectively, at Trangie in central New South Wales and at Corny Point, Yorke Peninsula, South Australia. Insects were sampled for 15 periods, each of 3-11 days, between October 1979 and February 1984, covering all months except January, March and May. N. vinitor was one of the most abundant insects caught in the upper air during the day and night (mean density of 652/106 m3), while the congeneric N. clevelandensis Evans was rarely caught at any time. N. vinitor was caught in all months sampled except for the winter months of July and August, and the largest daily catches occurred in September. Females were generally less common than males, although the relative incidence in the upper air catches frequently increased significantly from day to night. Fewer mature females were caught in the upper air (0-16·8%) than at the surface (0-48·4%). Densities were generally much greater in the surface air than in the upper air, although during the major flights of spring, there was less than a two-fold difference, indicating increased migratory activity. Migration occurred in a range of synoptic conditions resulting in the displacement of individuals in a variety of directions and distances depending on synoptic flow at the time of flight. Major migrations occurred at night, following dusk take-off, in disturbed weather associated with prefrontal airflows. These resulted in net southward displacements of ca 200-300 km depending on flight duration. It is suggested that major immigration flights into central-western New South Wales and regions to the south regularly occur in early spring (September-October) and probably arise from breeding areas in subtropical latitudes.

Loss rates of (Z)-8-dodecenyl acetate and related compounds from various dispensers were compared at 15, 20 and 29° C in the laboratory. Comparisons were also made of the performance of these dispensers in pheromone disruption trials against Cydia molesta (Busck) in peach orchards in Australia, in terms of the reduction of male captures at pheromone traps. Hollow-fibre and polymeric-laminate dispensers were superior to various polyethylene and silicone-rubber designs in providing a relatively constant release of pheromone in time, at rates readily modified by altering the dimensions of the dispensers.

The so-called ‘sewing blight ’ of tea in Assam is an effect of oviposition in the young leaves by two species of Eucharitid, Orasema initiator Kerrich and O. assectator Kerrich. The affected leaves develop brown spots round the oviposition punctures, wither prematurely and adversely affect the quality of the made tea. Normally only a small proportion of bushes is affected and these are associated with the presence of nests of an undetermined species of Pheidole.

An account is given of the life-history of O. assectator, and the developmental stages are briefly described. The eggs are laid singly in incisions made by the ovipositor on the underside of the leaf in parallel rows arranged lengthwise. The newly hatched larvae exist as free-living planidia on the leaf surface, whence they are carried by unknown means into the ants' nests in the soil beneath the tea bushes. Here the planidium transfers to the last-instar larva of the ant and penetrates its body. There it remains inactive until its host reaches the prepupal stage, whereupon endoparasitic feeding and development start. After the host pupa has formed, the parasite larva emerges, establishes itself below the thorax of its host, and remains there, feeding ectoparasitically, through two further instars, completely consuming the contents of its host. The mature larvae remain scattered in the ant's nest and pupate a few days later; both larvae and pupae are cared for by the worker ants.

The western part of the Mediterranean basin is a transitional biogeographical region for the distribution of the representatives of the main guilds of dung beetles; towards the south, Aphodiinae (dung-dwellers) become scarce, whereas northwards Scarabaeinae (soil-diggers) progressively disappear. The number of species in local dung beetle assemblages is enhanced by this double faunistic contribution. Annual dung beetle assemblages were sampled in two sub-Mediterranean sites, which differed by 600 m in elevation, in order to determine the phenological dynamics related to the way of using dung (dung-dwellers/Aphodiinae vs. soil-diggers/Scarabaeinae and Geotrupinae). Aphodiids were active all year round, although they were affected by summer drought and, at high elevation, by the length of the cold season. This reduced activity was related to an impoverishment of Aphodiinae and to reduced temporal segregation between species. In contrast, soil-diggers were not active all year round and showed different species assemblages in the two sites. An extension of the activity period of these beetles was observed due to the occurrence of cold resistant species at high elevation. Our results suggested that the occurrence of soil-diggers seemingly did not affect the seasonality of dung-dwellers; their local abundance showed no negative correlation and, most importantly, phenological differences between dung-dwellers were always significantly higher than the seasonal differences between dwellers and diggers.

Members of the pyrrole group are likely to have interesting properties that merit additional investigation as insecticides at the post-harvest stages of agricultural commodities. In the present work, the insecticidal effect of two new pyrrole derivatives, ethyl 3-(benzylthio)-4,6-dioxo-5-phenyl-2,4,5,6-tetrahydropyrrolo[3,4-c]pyrrole-carboxylate (3i) and isopropyl 3-(benzylthio)-4,6-dioxo-5-phenyl-2,4,5,6-tetrahydropyrrolo[3,4-c]pyrrole-carboxylate (3k) were studied as stored-wheat protectants against two major stored-product insect species, the confused flour beetle, Tribolium confusum Jaquelin du Val adults and larvae and the Mediterranean flour moth, Ephestia kuehniella Zeller larvae at different doses (0.1, 1 and 10 ppm), exposure intervals (7, 14 and 21 days), temperatures (20, 25 and 30°C) and relative humidity (55 and 75%) levels. For T. confusum adults, in the case of the pyrrole derivative 3i, mortality was low and it did not exceed 32.2% in wheat treated with 10 ppm 3i at 30°C and 55% relative humidity. Progeny production was very low (<1 individual/vial) in all combinations of 55% relative humidity, including control. In the case of the pyrrole derivative 3k, mortality reached 67.8% at 30°C and 55% relative humidity in wheat treated with 10 ppm after 21 days of exposure. Progeny production was low in all tested combinations (≤0.7 individuals/vial) of 55% relative humidity, including control. For T. confusum larvae, in the case of the pyrrole derivative 3i, at the highest dose, mortality was 82.2% at 25°C and 55% relative humidity whereas in the case of 3k it reached 77.8% at the same combination. In contrast, mortality at 75% relative humidity remained very low and did not exceed 13.3%. For E. kuehniella larvae, the highest mortalities, 44.4 and 63.3%, were observed in 10 ppm at 25°C and 55% relative humidity for both pyrrole derivatives. The compounds tested here have a certain insecticidal effect, but this effect is moderated by the exposure, the target species, the temperature and the relative humidity.

A method is described for the extraction of arthropods from soil.

Eleven soil samples from pastures in the neighbourhood of Moshi, Tanganyika, and at Kawanda, Uganda, yielded collections representing a population of 54,565 arthropods per sq. metre in the top 6 ins. of soil or, if three samples are adjusted in conformity with biological indications, of 38,417 per sq. metre.

Nine soil samples from coffee and cassava plantations and from fallow ground gave collections representing a population of 24,423 arthropods per sq. metre in the top 12 ins. (in some cases 8 ins.) of soil.

Twenty-five soil samples from a pasture near Cambridge, examined in a strictly comparable manner, gave collections representing a population of 90,238 arthropods per sq. metre in the top 6 ins. of soil.

It appears that the arthropod population in the uppermost 6 ins. of East African pasture soil is much smaller than, and only about half as large as, that in an English pasture.

The causes and consequences of the smaller arthropod population of tropical soil are briefly discussed, and a connection is suggested between the meagre arthropod (and earthworm) population and the large amount of ligneolis material found in the soil samples examined, This connection may also bear on the paucity of humus in some tropical soils.

The parasitoid Aphidius rhopalosiphi De Stefani-Perez was imported into New Zealand as a biological control agent against the rose-grain aphid (Metopolophium dirhodum (Walker)) in 1985. In 1988–89, the rate of parasitism by A. rhopalosiphi was studied by rearing fourth instar M. dirhodum collected from barley at Lincoln and other sites in Canterbury. The rate of parasitism at the time of peak aphid numbers at Lincoln was approximately 50% in winter barley and 100% in spring barley. In spring barley, peak numbers did not exceed five aphids per tiller, and regulation of aphid population density below this level was attributed to parasitism following a large immigration of adult A. rhopalosiphi. Suction trap catches of A. rhopalosiphi increased between 1984, prior to release, and 1989, while catches of M. dirhodum showed a corresponding decline.

The performance of Cactoblastis cactorum (Berg) as a biological control agent of the cactus weeds Opuntia ficus-indica and O. aurantiaca was assessed by compiling life-tables for each host-plant, in both a summer and a winter generation, at a site in South Africa. Egg predation, mostly by ants, ranged from 54 to 74% and was significantly higher on O. aurantiaca than on O. ficus-indica. Larval mortality on O. aurantiaca was high during the summer generation (65%), possibly because of dehydration of cladodes. Survival on O. aurantiaca was 55 and 60% of that on O. ficus-indica in the summer and winter generations, respectively. Adult mortality, calculated from the life-tables, was 45 and 84% in the summer and winter generations, respectively. The most important components of mortality were natural enemies in the summer generation and weather-related factors in the winter generation. Host-plant-related mortality was not as great as was formerly supposed.

Formulations of DDT have been applied to standard mud blocks. Toxicities to Glossina palpalis and Aëdes aegypti, and the proportions of insecticide recovered from an outer layer of approximately 0·1 mms. thickness have been compared.

Absorption of DDT in oil solutions was considerable, and amounts recovered from the outer layer were only from 8–19 per cent, of the total dosage applied. Adsorption of the insecticide from the oil on to mud occurred. There was some correlation between the capillary rise of the solvent and the extent of absorption. Toxicities of the blocks to test insects were low.

Using concentrations of 2 per cent., 5 per cent, and 10 per cent. in power kerosene, there was no increase in the proportion held on the surface. Application of excessively heavy dosages increased the amounts in the outer layers but there was a trend towards greater absorption, and therefore to greater waste, at the high dosages. Repeated applications similarly built up a larger dosage in the outer layer but did not increase the proportion there.

Emulsions were intermediate between solutions and wettable powders as regards absorption and toxicity.

Up to 77 per cent, of the insecticides applied as wettable powders was recovered from the outer layer, and toxicities were correspondingly high. When benzene hexachloride wettable powder was used there was rapid loss of benzene hexachloride from the surface by volatilisation. After fifteen days the dosage had decreased considerably and the percentage in the outer layer had fallen from over 70 per cent, to 20 per cent.

Loss of DDT by penetration of the carrier oil through the leaf cuticle may occur when an oil solution is sprayed on to vegetation. The extent of penetration varies with different plants.

There is an indication that small amounts of DDT are transferred from the inside of treated leaves to other untreated parts of young coffee and Avocado pear plants.

Deposits of DDT on leaves exposed to ordinary climatic conditions remained toxic to tsetse flies for a longer period when applied as an emulsion than as an oil solution. Deposits from a water suspension of a wettable powder were washed off readily by rain.

There is some evidence that continuous exposure to sunlight produced some chemical change in, and reduced the toxicity of, DDT deposits applied to glass plates as a solution in kerosene.

Sitophilus oryzae (L.) is a pest of stored grain, hut most strains tested so far fail to breed on yellow split-peas (Pisum sativum) and these can be used in admixture to protect other grains from infestation by the weevil. However, seven strains of S. oryzae have been found to breed on yellow split-peas, and the inheritance of this ability was investigated in two of these strains, one from Lesotho and the other from Trinidad. In each strain, the pattern of inheritance showed that the ability to breed on split-peas was controlled by a single autosomal recessive gene. It was not possible to distinguish whether the same genetic locus was involved in each strain. Control is either by two alleles at the same locus or by functionally similar alleles at different loci. There was some evidence that the genetic background of the two strains is different and that the Lesotho strain carries a sex-linked lethal gene. The existence of a heritable ability of some strains of s. oryzae to breed on split-peas suggests that the usefulness of admixture of split-peas with other grain may be limited

The practical results achieved in the past twenty-five years' work on the major insect pest problems of Mauritius are discussed.

The major insect pests studied are the white grubs of sugar-cane, Clemora smithi (= Phytalus smithi) and Oryctes tarandus; the sugar-cane moth borers, Proceras sacchariphagus, Sesamia vuteria, and Argyroploce schistaceana; the coconut scale-insect, Aspidiotus destructor; the pineapple mealybug, Pseudococcus brevipes; the cochineal insects of the prickly pears, Dactylopius tomentosus and D. indicus; fruit-flies; the biting flies, Stomoxys nigra and S. calcitrans; the red ant, Solenopsis geminata; the black ant, Technomyrmex detorquens; and termites.

The actual status of these pests is given in detail. Clemora smithi, which was first recorded in 1911, is still a major pest of sugar-cane in spite of the 43 species of parasites and 2 species of predators introduced to check it. Oryctes tarandus very seldom causes severe damage now to sugar-cane plantations. It is a sporadic pest, and has been definitely held in check since the Scoliid wasp, Scolia oryctophaga, was introduced from Madagascar in 1917.

The status of the three moth borers of sugar-cane and that of their parasites is fully dealt with. Of the five species of parasites introduced from Ceylon and Madagascar in 1938–40 to control Proceras sacchariphagus, only one has so far been recovered and its beneficial effect is very limited. An account is given of experiments on the mass liberation of the egg parasites, Trichogramma australicum and T. evanescens. The results were in both cases deceptive. The spotted borer, P. sacchariphagus, is a major pest of sugar-cane in some localities and further introductions of parasites from other cane-growing countries are recommended.

The coconut scale, Aspidiotus destructor, which, since 1927, threatened all the coconut plantations of the Island, is now under control, owing to the introduction from Ceylon and Java, respectively, of the predacious Coccinellids, Chilocorus nigritus and C. politus. The bionomics of the various parasites and predators of this scale in Mauritius are fully described.

A historical review is given of the introduction of the cochineal insects of prickly pear, Dactylopius indicus and D. tomentosus in the Island. The completely successful eradication of Opuntia tuna and O. monacantha, by these two Coccids is given as a typical example of the biological control of noxious plants by insects.

The pineapple mealybug. Pseudococcus brevipes, which is responsible for wilting disease, is considered to be one of the factors limiting the development of the pineapple industry in Mauritius. Spraying with a diesel-clay emulsion, though checking this pest, is limited in its application. Further introductions of parasites and predators are desirable.

The common white mealybug, Icerya seychellarum, is still a major pest of orchards and ornamental plants in spite of the presence of the local Coccinellid predators, Rodolia chertnesina and Exochomus laeviusculus. Practical control can be achieved by the use of banding grease coupled with the attacks of predators. No local parasite has been recorded in Mauritius.

Six species of Trypetids are recorded. Of these, the flies attacking cucurbitaceous fruits are the most harmful. Experiments with numerous attractants for fruit-flies are mentioned. The only bait showing any success in the control of the Dacus flies is the Mally fruit-fly bait. Parasites have been imported from South Africa and Ceylon without success. Further attempts should be made.

The bionomics and breeding places of the blood-sucking fly, Stomoxys nigra, are described.

The Red Ant, Solenopsis geminata, is a major pest of seedlings in Mauritius. It is now destroyed by the use of a diesel-clay emulsion. Baits containing thallium sulphate have been tried without success.

The rôle of the Black Ant, Technomyrmex detorquens, in preventing development of the Coccinellid predators on Icerya seychellarum is emphasised. Barber's poisoned bait has been found very useful against this household pest.

A review of the species of termites found in Mauritius as well as the various means of control used against them are given. An insecticidal powder containing arsenious oxide has given the best results.

During the last 25–30 years, 64 species of parasites and predators have been imported for the biological control of eight species of insects of major economic importance and of two species of noxious plants.

The results achieved indicate that the introduction of parasites and predators in insular countries like Mauritius should be carried out only after a thorough investigation of the various ecological, biotic and climatic factors existing between the country of exportation and the country of importation.

The rôle of cyclonic disturbance in the fluctuation of the parasite population is mentioned. Scoliid parasites, for instance, are generally scarce after violently disturbed weather and may sometimes remain so for two or three years after the disturbance.

Transgenic (Bt) cotton dominates Australian cotton production systems. It is grown to control feeding damage by lepidopteran pests such as Helicoverpa armigera. The possibility that these moths might become resistant to Bt remains a threat. Consequently, refuge crops (with no Bt) must be grown with Bt cotton to produce large numbers of Bt-susceptible moths to reduce the risk of resistance developing. A key assumption of the refuge strategy, that moths from different host plant origins mate at random, remains untested. During the period of the study reported here, refuge crops included pigeon pea, conventional cotton (C3 plants), sorghum or maize (C4 plants). To identify the relative contributions made by these (and perhaps other) C3 and C4 plants to populations of H. armigera in cotton landscapes, we measured stable carbon isotopes (δ13C) within individual moths captured in the field. Overall, 53% of the moths were of C4 origin. In addition, we demonstrated, by comparing the stable isotope signatures of mating pairs of moths, that mating is indeed random amongst moths of different plant origins (i.e. C3 and C4). Stable nitrogen isotope signatures (δ15N) were recorded to further discriminate amongst host plant origins (e.g. legumes from non-legumes), but such measurements proved generally unsuitable. Since 2010, maize and sorghum are no longer used as dedicated refuges in Australia. However, these plants remain very common crops in cotton production regions, so their roles as ‘unstructured’ refuges seem likely to be significant.

For optimal application of Nesidiocoris tenuis as a biological control agent, adequate field management and programmed mass rearing are essential. Mathematical models are useful tools for predicting the temperature-dependent developmental rate of the predator. In this study, the linear model and nonlinear models Logan type III, Lactin and Brière were estimated at constant temperatures and validated at alternating temperatures and under field conditions. N. tenuis achieved complete development from egg to adult at constant temperatures between 15 and 35°C with high survivorship (>80%) in the range 18–32°C. The total developmental time decreased from a maximum at 15°C (76.74 d) to a minimum at 33°C (12.67 d) and after that, increased to 35°C (13.98 d). Linear and nonlinear developmental models all had high accuracy (Ra2 >0.86). The maximum developmental rate was obtained between 31.9°C (Logan type III and Brière model for N1) and 35.6°C (for the egg stage in the Brière model). Optimal survival and the highest developmental rate fell within the range 27–30°C. The field validation revealed that the Logan type III and Lactin models offered the best predictions (95.0 and 94.5%, respectively). The data obtained on developmental time and mortality at different temperatures are useful for mass rearing this predator, and the developmental models are valuable for using N. tenuis as a biological control agent.

From field observations and laboratory rearings, the biology of Forcipomyia squamipennis I. & M. in cocoa plantations in Ghana was established as follows. Adult midges are found between buttresses of large shade trees, in crevices of decayed old logs, in hollow tree stumps and cocoa husk heaps. Swarming takes place at any time during the day in or around the resting place, while dispersal occurs in the early morning and in the late afternoon, the normal flight range being 5–6 m. The largest populations occur in the rainy season. Eggs are laid on moist decomposing wood, cocoa husks and other plant debris in batches of 40–90; the larvae hatch in 2–3 days and pupate after four moults, when about 12 days old; the pupal stage lasts 2–3 days. Adult females require liquid plant food for survival and oviposition, although the maturation of ova is independent of adult food intake or mating; unfertilised eggs do not develop. The maximum adult life span for both sexes is eight days in captivity. F. squamipennis undergoes at least 12 generations a year. Due to its abundance and continuous breeding in cocoa plantations, F. squamipennis is probably the most important Ceratopogonid cocoa pollinator in Ghana. Both sexes are efficient pollinators, but four times more males than females visit cocoa flowers.

Prostaglandin F (PGF) and E2 (PGE2) were assayed in the reproductive organs, salivary glands and egg-batches of laboratory-bred males and females of Hyalomma anatolicum excavatum Koch. Salivary glands and reproductive organs were dissected from unfed male and female ticks as well as from ticks that had fed for six days on rabbits; these organs were cultured for 24 and 72 h in tissue culture medium-199 with Earle's salt and HEPES buffer at pH 7·6 and 37°C. The amounts of PGF and PGE2 accumulated in the culture were determined by a radioimmunoassay using specific antibodies. Both salivary glands and reproductive organs were shown to synthesise PGEa and PGF. This synthesis and also the prostaglandin content of the organs were significantly increased after engorgement. The synthesising capacity and content of PGE2 and PGF in both the salivary glands and reproductive organs were higher in the female than in the male.

Reproductive interference is one of the major factors mediating species exclusion among insects. The cryptic species Middle East-Asia Minor 1 (MEAM1) and Mediterranean (MED) of the whitefly Bemisia tabaci complex have invaded many parts of the world and often exhibit niche overlap and reproductive interference. However, contrasting patterns of competitive displacement between the two invaders have been observed between regions such as those in USA and China. Understanding the roles of reproductive interference in competitive interactions between populations of the two species in different regions will help unravel other factors related to their invasion. We integrated laboratory population experiments, behavioural observations and simulation modelling to investigate the role of reproductive interference on species exclusion between MEAM1 and MED in China. In mixed cohorts of the two species MEAM1 always excluded MED in a few generations when the initial proportion of MEAM1 was ⩾0.25. Even when the initial proportion of MEAM1 was only 0.10, however, MEAM1 still had a higher probability of excluding MED than that for MED to exclude MEAM1. Importantly, we show that as MEAM1 increased in relative abundance, MED populations became increasingly male-biased. Detailed behavioural observations confirmed that MEAM1 showed a stronger reproductive interference than MED, leading to reduced frequency of copulation and female progeny production in MED. Using simulation modelling, we linked our behavioural observations with exclusion experiments to show that interspecific asymmetric reproductive interference predicts the rate of species exclusion of MED by MEAM1. These findings not only reveal the importance of reproductive interference in the competitive interactions between the two invasive whiteflies as well as the detailed behavioural mechanisms, but also provide a valuable framework against which the effects of other factors mediating species exclusion can be explored.

Grape phylloxera, Daktulosphaira vitifoliae Fitch, is an important pest of grapevines (Vitis vinifera L.) (Vitaceae). Using microsatellite DNA markers it was demonstrated strong associations can exist between D. vitifoliae asexual lineages and vine host type within a vineyard. Also, in excised root bioassays, D. vitifoliae collected from three regions where different genotypic classes predominated showed host-specific differences in life table parameters of reproductive rate and intrinsic rate of increase. Lastly, comparisons of mitochondrial DNA (cytochrome oxidase I) sequences revealed that D. vitifoliae in Australia have paraphyletic origins and fall into two clades partially related to vine host usage. These findings indicate introduction of separate lineages of D. vitifoliae which have close host associations and as such, have important implications for management of this pest in Australia.

In a field of six hectares, the number of palms foraged by Anoplolepis custodiens (Smith) increased from January to December 1988 from 32 to 85% and the ant activity scores (0–3 system) from 0.5 to 2.0. During the same time, the population of the coconut bug, Pseudotheraptus wayi Brown (Heteroptera: Coreidae) as well as the damage it caused, decreased significantly. A significant relationship between low percentages of damaged nutlets and high ant scores of the palms could be established. The nut set of ant foraged palms was 2–3 times higher than that of comparable palms in an immediately adjacent field free of A. custodiens. Palms with high A. custodiens scores had invariably high scores of the coconut aphid, Cerataphis variabilis Hille Ris Lambers (Homoptera: Aphididae). The performance of the palms was not visibly affected by the aphids.