In a variety of laboratory and field experiments, avermectins have been tested against some 84 species of insects in ten orders, most of which are pests of livestock or horticultural crops or are of general nuisance value. This work is reviewed, comparing doses used, methods of application, and responses of the insects. Avermectins (abamectin and ivermectin) are toxic to almost all insects examined, although tolerance varies and death can be uncommonly slow, taking 24 h to 30 days. There is a marked absence of information on physiological processes that are affected by the pesticides, although at the cellular level they are thought to disrupt receptors for y-aminobutyric acid and glutamic acid in the central nervous system and muscular system. At high doses, treated insects are progressively immobilized, and although initially many can move when stimulated, this ability becomes lost. Some show a disturbed water balance and become distended with fluid, while others show disruption of moulting and metamorphosis. Feeding inhibition is commonly observed at sub-lethal doses. Avermectins affect many aspects of reproduction including mating behaviour, egg development, oviposition and egg hatching. The possibility is raised that these diverse disturbances are not all due to disruption of neuromuscular or central nervous system synapses, and the need for work in this area is stressed. Field studies have shown ivermectin to be most valuable in eradicating insect pests of livestock, but the use of abamectin against horticultural pests has produced less impressive results. The limited work on non-target species is discussed, and attention is drawn to some possible environmental consequences of excreted ivermectin on dung-breeding insects.

Females of Musca vetustissima Walker in the first ovarian cycle and of a wide range of body size were fed a range of measured quantities of protein-rich liver exudate. For a given amount of exudate, a greater proportion of large flies than of small ones matured oocytes; for a given size of fly, the proportion that matured oocytes increased with the amount of exudate ingested. Additionally, large flies matured more oocytes on less exudate than did small flies, which had fewer ovarioles.

The significance of morphological variation within the Thrips hawaiiensis (Morgan) species-group is examined. Multivariate analyses of four characters from 344 females and seven characters from 90 males show two distinct groups found throughout the Oriental, Pacific and American Regions, corresponding to T. hawaiiensis and T. florum Schmutz, and an intermediate group, exilicornis Hood, from Africa. The results are compared with previously published morphometric data concerning the separation of T. hawaiiensis and T. florum, and additional distinguishing characteristics are assessed. The distributions of the three forms as recognized in this study are summarized.

An electrophoretic method for the study of enzyme variation, which uses cellulose acetate sheets with an agar overlay for staining, the use of a very good general purpose buffer (citric-aminopropyldiethanol amine) and the use of sodium azide as a bacteriocide to allow long term storage of chemicals as solutions are described. Tests are reported of the technique on Tetranychus urticae Koch, Aedes aegypti (L.) and several species of Drosophila. The results demonstrate that the technique offers sensitivity equal to or greater than starch or polyacrylamide gel electrophoresis and that it is applicable to very small organisms, allowing either the testing of single individuals for large numbers of enzymes or the testing of fewer enzymes under different electrophoretic conditions (i.e. to detect cryptic variation under a single condition). The technique is efficient of time and materials, and safer than conventional methods.

In previous laboratory studies, it was demonstrated that baldcypress (Taxodium distichum) diets eliminated a critical gut protozoan, Pseudotrichonympha grassii, from Coptotermes formosanus Shiraki. The present authors surveyed field colonies of C. formosanus confined within baldcypress trees growing in a river in Louisiana and found P. grassii was present. Termites inhabiting baldcypress trees preferred pine (Pinus) and rejected baldcypress in choice tests in the field. Significantly more termites were recruited to baits when twice as much pine was offered, indicating that C. formosanus adjusted its foraging response to resource amount. In laboratory tests, sound baldcypress sapwood and heartwood depressed survival and gut protozoan counts in C. formosanus, but baldcypress infected with the basidiomycete fungus Rigidoporus sp. and an unidentified imperfect species was favourable for the termites and their symbionts. These results suggest an important role for microbial modification in termite host selection.

The aphelinids Encarsia adrianae sp. n. and E. cibcensis sp. n. are described from material in culture ex Bemisia tabaci (Gennadius) on beans at the C·A·B International Institute of Biological Control, Ascot, UK. They are descendants of material collected in Rawalpindi, Pakistan, from B. tabaci on Lantana camara.

The toxicity of two pyrethroid insecticides, S-bioallethrin and cypermethrin, was investigated over time at 12, 25 and 31°C in susceptible and kdr resistant strains of Blattella germanica (L.). Both strains showed a negative temperature coefficient (i.e., greater kill with decreasing temperature) for S-bioallethrin. The susceptible strain had a negative temperature coefficient for knockdown, but a positive temperature coefficient for mortality towards cypermethrin. The resistant strain had a negative temperature coefficient towards cypermethrin at all times. Resistance to S-bioallethrin was generally greatest at 25°C initially, although the difference between temperatures and the level of resistance diminished with time. Resistance to cypermethrin was significantly less at 12°C than at 25 or 31°C.

Chelonus chailini sp. n., which was discovered recently during a survey of potential biocontrol agents of the cocoa pest Conopomorpha cramerella (Snellen) in Malaysia, is described and illustrated. Five other gracillariid leaf-miners and bud-borers (Acrocercops globulifera Meyrick, A. diffluella van Deventer, A. caerulea Meyrick, A. phaeospora Meyrick and Epicephala chalybacma Meyrick) are cited as hosts of C. chailini, and brief notes on its biology are given.

The within-plant dispersion characteristics of Megalurothrips sjostedti (Trybom) on cowpeas were determined in studies in Nigeria. Iwao's regression procedure and Taylor's power law analysis were used to determine the relationship between the mean and variance of thrips counts. Both methods showed that adult thrips were randomly distributed within cowpea plants at initial low populations. At later high densities, Iwao's method provided a better fit of the population dispersion of larvae and adults and showed that both were aggregated. The negative binomial best described this aggregation at high population densities. Sequential count plans suitable for pest management surveys were developed using critical stop lines derived from Iwao's regression procedure and Taylor's power law, but the latter was found to require less effort to achieve the same level of precision. There was a functional relationship between the variance and mean of untransformed population counts, and the suitability of transformation functions is discussed.

Five sampling methods were evaluated for efficiency in estimating field populations of Megalurothrips sjostedti (Trybom) on cowpeas in Nigeria. The methods (sticky traps, water traps, sweep netting, shaking plants and the collection of whole plant samples) were judged on the basis of low sample variance, low cost and fidelity to absolute population trends. Shaking plants and water traps were the best sampling techniques on the basis of sample variance and cost. Shaking plants also showed the closest correlation with absolute population trends and is therefore recommended for rapid estimation of field populations of thrips. The performance of the usual alcohol method of sampling M. sjostedti on cowpeas (collecting racemes and flowers in alcohol) was not comparable with those of shaking plants and water traps, but was considered important because it sampled the infested structures, eliminating more transient visitors which might also be sampled by shaking plants.

The survival of Oryzaephilus surinamensis (L.) and Sitophilus granarius (L.) adults at the surface and centre of two 40-tonne bins of wheat, each aerated at about 10 m3/h per tonne was studied in separate experiments over three successive years. In one bin, fan operation was controlled manually, but in the other an automatic differential thermostat was used. This switched on the fan when the centre of the bin was 2°C warmer than the ambient. O. surinamensis always survived better than S. granarius in the same bin and position. Both species survived better at the surface of each bin than at the centre, and both died quicker at the centre of the bin with aeration controlled with a differential thermostat, where the grain temperature was usually less than 4°C, than in the bin with aeration regulated manually, which was mainly above 6°C. However, there was no difference between bins in the survival of either species at the surface. S. granarius always died out in both positions in both bins, but O. surinamensis always survived at the surface of both bins, and in one year it survived at the centre of the bin with aeration controlled manually.

Acclimation had a beneficial effect on Scottish clones of Aulacorthum solani (Kaltenbach) as seen in enhanced reproduction and development at 5°C, compared with non-acclimated clones at this temperature. In contrast, not all Myzus persicae (Sulzer) clones tested benefited. When reared at 5°C for a second generation, both species had slower nymphal development and M. persicae also had less efficient adult reproduction (a longer pre-reproductive period and reduced fecundity) compared with the first generation. Both species demonstrated a high capacity for recovery from low temperatures, A. solani being the better of the two. In general however, the ability of clones to survive, reproduce and develop at low temperatures or upon transfer to high temperatures, was variable and was not related to annual cycle, origin or organophosphorus resistance. These differing responses support previous results and are suggested as being an efficient means of ensuring variability in aphid populations surviving after winter.

The species composition and population dynamics of mosquito adults trapped at 76 sites in southern Israel are described. Almost 200 000 specimens representing 23 species were collected. Five species, Aedes detritus (Haliday), Culiseta subochrea (Edwards), Culex antennatus (Becker), Cx. martinii Medschid and Cx. poicilipes (Theobald), are new records for this area, with Cx. poicilipes being recorded for the first time outside Africa. Six types of distribution patterns were discerned. The most abundant species was Cx. pipiens L. (79·7% of the total catch) followed by Ae. caspius (Pallas) (10%), Anopheles sergentii (Theobald) (2·1%), An. tenebrosus Dönitz (1·8%) and Cx. perexiguus Theobald (1·3%). All other species found each made up less than 1%. The spatial and temporal patterns of mosquito species in southern Israel are discussed.

Field studies in Zimbabwe of the orientation of males of Glossina morsitans morsitans Westwood to decoy ‘females’ (9 × 3-mm rectangles of 2-mm thick brushed nylon, baited with sex pheromone, 15,19,23-trimethyl-heptatriacontane, and placed on a vertical, 1-m2 black cloth screen) demonstrated that (1) no olfactory response to air-borne pheromone was involved in the orientation of males to decoys, (2) the presence of decoys on a stationary screen did not increase the numbers of males landing on the screen, but they directed landings onto the decoys or the adjacent screen surface, (3) males did not differentiate between black or brown decoys, (4) males were more attracted to vertically oriented decoys on the screen surface than to decoys held away from the surface, and (5) males were more attracted to decoys at the centre of the screen than to decoys near the top or bottom edges. Points 1, 2 and 4 also applied in the case of G. pallidipes Austen using decoys dosed with its pheromone (13,23-dimethylpentatriacontane), but this species preferred black to brown decoys and showed less overt sexual activity than G. m. morsitans. Males of G. m. morsitans each removed 1–2μg of pheromone by contact with a decoy, leading to a gradual loss of the decoy's stimulatory power.

The efficiencies of people sampling cabbage plants in the field for total numbers of Myzus persicae (Sulzer) were found to differ. Significantly more aphids were counted on leaves taken to the laboratory than on leaves examined by inexperienced people in the field, but field counts by an experienced person did not differ significantly from the laboratory sample. The implications of differences between people and the possibility of correcting for them in surveys are discussed.

Survival rates of females of Musca vetustissima Walker were estimated as a function of their reproductive age, based on age-distributions of field females whose headwidths ranged from 1·5 to 2·5 mm. Females had a mean life expectancy of 140 day-degrees above 8°C, which was independent of fly size. They did not respond to baited traps during the first 15 day-degrees C of adult life. Thereafter, trappability varied with reproductive age but was affected by fly size only during the initial stage of the first ovarian cycle. Because ovarian development rates and female fecundity are dependent on fly size, the expected numbers of eggs laid by field females 1·5–2·5 mm in headwidth during their lifetime range from 28 to 106.

A number of tettigoniids belonging to the genera Sexava, Segestes and Segestidea are responsible for severe defoliation of coconut palm, oil palm and Pandanus spp. in Papua New Guinea. Most chemical and cultural methods of control are either impractical or uneconomic. The possibility of biological control was examined with reference to some of the natural enemies of Segestes decoratus Redtenbacher, in particular a parasite of nymphs and adults, Stichotrema dallatorreanum Hofeneder, as well as the egg parasites Triteleia atrella (Dodd), a species of Tetrastichus near T. dubius (Waterston) and a second species of Tetrastichus. It was concluded that S. dallatorreanum contributed to the control of Segestes decoratus in areas with an evenly distributed rainfall and that the parasite had potential as a biological control agent in areas where it is not endemic against pest species of Sexava, Segestes and Segestidea. A survey of the egg parasites showed that they were not effective in controlling the pests as they were only able to parasitize eggs in exposed oviposition sites. Egg predators of unknown identity were responsible for higher egg mortality than were the egg parasites.

A method is presented for quantifying moth area densities in individual crops and average densities over the total crop area. Mortality within the total Heliothis armigera (Hübner) adult population as a result of insecticide applications against larvae on cotton in the Sudan Gezira was found to be very substantial for males and virgin and inseminated females. The level of adult mortality which was previously unknown, was shown to be an important factor in Heliothis control. The relative importance of alternative host crops as source sites of adults which infest cotton was demonstrated. Initially, larval populations built up in groundnut fields between July and early September. Females emerging from groundnut fields colonized sorghum in late August and early September and cotton slightly later. Larval densities found in groundnut and sorghum fields correlated strongly with the average densities of virgin females found 12 days later. Groundnuts provided the most important source of adults. The virgin female population was in turn highly correlated with the remainder of the adult population (males and inseminated females), demonstrating that H. armigera adults attacking cotton within the Gezira are locally produced. Adults were attracted to sorghum in large numbers for feeding and oviposition, but survival there of older larvae (fourth to sixth instars) to the adult stage was only 25% of that in groundnuts. The implications for pest management are discussed.

Field and cage observations were made on Heliothis armigera (Hübner) in the Sudan Gezira to quantify nocturnal patterns of moth emergence, copulation and oviposition and the ages at which copulation and egg-laying occur. The flight activity pattern of males, virgins and inseminated females was assessed for crops with scarce or abundant sources of honeydew or nectar. A pronounced redistribution of moths between crops during the peak flight activity period (18.15-19.30 h) was demonstrated and measured, with the net exchange being approximately balanced. The direction of this movement was dependent upon the attractiveness of crops for feeding or oviposition. Male and female moths developing from larvae reared on groundnuts had significantly shorter lifespans when fed only water and less fat-body at emergence than moths developing from larvae reared on sorghum. When offered sugar solution, lifespans were significantly greater and differences in the lifespan of moths from groundnuts or sorghum were no longer evident. Adult feeding appears to compensate for any deficiencies associated with a larval diet of groundnut. Feeding was important for adult survival; there was a strong attraction of moths to crops with plentiful honeydew or nectar. A descriptive behavioural model is presented for the first half of adult life, until peak oviposition, and the uses of this model for pest management are discussed.