Rapid, precise and timely identification of invasive pest insects such as aphids is important and a challenge worldwide due to their complex life cycles, parthenogenetic reproduction, sex and colour morphs. In this respect, DNA barcoding employing a 658 bp fragment of 5′ region of the mitochondrial cytochrome oxidase I (CO-I) gene is an effective tool in addressing the above. In the present study, we employed CO-I for discriminating 142 individuals representing 32 species of aphids from India. Sequence analyses revealed that the intraspecific and interspecific distances ranged from zero to 3.8% and 2.31 to 18.9%, respectively. In addition, the study also showed for the first time the prevalence of three cryptic species, namely Brevicoryne brassicae (Linnaeus), Hyperomyzus carduellinus (Theobald) and Brachycaudus helichrysi (Kaltenbach) from India. Our work has clearly demonstrated that DNA barcoding is an efficient and accurate method for identification of aphid species (including cryptic species), an approach that potentially could play an important role in formulating viable pest management strategies, more especially biocontrol.

Areas in Argentina, Bolivia, Brazil and Paraguay were searched for the cassava mealybug, Phenacoccus manihoti Matile-Ferrero. The mealybug was located in the Paraguay River basin in the Santa Cruz de la Sierra area of eastern Bolivia, the Mato Grosso do Sul state in South-Western Brazil and in Paraguay east of the Paraguay River. Mealybug populations were extremely low in all areas but there was a period of increase from August to December. Eighteen species of natural enemies were found attacking P. manihoti: the most abundant and also most important were a solitary, internal parasitoid, Epidinocarsis lopezi (DeSantis) (Hymenoptera: Encyrtidae), Hyperaspis notata Mulsant and Diomus spp. (Coleoptera: Coccinellidae), and Ocyptamus spp. (Diptera: Syrphidae). Collections of a closely related mealybug, Phenacoccus herreni Cox & Williams yielded two additional encyrtid parasitoids, Epidinocarsis diversicornis (Howard) and Aenasius sp. nr vexans Kerrich, but they did not survive on P. manihoti. Four parasitoids (E. lopezi, E. diversicornis, Parapyrus manihoti Noyes and Allotropa sp.) and four predators (H. notata, Diomus sp., Sympherobius maculipennis Kimmins, and Exochomus sp.) were sent for quarantine. With the exception of Parapyrus manihoti, all mentioned natural enemy species were forwarded to the International Institute of Tropical Agriculture at Ibadan, Nigeria for mass rearing and subsequent release.

Over a quarter of a century has now elapsed since the genius of Ross convicted mosquitos of responsibility for the spread of malaria, but the factors involved in the distribution of the insects in Nature are hardly better understood to-day—when, in addition to filariasis and malaria, they have been inculpated in respect of the transmission of at least two other major diseases—than they were at the time of the original discovery of August 1897.

Experiments in Malawi showed that the (log) number of males of Diparopsis castanea Hmps. attracted to sex pheromone traps was linearly related to the (log) number of virgin females used as attractant. Virgins remained sexually attractive for up to 31 days but were maximally attractive three nights following emergence; 97·7% of light-trapped females were mated, a small proportion having mated four times. Numbers of matings were directly correlated with temperature at 22.00 h, but relative humidity had little effect. Mean fecundity of mated females was 152 ± 10·3 eggs, multiple mating influencing egg fertility rather than total oviposition. Potential fecundity was linearly related to body weight on emergence. Peak oviposition of unfertilised eggs by virgins occurred at about nine nights following emergence. Of emerging females 2% were barren. Only 1·4% of females mated twice in one night when confined outdoors with males, and there was no difference in the abilities of newly emerged males or males up to four days old to mate with newly emerged females or females up to four days old. Although outdoors males mated on average 0·8 times per night throughout their life, and were capable of mating twice per night, mating propensity of males under laboratory conditions was much lower. Males responded to female sex pheromone throughout the calling period of the female, individuals completing up to 143 orientations during a night without the occurrence of lasting physiological habituation to the pheromone. The importance of this in any control programme aimed at disrupting pheromone communication between the sexes is discussed.

Delphacodes kuscheli Fennah is the vector of maize rough dwarf virus, that affects maize production in central Argentina. The spatial and temporal abundance pattern of the insect vector was studied from October 1992 to November 1994, within endemic and non-endemic areas of the crop disease. Insect density was estimated every 7–15 days during spring and summer (maize season) or monthly during autumn and winter from high (6 m) and low (1.5 m) sticky traps placed at eight sampling stations along a 300 km transect. Each year, D. kuscheli density increased from October, peaked in December, to decrease afterwards and disappear in May. Density was lower in the nonendemic area and higher in the endemic one. The average absolute difference of density between sampling station pairs increased with the distance between the sampling stations (R2=0.85), and the correlation of density changes decreased with the distance between the sampling stations (R2=0.78), suggesting that the population dynamics were affected more by local than by regional factors. There was a significant correlation (with a 36 days lag) between the normalized difference vegetation index (NDVI) (calculated from 15 days maximum value composites images of NOAA-11 meteorological satellites) and D. kuscheli abundance. Based on this regression model, and using the time series of the satellite derived NDVI values, maps of the distribution and abundance of D. kuscheli within the study area for the spring and summer of 1992 were produced.

Simple laboratory methods are described for assessing the potency and persistence of insecticides. Some of the newer synthetic insecticides have been tested by these methods against seven arthropod pests of medical importance.

Initial potency was judged by the mortality of insects exposed to standard films of oil solutions of the compounds, on filter papers. The approximate order of potency of the samples tested was:—

γBHC>dieldrin>aldrin=pyrethrins>chlordane=DDT= “Pyrolan” =allethrin> toxaphene.

Residual action was judged by the mortality of batches of bed bugs exposed to films of the insecticides, at intervals up to six months after preparation. The approximate order of persistence was:—

dieldrin=DDT=toxaphene>“Pyrolan”>γBHC=chlordane=aldrin>allethrin, pyrethrins.

The carob moth, Ectomyelois ceratoniae, a pest of Punica granatum, overwinters as a larva. In this study, physiological changes, water content, cold hardiness and supercooling points (SCPs) in relation to ambient temperature in the overwintering period (October to March) and changes of these factors between diapausing (February) and non-diapausing (September) larvae were studied. Pupae that were derived from diapausing larvae (April) and  from non-diapausing larvae (August) were also compared. Total body sugar, lipid and protein contents increased with decrease in the temperature and reached the highest levels (12.82, 1.99 and 6.11 mg g−1 body weight, respectively) in February, but glycogen content decreased and reached the lowest level (1.12 mg g−1 body weight) in February. There were significant differences in the levels of these compounds between diapausing and non-diapausing larvae, and pupae that were derived from diapausing and non-diapausing larvae. Trehalose and myo-inositol contents increased during diapause and reached the highest levels (0.50 and 0.07 mg g−1 body weight, respectively) in February. There were significant differences in the levels of these compounds between diapausing and non-diapausing larvae, but the differences between pupae that were derived from diapausing and non-diapausing larvae were not significant. The SCP of diapausing larvae (−17.3 °C) was significantly lower than in the non-diapausing larvae (−12.0 °C). SCP decreased gradually in autumn and reached the lowest level in the middle of winter. Changes of cold hardiness were inversely proportional to SCP changes. The lowest levels of water (65%) and weight (43.13 mg) were recorded in January and March, respectively. Most probably, lipids play a role as energy reserve, and low-molecular weight carbohydrates and polyols provide cryoprotection for overwintering larvae of the carob moth. Since the overwintering larvae die at temperatures above the SCP, the carob moth larvae were found to be a chill-intolerant insect.

To advance our restricted knowledge on mosquito biodiversity and distribution in Belgium, a national inventory started in 2007 (MODIRISK) based on a random selection of 936 collection points in three main environmental types: urban, rural and natural areas. Additionally, 64 sites were selected because of the risk of importing a vector or pathogen in these sites. Each site was sampled once between May and October 2007 and once in 2008 using Mosquito Magnet Liberty Plus traps. Diversity in pre-defined habitat types was calculated using three indices. The association between species and environmental types was assessed using a correspondence analysis. Twenty-three mosquito species belonging to traditionally recognized genera were found, including 21 indigenous and two exotic species. Highest species diversity (Simpson 0.765) and species richness (20 species) was observed in natural areas, although urban sites scored also well (Simpson 0.476, 16 species). Four clusters could be distinguished based on the correspondence analysis. The first one is related to human modified landscapes (such as urban, rural and industrial sites). A second is composed of species not associated with a specific habitat type, including the now widely distributed Anopheles plumbeus. A third group includes species commonly found in restored natural or bird migration areas, and a fourth cluster is composed of forest species. Outcomes of this study demonstrate the effectiveness of the designed sampling scheme and support the choice of the trap type. Obtained results of this first country-wide inventory of the Culicidae in Belgium may serve as a basis for risk assessment of emerging mosquito-borne diseases.

The effects of maize–cowpea intercropping on three lepidopteran stemborers (Chilo partellus (Swinhoe) C. orichalcociliellus (Strand) and Sesamia calamistis Hampson) and their natural enemies were studied in Kenya. Oviposition was not affected by intercropping, but significantly fewer larvae and pupae were found in the intercrop. Egg parasitism was significantly higher in the intercrop reaching as high as 80% and was positively density dependent. Larval and pupal parasitism remained between 3 and 20%, but neither of these were affected by intercropping or host density. The main predators, ants and wandering spiders, were not augmented by intercropping, but an inverse relationship in abundance was found between these two predator groups. It is concluded that maize intercropped with cowpea has only limited potential as a method of controlling the key pests in maize.

Migration and colonization of the coconut palm by Eriophyes guerreronis (Keifer) was studied in St Lucia in the West Indies. Mites were not found in unfertilized flowers but were present within a few weeks of fertilization. Nuts remained vulnerable to colonization for a number of months, and mites were present on nuts for up to 13 months. Protection of nuts for the first few months after fertilization is of most importance. On the tree, much migration could be due to mites walking in large numbers across nut surfaces, and they could move from one inflorescence to another if the two were in contact. Increased nut damage appeared to encourage mite migration.

Indications of the type of paddy grain most commonly infested by Sitophilus sasakii (Tak.) and Rhyzopertha dominica (F.) have been obtained from the examination of infested samples of paddy grown in Trinidad, W.I., and in British Guiana.

Small-scale experiments with sound mature paddy have shown that S.sasakii is unable to feed and breed in a grain with an intact husk, even when the moisture content is high. It is also probable that R. dominica finds it extremely difficult to attack and infest such grains.

The rapid multiplication of S. sasakii in paddy is dependent on there being a high proportion of grains with badly damaged husks. Infestation can occur in grains with a slight separation of the lemma and palea, or with slightly split husks, but the adult that develops is often unable to emerge from such grains.

In studies in southern England, the relative abundance of the hymenopterous parasites attacking Metopolophium dirhodum (Wlk.) and Sitobion avenae (F.) differed between their hosts, between years (1973–79) and on whether they were assessed using field or laboratory-reared mummies. Species of the complex of Aphidius uzbekistanicus Luzhetzki were usually the commonest parasites, especially from mummies of M. dirhodum, while Aphidius picipes (Nees) was less common and tended to attack mainly S. avenae; Toxares deltiger (Hal.) was common only in 1979. Species of hyperparasites emerged most frequently from mummies of M. dirhodum, except for Dendrocerus carpenteri (Curt.), which emerged most often from S. avenae.

Rastrococcus invadens Williams, a serious pest of fruit crops in West Africa was studied under controlled conditions. The different stages of the mealybug are described and data given on development times, adult lifespan, fecundity, sex ratio and mortality rates. Similar data are also given for a primary parasitoid, Gyranusoidea tebygi Noyes. The parasitoid completed almost two generations for each one of the mealybug and had a female-biased sex ratio compared with a male-biased one for R. invadens. The parasitoid did not parasitize other species of mealybugs offered. G. tebygi was considered a suitable candidate for a biological control programme and was introduced into Togo in October 1987.

Long distance migration by adults of Chortoicetes terminifera (Wlk.) in Australia was shown to be associated with the accumulation of fat-body lipid. Lipid was accumulated if the plant growth index was 0·3 or more within a week of the final moult; when the plant growth index was less than 0·3, there was little fat accumulation. Locusts with large amounts of fat-body lipid migrated on nights with warm strong winds, while those with little persisted.

A severe outbreak of the Spruce Sawfly (Diprion polytomum, Htg.) in Eastern Canada led to a request to Farnham House Laboratory to investigate, and if possible collect and export, the parasites of this insect in its native home in Europe.

Work started in 1932 and it was found that D. polytomum was a comparatively rare insect in Europe, though widely distributed. It is heavily parasitized, 31 species of Hymenopterous and Dipterous parasites having been found up to the present. Nearly twenty-eight million parasitized cocoons and eggs of this and other species of Diprion have been collected and despatched from Europe, and work is still continuing.

Previous to the present work only 13 species of parasites, a list of which is given, were recorded from this host.

Of the 31 species now known, 15 are primary, 5 can be primary or secondary, and 9 secondary only; in 2 cases the status is not known.

Descriptions of all the species are given and in the case of the obligatory and facultative primaries, the biology and immature stages are also described and notes added on their suitability for introduction into Canada. A key to the adult parasites is given, and a key to the larval stages of the primary and facultative primary parasites. Some practical notes are also given, including methods of accelerating the emergence of parasites in winter and methods of preparing parasite larvae for examination and identification.

In order to understand how the malaria vector Anopheles arabiensis Patton exists in the extremely hot and arid environment (mean annual rainfall 21 mm) in Northern Province, Sudan, regular sampling from breeding places and resting sites was undertaken during 1978 and 1979 at four villages along the River Nile downstream (i.e. northwards) from Dongola. The population density of A. arabiensis was lowest during the flood season (July—October) and increased as the river flow decreased during November—June. Thus there was an inverse relationship between the Nile water level and A. arabiensis production. Prolific breeding in riverside pools was the main source of A. arabiensis as the river receded. During the annual flood, when riverside pools were all inundated, A. arabiensis continued breeding at low densities in sheltered sites such as wells and pits. Breeding also occurred in all months in association with the weed Potamogeton crispus in slow reaches of the river. Adult females fed regularly on blood, with gonotrophic concordance in all months, and there was no evidence of aestivation. Outdoor biting activity occurred throughout the night, with a peak between 2100 and 0500 h. Daytime searches indoors and outdoors indicated that resting females A. arabiensis are almost entirely endophilic in the study area.

The tobacco-feeding race of Myzus persicae (Sulzer), formerly known as M. nicotianae Blackman, was introduced into Chile during the last decade. In order to evaluate the genetic diversity and insecticide resistance status of Chilean tobacco aphid populations, a field survey was conducted in 35 tobacco fields covering a 300 km latitudinal survey. The populations sampled were characterized using microsatellite markers and morphometric multivariate analysis. Insecticide resistance levels were assessed through a microplate esterase assay and the mutation status of the kdr gene. All samples collected corresponded to the same anholocyclic aphid genotype, and showed morphological variation within the range expected for the tobacco-feeding race of M. persicae. Esterase activity showed the level and variability expected for an R1 clone lacking mutations in the sodium channels (susceptible kdr), thus corresponding to a type slightly resistant to organophosphate and carbamate, and susceptible to pyrethroid insecticides.

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.

Serial exposure of a susceptible laboratory strain of Phthorimaea operculella (Zell.) recently obtained from the field to granulosis virus over six generations produced a 140-fold increase in LD50. The evidence suggests that this was due to a change in frequency of a resistance gene within the population. An attempt to select for even greater resistance in an already highly resistant laboratory strain resulted in only a small increase, due mainly to reduced variability in response of the population. The implications of resistance to viral insecticides developing under field conditions are discussed.