The subterranean termites in the genus Reticulitermes have a complex and plastic life cycle, which has been the subject of a number of publications over the past century. Given the inherent difficulties in studying such cryptic, eusocial organisms it is not perhaps surprising that the literature on their biology has failed to reach a consensus. An overview of the literature is given, which is followed by a discussion of the various theories on the life cycle of Reticulitermes spp. A substantial proportion of the review focuses on the French literature, which constitutes the majority of the primary sources and can be difficult to access. There are many discrepancies in the literature in terms of the number of instars, the definition of workers and the question of whether they should be termed pseudergates or, potentially, an additional terminology used to differentiate between pseudergates and the true workers seen in the higher termites (Isoptera: Termitidae). It remains very difficult to compare publications as there is little conformity; a problem that is aggravated by a general absence of drawings of the relevant instars. Further work on the biology of Reticulitermes is clearly required. There is also a need for researchers to agree on a standard terminology for this genus. A glossary is provided for the various synonyms and definitions.

A study was undertaken to identify the major larval habitats of the Anopheles gambiae (Giles) complex in rural Gambia. Mosquito larvae and pupae were sampled along transects and in specific habitats in the central region of the country during the rainy seasons of 1996 and 1997. The sampling showed that the major breeding sites were located on the flooded alluvial soils bordering the river. The largest numbers of larvae were found during September, one month after the peak rains. Polymerase chain reaction analysis of specimens showed that Anopheles melas (Theobald) was the dominant species in the flooded areas (81.5%), followed by A. gambiae sensu stricto (Giles) (18.0%) and A.arabiensis (Patton) (0.5%). By sampling in specific habitats it was evident that A.arabiensis was mainly breeding in rain-fed rice fields along the edge of the alluvial soils. Anophelesmelas and A.gambiae s.s. often coexisted but whereas A. melas were found in water with a salinity of up to 72% sea water (25.2 g NaCl l−1), A.gambiae s.s. only occurred in water with up to 30% sea water (10.5 g NaCl l−1). Anophelesmelas larvae were found in association with plant communities dominated by sedges and grasses (Eleocharis sp., Paspalum sp., Sporobolus sp.) and sea-purslane Sesuviumportulacastrum (L.) and the presence of cattle hoof prints, whereas A.gambiae s.s. larvae mainly occurred in association with Paspalum sp. and Eleocharis sp. The study showed that even during the peak rainy season, breeding of the A.gambiae complex is almost entirely restricted to the extensive alluvial areas along the river.

Intensive chemical treatments have led to the development of a number of insecticide resistance mechanisms in the peach–potato aphid Myzus persicae (Sulzer). Some of these mechanisms are known to be associated with negative pleiotropic effects (resistance costs). Molecular and biochemical methods were used to determine the genotypes or phenotypes associated with four insecticide resistance mechanisms in single aphids from sexually-reproducing populations in southern France. The mechanisms considered were E4 and FE4 carboxylesterase overproduction, modified acetycholinesterase, and kdr and rdl resistance-associated mutations. A new method for determining individual kdr genotypes is presented. Almost all resistant individuals overproduced FE4 carboxylesterase, whereas modified acetylcholinesterase was rare. Both the kdr and rdl resistance mutations were present at high frequencies in French sexually-reproducing populations. The frequencies of insecticide resistance genes were compared before and after sexual reproduction in one peach orchard at Avignon to evaluate the potential impact of selection on the persistence of resistance alleles in the over-wintering phase. The frequencies of the kdr and rdl mutations varied significantly between autumn and spring sampling periods. The frequency of the kdr mutation increased, probably due to pyrethroid treatments at the end of the winter. Conversely, the frequency of the rdl mutation decreased significantly during winter, probably because of a fitness cost associated with this mutation.

The establishment of the predatory histerid beetle, Teretrius nigrescens Lewis, following its field release in south eastern Kenya in 1992, and its impact on populations of the larger grain borer, Prostephanus truncatus (Horn), in woodland habitats is evaluated. Pheromone trap catch data show a single strong peak of P. truncatus from November to January, coincident with the short rains. Comparisons of P. truncatus pheromone trap catches before and after predator establishment, and in areas with and without T. nigrescens, show a sustained decline of over 80% in P. truncatus abundance over a 5-year period, following the establishment T. nigrescens. Concurrent laboratory studies of the impact of T. nigrescens on populations of P. truncatus raised on a wood substrate showed a 77% reduction in the growth of the pest population. These results are compared with published findings of the impact of T. nigrescens as a biological control agent of P. truncatus in west Africa.

In this study, the question of whether Childers canegrub, Antitrogus parvulus (Britton) overwinters in the subsoil was addressed. Irrigated fields of sugarcane were sampled during a 2-year period near Bundaberg in southern Queensland. Antitrogus parvulus overwintered as second and third instars at each of three sites. During autumn and winter third instars of different allochronic (separated in age by 12 months) populations occurred together and could not be readily separated. Field-collected third instars were reared on ryegrass and separated into two age groups based on the date of pupation. Third instars in the first year of their life cycle (young third instars) remained at shallow depth (100–200 mm) and did not overwinter in the subsoil as once thought. Minimum temperatures during winter were 13–16°C and did not prevent young third instars from feeding and gaining weight. Third instars in their second and final year moved downwards from late summer and pupated in the subsoil at 293–425 mm in spring. General phenology was as previously reported with first instar larvae occurring from January until April, second instars from January until November and third instar larvae throughout the year. Prepupae and pupae were found between October and December and adults occurred in soil during November and January. Batches of eggs occurred at a mean depth of 350 mm. First and second instars occurred predominantly at relatively shallow (100–200 mm) depths in the soil profile. All stages tended to be most common under rows of sugarcane rather than in the interrow.

The responses of male and female Lutzomyia longipalpis (Lutz & Neiva) to different wavelengths of light was tested by presenting the sandflies with two light sources simultaneously, a series of test wavelengths between 350–670 nm and a 400 nm control. To test whether L. longipalpis could discriminate between the test and control, three sets of experiments were carried out in which the test wavelengths were presented at higher, equivalent or lower intensity than the control. In all three experiments, ultra-violet (350 nm) and blue-green-yellow (490–546 nm) light was more attractive to L. longipalpis than the control wavelength. However, at low intensity, UV was less attractive, than equivalent or higher intensity UV light. At intensities equivalent to or higher than the control wavelength, ultra-violet light was more attractive than blue-green. Furthermore, at low intensity, green-yellow (546 nm) light was more attractive to males whereas blue-green (490 nm) was more attractive to females. Blue-violet (400 nm) and orange-red (600–670 nm) light were least attractive in all three sets of experiments. Response function experiments indicated that the responses were dependent on both intensity and wavelength and that therefore more than one photoreceptor must be involved in the response. The results indicated that L. longipalpis can discriminate between different wavelengths at different intensities and thus have true colour vision. It also suggests that L. longipalpis may be able to navigate at dusk or under moonlight or starlight conditions using light in the blue-green-yellow part of the spectrum. The difference in response of males and females to light in this region is interesting and may indicate the different ecology of the sexes at night. Overall, these results may have important implications for sandfly trap design.

Forty-one accessions of wild and cultivated wheats belonging to 19 Triticum species were tested in the field for resistance to three species of aphids, Rhopalosiphum padi Linnaeus, Sitobion avenae Fabricius and Schizaphis graminum Rondani. Antibiotic resistance was estimated by the increase in biomass of aphids over 21 days on adult plants. Overall resistance was estimated by the plant biomass lost due to aphid infestation. All three species of aphids survived and reproduced on all wheats, and reduced spike biomass compared to uninfested controls. The level of antibiosis varied among wheat species and among accessions, with accessions from three, five and one species showing antibiosis to R. padi, S. avenae and S. graminum, respectively. Overall resistance to the three aphid species was observed in five to seven accessions per aphid species. Resistance was usually specific to one aphid species. The frequency of accessions with antibiosis or overall resistance was associated with the ploidy level of the plant species. Except for overall resistance to R. padi, resistance was highest for diploid species and lowest for hexaploid species. No consistent relationship between resistance and level of domestication was detected. Accessions of the wild wheats, Triticum boeoticum Bois, Triticum tauschii (Coss.) Schmal. and Triticum araraticum Jakubz. exhibited high levels of resistance to aphids, as did Triticum monococcum L. which is derived from T. boeoticum. Nevertheless, individual susceptible or resistant accessions occurred at all levels within the evolutionary tree of wheat.

Peach shoot volatiles were attractive to mated female oriental fruit moth, Cydia molesta (Busck), in a dual choice arena. No preference was observed between leaf odours from the principle host plant, peach, and the secondary host plant, apple. Twenty-two compounds were identified in headspace volatiles of peach shoots using gas chromatography–mass spectrometry. Green leaf volatiles accounted for more than 50% of the total emitted volatiles. A bioassay-assisted fractionation using different sorbent polymers indicated an attractant effect of compounds with a chain length of 6–8 carbon atoms. The major compounds of this fraction were tested either singly or in combinations for behavioural response of females. Significant bioactivity was found for a three-component mixture of (Z)-3-hexen-1-yl acetate, (Z)-3-hexen-1-ol and benzaldehyde in a 4:1:1 ratio. This synthetic mixture elicited a similar attractant effect as the full natural blend from peach shoots as well as the bioactive fraction.

The effect of plant architecture, in terms of leaf hairiness, and prey spatial arrangement, on predation rate of eggs of the spider mite, Tetranychus urticae Koch, by the predatory mite Phytoseiulus persimilis Athias-Henriot was examined on cut stems of chrysanthemums. Three levels of leaf hairiness (trichome density) were obtained using two different chrysanthemum cultivars and two ages within one of the cultivars. The number of prey consumed by P. persimilis was inversely related to trichome density. At low prey densities (less than ten eggs per stem), prey consumption did not differ in a biologically meaningful way between treatments. The effect of prey spatial arrangement on the predation rate of P. persimilis was also examined. Predation rates were higher in prey patches on leaves adjacent to the release point of P. persimilis, but significantly greater numbers of prey were consumed in higher density prey patches compared to low density patches. The predators exhibited non-random searching behaviour, spending more time on leaves closest to the release point. The implications of these findings for biological control and predator–prey dynamics are discussed.

Using a large set of microsatellites, the genetic relationships between three closely related Australian fruit fly species, Bactrocera tryoni (Froggatt), B. neohumeralis (Hardy) and B. aquilonis(May) were investigated. Bactrocera tryoni and B. neohumeralis are sympatric, while B. aquilonis is allopatric to both. The sympatric species, B. tryoni and B. neohumeralis, were found to be genetically distinct. It is likely that despite differences in mating time between these two species, some gene flow still occurs. In contrast, the sibling species B. tryoni and B. aquilonis were found to be closely related, despite allopatry. The level of genetic divergence was similar to that found within eastern Australian populations of B. tryoni. Consideration of all available genetic data suggests that this similarity is not due to recent (i.e. within the last 30 years) displacement of B. aquilonis by B. tryoni from the B. aquilonis region (north-western Australia). Instead the data suggests that, at least in the areas sampled, asymmetrical hybridization may have occurred over a longer timescale.

Studies examining and using pattern variation in insects for identification and characterization of individuals and populations have been limited by the methods available for quantifying wing patterns objectively. In this paper, differences in wing pattern are demonstrated statistically using moment invariant data sets generated automatically from digitized images of the speckled wood butterfly, Pararge aegeria (Linnaeus). Studies with other biological subjects have already shown moment invariants to work well with outline shapes and silhouettes. A pilot study with replicated monochrome photographs of a single butterfly showed the method could detect pattern differences between wing surfaces, even in the presence of simulated wing fading and damage. In a further study of the wings of 228 specimens, multivariate analyses of variance using the moment data reliably detected differences between groups of butterflies according to sex, geographical origin and culture history. Potential applications and future improvements of the moment methodology are considered.