The occurrence of Eldana saccharina (Lepidoptera: Pyralidae) was monitored in grids represented by plots in 12 nematicide trials in South African sugarcane fields. The trials encompassed a total of eight plant cane crops and 22 ratoon crops and were situated within commercial cane fields. Several measurements were made to characterize the damage caused by E. saccharina. These included the number of internodes per stalk, the percentage of internodes damaged and the percentage of stalks damaged. The mapping of E. saccharina infestation in plant crops of sugarcane showed that the borders of the trials were as infested as the centre, indicating invasion from outside the field plus internal spread within the field. Ratoon crops were less infested than plant crops. This could be explained by a shorter ratoon crop cycle and by the fields having areas that were more suitable for the borer than elsewhere. The location of these preferred areas could be predicted from one ratoon crop to the next but was not related to the distribution of the borer in the plant crop. This situation was thought to explain the apparent stabilization of E. saccharina infestation in ratoon cane. Because the borer was found at harvest only in stalks with more than 14 to 16 internodes, it appeared that the oldest shoots, or the shoots with the greatest growth potential, attracted the insect, possibly due to their higher nitrogen content, which would stimulate growth. All the trials were on sandy soil, and crop loss from nematodes was greater than that caused by E. saccharina.

Diadromus pulchellus Wesmael (Hymenoptera: Ichneumonidae) is a pupal parasitoid under consideration for introduction into Canada for the control of the invasive leek moth, Acrolepiopsis assectella (Zeller) (Lepidoptera: Acrolepiidae). Since study of the parasitoid outside of quarantine was not permitted in Canada at the time of this project, we assessed its efficacy via field trials in its native range in central Europe. This was done by simulating introductory releases that would eventually take place in Canada when a permit for release is obtained. In 2007 and 2008, experimental leek plots were artificially infested with pest larvae to mimic the higher pest densities common in Canada. Based on a preliminary experiment showing that leek moth pupae were suitable for parasitism up to 5–6 days after pupation, D. pulchellus adults were mass-released into the field plots when the first host cocoons were observed. The laboratory-reared agents reproduced successfully in all trials and radically reduced leek moth survival. Taking into account background parasitism caused by naturally occurring D. pulchellus, the released agents parasitized at least 15.8%, 43.9%, 48.1% and 58.8% of the available hosts in the four release trials. When this significant contribution to leek moth mortality is added to previously published life tables, in which pupal parasitism was absent, the total pupal mortality increases from 60.1% to 76.7%. This study demonstrates how field trials involving environmental manipulation in an agent's native range can yield predictions of the agent's field efficacy once introduced into a novel area.

Stored grain insect species in bulk-stored barley were sampled during 15 consecutive weeks in two ways: direct sampling based on grain trier samples and indirect sampling based on probe trap captures. A total number of 22 insect taxa were found; this study focused on the six most abundant species and their natural enemies. Four aspects were addressed: (i) differences in insect counts when based on either probe trap captures or grain trier samples, (ii) usefulness of grain temperature and moisture content as explanatory variables for insect densities, (iii) density-dependent relationships between natural enemies and their hosts, and (iv) spatial and non-spatial analyses of insect counts. Both total captures and frequencies of insect taxa were consistently higher in captures with probe traps than insect numbers obtained from grain samples. Regression analysis with abiotic conditions and probe trap captures as explanatory variables provided good fits to insect counts in grain samples for four of the six insect species (R2-values>0.40). Using multi-regression analyses, we showed that: (i) the occurrence of natural enemies was only weakly associated with the abundance of hosts; (ii) grain moisture content and temperature appeared to be at least as important variables as host availability; and (iii) the predictive strengths of regression models were similar when based on either data from grain samples or probe traps. Spatial analyses (SADIE) of both sampling data suggested that all data sets followed a spatially random distribution; re-arrangement of the data provided insight into important aspects of SADIE analyses of small data sets. Non-spatial analysis (Lloyd's aggregation index) showed significant differences among species and that the level of non-spatial aggregation was quite sensitive to sampling method used.

Oligo- and mesotrophic wetlands, such as bogs, fens and swamps, have become more and more restricted in Europe, and wetland species related to them have increasingly been threatened. Due to increasing habitat fragmentation, the exchange of individuals of these species among sites and, as a consequence, gene flow has been reduced or even eliminated. Therefore, we analysed the genetic structure of 11 populations of an endangered stenotopic damselfly, Nehalennia speciosa (Odonata: Coenagrionidae), in Poland and Lithuania by means of allozyme electrophoresis of 14 gene loci. The overall genetic diversity of all populations was low (A: 1.32; H: 2.6%; Ptot: 29.2%), and no significant differences were observed among the different groupings of populations (degree of fragmentation, habitat type and size, population size). The genetic differentiation among populations was also low (FST: 2.0%) and no regional groups were detected. A low degree of isolation by distance was observed for genetic distances. Taking into account these results, the conservation effort for this species should be focused on large local populations and not necessarily on metapopulation structures. Furthermore, N. speciosa could be (re-)introduced in extinct patches and seemingly suitable localities. Genetically, such relocations should be feasible due to the generally high genetic homogeneity of populations.

Diagnostic molecular markers for the females of Phlebotomus (Paraphlebotomus) caucasicus and P. mongolensis were sought by characterizing from individual Iranian specimens a gene fragment, namely mitochondrial cytochrome b, that had previously proven useful for the taxonomy of phlebotomine sandflies. Males of both species were used as reference material because their external genitalia provide the only diagnostic morphological characters. A phylogenetic analysis of the new sequences, and those previously reported for P. grimmi, found no support for recognizing more than one species (P. caucasicus s.l.) in Iran. Most of the genetic variation was geographical. An absence of lineage sorting was demonstrated, and it is proposed that any search for species-specific molecular markers for these three taxonomic species should be continued by applied biologists only if there is better evidence for associating any one of them with phenotypes important for understanding the transmission of Leishmania species in foci of zoonotic cutaneous leishmaniasis.

Comparative studies of the population genetic structures of agricultural pests can elucidate the factors by which their population levels are affected, which is useful for designing pest management programs. This approach was used to provide insight into the six Tortricidae of major economic importance in South Africa. The population genetic structure of the carnation worm E. acerbella and the false codling moth T. leucotreta, analyzed using amplified fragment length polymorphism (AFLP) analysis, is presented here for the first time. These results were compared with those obtained previously for the codling moth Cydia pomonella, the oriental fruit moth Grapholita molesta, the litchi moth Cryptophlebia peltastica and the macadamia nut borer T. batrachopa. Locally adapted populations were detected over local geographic areas for all species. No significant differences were found among population genetic structures as result of population history (whether native or introduced) although host range (whether oligophagous or polyphagous) had a small but significant effect. It is concluded that factors such as dispersal ability and agricultural practices have the most important effects on genetically structuring populations of the economically important Tortricidae in South Africa.

Species richness and species turn-over of Chironomidae was studied in irregularly flooded wetlands of the River Dalälven flood-plains in central Sweden. The chironomid fauna, sampled with emergence traps in six wetlands over six summers, contained as much as 135 species, and the cumulative species curves indicated that the regional species pool contain several more species. Recurrent irregular floods may have induced this high chironomid species richness and the high species turn-over in the temporary wetlands, as the dominance between terrestrial and aquatic species shifted between years. Half of the wetlands were treated with Bacillus thuringiensis var. israelensis (Bti) against larvae of the flood-water mosquito Aedes sticticus. These treatments had no significant effect on chironomid species richness, but there was a higher species turn-over between years of primarily low abundance species in the treated wetlands. The cumulative number of species was also higher in the Bti-treated experimental wetlands than in the untreated reference wetlands. Thus, Bti treatment against mosquito larvae seemed to have only small effects on chironomid species richness but seemed to increase the colonisation-extinction dynamics.

The existence of genetic differences among Australian populations of the pest moth Helicoverpa armigera based on microsatellite markers is contentious. To resolve this issue, we analyzed microsatellite variation in moth samples from multiple locations simultaneously in two laboratories that have previously reported contrasting patterns. Alleles and allele numbers detected in the laboratories differed, as did the genetic differences found between the samples. The automated scoring system used in one of the laboratories combined with non-denaturing polyacrylamide gels led to inaccurate identification of alleles and high FST values between the populations. However, H. armigera in Australia is probably not structured geographically, with high gene flow between populations. This influences management of H. armigera and the development of area-wide control options, as populations need to be considered as one panmictic unit. The results also highlight potential problems of automated scoring systems when these are not checked carefully.

The population of peach-potato aphid, Myzus persicae (Sulzer), in Scotland comprises large numbers of a few superclones with much smaller numbers of other clones, and the reason for their differential success has yet to be elucidated. In the current study, the reproduction of lineages derived from these clones was measured by counting the numbers of offspring produced by a one-day-old nymph after 15 days. This was measured on four plant species, including local agricultural hosts and at two different temperatures (14 and 18°C). There were significant differences in clonal lineage reproduction on different hosts and at different temperatures and amongst clonal lineages on the same hosts at the same temperature. Lineages of local insecticide sensitive clones did not have the best reproductive potential; instead, a recently introduced clonal lineage carrying MACE insecticide resistance was the best reproducer. The clonal lineage with the lowest reproductive potential also carried insecticide resistance, but this was kdr. A lineage from a local insecticide-sensitive clone was the least affected by reduced temperature. There was evidence of host plant specialisation in some of the clonal lineages.

The generally accepted assumption on the low mortality pressure for inside-tree habitat was challenged in this study. To achieve this objective, the number of larval instars of xylem-feeding Aredolpona rubra (L.) (Coleoptera: Cerambycidae) was determined using multidimensional statistics, and the life table was constructed based on the head-width distribution of larvae taken from the field. The mean value of natural mortality of an average larva was then compared with data available for other wood-feeding species and contrasted with insects from other feeding guilds. The results show that larvae living in wood experience lower mortality rates than those from other habitats and that, among the wood-feeders, the mortality rate of larvae decreases while development time increases further inside the tree.

The biology of the immature stages and adult eclosion of Ufens principalis Owen, an important parasitoid of Homalodisca eggs in southern California, were studied. The duration of the egg, larval and pupal stages at 26.7°C were 0–1, 7 and 9 days, respectively. Sacciform larvae, which developed gregariously within host eggs, were motile until about five days of age, and then became sessile. Parasitized host eggs changed from whitish and soft when freshly-laid to yellow-orange and hard at five days and older. This change was accompanied by formation of septal walls separating the mature larvae and pupae. The rate of immature development had a strong positive linear relationship (R2=0.853, n=98) with temperatures in the range of 20.0–30.3°C. The theoretical minimum threshold for immature development was 13.5°C, and the required heat units were 241.0 degree-days. Adult eclosion from host eggs occurred mostly (85%) on the first two days of emergence. Although most females emerged during the morning hours (0600–1200 h), males tended to emerge earlier than females with equal emergence during the morning and late night hours (2400–0600 h). The rate of successful adult emergence was high (88%). The ratio of eclosed adults to the number of exit holes was 1.18, indicating that most adults tended to independently cut their exit holes. The number of exit holes had a strong negative relationship (R2=0.711, n=125) with exit hole size, suggesting that larger numbers of developing immatures per host egg result in an overall decrease in adult size.

Ruminant dung is a highly ephemeral, patchily distributed resource, which is used by a diverse community of invertebrate species. In such environments, high levels of insect aggregation may be important in facilitating stability and coexistence across patchily distributed populations. The aim of the present work was to quantify the aggregation of the insects colonising cow-dung in cattle pasture in southwest England and to test the hypothesis that the dung-pat community assemblage observed was the result of stochastic colonization. This was examined using batches of ten standardised, 1.5 kg, artificial cow pats placed out in cattle pastures in each of 24 weeks between May and October in 2001. Pats were left exposed in the field for seven days before being brought back to the laboratory, where any insect colonizers were collected and identified. Individual pats contained, on average, only half the number of insect taxa present in an entire batch put out at any one time. All larval coleopteran taxa, 20 of the 22 adult coleopteran taxa and 22 of the 23 dipteran taxa, showed significant aggregation, with the abundance of most taxa within pats approximating a negative binomial distribution. A simulation analysis was used to show that the observed relative frequency of taxa within pats did not differ from that expected by chance if colonisation is a random binomial event in which each species colonises a pat independently of all other species. Aggregated populations, of even highly abundant insects, may be more susceptible to the deleterious effects of insecticidal contaminants in dung than if they were evenly distributed, if by chance they colonize a pat containing insecticidal residues from a recently treated animal.

The effect of ground cover upon the communities of beneficial arthropods established in the canopy of lemon trees was investigated, by comparing three ground-cover management treatments applied: RV, resident vegetation; S, sowed selected species; and BS, bare soil by controlling weeds with herbicide. Over two consecutive years, arthropod communities in the tree canopy were sampled periodically by beating and suction techniques. Significantly higher numbers of beneficial arthropods were found in the RV and S treatments in comparison with bare soil. Spiders and parasitoid wasps were the two most common groups, representing, respectively, 70% and 19% of all catches in beating samples and 33% and 53% in suction samples. For the RV and S treatments, significant seasonal deviations from the bare soil treatment were observed using principal response curves. Similar seasonal patterns were observed over the two years. The RV and S treatments showed significant positive deviations from the BS treatment in late spring and summer, accounted for the higher numbers of parasitoid wasps, coccinelids and lacewings present. By contrast, the seasonal deviations observed for the spider community differed from those of the remaining arthropods. During late winter and early spring, the RV and S treatments presented a higher abundance of spiders in the tree canopy, in comparison with bare soil, whereas in the summer significantly more spiders were found in the bare soil treatment. Spider movements between tree canopy and ground vegetation layers may justify this result.