Effective communication in multilingual environments requires bilinguals to constantly monitor linguistic cues. It is hypothesized that the constant need to monitor may result in improved attention. However, previous investigations have reported mixed, often null results, with positive findings attributed to non-linguistic variables. To address these issues, we investigated whether higher levels of bilingualism were associated with improved attentional function in a sample of culturally and socioeconomically homogenous Mandarin–English speaking bilingual adolescents. Participants completed the Attention Network Task to assess attentional network function. Data were analyzed using linear mixed-effects models in order to account for nontrivial differences. Mixed results provide partial support for domain general cognitive benefits associated with higher levels of bilingualism. Both improved and reduced performance differed based on the specific dimension of bilingualism and the attentional network assessed. Findings support the conclusion that separable dimensions of bilingual language experience assert different influences on attentional network function.

Stictococcus vayssierei is a major pest of root and tuber crops in central Africa. However, data on its ecology are lacking. Here we provide an updated estimate of its distribution with the aim of facilitating the sustainable control of its populations. Surveys conducted in nine countries encompassing 13 ecological regions around the Congo basin showed that African root and tuber scale was present in Cameroon, Central African Republic, Congo, Democratic Republic of Congo, Equatorial Guinea, Gabon and Uganda. It was not found on the sites surveyed in Chad and Nigeria. The pest occurred in the forest and the forest-savannah mosaic as well as in the savannah where it was never recorded before. However, prevalence was higher in the forest (43.1%) where cassava was the most infested crop, compared to the savannah (9.2%) where aroids (cocoyam and taro) were the most infested crops. In the forest habitat, the pest was prevalent in all but two ecological regions: the Congolian swamp forests and the Southern Congolian forest-savanna mosaic. In the savannah habitat, it was restricted to the moist savannah highlands and absent from dry savannahs. The scale was not observed below 277 m asl. Where present, the scale was frequently (87.1% of the sites) attended by the ant Anoplolepis tenella. High densities (>1000 scales per plant) were recorded along the Cameroon–Gabon border. Good regulatory measures within and between countries are required to control the exchange of plant materials and limit its spread. The study provides information for niche modeling and risk mapping.

Augmentative biological control is not commonly used in commercial orchards. We used an exclusion system to evaluate the potential of early-season releases of the European earwig (Forficula auricularia L., Dermaptera: Forficulidae) for control of the rosy apple aphid (Dysaphis plantaginea Passerini, Hemiptera: Aphididae) in the spring of 2009 in two pesticide-free apple orchards. In order to conduct this experiment we successfully reared earwigs with a high survival rate of nymphs (more than 96%) which may have commercial application. There were three treatments in the study: (i) a ‘release treatment’ where we confined the released earwigs in the canopy by using a barrier system; (ii) an ‘exclusion treatment’ where we blocked free access of earwigs into the canopy using the same barrier system; and (iii) a ‘control treatment’ that represented the natural situation. Contrary to expectations, earwig releases did not reduce D. plantaginea populations. In general, the abundance of natural enemies and their groups did not differ significantly among treatments, except for earwigs. We observed that the exclusion systems we used successfully kept both earwigs and ants away from tree canopies; total numbers on trees in the ‘exclusion treatment’ were significantly lower than on the other two treatments. Due to the complexity and difficulty of evaluating augmentative releases of natural enemies in open orchard conditions, we conclude that new technical approaches to control site conditions are needed when conducting such studies.

The decomposition of leaf litter is governed, in part, by litter invertebrates. In tropical rain forests, ants are dominant predators in the leaf litter and may alter litter decomposition through the action of a top-down control of food web structure. The role of ants in litter decomposition was investigated in a Costa Rican lowland rain forest with two experiments. In a mesocosm experiment, we manipulated ant presence in 50 ambient leaf-litter mesocosms. In a litterbag gradient experiment, Cecropia obtusifolia litter was used to measure decomposition rate constants across gradients in nutrients, ant density and richness, with 27 separate litterbag treatments for total arthropod exclusion or partial arthropod exclusion. After 2 mo, mass loss in mesocosms containing ants was 30.9%, significantly greater than the 23.5% mass loss in mesocosms without ants. In the litter bags with all arthropods excluded, decomposition was best accounted by the carbon: phosphorus content of soil (r2 = 0.41). In litter bags permitting smaller arthropods but excluding ants, decomposition was best explained by the local biomass of ants in the vicinity of the litter bags (r2 = 0.50). Once the microarthropod prey of ants are permitted to enter litterbags, the biomass of ants near the litterbags overtakes soil chemistry as the regulator of decomposition. In concert, these results support a working hypothesis that litter-dwelling ants are responsible for accelerating litter decomposition in lowland tropical rain forests.

In tropical climates, nest movements by mature ant colonies are probably widespread but the phenomenon of nest relocation is poorly described (McGlynn 2007, McGlynn et al. 2004, Smallwood 1982a). For species that nest in soil, the costs and risks associated with excavating and establishing new nests are consequential, and it is assumed that relocation occurs when the costs are offset by a more advantageous nest location (Avargues-Weber & Monnin 2009, Banschbach & Herbers 1999). Nest movements may occur to areas with greater availability of food resources or to a more favourable microclimate. Here we provide the first report of nest relocation in one of the most widespread and well described ant species in the Neotropics, Ectatomma ruidum (Roger), and we perform a manipulative experiment to test whether food availability or light environment influence nest movement.

Recent studies have reported specific executive and attentional deficits in preterm children. However, the majority of this research has used multidetermined tasks to assess these abilities, and the interpretation of the results lacks an explicit theoretical backdrop to better understand the origin of the difficulties observed. In the present study, we used the Child Attention Network Task (Child ANT; Rueda et al. 2004) to assess the efficiency of the alerting, orienting and executive control networks. We compared the performance of 25 preterm children (gestational age ≤ 32 weeks) to 25 full-term children, all between 5½ and 6½ years of age. Results showed that, as compared to full-term children, preterm children were slower on all conditions of the Child ANT and had a specific deficit in executive control abilities. We also observed a significantly higher correlation between the orienting and executive control networks in the preterm group, suggesting less differentiation of these two networks in this population. (JINS, 2010, 16, 130–137.)

In the Cerrado of Itirapina, Brazil, 34% of the shrubs of Didymopanax vinosum (Araliaceae) were colonized by the honeydew-producing homopteran Aconophora teligera (Membracidae) which was found exclusively on this species of plant. Correlations were made between membracid density and ant frequency, as well as between these parameters and plant damage. We found that: (1) ant frequency was higher on branches with membracids and both were more frequently found near apical meristems; (2) herbivore damage was lower on apical meristems where the membracids concentrate than on ones where they are absent; (3) the presence of membracids on the plant was correlated with a reduction in the occurrence of other potential herbivores, especially on the branches housing membracids; (4) plants with more tillers tended to have a larger number of membracids. The data suggest that the presence of A. teligera and associated ants probably reduce herbivory on apical meristems of D. vinosum.

The Attention Network Test (ANT) uses visual stimuli to separately assess the attentional skills of alerting (improved performance following a warning cue), spatial orienting (an additional benefit when the warning cue also cues target location), and executive control (impaired performance when a target stimulus contains conflicting information). This study contrasted performance on auditory and visual versions of the ANT to determine whether the measures it obtains are influenced by presentation modality. Forty healthy volunteers completed both auditory and visual tests. Reaction-time measures of executive control were of a similar magnitude and significantly correlated, suggesting that executive control might be a supramodal resource. Measures of alerting were also comparable across tasks. In contrast, spatial-orienting benefits were obtained only in the visual task. Auditory spatial cues did not improve response times to auditory targets presented at the cued location. The different spatial-orienting measures could reflect either separate orienting resources for each perceptual modality, or an interaction between a supramodal orienting resource and modality-specific perceptual processing (JINS, 2006, 12, 485–492.)

Recent surveys have shown that ant-Homoptera associations are not limited to cocoa trees only but a large number of other plant species serve as hosts for such associations. It has been observed that some ant species may tend more than one Homopteran species on a number of different host plants. Seasonal abundance of the homopterans and their tending ants was studied on cocoa, mango and pigeon pea.

The populations of the ants tend to synchronize with the populations of the Homopterans which they tend during the season.

The activity pattern of the ant, Cataulacus guineensis F. Smith, was found to be diurnal; trailing starts around 6.00 a.m. and ends around 6.00 p.m. The effect of meteorological factors on the activity pattern of the ant was also investigated and rainfall was found to be the most important factor influencing the ant's activity. The ant was found to be generally very active throughout the year, except when the harmattan conditions were very severe.

The species was found to be mainly a canopy forager, although occasionally it might forage on the ground. The mean foraging space was 555.0 m2; but when nests (colonies) were close together, overlapping of foraging spaces did occur.