Simultaneous removal of carbon and nitrogen from municipal-type synthetic wastewater using net-like rotating biological contactor (NRBC)

The treatment of municipal-type synthetic wastewater was carried out using a three stages net-like rotating biological contactor (NRBC). The results indicated that, compared with conventional rotating biological contactor (RBC), NRBC have several advantages, such as quick start-up, high biomass concentration and can handle high organic loading rates. The COD and total nitrogen removal rates achieved were 78.8–89.7% and 40.2–61.4%, respectively, in aerobic treatment of low COD municipal-type wastewater at hydraulic retention times (HRT) from 5 to 9 h. The COD removal rate achieved 80–95% when organic loading varied between 16 and 40 gCOD/m² d. A large amount of nematodes were found in the NRBC system, which made the NRBC system produce relatively low amounts of waste sludge, due to their grazing.     

Search Efficiency of Spalangia cameroni and Muscidifurax raptor on Musca domestica Pupae in Dairy Cattle Farms in Denmark

Indoor releases of Spalangia cameroni Perkins and Muscidifurax raptor Girauelt & Sanders (Hymenoptera: Pteromalidae) were conducted in five organic dairy cattle farms to evaluate the overall effect on parasitism and efficiency at different pupal depths of Musca domestica L. (Diptera: Muscidae). Overall, parasitism increased significantly from 5.3 to 28.8–28.7% of the exposed house fly pupae due to the release of pupal parasitoids. Spalangia cameroni was by far the most dominant species, contributing approximately 71.5–72.3% of the parasitism in the release and post-release period, whereas 20.9–24.4% could be attributed to Muscidifurax raptor. A naturally occurring ichneumonid, Phygadeuon fumator Gravenhorst (Hymenoptera: Ichneumonidae) parasitized 4.1–6.8% of the exposed fly pupae. The placement of house fly pupae at two depths of the bedding, 5–10 and 15–20 cm had no significant effect on overall parasitism whereas M. raptor attacked the house fly pupae significantly more when placed in the 5–10 cm stratum (10.0%) compared to the 15–20 cm stratum (3.2%). The two pupal depths had no significant effect on parasitism by S. cameroni and P. fumator. Albeit S. cameroni contributed significantly to overall parasitism, M. raptor had a significantly higher attack rate when first a female had located bags with sentinel pupae. Based on the above results, however, S. cameroni seems the most appropriate species for managing house flies in straw bedded dairy cattle farms in Denmark. A biological control strategy of simultaneous releases of S. cameroni and M. raptor is discussed.     

The biology of Bracon celer as a parasitoid of the olive fruit fly

A series of laboratory experiments was conducted on a colony of Bracon celer Szépligeti (Hymenoptera: Braconidae) reared on the olive fly, Bactrocera oleae (Rossi) (Diptera: Tephritidae). Female B. celer preferentially probe and oviposit into olives containing late third-instar fly larvae. The parasitoid develops as a solitary, ectoparasitic idiobiont. Mean development time (oviposition to adult eclosion) at 22 °C was, for females, 36±1 (SE) days, and for males, 34±1 days. The mean longevity of adult female wasps when provided honey and water was significantly greater than when they were provided water alone, or nothing. The females produced an average of 9.7±7.2 progeny during their lifetimes, but production levels in the insectary colony suggested that this level of fecundity was artificially low and could be improved. The discrepancy may be a consequence of constraints on oviposition behavior imposed by the experimental design. The results are discussed with respect to insectary production methods and the potential use of B. celer as a biological control agent for olive fly in California.     

A potential native natural enemy of invasive aquatic weed – water hyacinth

A potential native natural enemy of invasive aquatic weed water hyacinth was found in Shanghai of China: Chironomus larva. The larva can dig into the bulbiform petiole of water hyacinth, the petiole will be broken and decomposed soon, and also, the canker of water hyacinth will fall off. So this larva will be a native natural enemy of water hyacinth for controlling its invasion. From other side, water hyacinth will be gradually naturalized to a component of native ecosystem, although it maybe needs a long time.     

A Disjunct Argentine Ant Metacolony in Macaronesia and Southwestern Europe

The Argentine ant, Linepithema humile, originally from South America, is now a major pest in many parts of the world with Mediterranean-like climates. Earlier research indicated that southwestern European L. humile populations are segregated into two distinct supercolonies, the ‘Main’ supercolony extending through Portugal, Spain, southern France, and Italy, and the ‘Catalonian’ supercolony in eastern Spain. Both supercolonies are unicolonial, with workers showing no aggression towards members of the same supercolony, but severe aggression towards members of the other supercolony. Here we evaluated the behavioral relationships among non-native L. humile populations on the Macaronesian islands of Madeira and the Azores and non-native populations in southwestern Europe. We conducted aggression assays among L. humile workers from Madeira, the Azores, and the two southwestern European supercolonies. We found no aggressive interactions among any combination of workers from Madeira, the Azores, and the Main supercolony. However, workers from Madeira and the Azores always fought aggressively with workers from the Catalonian supercolony. Thus, the populations of L. humile in Madeira and the Azores appear to be unicolonial and act as if they belong to the Main supercolony of southwestern Europe. This set of geographically separated but mutually compatible supercolonies, which we term a ‘metacolony,’ appears to descend from one supercolony. Historical evidence suggests that the first L. humile population in the greater Mediterranean region was established in Madeira and that propagules from the dominant supercolony in Madeira gave rise to the dominant supercolonies in to other parts of the region.     

Spatial Segregation of Congeneric Invaders in Central Pennsylvania, USA

Carduus acanthoides and Carduus nutans (plumeless and musk thistles) are among the most noxious weeds in the United States of America, presenting a serious challenge in cropping and pasture systems. Unfortunately, a lack of detailed spatial distribution information hampers both our ability to understand the factors affecting their invasive success, and the effectiveness of monitoring and management efforts. To examine patterns of distribution and co-occurrence at a local level, we sampled a 5000 km² area of central Pennsylvania that cut a transect across known areas of C. acanthoides and C. nutans infestation. A number of potential environmental explanatory variables were recorded and analyzed to examine whether they correlated with observed species distribution patterns. Patterns of forest density and spatial aggregation of the thistles were the primary covariates that significantly impacted both species’ distributions. The survey established that the frequency of sightings for each species diminished as the ranges converged, with only brief overlap: the two species are strongly negatively correlated in space. Understanding environmental correlates of infestation and the pattern of spatial dissociation of these two invasive species is an important step towards an improved understanding of the mechanisms underlying their invasive potential, and hence towards effective weed control.     

Native and Introduced Ecosystem Engineers Produce Contrasting Effects on Estuarine Infaunal Communities

Cordgrasses in the genus Spartina are good examples of ecosystem engineers that modify habitat structure in estuaries throughout the world. In San Francisco Bay, California, USA, marshes containing native California cordgrass (Spartina foliosa) are being invaded by a hybrid (S. alterniflora × S. foliosa) formed after introduction of S. alterniflora. This study compared vegetation, sediment structure, and infaunal invertebrates in native and invaded marshes. We hypothesized that differences in the physical structure between S. foliosa and hybrid Spartina would be reflected in differences in density, biomass, diversity, and taxonomic composition of infauna. Hybrid Spartina modifies habitat structure more than S. foliosa by producing taller stems, and greater plant biomass both above- and belowground while occupying a much wider tidal range, thereby transforming open mudflats to a vegetated habitat. In general, S. foliosa areas contained significantly higher densities of benthic infauna than adjacent mudflats, while hybrid Spartina areas never contained greater infaunal densities than mudflats. This is because S. foliosa produces a moderate level of structure that can facilitate benthic invertebrates, whereas hybrid Spartina produces so much structure, particularly belowground, that it actually excludes invertebrates. Therefore, we suggest that these two closely related species both act as ecosystem engineers, but with opposing effects on invertebrate communities.     

Population Dynamics and Potential for Biological Control of an Exotic Invasive Shrub in Hawaiian Rainforests

Introduction of biological control agents to reduce the abundance of exotic invasive plant species is often considered necessary but risky. I used matrix projection models to investigate the current population dynamics of Clidemia hirta (Melastomataceae), an invasive shrub, in two rainforest stands on the island of Hawaii and to predict the efficacy of hypothetical biological control agents in reducing population growth rates. Stage-structured matrix models were parameterized with field data collected over 3 years from 2906 C. hirta plants in a recently invaded forest with an open overstory (Laupahoehoe) and 600 plants in a less recently invaded forest with a closed canopy (Waiakea). Asymptotic population growth rates (λ) for both populations in all years were greater than one, demonstrating that both populations were growing. Composite elasticities were high for the seedling life-history stage and fecundity, and near-term demographic elasticities suggested that changes in seedling survival would have the largest effect on population size in the short term. However, simulations showed that almost 100% of seedlings or new recruits produced per reproductive adult would have to be destroyed to cause populations to go locally extinct under current environmental conditions. Herbivores or pathogens that decrease survival across all vegetative stages by 12% at Waiakea and 64% at Laupahoehoe were projected to cause the populations to decline. Thus, biocontrol agents that reduce survival of multiple life-history stages rather than seed production should be pursued to control C. hirta in Hawaiian rainforests.     

Molecular and morphological examination of Cyrtobagous sp. collected from Argentina, Paraguay, Brazil, Australia, and Florida

Two members of the floating fern genus Salvinia (Salviniaceae), S. minima Baker and S. molesta Mitchell, have established in the United States. Cyrtobagous salviniae Calder and Sands (Coleoptera: Curculionidae), long established on Florida S. minima, was released in Texas and Louisiana as a biocontrol agent for both species. Subsequently, sequence analysis of the 28S rRNA D2 expansion domain suggested that the Florida and Brazilian populations (used worldwide for biocontrol) of C. salviniae might constitute two cryptic species. In response, the Brazilian weevil was imported from Australia and released instead onto S. molesta. We sampled C. singularis Hustache and C. salviniae from their native ranges in Brazil, Argentina, and Paraguay and sequenced them (D2) along with Australian and Florida samples. The genetic distance between C. singularis and C. salviniae samples is much greater (almost 5×) than the distance between either the Florida and Brazilian samples or the Brazilian and Argentinean/ Paraguayan C. salviniae samples. Since C. singularis and C. salviniae are cryptic species, the Florida and Brazilian populations (or for that matter Brazilian and Argentinean/Paraguayan) could reasonably be described as demes or ecotypes. Occurrence data indicates that, in parts of their ranges, C. salviniae and C. singularis are not only sympatric but also feed on the same plant species at the same site. While host adaptation (species preferences) likely occurs within local demes, both species seem capable of adapting to the available resource (Salvinia species). Finally, a polymerase chain reaction (PCR) primer was developed to distinguish the Florida and Brazilian/Australian types.     

Soybean Aphid Predators in Québec and the Suitability of Aphis glycines as Prey for Three Coccinellidae

Since its invasion of North America in 2000, the soybean aphid, Aphis glycines Matsumura (Homoptera: Aphididae) has notably changed the arthropod community of the soybean agroecosystem. The objectives of this study were to characterize the foliar predatory fauna associated with A. glycines in commercial soybean fields in Québec, Canada, and to evaluate the suitability of A. glycines as prey for three coccinellid species: Harmonia axyridis Pallas, Propylea quatuordecimpunctata L. and Coleomegilla maculata lengi Timberlake (Coleoptera: Coccinellidae). Field surveys showed that several predators responded rapidly to expanding and increasing populations of the soybean aphid. Coccinellidae were the most important aphidophagous predators observed in 2002 (58.6%) and 2003 (44.8%), with mainly four native and naturalized species co-occurring with the soybean aphid throughout the growing season. Measurement of fitness parameters under laboratory conditions (survival, development time, longevity, fecundity) indicated that A. glycines is an excellent prey for the development and reproduction of all three of the coccinellid species studied. The intrinsic rate of natural increase (r_m) was highest for H. axyridis (0.238 d⁻¹), intermediate for P. quatuordecimpunctata (0.215 d⁻¹) and lowest for C. maculata (0.134 d⁻¹).