CABI

About: CABI is a nonprofit organization based out in Wallingford, United Kingdom. It is known for research contribution in the topics: Population & Introduced species. The organization has 789 authors who have published 1759 publications receiving 73843 citations. The organization is also known as: Centre for Biosciences and Agriculture International.

Presence of banana bacterial wilt (Xanthomonas campestris pv. musacearum) in Rwanda

Abstract: In September 2005, visits were made to five sites within the Gisenyi province in northern Rwanda to investigate reports of a damaging banana disease affecting brewing, dessert and cooking varieties. Symptoms included progressive yellowing and wilting of leaves, shrivelling of male buds, premature ripening and internal discoloration of fruits plus characteristic yellow ooze from the vascular tissue of cut pseudostems. These symptoms resembled those of banana bacterial wilt (BBW) caused by Xanthomonas campestris pv. musacearum (Xcm). A yellow-pigmented bacterium was consistently isolated on yeast extract dextrose calcium carbonate agar from the internal tissues of flower stalks. Four isolates were identified as Xanthomonas campestris by fatty acid (Microbial ID Inc. [MIDI]) and metabolic (Biolog, Inc) analyses [ID probability score approx. 0·9]. Molecular studies using rep-PCR (Louws et al ., 1994) with ERIC and BOX primers confirmed that isolates had an identical DNA fingerprint to other Xcm isolates from Musa spp. in Ethiopia, Uganda and the Democratic Republic of Congo (DRC) and ensete (Ensete ventricosum) from Ethiopia. Pathogenicity was confirmed by injecting bacterial suspensions of isolate (IMI 393 640) into the stems of six young banana plants. Typical wilt symptoms were observed after three weeks. Bacteria were re-isolated from plants with symptoms and their identity confirmed by rep-PCR analysis. Xcm was first described from Ethiopia in the 1960s, infecting ensete and cultivated banana (Yirgou and Bradbury, 1968) but was only recently confirmed infecting bananas in Uganda and the DRC (Tushemereirwe et al ., 2004; Ndungo et al ., 2006). In Gisenyi province, banana is extensively cultivated in the highland plateaux. The wilt disease has been reported from three districts (Cyanzarwe, Gisenyi, Kanama), though it may have spread more widely. Local farmers report that wilt symptoms were first seen around 2002-2003. The disease may have spread from the DRC when Congolese people fled to Ruhengeri and Gisenyi provinces following the eruption of Mount Nyiragongo in January 2002. There is a regular interchange of people and goods across the Rwanda-DRC border and the first confirmed outbreak of Xcm in the DRC was in Masisi region (Lacs Mokotos), which is close to Gisenyi. This is the first report of BBW in Rwanda and poses a serious threat to banana production, endangering the livelihoods of banana growing households throughout the country. Ethiopian and Ugandan isolates and isolate (IMI 393 640) are held in the CABI Genetic Resource Collection. (Author's abstract).

Biogeographical comparison of the arthropod herbivore communities associated with Lepidium draba in its native, expanded and introduced ranges.

Abstract: Aim To examine the composition and structure of the arthropod community on the invasive weed Lepidium draba in its native, expanded and introduced ranges, in order to elucidate the lack of a biotic constraint that may facilitate invasion. Location Europe and western North America. Methods Identical sampling protocols were used to collect data from a total of 35 populations of L. draba in its native (Eastern European), expanded (Western European) and introduced (western US) ranges. A bootstrapping analysis was used to compare herbivore richness, diversity and evenness among the regions. Core species groups (monophages, oligophages and polyphages) on the plant were defined and their abundances and host utilization patterns described. Results Species richness was greatest in the native range, while species diversity and evenness were similar in the native and expanded range, but significantly greater than in the introduced range of L. draba. Specialist herbivore abundance was greater in the native and expanded compared with the introduced range. Oligophagous Brassicaceae-feeders were equally abundant in all three ranges, and polyphagous herbivore abundance was significantly greater in the introduced range. Overall herbivore abundance was greater in the introduced range. Host utilization was more complete in the two European ranges due to monophagous herbivores that do not exist in the introduced range. Root feeders and gall formers were completely absent from the introduced range, which was dominated by generalist sap-sucking herbivores. However, one indigenous stem-mining weevil, Ceutorhynchus americanus, occurred on L. draba in the introduced range. Main conclusions This is, to our knowledge, the first study documenting greater herbivore abundance on an invasive weed in its introduced, compared with its native, range. However, greater abundance does not necessarily translate to greater impact. We argue that, despite the greater total herbivore abundance in the introduced range, differences in the herbivore community structure (specialist vs. generalist herbivory) may contribute to the invasion success of L. draba in the western USA.

The role of management and landscape context in the restoration of grassland phytophagous beetles

Abstract: 1. Declines in area and quality of species-rich mesotrophic and calcareous grasslands have occurred all across Europe. While the European Union has promoted schemes to restore these grasslands, the emphasis for management has remained largely focused on plants. Here we focus on restoration of the phytophagous beetles of these grasslands. Although local management, particularly that which promotes the establishment of host plants, is key to restoration success, dispersal limitation is also likely to be an important limiting factor during the restoration of phytophagous beetle assemblages. 2. Using a 3-year multi-site experiment, we investigated how restoration success of phytophagous beetles was affected by hay-spreading management (intended to introduce target plant species), success in restoration of the plant communities and the landscape context within which restoration was attempted. 3. Restoration success of the plants was greatest where green hay spreading had been used to introduce seeds into restoration sites. Beetle restoration success increased over time, although hay-spreading had no direct effect. However, restoration success of the beetles was positively correlated with restoration success of the plants. 4. Overall restoration success of the phytophagous beetles was positively correlated with the proportion of species-rich grassland in the landscape, as was the restoration success of the polyphagous beetles. Restoration success for beetles capable of flight and those showing oligophagous host plant specialism were also positively correlated with connectivity to species-rich grasslands. There was no indication that beetles not capable of flight showed greater dependence on landscape scale factors than flying species. 5.Synthesis and applications. Increasing the similarity of the plant community at restoration sites to target species-rich grasslands will promote restoration success for the phytophagous beetles. However, landscape context is also important, with restoration being approximately twice as successful in those landscapes containing high as opposed to low proportions of species-rich grassland. By targeting grassland restoration within landscapes containing high proportions of species-rich grassland, dispersal limitation problems associated with restoration for invertebrate assemblages are more likely to be overcome.

Comparative susceptibility of larval instars and pupae of the western corn rootworm to infection by three entomopathogenic nematodes.

Abstract: As a first step towards the development of an ecologically rational control strategy against western corn rootworm (WCR; Diabrotica virgifera virgifera LeConte, Coleoptera: Chrysomelidae) in Europe, we compared the susceptibility of the soil living larvae and pupae of this maize pest to infection by three entomopathogenic nematode (EPN) species. In laboratory assays using sand-filled trays, Heterorhabditis bacteriophora Poinar and H. megidis Poinar, Jackson & Klein (both Rhabditida: Heterorhabditidae) caused comparable mortality among all three larval instars and pupae of D. v. virgifera. In soil-filled trays, H. bacteriophora was slightly more effective against third larval instars and pupae, and H. megidis against third larval instars, compared to other developmental stages. In both sand and soil, Steinernema feltiae (Filipjev) (Rh.: Steinernematidae) was least effective against second instars. In conclusion, all larval instars of D. v. virgifera show susceptibility to infection by all three nematodes tested. It is predicted that early application against young larval instars would be most effective at preventing root feeding damage by D. v. virgifera. Applications of nematodes just before or during the time period when third instars are predominant in the field are likely to increase control efficacy. According to our laboratory assays, H. bacteriophora and H. megidis appear to be the most promising candidates for testing in the field.