Assessment of damage caused by evolved fall armyworm on native and transgenic maize in South Africa

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) is a transboundary polyphagous insect pest which preferentially feeds on grain crops. The FAW was responsible for economic damage to maize crops in more than 44 African countries by 2019 accounting for the loss of over US$2–5.5 billion. The parallel cultivation of Bt-maize expressing Cry1Ab protein and indigenous maize varieties in some African countries was aimed to enhance output and mitigate the harmful impact of the Lepidopteran insect below the economic injury level. A total of six maize farms (holding at least 4–20 ha of land) in delocalized geographies of Gauteng province, South Africa were randomly selected and assessed for the impact of FAW during the 2017 outbreak. A biotype of S. frugiperda that significantly destroyed Bt maize and non-Bt maize and exhibited tolerance to pesticides under field conditions is reported. It is observed that, whether maize at the tasseling stage carried the Cry1Ab trait or not, S. frugiperda caused a minimum damage of ~62.6% (P?<?0.05, P?=?0.0001, |t|?=?2.78) and maximum damage of ~83.33% (P?<?0.05, P?=?0.0001, |t|?=?2.78) in farms without refuge strategies. Phylogenetic analysis using the mitochondrial cytochrome oxidase I gene, revealed divergent evolution amongst reported S. frugiperda lineages, the emergence of singleton, and distinct haplotypes within the African continent. It is concluded that S. frugiperda that invaded maize farms in the Gauteng region of South Africa is genetically evolved from those identified in São Tomé and Príncipe, and Nigeria, and tolerant to certain insecticides. Thus, the African continent might have been invaded by several routes and distinct haplotypes.

     

Early growth and survival of 49 tropical tree species across sites differing in soil fertility and rainfall in Panama

Reforestation in the tropics takes place across a wide variety of edaphic and climatic conditions. Reforestation trials have demonstrated that edaphic conditions may have a strong effect on species growth and survival. However it is unclear how the relative importance of soil conditions influences species survival and growth under varying amounts of rainfall and lengths of dry season.Two-year growth and mortality of 49 tree species were evaluated in four sites across Panama, representing a soil fertility-rainfall matrix. Despite strong contrasts in environmental conditions, 65% of individual species did not show consistent differences in growth between high- and low-fertility sites or between wet and dry sites. However, early growth and survival were more strongly affected by soil fertility than by rainfall patterns for the second-largest group; 30% of the species grew significantly better in both high-fertility sites than in both low-fertility sites, compared to 6% in both wet sites vs. both dry sites. In the two high-fertility sites, growth of 47% and 69% of the species was better than their across-site means. On the other hand, 55% and 73% of the species grew significantly slower than their across-site averages in the two low-fertility sites.Survival did not appear to be associated to either soil fertility or rainfall. In each site, only a few species had a significantly higher or lower within-site survival than across-site survival.Diversifying the choice of tree species increases the options for reforestation strategies that match species characteristics to local site conditions and to the objectives and management possibilities of landholders. Testing the performance of potential species under different site conditions in screening trials is paramount, both to inform selection from among the vast diversity of tree species in the tropics that show good growth and survival under different local site conditions and to filter out unsuitable species and avoid early failure of the reforestation effort.     

Prospective study of blackthorn injury and synovitis in 35 horses

The objective of this prospective clinical study was to investigate the cause and describe the presentation, diagnosis, treatment techniques and outcome of Prunus spinosa (blackthorn) injury and synovitis in the horse. In all cases presented with blackthorn injury and synovitis, surgical treatment was performed within 24 h, using a two-stage procedure: 1-Perisynovial technique using ultrasound guided electrosurgical dissection; 2-Endoscopic technique. The diagnosis was confirmed by retrieval of black plant material from or close to the affected synovial structure. Mean lameness score on presentation was 4/5 (range 1–5). The most commonly affected structures were extensor tendon sheaths (12/35) and fetlock joints (11/35). All cases had thorn material removed, 80% had thorn material removed at surgery and in 49% it was intra-synovial. On presentation, the mean synovial fluid total protein level (TP) was 47.6 g/L (range 18–66); mean total nucleated cell count (TNCC) was 176 × 10⁹ cells/L (range 12–312). Two days post-surgery, mean total protein levels were 33 g/L (range 16–52), mean TNCC was 13 × 10⁹ cells/L (range 1–35). At 5 days post-surgery, the mean total protein was 23 g/L (range 12–28) and TNCC was 5 × 10⁹ cells/L (range 1–12). All synovial fluid cultures were negative. Twenty-eight (80%) horses were sound 5 days post-operatively, seven (20%) were not lame in walk; they all returned to full work in an average time of 8 weeks (range 3–48 weeks). Surgery achieved accurate identification and removal of thorn material. In contrast to previous studies of synovial sepsis, these cases had a positive outcome despite high pre- and post-operative synovial fluid TP and TNCC. These findings suggest that Prunus spinosus (blackthorn) synovitis has a different aetiology to synovitis originating from sepsis or other types of contamination.     

Germination and seedling growth of Quercus (section Erythrobalanus) across openings in a mixed-deciduous forest of southern New England, USA

In this study three species of the genus Quercus section Erythrobalanus (Quercus coccinea, Quercus rubra, Quercus velutina) were investigated. All occur together as canopy trees in forests of southern New England. Acorns of each Quercus species were planted in plots located in five zones that represent a range of forest gap/canopy conditions that can occur within a southern New England forest. These five zones were demarcated adjacent to and across large openings of two physiographic sites—valley and ridgetop. Experiments were designed to monitor germination and initial growth of seedlings for the first three growing seasons. During the start of the first growing season germination was monitored. At the end of the first growing season measurements of height and number of flushes were taken and destructive samples of seedlings made for dry mass of root, stem and leaves. At the end of the third growing season height was recorded for surviving seedlings. Comparisons were made of germination and growth of seedlings located in the different gap/canopy conditions.

Results demonstrated clear differences in patterns of germination and early growth among species and among gap/canopy conditions of the sites. All species showed an increased lag in germination with reduced amounts of light. Highest growth and flushing rate were in the center conditions of the openings for all species during the first growing season. Quercus rubra had the greatest height growth the first growing season but a lower number of flushes than Q. velutina and Q. coccinea. In comparison with the other species, Q. rubra had the greatest total dry mass in most gap/canopy conditions after the first growing season. However, Q. velutina had the greatest total dry mass in the center of the ridgetop opening. In almost all gap/canopy conditions Q. velutina had greater proportions of dry mass allocated to roots compared with the other species.

After 3 years, greatest height growth in any of the gap/canopy conditions was recorded for all three species in the center of the valley site. Under this condition Q. rubra had significantly greater growth than Q. velutina and Q. coccinea. Quercus rubra also had significantly greater height growth and survival beneath the canopy conditions of the valley site than the other species. On the ridgetop site regeneration failed to establish beneath canopy conditions that provided low amounts of light. Quercus velutina showed greatest height growth after three years in the center and edge conditions of the ridgetop opening compared with the other species. Environmental influences that determine species germination and growth performance are suggested.     

The regeneration status of Fitzroya cupressoides in the cordillera Pelada,Chile

The large conifer, Fitzroya cupressoides (Mol.) Johnston, which is native to southern Chile and Argentina, has been intensively exploited for its valuable wood since European colonization in the 16th century. Today F. cupressoides persists only in relatively small, remote stands and reports of inadequate regeneration have given rise to considerable concern for its survival. A reconnaissance study of virgin stands in the Cordillera Pelada, Chile, indicates that regeneration by both seedling establishment and root suckering is generally adequate to assure local persistence. Regeneration following very light burning is also adequate; however, following intense fires where soil peat burns and bare areas on the sterile, podzolic soils are created, forest re-establishment is exceedingly slow. The presence of regenerating virgin stands of F. cupressoides in the Cordillera Pelada is a strong reason for this area to be set aside for in situ preservation.