A comparative genomics study of genetic products potentially encoding ladderane lipid biosynthesis

Background  

The fatty acids of anaerobic ammonium oxidizing (anammox) bacteria contain linearly concatenated cyclobutane moieties, so far unique to biology. These moieties are under high ring strain and are synthesised by a presently unknown biosynthetic pathway.     

Bemisia tabaci (Homoptera: Aleyrodidae) instar effects on rate of parasitism by Eretmocerus mundus and Encarsia pergandiella (Hymenoptera: Aphelinidae)

Studies were conducted to compare preference among Bemisia tabaci Gennadius, biotype B instars for parasitization by Eretmocerus mundus Mercet and Encarsia pergandiella Howard when provided one instar only, two different instars, and four different instars simultaneously. In the single‐instar no choice treatment, Er. mundus was more successful in parasitizing the younger host instars, while En. pergandiella parasitized a greater proportion of the older instars. Similar results were observed when parasitoids were provided a choice of two instars in six different pair combinations. When all four instars were provided simultaneously, the numbers of first, second, and third instars parasitized by Er. mundus were not significantly different from each other (range 10.3–16.4%), but all were significantly higher than parasitism of fourth instar nymphs (2.1%). The highest percentage parasitization by En. pergandiella was in third instar (17.2%), and the lowest in first instar (2.8%).     

The ecological integrity of the Lower Olifants River,Limpopo province,South Africa: 2009–2015 – Part A: Olifants River main stem

The major rivers of the South African ‘Lowveld’ (low-latitude savanna) suffer numerous impacts from upstream economic activities. Whereas monitoring these rivers is required to detect biodiversity losses, record pollution events and devise mitigation strategies, current monitoring programmes are inadequate. In 2009, the South African Earth Observation Network initiated an intensive long-term research programme on the Lowveld reaches of the Olifants River. Physico-chemical parameters, aquatic macroinvertebrates and fish abundances were recorded at four Lowveld sites in the Olifants River. We review six years of this programme. The results suggest deterioration in the ecological condition of the Olifants River with no discernible improvement through protected areas. Trends could not be detected. The parameters measured, sampling methods and/or sampling frequency might be responsible for the limited trends observed, or alternatively the results simply reflect stable conditions despite on-going pollution. Real time monitoring and an expansion in the parameters monitored would add value to the monitoring programme.