A comparison of control results for the alien invasive woodwasp,Sirex noctilio,in the southern hemisphere

1 Sirex noctilio has resulted in one of the most damaging biological invasions of pine forestry in the southern hemisphere. 2 An intensive, integrated control programme has been developed for this pest and is generally considered very successful. However, a critical comparison of S. noctilio infestations and control efforts throughout the southern hemisphere reveals that control has not been uniformly effective. Of particular concern is the apparently unexplained variability in establishment and success of biological control agents, including various parasitic wasps and the parasitic nematode Deladenus siricidicola. 3 An overlooked aspect in the establishment of the biological control interventions for S. noctilio is the potential influence of genetic bottlenecks on the ability of the agents to adapt to different environments and different populations of S. noctilio. 4 Despite established biological control agents, stress in forests caused by silvicultural practices or the environment will predispose trees to heavy infestation. Unfortunately, improved silvicultural practices are not always economically feasible and environmental changes are often unavoidable. 5 Sirex noctilio continues to pose a serious threat to pine forestry in many areas. Despite extensive earlier research into a single integrated control for S. noctilio, it is important to recognize that such a strategy will probably require significant local adaptation in new areas of infestation and over time.     

Neural Plasticity and Consciousness

We introduce a distinction between cortical dominance andcortical deference, and apply it to various examples ofneural plasticity in which input is rerouted intermodally orintramodally to nonstandard cortical targets. In some cases butnot others, cortical activity `defers' to the nonstandard sourcesof input. We ask why, consider some possible explanations, andpropose a dynamic sensorimotor hypothesis. We believe that thisdistinction is important and worthy of further study, bothphilosophical and empirical, whether or not our hypothesis turnsout to be correct. In particular, the question of how the distinction should be explained is linked to explanatory gapissues for consciousness. Comparative and absolute explanatorygaps should be distinguished: why does neural activity in aparticular area of cortex have this qualitative expressionrather than that, and why does it have any qualitativeexpression at all? We use the dominance/deference distinction toaddress the comparative gaps, both intermodal and intramodal (notthe absolute gap). We do so not by inward scrutiny but rather by expanding our gaze to include relations between brain, body andenvironment.     

The emergence period of sea trout fry in a Lake District stream correlates with the North Atlantic Oscillation

The date of fry emergence over 30 years in a sea trout nursery stream, predicted by an individual-based model, correlated significantly ( r =0·660, P <0·001) with an index of the North Atlantic Oscillation. Water temperature is the main driving variable in the model and stream temperature also correlated significantly ( r =0·662, P <0·001) with the index, providing a probable causal link. Therefore, the inter-annual variations in emergence may not be unique to this one stream, but may be typical of other trout streams with similar climatic conditions.     

Purification and characterization of bovine lactoferrin from secretions of the involuting mammary gland: identification of multiple molecular weight forms

1. Lactoferrin was isolated from bovine mammary secretions collected during the nonlactating period. 2. A method utilizing heparin-agarose affinity chromatography was more efficient for purifying lactoferrin than a method including gel filtration, ion exchange chromatography and a second gel filtration. 3. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis demonstrated that the purified lactoferrin was composed of two protein bands of apparent mol. wt. of 83,000 and 87,000. 4. Digestion with endoglycosidase H resolved the lactoferrin into two lower mol. wt. bands of 78,000 and 81,000. 5. The biochemical differences between the forms of lactoferrin are not exclusively due to differences in endoglycosidase H-sensitive oligosaccharide composition.     

Interactions between hymenopteran species associated with gall-forming wasps: the Leptocybe invasa community as a case study

1. Leptocybe invasa is native to Australia and induces galls on various species of Eucalyptus. Two genetically distinct lineages of this wasp have been detected outside its native range, namely, Leptocybe Lineage A and Leptocybe Lineage B.
2. The parasitoid Selitrichodes neseri was released in South Africa as a biological control agent against L. invasa. Another parasitoid of L. invasa, Quadrastichus mendeli, as well as Megastigmus zebrinus (parasitoid) and Megastigmus pretorianensis (role unknown), have also been recorded emerging from L. invasa galls. The objective of this study was to investigate the interactions between the different hymenopterans associated with L. invasa galls in South Africa.
3. L. invasa galls were dissected and species-specific primers and restriction enzymes were used to identify the larvae where interactions were noted.
4. S. neseri, Q. mendeli and M. zebrinus were confirmed to parasitize Leptocybe Lineage A, and S. neseri was confirmed to parasitize Leptocybe Lineage B. Furthermore, there were direct interactions between these parasitoids, where parasitoids were found parasitising each other. The gall forming experiment confirmed that M. pretorianensis is not a gall former, but other potential roles remain uncertain.

     

Flow scintillation counting of 14C-labeled microalgal photosynthetic pigments

Photopigment radiolabcling, a useful method for measuring thein situ carbon-specific growth rates of microalgae, is basedon the determination of synthesis rates of chemosystematic (i.e.specific for microalgal phylogenetic groups) chlorophylls andcarotenoids using photosynthetically assimilated ¹⁴C as a radiotracer.The reliability of this method depends on accurate measurementsof the ¹⁴C-specific activity of individual photopigments. Typically,photopigments are separated by high-performance liquid chromatography(HPLC) with fraction collection of individual peaks, followedby further purification and standard scintillation counting.To simplify analyses, we evaluated in-line flow scintillationcounting to determine its applicability and reliability formeasuring the activity of radio-labeled photopigments. Incubationswere conducted using both pure cultures and natural phyto-planktonsamples. The radiochemical purity of photopigments was determinedby extract acidification (10% HC1) to transform chlorophyllsinto degradation products. Purity was also checked by comparingabsorbance spectra with purified standards. Although ¹⁴C-labeledcolorless compounds are a common feature in radiograms, thesecompounds do not co-elute with photopigments using our HPLCprotocol. Flow scintillation counting, coupled with a highlyselective HPLC protocol, provides an efficient, reliable andfeasible alternative to fraction collection/repurification methodsfor measuring the ¹⁴C-specific activity of microalgal photosyntheticpigments.