Postgraduate Seminar Series - Speakers 4th August 2016

Postgraduate Seminar Series - Speakers 4^th August 2016

1pm - Zoology Museum (Wallace 129)

S P E A K E R   1

Seaweed aquaculture - challenges and perspectives

Jessica Knoop 

When it comes to seaweeds many people associate them with slimy rotting masses along beaches and are not aware of their ecologic importance and economic potential. They are used since ancient times for a variety of applications, as a food source in Asian countries and mainly for non-food applications in the West. Recently, seaweed popularity increased in western countries – it was rebranded as a superfood and used as a biofilter in Integrated Multi-Trophic Aquaculture (IMTA) systems. Especially red algae of the genus Porphyra have gained fundamental attention because of their economic value, high content in health-beneficial substances and the growing interest of the public and the industry to use natural and local products. Because the European industry is relying on seaweed harvesting instead of farming, Porphyra populations are facing increasing pressure in South Wales. Successful cultivation would conserve natural stocks and improve product yield and quality through optimising culturing conditions and strain selection. However, seaweed aquaculture is at its infancy and nearly non-existent in Europe with many challenges to be solved for a successful and reliable cultivation. 

S P E A K E R   2

Natural enemy composition rather than richness determines pest density and plant biomass

Sanaa N. Abed

Natural enemy (NE) biodiversity is thought to play an important role in agricultural pest suppression. However, the relative importance of the number of NE species (diversity per se), versus the particular combinations of species (species composition), in determining aphid suppression and ultimately crop yields remains poorly understood. We tested the effects of NE diversity and composition on pea aphids Acyrthosiphon pisum and broad bean plants Vicia faba. The NEs we used were the larvae of two predator species, the ladybird Adalia bipunctata and the green lacewing Chrysopa carnea, and the parasitic wasp Aphidius ervi. We found NEs generally reduced aphid density and indirectly increased the biomass of plants. Among NE treatments, the richness of species did not affect aphid density or plant biomass, but the composition of NEs within richness levels affected both responses. The best-performing treatments in control of aphids were the single species treatment of ladybird, the ladybird and parasitoid treatment, and the three species treatment. Planned contrasts showed that the ladybird was the key species among the treatments. Plant biomass was increased in treatments that treated by NEs comparing to the once did not treat with NEs, which indicated decreasing aphid density will increase plant biomass. In conclusion, increasing NE diversity did not consistently affect aphid density or plant biomass. Rather, having a key species (the ladybird) among the divers NEs species was more important than species number per se in the biological control of aphids and their impacts on plant biomass.