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Better Understanding of Bugs for Improved Environment

Final Report Summary - BUGSIE (Better Understanding of Bugs for Improved Environment)

The main objective of BUGSIE project supported by EU Marie Curie IRSES was to advance research and higher education in the field of Biological Control of insect pests and develop sustainable collaboration between research institutions in EU and New Zealand. The research carried out by the programme focused on to improving success of the egg parasitoid Trissolcus basalis against the worldwide distributed pest Nezara viridula aiming to address the common problem of food security consistently with increasing global recognition that agro-ecology has to be the approach for future farming.

The overall objectives of the project were to investigate aspects on behavioural and chemical ecology that can improve the efficiency of biocontrol program based on the egg parasitoid Trissolcus basalis to be used against Nezara viridula, an important pest of several crops.

Work packages
BUGSIE was carried out in five research packages. 1. “Evaluating geographical variations in Trissolcus basalis foraging behavior in response to synomones and kairomones” In this package strains of T. basalis collected from Europe (Italy and France) and from New Zealand were compared with laboratory experiments. 2. “Developing habitat manipulation strategies to reduce crop colonization rates of Nezara viridula and improve efficiency of T. basalis” In this package the essential role of flower attractiveness for foraging parasitoids was studied through chemical analysis on Volatile Organic Compounds (VOCs) collected from all flowering plants to identify the active compounds able to improve the egg parasitoid efficacy. 3. “Investigating the foraging behaviour of T. basalis on plants that are colonized by endophytic fungus” 4. “Exploring conflict/synergies in controlling N. viridula population with one or more egg parasitoid species” In this package we evaluated the ability of T. basalis to coexist with other egg parasitoids and the possibility to use different natural enemy species to control an insect pest. 5. “Managing the effective dissemination of knowledge between the Network Partners and international stakeholders”.

One of the main goals of the project is developing habitat manipulation strategies to reduce crop colonization rates of Nezara viridula, widely distributed agricultural pest throughout the world, and improve efficiency of Trissolcus basali, the most important biological control agent of N. viridula. Conservation biological control is not been attempted for this system and so far there is only one study looking at the longevity of this biological control agent. Nectar-producing plants can improve biological control of pests by supplying parasitoids with food resource, which is often limited in monocultures. Experiments conducted on four selected flowering plants, French marigold, basil, alyssum and buckwheat, showed the best fitness of T. basalis on buckwheat plants. The essential role of flower attractiveness for foraging parasitoids was studied through chemical analysis on Volatile Organic Compounds (VOCs) collected from all flowering plants to identify the principal compounds and buckwheat VOCs showed that its floral scent is characterized by a range of carboxylic acids. Bioassays showed that the T. basalis females are attracted to the flowers of buckwheat in comparison with its leaves and VOCs collected from buckwheat using only flowers showed that the carboxylic acids are only present in flower VOCs. Coupled GC-EAD recordings showed that T. basalis is olfactory attracted to the carboxylic acids and conducted bioassays with reconstructed buckwheat-blend showed attractive behaviour. In conclusion, laboratory tests suggests that Buckwheat is the optimal floral resource for conservation biological control using T. basalis and isolated attractive compounds may serve as trap lures for monitoring the presence of biological control agents in the field.
Intraguild interactions between parasitoids can shape species coexistence and community structure with important consequences for basic and applied ecology. Intraguild interactions between Trissolcus basalis and Ooencyrtus telenomicida, two egg parasitoids of Nezara viridula, have been studied with laboratory and field investigations. Results indicated that these parasitoid species adopt different strategies that allow for coexistence on the same host resources. Indeed T. basalis is more efficient at locating and exploiting N. viridula egg masses, being superior in terms of “extrinsic competition” whereas O. telenomicida dominates intrinsic competition via physiological suppression when multiparasitism occurs. Interactions between T. basalis and O. telenomicida are not only limited to competition since the latter species can also act as a facultative hyperparasitoid of the former extending the window of opportunity for parasitism. In the field T. basalis occurs in May and successfully parasitizes hosts until the end of September/beginning of October, whereas O. telenomicida is mainly occurring in July-August. Trissolcus basalis achieves a higher impact on N. viridula than O. telenomicida and coexistence of these egg parasitoids species is also affected by the host egg mass size.

Benefits and outgrowth
BUGSIE promoted visits, seminars, workshops, conference sessions, and collaborative writing of abstracts, conference proceedings, and journal papers among researchers from the different involved institutes. They learnt from each other, helped academies create new international cross-disciplinary colloborative projects and furthered knowledge transfer between EU and 3rd Country partners.
Overall, a total of 31 months of research staff exchange were carried out during the 3 years of the BUGSIE project from Europe to New Zealand. In details, a total of about 22 months (representing 73%) were carried out by early-stage researchers (i.e. professional researchers in the first 4 years of their research careers, such as doctoral students or research technicians). The remaining 8 months (27%) were carried out by experienced researchers (i.e. professional researchers already in possession of a doctoral degree or having at least 4 years of research experience, such as post doctoral researchers, lab group leaders, and professors). Moreover, 5 months, of research staff exchange were carried out from New Zealand to Europe, 3 by early-stage researchers and 2 by experienced researchers.