Selecting biological control agents
Predicting direct non-target impacts
Selecting agents for safety
First estimation of the host range and relationships: literature
The known host associations of a proposed or selected natural enemy can be accessed from the burgeoning array of electronic and physical information sources now available including abstracts, catalogues, journals, databases, websearch, and other grey literature. Several worldwide catalogues summarise or provide access to host association records:
- arthropods and pathogens for weed control (Julien et al. 1999)
- parasitoids and predators of insects (Thompson and Simmonds 1964-1965, Krombein et al. 1979)
- biological control agents in general including BIOCAT (Greathead and Greathead 1992)
- Review of Applied Entomology
- electronic databases including CAB Abstracts, Agricola, Biosis and Zoological Record
- The internet book of biological control (van Lenteren 2006)
These records are the base data on which the safety of a natural enemy can be initially assessed. However, such information must be interpreted with care. The validity of host records determined from museum specimens and records is limited by the accuracy of the identification of the natural enemy (Sands and van Driesche 2004), and the precision of the host data associated with the specimen. Care must be taken with museum records because of some tendency to 'bulk rear' parasitoids from host insects on field-collected plants. There is a danger then that a parasitoid will emerge from unseen 'other' species, and be attributed to the insect of interest on the plant sample. Many museum specimens of parasitoids are, in fact, collected with no knowledge of their hosts.
Field collection of a phytophage 'from' a plant may not guarantee a host association, since the insect might be simply resting on the plant. The enshrining of dubious records in databases may lead to overestimation of the host-range, and such records should not automatically exclude a potential agent from further assessment. Host range can usually only be determined by rearing them from a host. Some host records may originate from laboratory studies, and may reflect the physiological host range rather than the likely range of the natural enemy in the field. For well-known control agents such as Macrocentrus grandii (Braconidae), gaps in knowledge can in themselves be useful indicators of host-range (De Nardo and Hopper 2004).
Greathead D.J. and Greathead A.H. (1992). Biological control of insect pests by insect parasitoids and predators: the BIOCAT database. Biocontrol News and Information 13: 61N-68N
Julien, M. and Griffiths M.W. (1999). Biological Control of Weeds. A World Catalogue of Agents and their Target Weeds. CABI Publishing, Wallingford, UK. 223 p.
Krombein K.V., Hurd P.D., Smith D.R. and Burks B.D. (1979). Catalog of Hymenoptera in America North of Mexico. Smithsonian Institution Press, Washington, DC, USA
Thompson W.R. and Simmonds F.J. (1964-1965). A Catalogue of the Parasites and Predators of Insect Pests. Commonwealth Agricultural Bureaux, Bucks, United Kingdom.
van Lenteren J.C. (2006). The internet book of biological control http://www.unipa.it/iobc/downlaod/IOBC%20InternetBookBiCoVersion4October2006.pdf