Background information

Biological control best practice

Host life stage attacked

The stage of the life cycle of the target host that is attacked by a potential biological control agent is clearly important in terms of efficacy, and impact on population density. In terms of biosafety it is also potentially significant. For example, a parasitoid of a sedentary stage of the life cycle might pose less of a risk to non-target hosts than one which attacks a dispersive phase of the life cycle. Biological control agents of weeds might target the foliage, reproductive structures, stems, crown, roots etc. and the impact of the biological control agent will be dependent upon the ability of the plant to recover and/or compensate for damage. When combinations of biological control agents are used, the approach taken is often to target different parts of the plant. The possibility of one biological control agent compromising the impact of another is clearly best avoided as noted below.