Both the authors contributed equally to this work.
The role of transient dynamics in biological pest control: insights from a host–parasitoid community
Article first published online: 1 JUL 2011
© 2011 The Authors. Journal of Animal Ecology © 2011 British Ecological Society
Journal of Animal Ecology
Volume 81, Issue 1, pages 47–57, January 2012
How to Cite
Kidd, D. and Amarasekare, P. (2012), The role of transient dynamics in biological pest control: insights from a host–parasitoid community. Journal of Animal Ecology, 81: 47–57. doi: 10.1111/j.1365-2656.2011.01881.x
- Issue published online: 8 DEC 2011
- Article first published online: 1 JUL 2011
- Received 8 March 2011; accepted 29 May 2011 Handling Editor: Tim Coulson
- attack rate;
- biological control;
- functional response;
- handling time;
- transient dynamics
1. Identifying natural enemies that can maintain pests at low abundances is a priority in biological control. Here, we show that experiments combined with models generate new insights into identifying effective control agents prior to their release in the field. Using a host–parasitoid community (the harlequin bug and its egg parasitoids) as a model system, we report three key findings.
2. The interplay between the host's self-limitation and the parasitoids’ saturating functional response causes the long-term (steady-state) outcomes for pest suppression to differ from those of short-term (transient) dynamics. When the bug's self-limitation is moderately strong, the parasitoid with the higher attack rate and conversion efficiency (Ooencyrtus) achieves greater host suppression in the long term, but its longer handling time causes long periods of transient dynamics during which the bug can reach high abundances; when the bug's self-limitation is weak, host fluctuations amplify over time and Ooencyrtus fails at host suppression altogether. In contrast, the parasitoid with the lower attack rate and conversion efficiency but the shorter handling time (Trissolcus) induces only weak transient fluctuations of short duration and can maintain the host at low abundances regardless of the strength of the bug's self-limitation.
3. Release of multiple enemy species can compromise host suppression if an enemy that induces stronger transient fluctuations excludes one that induces weaker fluctuations. For instance, Ooencyrtus excludes Trissolcus despite having a longer handling time because of its higher conversion efficiency. The model correctly predicts the time to exclusion observed in experiments, suggesting that it captures the key biological features of the host–parasitoid interaction.
4. Intraspecific interference reduces long-term pest suppression but improves short-term pest control by reducing the magnitude and duration of transient fluctuations.
5. These results highlight the importance of transient dynamics in pest suppression. Pests are unlikely to be strongly self-limited because they attack crop monocultures. Hence, pest fluctuations are likely to dominate short-term dynamics even when the long-term outcome is a stable equilibrium. The tendency to induce strong transient fluctuations (e.g. through a long handling time) is therefore a crucial consideration when identifying effective pest control agents.