Pest Management Science (2015) 71, 1462-1470

Aston L. Arthur, Ary A. Hoffmann and Paul A. Umina (2015)
Challenges in devising economic spray thresholds for a major pest of Australian canola, the redlegged earth mite (Halotydeus destructor)
Pest Management Science 71 (10), 1462-1470
Abstract:
BACKGROUND
A key component for spray decision-making in IPM programmes is the establishment of economic injury levels (EILs) and economic thresholds (ETs). We aimed to establish an EIL for the redlegged earth mite (Halotydeus destructor Tucker) on canola.
RESULTS
Complex interactions between mite numbers, feeding damage and plant recovery were found, highlighting the challenges in linking H. destructor numbers to yield. A guide of 10 mites plant^-1 was established at the first-true-leaf stage; however, simple relationships were not evident at other crop development stages, making it difficult to establish reliable EILs based on mite number. Yield was, however, strongly associated with plant damage and plant densities, reflecting the impact of mite feeding damage and indicating a plant-based alternative for establishing thresholds for H. destructor. Drawing on data from multiple field trials, we show that plant densities below 30–40 plants m^-2 could be used as a proxy for mite damage when reliable estimates of mite densities are not possible.
CONCLUSION
This plant-based threshold provides a practical tool that avoids the difficulties of accurately estimating mite densities. The approach may be applicable to other situations where production conditions are unpredictable and interactions between pests and plant hosts are complex.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Aston L. Arthur, Paul A. Umina, Ary A. Hoffmann

Research topic(s) for pests/diseases/weeds:
damage/losses/economics
thresholds/decision-support systems

---

Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Halotydeus destructor	Rape/canola (Brassica napus)