Journal of Pest Science (2018) 91, 1199-1211

A. Thancharoen, S. Lankaew, P. Moonjuntha, T. Wongphanuwat, B. Sangtongpraow, R. Ngoenklan, P. Kittipadakul and Kris A.G. Wyckhuys (2018)
Effective biological control of an invasive mealybug pest enhances root yield in cassava
Journal of Pest Science 91 (4), 1199-1211
Abstract: Insects provide critical ecosystem services to humanity, including biological control of pests. Particularly for invasive pests, biological control constitutes an environmentally sound and cost-effective management option. Following its 2008 invasion of Southeast Asia, biological control was implemented against the cassava mealybug Phenacoccus manihoti (Hemiptera: Pseudococcidae) through the introduction and subsequent release of the host-specific parasitoid Anagyrus lopezi (Hymenoptera: Encyrtidae) in Thailand. In this study, we quantify yield benefits of mealybug biological control in Thailand's cassava crop by using two different types of manipulative field trials: i.e., 'physical exclusion' cage trials and field-level 'chemical exclusion' assays. In cage trials with two popular cassava varieties, root yield and total dry matter (or 'biological yield') were a respective 4.0–4.2 times and 3.5–3.9 times higher in the presence of biological control. Extrapolating results from cage trials, biological control thus ensured an approximate yield gain of 5.3–10.0 T/ha for either variety. Under chemical exclusion trials, P. manihoti populations attained levels of 3266 ± 1021 cumulative mealybug-days (CMD) over a 10-month time period, and no longer impact yields. Moreover, under effective P. manihoti control, both root yield and biological yield increased with season-long CMD measures, and pest management interventions-including insecticide sprays-led to notable reductions in yield. This study is the first to show how biological control effectively downgrades the globally invasive P. manihoti to non-economic status and restores yields in Thailand's cassava crop. Our work emphasizes the economic value of biological control, reveals how current P. manihoti populations do not necessarily cause yield penalties, and underlines the central importance of nature-based approaches in intensifying global agricultural production.
(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): Kris A.G. Wyckhuys

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
evaluation - screening - selection

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Phenacoccus manihoti	Cassava (Manihot esculenta)	Thailand
Apoanagyrus lopezi (parasitoid)	Phenacoccus manihoti	Cassava (Manihot esculenta)	Thailand