Comparing biocontrol and herbicide for managing an invasive non‐native plant species: Efficacy, non‐target effects and secondary invasion

Abstract

1. Globally, invasive non-native plants are an increasing threat to indigenous biodiversity and ecosystems, but management can be compromised by poor efficacy of control methods, harmful non-target effects or secondary invasions by other non-native plant species. 2. A 5-year field trial compared two stakeholder-selected control methods for heather, a European plant invading native ecosystems in and adjoining Tongariro National Park in New Zealand. The control methods were a selective herbicide (Pasture Kleen ® ; 2,4-D ester) and biocontrol with an introduced beetle Lochmaea suturalis (Coleoptera: Chrysomelidae). 3. Biocontrol reduced mean heather cover by 97%, slightly more than herbicide at 87%, compared with a 20% increase in heather under no management. 4. Cover of native dicots, the most species-rich plant group, increased following biocontrol. In contrast, herbicide application had major non-target effects on native dicots, reducing their percentage cover and species richness. Native monocot cover and species richness increased following both herbicide and biocontrol treatments. 5. A similar eightfold increase in non-native monocots occurred following both biocontrol and herbicide treatments. Overall, secondary invasion was greatest with biocontrol because non-native dicot cover also increased, whereas herbicide almost eliminated non-native dicots. 6. Synthesis and applications. Biocontrol and herbicide treatments both controlled heather but herbicide application was associated with severe non-target impacts on native dicots. Benefits to the native flora were consequently greatest in the biocontrol treatment, despite greater secondary invasion. Control strategies for management of widespread non-native plants to optimize ecosystem outcomes should include more consideration of biocontrol.

Canals as invasion pathways in tropical dry forest and the need for monitoring and management

“…Taken together, these results suggest that the critical stage for the spread of invasive species is immediately after construction work finishes. Thus, monitoring and control of invasive species, followed by active ecological restoration efforts must be done right after construction has ended to prevent a secondary wave of invasions (Pearson et al, 2016;Peterson et al, 2020) and to avoid continuous spread into susceptible areas.…”

Improvement of the soil pollution monitoring system

“…In the agrocenosis, heavy metals and pesticides can enter and accumulate in plants from the soil, which further along the trophic chain enter human food or animal feed and have a negative impact primarily on human health [2][3]. The problem of soil contamination with pesticides and heavy metals is being investigated by scientists from different countries [4][5][6][7]. The Russian Federation has established an extensive and fairly effective environmental monitoring system.…”

An innovative approach combining metabarcoding and ecological interaction networks for selecting candidate biological control agents

“…CBC involves the release of natural enemies, specific to the target organism and originating from its native range, to keep the density of the invasive species below an economically and ecologically acceptable threshold (Keane & Crawley, 2002;McFadyen, 1998;Van Driesche et al, 2010). From an economical and environmental point of view, CBC is considered more sustainable than mechanical and chemical control (Peterson et al, 2020), although the introduction of biocontrol agents (BCA) into a new territory may itself represents a risk for the recipient communities (Barratt et al, 2018;Hinz et al, 2019;Suckling & Sforza, 2014). Once introduced, the BCA may affect non-target species, especially if it lacks specificity (Müller-Schärer & Schaffner, 2008).…”