Pathogens continue to impress as weed biological control agents in Australia

Abstract Classical biological control has been used as a management tool for invasive non-native plant species globally for over 200 years. There have been some very successful programmes, most notably on waterweeds, cacti and seed reduction in perennial trees. Seventy per cent of agents released have established in at least one instance, and 66% of the targeted invasive species have showed some level of control. However, some programmes have failed to meet expectations, for example on Lantana camara. The most commonly cited reasons for the failure of establishment or limited efficacy of biological control agents are unsuitable climatic conditions and genotype incompatibility. We propose that antagonistic biotic interactions play a significant role in the outcomes of weed biological control programmes. Induced plant defences (physical and chemical) that can be mounted rapidly by the invasive non-native plants can result in the reduction in agent populations after initial attack. Rapid induction of plant defences have been implicated in the lack of long-term establishment of the agent Falconia intermedia that showed great initial promise against the widespread invasive shrub L. camara. Host range expansion by native natural enemies onto biological control agents have also been shown to reduce population growth of agents. Finally, competition from indigenous plant species aids invasive alien plant population reduction in the presence of herbivory. All three factors have been poorly studied and further work is needed to better explain the outcomes of weed biological control programmes.

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Is host-specificity of weed biological control agents likely to evolve rapidly following establishment?

Ecology Letters ◽

10.1046/j.1461-0248.2002.00343.x ◽

2002 ◽

Vol 5 (4) ◽

pp. 590-596 ◽

Cited By ~ 88

Author(s):

Rieks Dekker van Klinken ◽

Owain Rhys Edwards

Keyword(s):

Biological Control ◽

Host Specificity ◽

Biological Control Agents ◽

Weed Biological Control

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A proposal to use plant demographic data to assess potential weed biological control agents impacts on non-target plant populations

BioControl ◽

10.1007/s10526-018-9886-4 ◽

2018 ◽

Vol 63 (3) ◽

pp. 461-473 ◽

Cited By ~ 11

Author(s):

Bernd Blossey ◽

Andrea Dávalos ◽

Wade Simmons ◽

Jianqing Ding

Keyword(s):

Biological Control ◽

Demographic Data ◽

Biological Control Agents ◽

Weed Biological Control ◽

Plant Populations ◽

Target Plant

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European ectoparasitoids of two classical weed biological control agents released in North America

The Canadian Entomologist ◽

10.4039/n10-057 ◽

2011 ◽

Vol 143 (2) ◽

pp. 197-210 ◽

Cited By ~ 2

Author(s):

Franck J. Muller ◽

Peter G. Mason ◽

Lloyd M. Dosdall ◽

Ulrich Kuhlmann

Keyword(s):

Biological Control ◽

North America ◽

Test List ◽

Single Species ◽

Biological Control Agents ◽

Weed Biological Control ◽

Feeding Niche ◽

Important Pest ◽

Nontarget Species ◽

Cabbage Seedpod Weevil

AbstractThe ceutorhynchine weevils Hadroplontus litura (F.) and Microplontus edentulus (Schultze) (Coleoptera: Curculionidae), are established in North America as biological control agents for Canada thistle, Cirsium arvense (L.) Scop., and scentless chamomile, Tripleurospermum perforatum (Mérat) M. Lainz (Asteraceae), respectively. In North America, both weeds occur sympatrically and in similar habitats as another ceutorhynchine, Ceutorhynchus obstrictus (Marsham) (cabbage seedpod weevil), an important pest of canola, Brassica napus L., and Brassica rapa L. (Brassicaceae). Ceutorhynchinae weevils released to control weeds in cultivated crops may serve as alternate hosts if agents released for biological control of C. obstrictus are not specific to that species. Parasitoids associated with M. edentulus and H. litura inflict similar levels of mortality on their hosts, yet a single species was associated with the latter host, whereas 13 species attacked the former. The stem-mining M. edentulus appears to be at some risk but not the root-crown feeding H. litura, should the parasitoids Trichomalus perfectus (Walker) and Mesopolobus morys (Walker) (Hymenoptera: Pteromalidae) be introduced as biological control agents of the silique-feeding C. obstrictus. These findings suggest that feeding niche may be an important criterion for developing a nontarget species test list for host-range testing of potential biological control agents.

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