Mass-production of arthropods for biological control of weeds: A global perspective

Authors: Moran, Patrick; DE CLERCK-FLOATE, ROSEMARIE - Agriculture And Agri-Food Canada; HILL, MARTIN - Rhodes University; RAGHU, S - Commonwealth Scientific And Industrial Research Organisation (CSIRO); PAYNTER, QUENTIN - Landcare Research; Goolsby, John

Submitted to: Mass Production of Beneficial Organisms: Invertebrates and Entomopathogens
Publication Type: Book / Chapter
Publication Acceptance Date: 12/9/2021
Publication Date: 9/26/2022
Citation: Moran, P.J., De Clerck-Floate, R., Hill, M.P., Raghu, S., Paynter, Q., Goolsby, J. 2022. Mass-production of arthropods for biological control of weeds: A global perspective. In: Morales-Ramos, J.A., Rojas, M.G., Shopiro-Ilan, D.I., editors. Mass Production of Beneficial Organisms. 2nd edition. London, UK: Academic Press. p. 157-194.
DOI: https://doi.org/10.1016/B978-0-12-822106-8.00014-2

Interpretive Summary: Non-native, invasive weeds that grow mostly or entirely outside of crop lands-in or on lakes, ponds, rivers, wetlands, shorelines, rangelands, pastures and forests-degrade the quality and quantity of water and soil resources for agriculture and threaten survival of native plant and animal species, especially species that are Federally- or state-listed as Rare, Threatened or Endangered. Control methods such as application of chemical herbicides or the use of mechanical equipment and hand-removal are not adequate when invasive weeds spread over entire states, regions, or countries. Biological control of weeds can be carried out using insects, mites or plant pathogens (that cause disease) that are imported from the weed's native range and rigorously tested to ensure that they can feed and reproduce only on the weed and not on crop plants or native plants in the environment. These candidate 'biological control agents' are also pre-tested to verify that they can cause a lot of damage to the targeted weed, and their life cycles are determined. After a strict regulatory review process at the U.S. Federal and state levels, permits for field release are granted for agents that are safe and have potential for impact against the weed. A key concern in releasing insects or mites ('arthropods') for biological weed control is getting them established quickly, and at many field sites where the targeted invasive weed is present. Mass-rearing (or 'mass-production') of arthropods for biological weed control can be carried out to aid this process. Most of these arthropods can only be reared on the one plant that they survive on naturally, and not artificial diets. Mass-rearing thus involves growing the weed in greenhouses or field gardens to feed to the insect or mite under controlled or semi-controlled, protected conditions. Since the 1920s, across five countries where the most biological control agents of weeds have been released (United States, Canada, South Africa, Australia and New Zealand) and using 25 specific arthropods as examples, between 4,500 and 2.8 billion offspring of specific arthropod species have been mass-reared and released. In some cases, rearing was carried out by government agencies, while in others various stakeholders including natural resource managers, landowners and school children were involved. Release of these biological control agents has led to ecosystem- and country-wide establishment of these insects and mites, and weed populations and the damage they caused have been reduced. Mass-rearing of biological control agents of weeds is often challenging, but continues to offer promise in improving management of major weed invasions.

Technical Abstract: Mass-production of arthropods for biological weed control has the potential to increase the geographic spread or rate of field establishment of agents for control of damaging non-native, invasive weeds of aquatic, riparian, rangeland and forest environments, with rare applications to crop weeds. Mass-rearing of these host-specific agents is almost always performed on undefined diets of host plant material, often under conditions such as shadehouses or field gardens which are only partly controlled, and in some cases by non-technical stakeholders. Results from 25 examples including seven case studies spanning five countries indicate variable rearing output from a few thousand to millions or even billions of individuals, dependent largely on arthropod agent biology but also on investment of expertise and funds. Mass-production of weed biological control agents stands to benefit from increased genetic information about weeds and agents, and its importance and role in improving control of environmental weeds may increase.