Controlling mesquite in northern Australia

Potential for new biological control agents

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New biological control agents will undoubtedly be required in Australia, and elsewhere, if mesquite is to be successfully contained and managed. Additional agents in the Pilbara region, where the leaf-tier has dramatically reduced seed production, will almost certainly be required to reduce the longevity of mesquite plants.

Elsewhere in Australia new agents will be required that are better climatically adapted to local conditions.

The native fauna of mesquite has been relatively well surveyed in the United States (Ward et al. 1977), Argentina and Paraguay (Cordo and DeLoach 1987). Considerable information has also been obtained from other countries, including Peru.

As a result, over 945 phytophagous insects species, which attack all parts of the plant, and many pathogens, have now been recorded from Prosopis in its native range.

This is likely to increase further with additional systematic surveying in areas that have received relatively little systematic attention (such as northern and north-western parts of South America) and on insect and pathogen groups that have remained largely overlooked (such as stem-borers and root-feeders).

There is therefore a large pool of potential biological control agents available, many of which are likely to be specific to mesquite and therefore safe to release. The challenge is to identify which potential agents are most likely to impact on mesquite in the target regions.

Climatic suitability will be important. Mesquite grows in diverse climates and therefore it may not be possible to find agents that will do equally well in all regions.

Also, ecological research on mesquite is ongoing to help determine what type of damage will result in greatest impact, but it is already clear that agents will be required which decrease adult longevity of mesquite.

Feeding damage on mesquite by the leaf-tying gelechiid.

A leaf-tying gelechiid is a defoliator of mesquite.

Mesquite biological control agent Prosopidopsylla flava, a Sap-sucking psyllid.

This sap-sucking psyllid was released throughout Australia to help control mesquite.

Existing biological control agents for mesquite include:

  • Evippe species #1 (Gelechiidae): leaf-tying moth
  • Prosopidopsylla flava (Psyllidae): sap-sucking bug
  • Algarobius bottimeri (Bruchidae): seed-feeding beetle
  • Algarobius prosopis (Bruchidae): seed-feeding beetle

Potential biological control agents that have been tested and rejected include:

  • Mozena obtusa (Coreidae): sap-sucking bug
  • Oncideres rhodosticta (Cerambycidae): girdling beetle
  • Heteropsylla texana (Psyllidae): sap-sucking moth.

References

  • Cordo HA, DeLoach CJ. 1987. Insects that attack mesquite (Prosopis spp.) in Argentina and Paraguay: their possible use for biological control in the United States. United State Department of Agriculture, ARS-62. South American Biological Control Laboratory, Hurlingham, Buenos Aires. Argentina.
  • De Loach CJ. 1985. Conflicts of interest over beneficial and undesirable aspects of mesquite (Prosopis spp.) in the United States as related to biological control. In: Delfosse ES. (Ed.). Proceedings of VI International Symposium on the Biological Control of Weeds 1984. Minister of Supply and Services. Vancouver, Canada. Pp. 301-40.
  • Impson FAC, Moran VC, Hoffmann JH. 1999. A review of the effectiveness of seed-feeding bruchid beetles in the biological control of mesquite, Prosopis species (Fabaceae), in South Africa. African Entomology Memoir. 1:81-88.
  • Paulsen HA, Ares FN. 1961. Trends and carrying capacity and vegetation on an arid southwestern range. Journal of Range Management. 14: 78-83.
  • Ward CR, O'Brien CW, O'Brien LB, Foster DE, Huddlestone EW. 1977. Annotated checklist of New World insects associated with Prosopis (mesquite). United States Department of Agriculture, Research Services Bulletin. 1557.