Original Research

Dispersal of Dactylopius opuntiae Cockerell (Homoptera: Dactylopiidae), a biological control agent of Opuntia stricta (Haworth.) Haworth. (Cactaceae) in the Kruger National Park

L.C. Foxcroft, J.H. Hoffmann
Koedoe | Vol 43, No 2 | a194 | DOI: https://doi.org/10.4102/koedoe.v43i2.194 | © 2000 L.C. Foxcroft, J.H. Hoffmann | This work is licensed under CC Attribution 4.0
Submitted: 01 July 2000 | Published: 02 July 2000

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L.C. Foxcroft,
J.H. Hoffmann,

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Abstract

Chemical control efforts, the introduction of Cactoblastis cactorum and attempted releases of Dactylopius opuntiae Cockerell into the expanding infestation of Opuntia stricta in the Skukuza region of the Kruger National Park (KNP) have had limited suc- cess in preventing the spread and densification of 0. stricta. To boost the biological control component, a new strain of D. opuntiae was introduced into KNP during 1997. The new strain established readily and has destroyed large clumps of plants in the vicin- ity of the release site. A large-scale redistribution programme with D. opuntiae is now needed to exploit this biological control agent to the full. In order to match the frequency of manual releases with the natural rates of spread of the insects, surveys were conducted under field conditions to determine the dispersal abilities ofD. opuntiae, with regard to rate and direction of movement. Dispersal of D. opuntiae was found to be slow and restricted and that the insects need to be redistributed by placing them onto plants at approximately 10 m intervals to ensure that they become quickly and evenly distributed on the weed. This information will be crucial in the revision of the integrated management plan for 0. stricta in the KNP, in integrating the cochineal and other control mechanisms.

Keywords

Dactylopius opuntiae, dispersal, biological control agent, Opuntia stricta,

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Crossref Citations

1. Environmental factors influencing the distribution of Opuntia stricta, an invasive alien plant in the Kruger National Park, South Africa
L.C. Foxcroft, J.H. Hoffmann, J.J. Viljoen, J.J. Kotze
South African Journal of Botany  vol: 73  issue: 1  first page: 109  year: 2007  
doi: 10.1016/j.sajb.2006.09.008