Action: Water primrose: Biological control using co-evolved, host specific herbivores
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- A controlled, replicated field study in China, found a flea beetle caused heavy feeding destruction when added to field cages containing prostrate water primrose seedlings, and was specific to the prostrate water primrose and Indian toothcup.
- A replicated, before-and-after field study in the USA found that introduction of flea beetles to a pond significantly reduced the abundance of large-flower primrose-willow.
One-off introduction of a co-evolved, host-specific herbivore from the area of origin of the invasive pest can potentially provide sustainable control without affecting non-target indigenous plants.
Some studies have reported heavy damage caused to water primrose in the field by herbivorous insects. For example, the flea beetle Lysathia flavipes has been reported to cause heavy damage in the field to creeping water primrose Ludwigia peploides, although feeding behaviour was reportedly not specific (Cordo & DeLoach 1982a). It has also been reported that sterile grass carp Ctenopharyngodon idella have been used to control large-flower primrose-willow Ludwigia grandiflora (Manuel 1989) although grass carp are non-selective herbivores in which case they could harm native species.
Some studies reference damage caused to water primrose by certain species of insects without referencing their specificity. For example, a study published in 2000 reports that three beetles, comprising two Lysathia spp. and a Macrohaltica spp., and also the lesser vine Sphinx moth Pholus fasciatus, damage water primrose in Colombia but no reference is made to specificity (Cuevas Medina 2000).
In contrast, other studies appear to have found host-specific agents. For example, a specificity study in Argentina, found that adults of the weevils Tyloderma spp. A and Tyloderma spp. B appear to have creeping water primrose as their only host plant (Cordo & DeLoach 1982b).
Cordo, H. A. & DeLoach, C.J. (1982a) The flea beetle, Lysanthia flavipes, that attacks Ludwigia (water primrose) and Myriophyllum (parrotfeather) in Argentina. The Coleopterists Bulletin, 36, 298-301.
Cordo, H.A. & DeLoach, C.J. (1982b) Notes on the Weevils Tyloderma, Auleutes, and Onychylis That Feed on Ludwigia and Other Aquatic Plants in Southern South America. The Coleopterists Bulletin, 36, 291-297.
Cuevas Medina, A. (2000) Biological control of the weed ‘palo deAgua’ in rice with Coleoptera. Arroz, 49, 14–18.
Manuel, K.L. (1989) Proceedings of Workshop on Management of Aquatic Weeds and Mosquitoes in Impoundments March 14-15, Charlotte, North Carolina. Water Resources Research Institute, Report, 247. Water Resources Research Institute, University of North Carolina, 21-26.
Supporting evidence from individual studies
A controlled, replicated field study carried out in 1985 in Jiangxi Agricultural University, China (Xiao-Shui 1990) found the flea beetle Altica cyanea caused heavy feeding destruction to the prostrate water primrose Ludwigia prostrata and was specific to the prostrate water primrose and Indian toothcup Rotala indica. In field cage experiments, flea beetles decimated prostrate water primrose plants within a month. Wooden frame field cages were covered with nylon mesh on the sides and a mesh window on the top. One hundred prostrate water primrose seedlings were planted per cage. Flea beetle adults were collected from the field and zero, two, four, and eight pairs of them were released at random into each cage when young caged plants had at least nine leaves. There were three replicates of each population size on the plants. Observations were made at 10 day intervals. To test food specificity, laboratory-based larval starvation tests were carried out on 24 different plant species at temperatures of 20-30OC.
A replicated, before-and-after field study conducted in 1994 in the USA (McGregor et al. 1996) found that introduction of flea beetles Lysathia ludoviciana to a pond significantly reduced the abundance of large-flower primrose-willow Ludwigia grandiflora. When the beetles were introduced to the pond, the abundance of large-flower primrose-willow declined from an initial average 61 g/m2 to an average of 7 g/m2 from July to September. Beetles were introduced in July into a one hectare pond containing the water primrose. The mean density of flea beetles varied throughout the study from 1-12/m2. Changes in abundance of large-flower primrose-willow was monitored in six enclosures measuring 5 x 10 m.
- Xiao-Shui W. (1990) Altica cyanea (Col: Chrysomelidae) for the biological control of Ludwigia prostrata (Onagraceae) in China. Tropical Pest Management, 36, 368-370
- McGregor M.A., Bayne D.R., Steeger J.G., Webber E.C. & Reutebuch E. (1996) The Potential for Biological Control of Water Primrose (Ludwigia grandiflora) by the Water Primrose Flea Beetle (Lysathia ludoviciana) in the Southeastern United States. Journal of Aquatic Plant Management, 34, 74-76