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Other invasives in Israel

> Invasive plants in Israel > Pistia stratiotes L.

Pistia stratiotes L.
Life form: Perennial aquatic
En: Water lettuce. Fr: Laitue d'eau
Provenance: Uncertain, probably tropical southern America

Young individuals of Pistia stratiotes in the Alexander river (Sept. 11th, 2005)

Distribution in Israel
Two developing populations of Pistia stratiotes have been recorded in Israel since 2004: The first has developed since mid 2005 in the Alexander river, northeast to the city of Netanya together with Eichornia crassipes. The second population was found in September 2005 in the Lakhish river, east of the city of Ashdod in the southern coastal plain.


Mature individuals of Pistia stratiotes froming a dense mat in the Lakhish river (Dec. 11th, 2005)

Proliferation status
The water lettuce in Israel is an 'invasive' alien according to the terminology suggested by Richardson et al. (2000).

Pistia stratiotes in Israel
So far no evidence has been found of previous infestations in rivers in Israel.
The species has been introduced in Israel presumably for ornamental purposes. It is still sold in plant nurseries. Its’ very rapid vegetative reproduction allows the water lettuce to completely cover a waterbody as it does in the Lakhish river.
The water lettuce rapidly forms a compact mat on the water surface that crowds out native species. Since it modifies water temperatures and significantly decreases water oxygenation, the biological diversity in infested aquatic ecosystems drops dramatically.
This invasive has been reported only very recently, so as yet no control programs have been elaborated in Israel in order to eradicate the water lettuce. The Ministry of Environment and the Nature and Parks Authority have been informed of the proliferation of Pistia stratiotes.
The threat posed by the water lettuce in aquatic ecosystems in Israel is quite similar to that of the water hyacinth: It could rapidly infest the few rivers and ponds exiting in the Mediterranean region of Israel. Preventing the proliferation of the water lettuce in Israel is a still a realistic goal for it is, so far, restricted to only four foci of infestation.

The water lettuce in the Lakhish river (December 11th, 2005)

The water lettuce can be removed mechanically from water bodies with harvester machines. The most effective chemical control requires use of diquat herbicides approved for aquatic use.
Biological control has proved quite effective with a leaf weevil (Neohydronomus affinis) introduced in Australia and in the USA from South America. The use of a Thailand native moth (Spodoptera pectinicornis) has brought positive results in the control of the water lettuce in Florida and in Texas.

Water lettuce in the Hula region (northern Israel) (October 9th, 2006)

Den Hollander N.G., Schenk I.W., Diouf S., Kropff M.J. & Pieterse A.H. (1999) Survival strategy of Pistia stratiotes L. in the Djoudj National Park in Senegal. Hydrologia 415:21-27.

Dewald L.B. & Loubinos L.P. (1990) Seasonal growth of Pistia stratiotes L. in south Florida. Aquatic Botany 36:263-275.

Dray F.A. & Center T.D. (1989) Seed production by Pistia stratiotes L. (Water Lettuce) in the United States. Aquatic Botany 33:155-160.

Last Modified: October 9th, 2006

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