Abstract: Not Available.
Specimens of Xiphinema basiri, X. oxycaudatum (Lamberti and Bleve-Zacheo, 1979) and Paralongidorus lemoni, were extracted from soil samples collected from citrus orchards in March, 1993 at Faisalabad and in September, 1993 at Karachi, Pakistan. Nematodes were collected using the Baermann funnel technique with 48 h incubation and stored for 1-5 days at 16'C in a cooling incubator. Approximately 40 percent of living nematodes appeared parasitized by fungus and 100 nematode specimens examined by light microscope at 10 percent. Some of these specimens (20-25) were transferred aseptically onto 2 percent water agar supplemented with streptomycin sulphate at a concentration of 200 mg/lit. Portion of advancing edges of fungal colonies growing in water agar were aseptically transferred to petri dishes containing potato dextrose agar and incubated at 25°C (Jaffee, 1986). Some healthy, infected and non infected specimens were killed by gentle heat, fixed in TAF, transferred to 1.25 percent glycerin solution containing traces of picric acid and allowed to dry. Specimens were then mounted in pure glycerin on permanent slides for observations and measurements.
Specimens of P. lemoni, X. oxycaudatum and X. basiri were parasitized by the zoosporic fungus Catenaria anguilullae. Zoosporangia measuring 25-45 pm diameter in size were observed within infected nematodes with discharge tubes emerging through the cuticle. Zoospores were observed to emerge in clusters through the zoosporangia discharge tubes. Aseptic hyphae were observed within nematodes early during colonization. C. anguilullae produced sporangia on water agar or potato dextrose agar.
Catenaria spp., are generally isolated from nematodes and considered common parasites. C. anguilullae attacks dead or injured nematodes as well as healthy specimens. It is not considered, however, useful antagonist of plant parasitic Tylenchida, because needs high water contents in soil for successful parasitism and spreading. Dorylaim nematodes are easily attacked by the motile zoospores of C. anguilullae especially when stored in water for a long time (Esser and Ridings, 1973). Among the zoosporic fungi parasitic in Dorylaimids C. anguilullae has also often been reported as parasite of several species including X. americanum, X. chambersi, X. index, X. rivesi and Paralongidorus buchae (Ciancio and Chinappen, 1987; Esser and Ridings, 1973) (Fig. 1). It seems to be a world wide, nonspecific nematode antagonist (Sparrow, 1960) and has been reported from England, The Netherlands, Germany, Sweden, Czechoslovakia, Italy and California (Tribe, 1977; Jaffee, 1986; Ciancio and Chinappen, 1987).
| Fig. 1: | Naturally infected nematodes parasitized by Catenaria anguilullae showing zoosporangia and discharge tube emerging from the nematode body, A: Xiphinema basiri, B: X. oxycaudaturn, C: Paralongidorus lemoni (scale bar = 100 μm.) |
This is the first report of C. anguilullae as a parasite of X. basiri, X. oxycaudatum and P. lemoni and is also the first record from Pakistan.
Acknowledgements
Author thanks to Dr. Brian Kerry for confirmation of species identification, Dr. B.A. Jaffee and Dr. R.P. Esser for providing literature.