Biological control ofOstertagia ostertagiby feeding selected nematode-trapping fungi to calves

Abstract

Three nematode-trapping fungi, one Arthrobotrys oligospora and two Duddingtonia flagrans isolates, were fed to Ostertagia ostertagi-infected calves to test their ability to destroy larvae of this parasite in faeces and consequently to reduce the transmission of infective larvae to herbage. The fungi had previously been selected for their capability to pass the alimentary tract of cattle without losing growth and nematode-trapping potentials. Dung was collected from three calves each fed one of the three fungi and placed as 1-kg cow pats on a parasite-free grass plot together with control cow pats from a calf that was not given fungi. The cow pats contained comparable concentrations of parasite eggs. The two D. flagrans isolates were highly effective in that they reduced herbage larval infectivity by 74–85%. In contrast, A. oligospora did not show any effect in the present experiment. Field experiments will demonstrate if D. flagrans represents a potential organism for biological control of bovine gastrointestinal nematodes under practical agricultural management conditions.

Nematophagous fungi as a biological control agent for nematode parasites of small ruminants in Malaysia: a special emphasis on Duddingtonia flagrans

“…As in the studies in Denmark [8,9] and Australia [13,23], the Malaysian D. flagrans isolate was found to grow most satisfactorily on moist, sterilized cereal grains. Autoclaving the moistened green peas and small red beans caused them to adhere into sticky solid masses, and the hard pericarp of large red beans, soya beans and black beans prevented the complete absorption of the added water.…”

“…Although the Malaysian isolate of D. flagrans grew profusely, as evidenced by the abundant white mycelial growth on the grain substrates, its production of chlamydospores was much lower after 6 weeks of incubation (Х 1 × 10 5 /g dried grain), compared with Australian isolates (Х 5 × 10 5 /g dried grain, after 4-5 weeks incubation [23]) and Danish isolates (Х 2.5 × 10 5 / grain of barley incubated for 2 weeks at 20-22 o C [9]). Intra-species variation of nematophagous fungi in various morphological and physiological characteristics, including the production of conidia and/or chlamydospores, is well known [16,19].…”

Growth rate and trapping efficacy of nematode-trapping fungi under constant and fluctuating temperatures

“…The ®ve isolates were cultivated according to Grùnvold et al (1993a) for use in faecal cultures (see below). After 3 weeks of incubation, fungal spores were washed o and strained through a nylon mesh (100-lm mesh size), and the concentration of spores per milliliter of water was calculated using a Fuch-Rosenthal haemocytometer.…”

Occurrence, morphological characteristics and ribotyping of New Zealand isolates ofDuddingtonia flagrans,a candidate for biocontrol of animal parasitic nematodes

“…In warm dung, the parasite eggs hatch to release free-living, bacterial-feeding, juvenile stages, while the chlamydospores germinate to form mycelium that produces traps in response to nematode activity. The efficacy of D. flagrans as a biocontrol tool against pre-parasitic stages of intestinal nematodes has been demonstrated in experiments with sheep (Githigia et al 1997;Faedo et al 1998;Mendoza de Gives et al 1998;Chandrawathani et al 1999;Sanyal 2000), cattle (Grønvold et al 1993;Larsen et al 1995;Fernández et al 1999), horses (Fernández et al 1997), pigs , and goats (Gawor et al 1999).…”