The ecology of the immature phases of trichostrongyle parasites. V. The estimation of pasture infestation

1. Methods of sampling pastures for infective larvae are discussed.

2. An account is given of the methods of operation and identification of larvae from herbage.

3. The distribution of larvae on pastures is discussed in relation to choice of method of sampling and interpretation of results.

4. The significance of grazing patterns to distribution of larvae is considered.

5. An attempt is made to evaluate the use and limitations of pasture sampling methods.

The author is indebted to the Agricultural Research Council for financial assistance in the form of a special research grant.

The vertical migration of infective larvae of strongyloid nematodes

Using a technique to reduce the possibility of establishing gradients of temperature, illumination, etc., it has been shown that infective larvae of T. retortaeformis, sheep trichostrongyles and horse trichonemes move in random directions when on a vertical plane at temperatures of 16°–17°C. and at 27°C.

In a horizontal plane the same randomness was shown.

Larvae moving in channels of different widths moved different distances along the channels in the same time. In narrow channels the distance moved was approximately proportional to the time (T) of movement. In wide channels the distance was approximately proportional to ✓T.

The effect of a drying water film on the movements of larvae of T. retortaeformis are described.

It is concluded that vertical migration of the larvae may be described in terms of normal larval movements without reference to geotropism or undescribed special receptors in the larvae.

On the synonymy of Marshallagia orientalis (Bhalerao, 1932) with Marshallagia marshalli and a record of its occurrence from the mountainous region of the Punjab

In June 1946, one male and one female helminth of the species Marshallagia marshalli (Ransom, 1907) were collected from one of two goats (Capra sibirica), at Manali, which had been slaughtered soon after their arrival from Spiti (Kangra district, Punjab, India). The abomasa, small intestines, lungs and livers of both the animals were available for examination. The lungs, livers and small intestines did not yield any helminths, but one male and one female of Marshallagia marshalli, were collected from the abomasum of one goat, and a single male specimen of Haemonchus contortus was collected from the abomasum of the other goat.