TIMING THE TREATMENT OF CATTLE WITH TROLENE FOR SYSTEMIC CONTROL OF THE CATTLE GRUBS HYPODERMA LINEATUM (DE VILL.) AND H. BOVIS (L.) IN ALBERTA AND BRITISH COLUMBIA

Abstract

Experiments on timing the oral treatment of calves for cattle grub control with Trolene at 100 mg./kg. were carried out on ranches near Lethbridge, Alberta, and Kamloops, British Columbia. Groups of 30 and 25 calves, respectively, were treated in November, January, March, and April at Lethbridge and in December, January, February, and March at Kamloops.Control of the pre-hypodermal grubs was equally effective on the first three treatment dates, varying from 94 to 98 per cent mortality. However, variations in the numbers of grubs precluded stating the mortality more precisely than within a range of 95 to 100 per cent at Lethbridge and 89 to 100 at Kamloops.There was no significant difference in mortality between the two species of cattle grubs. However, the third hypodermal instar larvae of both species were less affected by the treatment (P <.01) than those of the preceding instars. Early autumn treatments are recommended to avoid the presence of third-instar larvae and to forestall early damage caused by the hypodermal grubs.Slight symptoms of toxicity, in the form of lethargy and reduced food consumption at Kamloops and ataxia of the hindquarters at Lethbridge, were observed in the calves treated in December and January, respectively. The symptoms disappeared within 48 hours of treatment without the use of antidotes at either locality. The level of treatment used in this study was lower than that reported in the literature to produce first symptoms of toxicity.

LOW-LEVEL FEEDING OF TROLENE FOR CONTROL OF THE CATTLE GRUBS HYPODERMA LINEATUM (DE VILL.) AND H. BOVIS (L.)

“…Indizt'idual Feed,ing Laboratory Equipment In November 1956, 60 weaner calves were selected randomly from the herd that was used in Alberta in a concurrent study (4). They were brought to the laboratory and distributed randomly into low-level-treated and rO, O-dimethyl O-2,4,5-trichlorophenyl phosphorothioate, obtained under the name Dow ET-57 from Dow Chemical Company, Midland, Mich.…”

“…so that the treated animals received anaverage dose of Trolene of 10 + 1 mC./kC. To compare this treatment with a single bolus treatment at 100 mg./kg., the data were used from another group of the same herd, treated on March 7 in the concurrent experiment (4).…”

“…The grubs were counted weekly by charting their positions in the backs of the cattle (2) from the beginning to the end of the hypodermal grub season. Mortality of the pre-hypodermal grubs was calculated as previously described (4). Canvas girdles, modified from those of Gregson and Holland…”

“…This method of treatment required further investigation as a form more acceptable than the cumbersome bolus or oral drench, both of which produced toxic symptoms in cattle at a single dose of 100 mg./kg. (4). The objectives of a laboratory experiment were to delimit the number of days of lowJevel treatment required to produce control of grubs comparable to that produced by a single dose at 100 mg./kg.…”

Studies of Bolus and Feed Formulations of Two Systemic Insecticides for Reduction of Cattle Warble Infestations, (Oestridae: Diptera), in British Columbia, 1957–1958

“…In 1957 extensive tests of drench and bolus formulations were carried out by Canadian and United States agencies and many reports appeared in the literature. Weintraub, Rich and Thompson (10) found that H. boai.s (L.) and H. lineatum (De Vill.) were equally susceptible but larvae became highly resistant after encystment in the hypodermal stage.…”