THE SPREAD OF SHEEP GADFLY (Oestrus Ovis L.) AND HIS SHEEP INFECTED LARVAE IN THE ALTAI REPUBLIC

Abstract

A retrospective analysis of the distribution and infection of sheep by gadfly larvae (Oestrus ovis L.) was carried out in 34 farms of the Altai Republic for a population of more than 3.6 thousand animals. The sheep of all the households surveyed were infected with gadfly larvae. Extensivity of the invasion (EI) of sheep in the farms of the Altai Republic ranged from 16.6 to 100%. The intensity of the invasion (II) an average of one infected animal was ranging from 6.9 to 31.8 larvae, the abundance index (AI) from 1.2 to 29.4. The extensiveness of invasion (EI) in the farms of the Altai Republic ranged from 16.6 to 100%. The intensity of invasion (II) on average per infected animal ranged from 6.9 to 31.8 larvae, the abundance index (AI) from 1.2 to 29.4. The sheep of the Ust-Koksinsky district (EI – 87.8%, AI – 16.3) located in the Central Altai, to a lesser extent – Ust-Kansky (EI – 56.4%, AI – 8.4) belonging to the Central Altai, were found to be the most infected. Also low infection of sheep in Shebalinsky (EI – 69.2%, AI – 7.5) and Kosh-Agachsky (EI – 60.6%, AI –- 8.4) areas (Northern and Southeast Altai). In general, the infection of sheep in different areas of the Altai Republic does not differ substantially and is at a relatively low level (EI – 66.7%, II – 13.5 larvae, AI – 9.0). Maximum infection rates in all regions between 1981–1985 was EI 65.5–94.0%, AI 10.2–18.5. Subsequently, they steadily decreased and stabilized at a lower level since 2001 (EI 57.9 – 72.7%, AI 5.8 – 13.9), which is primarily due to the change of generations of drugs used in the treatment of sheep with estrosis.