| 摘要 |
This invention describes a preparation for the biological control of harmful insects such as aphids which consists of a number of spores of the fungus Alternaria alternata (a new pathotype) and a suitable and agriculturally acceptable carrier. The carrier may be water, an aqueous solution of some adsorbent or dispersant substance, or powder. The preparation may be used therapeutically or prophylactically. This new pathotype is very effective in dealing with aphids. Infection of the aphids with spores of the fungus invariably results in their death. It is possible that the death of the aphids is due to production of an enzyme (a powerful chitinase) by the pathogen which damages the exoskeleton or to production of a toxic metabolite (toxin) or to both resulting in the death of the insect host. The new pathotype has been shown to be a powerful pathogen for the following species of aphid: Myzus nicotianae, M. Persicae, Aphis fabae, Macrosiphum euphorbiae, Brevicoryne brassicae, Uroleucon sp, as well as at least 5 as yet unidentified species. The invention also describes the use of the preparation to control harmful insects such as aphids as well as a method of putting it on the foliage of the infested plants - hosts. The most effective concentration of the live spores is 4 5 10 -10 spores per ml of preparation when the carrier is water. Lower concentrations are also effective in certain circumstances e.g. when the aphid population on the leaves of the plant - host is very dense. The carrier may also be another aqueous solution or powder. |
