Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Biocides; animal or insect repellents or attractants
Patent
1994-08-23
1997-01-21
Page, Thurman K.
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Biocides; animal or insect repellents or attractants
424400, A01N 2502
Patent
active
055957463
DESCRIPTION:
BRIEF SUMMARY
This invention relates to the use of fungus, particularly Metarhizium anisopliae, for control of termites and other pest insects. The invention provides methods for selection of suitable fungal species and strains, formulations and methods of culture and preparation.
Termite infestations have previously been controlled by the use of highly toxic chemicals such as arsenic and organochlorine based compounds. With the increase in awareness of the dangers of these chemicals it is now desirable to develop other effective means to control termites and other pest insects.
The fungus, Metarhizium anisopliae, is a known insect pathogenic fungus which infects a wide range of insects from many orders. The life cycle is simple: the asexual haploid conidia germinate on the cuticle of an insect sending out a germ tube which penetrates the cuticle and then buds off hyphal fragments into the haemolymph of the new host; these hyphal fragments grow and multiply eventually killing the insect; then, after death, the fungus grows through the cuticle of the insect and forms new conidia on the outside of the insect; and finally, the new conidia are passively dispersed.
The terms "spores" and "conidia" as used throughout the description and claims have the same meaning and as such may be read interchangeably.
Metarhizium anisopliae may be grown easily in vitro and will form copious conidia on standard mycological media such as Sabourauds's Dextrose Agar and natural substrates such as wheat, rice and barley. In liquid fermenters, the fungus may form mycelium which will sporulate either immediately or, if dries, after an interval of up to a year or more. Other methods of culture and preparation are reviewed below.
(i) In Brazil Metarhizium anisopliae is presently used on sugar cane for control of sap-feeding homopteran insects, particularly sugar cane froghopper (Mahanarva). The fungus is grown on moist boiled rice, allowed to sporulate, dried and milled into a powder. This powder may be stored under cool conditions and is generally mixed with water to form a suspension before spraying.
(ii) Bayer (Germany) have produced an experimental product (Bio-1020) including a strain of Metarhizium anisopliae as its active ingredient. This product consists of small granules of liquid fermenter-grown mycelium which, when applied to a moist substrate such as soil, sporulate within a few days to form conidia which in turn infect and kill the target pest.
(iii) Other workers have shown that strains of Metarhizium anisopliae when applied to termites as conidia will infect and kill the target termites. Furthermore, fungus mixed with talc and applied by dusting to nests or feeding sites of Nasutitermes exitiosus will cause substantial colony decline sometimes resulting in colony mortality. In particular, Hanel and Watson (Bull. ent. Res., 73, 305-313) found in field tests that the effect of Metarhizium anisopliae whilst useful for immediate use had a limited life span, and concluded that the factors inhibiting the completion of fungal development in the nest are unknown.
(iv) Kramm et al. [Journal of Invertebrate Pathology 40, 1-6 (1982)] observed that termites which have been exposed to whole cultures of Metarhizium anisopliae may transfer disease to previously healthy termites. It is suggested that this occurs by the healthy termites grooming live dosed termites. Importantly, however, it was noted that termites which have been killed by the fungus are avoided by healthy individuals.
In summary, whilst it is known that Metarhizium anisopliae has the ability to infect pests such as termites and subsequently infect previously healthy termites, the effective use of this fungus in the field has not been achieved. One reason for this is that it has been observed that healthy termites avoid infected termites which have died. However, Metarhizium anisopliae is highly variable genetically and individual strains differ substantially in their virulence for a particular host. These and a range of other difficulties with effectively using this technology in t
REFERENCES:
patent: 5057315 (1991-10-01), Gunner et al.
Haemel, H., Biological Abstracts, vol. 73, 1982, #9273.
Haenel, H. Biological Abstracts, vol. 76, 1983, #79203.
Haenel et al., Biological Abstracts, vol. 76, 1983, #321, 715.
Fernandes, P.M., Biological Abstracts, vol. 92, 1991, #499867.
Lenz Michael
Lutton George G.
McRae Cheryl F.
Milner Richard J.
Staples Judith A.
Commonwealth Scientific and Industrial Research Organization
Page Thurman K.
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