FI80189C - Insect Pathogenic Procedure - Google Patents

Description

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This invention relates to a method for controlling larvae of a large flycatcher (Delia Floralis) and a flycatcher (Delia radicum) in a culture medium.

Attempts have been made to control flies chemically in the crop by treating clump seedlings or the roots of seedlings planted without clumping with an insect pathogenic chemical such as diazinone, dimethoate or isofenphos. In J. of the Scientific Agric. Soc. of Finland vol. 52 (1980) pp. 7-13 describes the chemical control of cabbage fly larvae using dimethoate and lindane. However, pesticides degrade in the soil e.g. microbial activity, and in addition, repeated use of pesticides over several years has been found to accelerate this degradation. Thus, pesticides protect plants only from early summer, from the first generation larvae of the cabbage fly. Second-generation larval larvae or large cabbage fly larvae present in mid- and late summer cannot be controlled economically by chemical means.

It has now surprisingly been found that the addition of Beau-Veria bassiana and / or Metarhizium anisooliae fungal species, optionally in combination with a biologically acceptable carrier, to effectively control the larvae of both species of cauliflowers. The effect of these microbes on the medium lasts throughout the growing season, which also helps to control the larvae of cabbage flies that occur in mid- and late summer.

Fungal species used in the method according to the invention, Beauvena bassiana and Metarhizium anisopliae. has been isolated from different types of soil from several different localities.

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Beauveria bassiana and Metarhizium amsopliae have previously been used to control insect pathogens. A biological control method is already known in which the fungus Metarhizium anisopliae is added to the culture medium to control eaksanturila.

Australian Patent Application 54766/86 also describes a biological method and preparation for controlling insects. The method uses a mixture of Metarhizium anisopliae and Beauveria bas-siana to control scarabide larvae (Scarabeid beetle larvae) by adding an effective amount of fungal species to the medium. However, these fungal species have not previously been found to be effective against difficult-to-control larval larvae.

Beauveria bassiana (Deuteromycetes) belongs to the group Fungi imperfecti, te. it is not known to have sexually increasing stages of development. When growing on a nutrient medium, the fungus forms white or creamy whites, sometimes pinkish-tinged colonies, which, as the spores develop, acquire a powdery appearance. The spores (conidia) are round, smooth-surfaced, 2-2.5 μm in diameter.

Beauveria bassiana is a common insect pathogenic fungus in nature that can infect representatives of several different groups of insects. In experiments, it has been effective against locusts, bedbugs, aphids, stingrays, beetles, butterflies, banks and flies. To work effectively, the fungus needs the right humidity and temperature. Ultraviolet rays adversely affect spores. For these reasons, the soil is the best environment for the use of B. bae-siana.

The minimum temperature required by B. bassiana to be able to infect an insect is 3 to 8 C. Upon contact with the surface of the insect, the spore begins to grow a germ tube, which first mechanically, then through enzymatic reactions, penetrates the insect's body through the spawn. The insect dies on the fungus 3,80189 tons of growth when suppressing its vital functions. B. bassiana also secretes toxins (beauvericin) that are lethal to insects. After the death of the insect, the fungus grows saprophytically in its body, and as the mycelium grows out of the insect, spores form again. Based on the saprophytic growth potential of B. bassiana, it can be mass grown with either solid or liquid artificial nutrient areas.

Like Beauveria bassiana, Metharhizium anisopliae belongs to the group Deuteromycetes and Fungi imperfecti. The species is easy to recognize from its dense, cone-shaped clusters of spores that are dark green in color and 5-8 μm long. The hyphalia is initially white or yellowish, but eventually completely covered under green spores.

M. anisopliae is also a common entomopathogenic fungus in nature that can be isolated from both insects infected with green muscus and soil. The optimum temperatures required by M. anisopliae are slightly higher than in B. bassiana. In order to infect an insect, M. anisopliae requires a temperature of approximately o + 10 ° C.

M. anisopliae is capable of infecting and killing members of many different groups of insects. It infects and kills the insect in the same way as B. bassian. M. anisopliae produces destruxin toxins as well as proteases that are also toxic to insects. M, anisopliaen as well as B. bassianan. different strains or isolates may differ significantly in their temperature requirements, pathogenicity, and virulence.

Beauveria and Metarhizium fungi isolated from soil are grown in a fermentor on a conventional medium (PDB medium) at a temperature of 25-35 ° C at a pH of 5-7. The fungi thus grown are added to the plant growth medium, for example, by treating the root clumps of the seedlings to be planted with an aqueous suspension of fungi formulated as a powder containing at least about 1x10 fungal spores / ml.

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The suspension is applied at least 15 ml / seedling to achieve effective control. Alternatively, the roots of non-caking seedlings to be planted can be immersed in an aqueous suspension.

The microorganisms used in the invention are deposited with the Deutsche Sammlung von Mikroorganismen <DSM> Gesellschaft fur Biotechnologische Forechung mbH, Grisebachstr. 8, Gottingen, Federal Republic of Germany, 1 June 1988. Beauveria bassiana strains with accession numbers DSM 4646, DSM 4647 and DSM 4648 and Metarhizium anisoplia strains with accession numbers DSM 4649, DSM 4650 and DSM 465 1.

In the following, the invention will be described in more detail by means of examples. Example 1

Cabbage flies infested with cauliflower were planted in the field, the root lumps of which were irrigated with Beauveria bassiana or Metarhizium anisopliae fungal suspensions at 15 ml / seedling. The strength of the suspension was 8x10 fungal spores / ml. The other test members were a 0.1% ophthalmically treated test member (active ingredient isofenphos) and an untreated test member. In the autumn after harvest, the number of larvae and shells of cabbage flies in the cabbage root system was counted. The results are shown in Table 1.

table 1

Effect of Beauveria and Metarhizium fungi on the preynthesis of cauliflowers

Handling of larvae and housings avg. Number / plant

Beauveria bassiana 12.26 pcs

Metarhizium anisopliae 46.10 pcs

Ophthalmic 0.1% 80.95 pcs Untreated 70.83 pcs

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It is observed that both Beauveria bassiana and Metarhizium anisopliae have significantly reduced the number of larvae and shells of the cabbage fly in the plant.

Example 2

The organism to be controlled in the experiment was the larvae of the small cabbage fly (Delia radicum). The cabbage fly eggs were placed in a jar of sterilized, moistened sand with a whole radish in the middle. There were 10 eggs / jar. They were placed around the radish so that each egg was approximately the same distance (about 3 cm) from it. Before laying the eggs, 10 ml of a spore suspension with a concentration of 1x10 spores / ml had been pipetted around and on top of the radish. The concentration was also the same in the jar where the spores of Beauveria (Bb) and Metarhizium (Ma) were used together. Half of the spores were then Beauverian. half of the spores of Metarhizium. The fungi were grown on PDA agar.

o

There were 5 jars / treatment. They were maintained at 23 ° C and about 70% relative humidity. The number of larvae in the jars was checked 10 days after the start of the experiment. The proportion of eggs that did not hatch was calculated first. The radishes were cut into thin slices to find the larvae inside. Some of the radishes were spoiled at the inspection stage so that the the jars were discarded when calculating the final results. No larvae were found in the contaminated radishes. They had either died of malnutrition or moved out of the radish into the sand, where it was impossible to find small larvae.

Table 2 shows the number of eggs not hatched, the number of larvae found alive and dead, and the mortality rate for the different treatments.

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Table 2

Hatching Live Lost and Handling eggs larvae dead larvae total

Cont. Il 63 "II 2 7 1" III 2 7 1

Total 5 20 5% 16.7 80 20

Bb I - 28 II - 4 6 III - 3 7 IV 3 6 4

Total 3 15 25% 7.5 40.5 67.5

Ma I 3 34 II - 5 5 III 2 3 5 IV - 3 7 V - 2 8

Total 5 16 29 X 11.1 35.6 64.4

Bb + Ma I - 64 II - ions - 1 9 IV 3 7

Total - 20 20% 50 50

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Based on the results, Beauveria bassiana and Metarhizium anipopiaiae are effective against cabbage fly larvae both individually and when present together. The actual synergistic effect of these fungal species cannot be detected on the basis of this experiment. It should be noted, however, that in the jar where both mushrooms were together, the concentration of each was only half of what it was in those treatments where the mushrooms were alone. Nevertheless, mortality was almost as high as in jars treated with only one of the two sponges. The concentration used 9 (1x10 spores / ml) is apparently so high that its halving did not affect the efficacy. Based on the experiment, it is not possible to say which fungus was more effective in processing Bb + Ma because dead larvae could not be found in the jars (at death the larvae are still very small and decompose rapidly in moist sand!). However, a synergistic effect on fungi may occur under field conditions, in which case the soil type may affect the performance of the fungi differently depending on the fungal species.

Claims (5)

8 80189 A method for controlling larvae of large cabbage fly (Delia Floralis) and cabbage fly (Delia radicum) in a culture medium, characterized in that Beauveria basaiana (DSM 4646, DSM 4647, DSM 4648) and / or Metarhizium anieopliae (DSM 4649, DSM 4650, DSM 4650, DSM 4651), optionally in combination with a biologically acceptable carrier. Method according to Claim 1, characterized in that the fungal species are added to the medium as an aqueous suspension at a concentration of at least 10 spores / ml. Method according to Claim 1 or 2, characterized in that the fungal spore suspension is added at a rate of at least 15 ml / seedling. Method according to Claim 1 or 2, characterized in that the roots of the seedlings are immersed in a fungal spore suspension. 5. Use of Beauveria bassiana (DSM 4646, DSM 4647, DSM 4648) and / or Metarhizium anisonliae (DSM 4649, DSM 4650, DSM 4651) fungi to control large cabbage fly (Delia Floralis) and cabbage fly (Delia radicum) larvae in the culture medium. 9 80189