COMPOSITE PARTICLES

Abstract

A delivery method for bacteria, viruses, fungi and dsRNA in which the bacteria, virus, fungus or dsRNA is protected from degradation by UV light by encapsulation in a particle of wax also containing a UV blocker. The formulation may also include other chemistry, such as insecticides. The particles are edible by insects and their larva and result in ingestion of the bacteria, virus, fungi and/or dsRNA by the insect or larva, resulting in control thereof.

Claims

1. A composite particle having a volume median diameter in the range 2-200 microns comprising: i. at least one biological agent comprising Bacillus thuringiensis; ii. at least one UV blocker; and iii. wax.

2. The composite particle according to claim 1, wherein the UV blocker is distributed throughout the wax.

3. The composite particle according to claim 1, wherein the UV blocker is present in an amount up to 20% by weight of the particle.

4. The composite particle according to claim 1, wherein the biological agent is present in an amount up to 20% by weight of the particle.

5. (canceled)

6. (canceled)

7. (canceled)

8. The composite particle according to any preceding claim 1, wherein the wax is selected from natural waxes, synthetic waxes, mineral waxes and mixtures thereof.

9. The composite particle according to claim 1, further comprising a chemical active agent.

10. The composite particle according to claim 1, having a volume median diameter in the range of 5-100 microns.

11. A composition comprising a plurality of particles according to claim 1.

12. A method of using the composite particle according to claim 1, for use in control of an insect infestation of a plant or animal.

13. The method according to claim 12, for control of an insect infestation of a genetically modified GM plant.

14. The method according to claim 12, wherein the composite particle is dry.

15. The method according to claim 12, wherein the composite particle is in the form of a liquid suspension.

16. The method according to claim 13, for control of infestation by insects that are resistant to the GM plant.

17. The composition according to claim 11, which is dry.

18. The composition according to claim 11, which is in the form of a liquid suspension.

Description

[0073] The following is accompanied by the drawings which show:

[0074] FIGS. 1, 2 and 3 shows protection of baculovirus biopesticide from UV radiation in a formulation of the invention.

EXAMPLE 1

[0075] Introduction

[0076] Biological agent (virus) was formulated in wax particles comprising UV blocker.

[0077] Key:

[0078] BV: Baculovirus Occlusion Bodies raw material

[0079] NPV: Nucleopolyhedrovirus, a genera of the baculoviridae family of viruses included under the BV umbrella

[0080] GV: Granulovirus, a genera of the baculoviridae family of viruses included under the BV umbrella

[0081] 1. Materials: [0082] Active ingredient (BV of the chosen speciesSpliNPV targeting Spodoptera littoralis, or the Egyptian cotton leaf worm) sourced from NRI Candelilla wax and Rice bran wax. [0083] Titanium dioxide (TiO2)

[0084] 2. Equipment: [0085] Hotplate that heats up to 150 C. (Stuart scientific Ltd) Two decimal place balance (Ohaus) [0086] Freezer that cools down to at least 24 C. (any make/model will do) [0087] High shear mixer/homogenizer (IKA T18 digital) [0088] Kibbler mill (KT handling limited model 04) [0089] Comminuting mill (Apex LTD type 314s) [0090] Air jet mill (any make/model will do) [0091] Suitable size sample pots

[0092] 3. Detailed Procedure [0093] 3.1. Using a calibrated balance weigh out the required quantity of carrier waxes125.0 g of rice bran wax, 125.0 g of candelilla wax and 12.50 g of TiO.sub.2. [0094] Place a 50:50 mixture candelilla wax: rice bran wax (% w/w) into a pan and place onto a hotplate set to a temperature of 120 C. The wax is heated until completely melted and a clear liquid with no solids is observed. [0095] Using a calibrated balance a quantity of the active BV at 1% w/w is weighed out. [0096] 3.1.1. The BV and TiO.sub.2 are added together to the molten wax quickly over a total time period of 60 s and dispersed within the molten wax by high shear mixing (using a high shear mixer IKA T18) to ensure even distribution within the wax. [0097] 3.2. The wax is then transferred to a foil lined shallow tray and transferred to a freezer set at 24 C. to rapidly cool and solidify within approximately 1-2 h. [0098] 3.3. Once the formulated material is frozen into a completely solid block or slab it is broken into large chunks and sent for milling. The chunks are ground in a kibbler mill (KT Handling Limited, Model 04) to particles of approximately 2 mm average diameter [0099] 3.4. The kibbled material is then comminuted into smaller particles in a comminuting mill (model 314 s, from Apex Ltd) to particles of 150 m average diameter. [0100] 3.5. The comminuted material is further micronized in a jet mill (Hosokawa Alpine Jet AFG 100 fluidised bed jet mill) to achieve granulation of particle size 10 m. [0101] 3.6. The micronized material containing baculovirus particles and TiO.sub.2 is stored in a suitable sample container under refrigeration conditions at 4 C., until use.

[0102] The particles were used for testing pest mortality rates against controls.

[0103] Key Findings

[0104] Study results showed consistent protection of baculovirus biopesticide from UV radiation in the formulation. See FIG. 1.

[0105] Replicated bioassays showed a consistent effect of the UV blocker-containing formulation (top line), with >80% efficacy being retained after 16 hours UV exposure (equivalent to 5 days exposure to sunlight in the field), compared to around 30% for the raw NPV virus (middle line) or commercial biopesticide product (lower line). A further bioassay indicated that >80% efficacy was retained even after 96 hours UV exposure (equivalent to around 30 days in the field). See FIG. 2.

[0106] Spraying of a single dose of raw NPV, the commercial standard or formulations of the invention onto tomato or cabbage plants, then exposing them to UV lights simulating sunlight for 12 hours per day for 0,1,2,3,4 or 5 days showed the two formulations of the invention (top two lines) gave >90% efficacy after 5 days, compared to the commercial standard (lower two lines) which gave around 30%.

[0107] Tomato Plant Trial

[0108] A further example was carried out comparing a formulation of the invention against a commercially available product (Littovir (SpliNPV). Data were obtained for mortality up to 8 days post-infection and showed mortality retained at 60% after 8 days exposure to UV compared with 10% for Littovir (which after 8 days had mortality reduced to that of the control, namely water). See FIG. 3.

[0109] Subsequent analysis showed that loss of activity for the formulations of the invention occurred within the first hour of UV exposure. This may be due to degradation of any non-encapsulated virus present; in which case, protection conferred by the formulation may have retained the virus with essentially no degradation as a result of UV exposure.

[0110] Discussion

[0111] One of the limitations of the use of biological agents, e.g. baculoviruses, as biological control agents is their loss of activity under field conditions due to inactivation by ultraviolet light.

[0112] When used in the field, the formulations of the invention can extend and even dramatically extend the field life of active agents, e.g. biopesticides, meaning that farmers can reduce the number of sprays required to protect the crops and/or that biopesticide producers can drastically reduce the amount of active ingredient to achieve the same result. Prophylactic spraying of the biopesticide is now made an option because of the longevity achieved by the invention. The examples used virus but the invention is of application to other UV sensitive biological agents.

[0113] UV stable formulations of the invention can also increase the plant range and growing conditions for virus biopesticide applications.

EXAMPLE 2

[0114] Bt toxins are known to be broken down rapidly by sunlight; e.g. in preliminary studies forty-one percent (41%) of toxins tested remained after 24 hours. On plant surfaces, sunlight breaks down Bt; the half-life of Bt toxins may be 1-4 days.

[0115] We tested a formulation of the invention for its ability to prevent UV-induced inactivation. The results showed that after 96 hours in the UV cabinet (equivalent to one month in the field) the Bt formulation was effective as seen in the table below:

TABLE-US-00001 Bioassay DBM on Slide wash-off - 96 cabbage leaf - hours UV exposure 16DAT Wax particles - no <10% mortality <10% UV blocker Wax particles - 50% 60% TiO.sub.2 blocker

[0116] Bt is an aerobe, requiring oxygen to grow (be activated). The results showed that: [0117] 1) it survived the hot-melt inclusion process >120 degrees [0118] 2) it survived with the wax encapsulation [0119] 3) mortality was not significantly reduced in the presence of UV blocker.

[0120] The invention thus provides composite particle having a volume median diameter in the range 2-200 microns comprising active(s) plus at least one UV blocker.