Composition comprising arthropods and astigmatid mite eggs

Abstract

The present invention relates to a biological control composition comprising at least arthropod biological control agents and astigmatid mite eggs. The invention also relates to the use of astigmatid mite eggs as a nutrient source for arthropod biological control agents. The invention also relates to a biological control composition comprising at least one population of arthropod biological control agents, a nutrient source comprising astigmatid mite eggs, and optionally, a support and/or dissemination substrate. Finally, the present invention further relates to a method for rearing arthropods from astigmatid mite eggs as a nutrient source.

Claims

1. A method of rearing a population of arthropod biological control agents wherein the control agents are predators selected from the family Phytoseiidae, comprising feeding an effective amount of a nutrient source to the population of arthropod biological control agents, wherein the nutrient source comprises astigmatid mite eggs selected from eggs of Acarus farris, Acarus immobilis, Acarus chaetoxysilos, Tyrophagus longior, Tyrophagus similis, Lardoglyphus konoi, Caloglyphus mycophagus, Caloglyphus berlesei, Suidasia nesbitti, Carpoglyphus munroi, Glycyphagus domesticus, Lepidoglyphus destructor, Blomia freemani, or Chortoglyphus arcuatus, and wherein the nutrient source does not contain larvae, nymphs or adult astigmatid mites.

2. The method of claim 1, wherein the population of arthropod biological control agents comprises at least the species Amblyseius swirskii.

3. The method according toof claim 1, wherein the astigmatid mite eggs represent at least 10%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 98%, 100% by weight in relation to the total weight of the nutrient source.

4. The method of claim 1 wherein the arthropods and the astigmatid mite eggs are combined in a weight ratio between 1:3 and 1:7.

5. The method of claim 1 wherein the nutrient source further includes eggs of at least one lepidopteran species.

6. The method of claim 5 wherein the lepidopteran eggs are Ephestia kuhniella eggs.

7. The method of claim 5 wherein the lepidopteran eggs are Sitotroga cerealella eggs.

8. The method of claim 1 wherein the population of arthropod biological control agents includes arthropods within the genus Amblyseius, Neoseiulus or Typhlodromips.

9. The method of claim 1 wherein the population of arthropod biological control agents includes arthropods within the genus Amblyseius.

Description

DESCRIPTION OF THE FIGURES

(1) FIG. 1: Combined rates of dead or escaped Amblyseius swirskii at different stages of development (in percent of the original population), depending on the food proposed, at 25° C., 75% HR and 16/8 (L/D).

(2) FIG. 2: Amblyseius swirskii fecundity depending on the food proposed expressed in eggs per female for the whole adult period at 25° C., 75% HR and 16/8 (L/D).

(3) FIG. 3: Amblyseius swirskii longevity in days depending on the food given at 25° C., 75% HR and 16/8 (L/D).

(4) FIG. 4: Amblyseius swirskii escape rate (in % of the original population), while submitted to starving, at 25° C., 75% HR and 16/8 (L/D). The populations represented were fed either A. ovatus sub-lethal eggs (balck plot), or a mixture of all stages of A. ovatus (light grey plot).

(5) FIG. 5: A. ovatus eggs (A) and all stages of A. ovatus (B) after two months of cold storage and then one week at ambient temperature (eggs are in mean 132.5 μm long and 86.2 μm large). (A)

EXAMPLES

Example 1: Effect of a Diet Consisting in Astigmatid Mite Eggs on Growth and Health of Arthropod Biological Control Agents

(6) Eggs of A. swirskii were deposited in distinct cells and raised at 25° C., 75% HR (for “relative Humidity”) and 16/8 (L/D, for “Light/Dark”, indicating the time in hours spent in the referred condition).

(7) The resulting A. swirskii populations were fed with one of the two following conditions: a mixture of all stages of A. ovatus, only A. ovatus sub-lethal eggs.

(8) Every 12 hours, the A. swirskii individuals that escaped or died were noted, along with their developmental stage.

(9) Results are represented FIG. 1.

(10) The combined A. swirskii rate of juveniles that died or escaped when only eggs are proposed is lower (37%) than when a mixture of all stages of A. ovatus is given to A. swirskii (63%).

(11) Conclusion: populations of Amblyseius swirskii fed with Aleuroglyphus ovatus eggs suffer less death and escapes from individuals than populations of Amblyseius swirskii fed with all stages of Aleuroglyphus ovatus. Populations of arthropod biological control agents reared on astigmatid mite eggs are likely to be more healthy and numerous than populations of arthropod biological control agents reared on all stages of astigmatid mite.

Example 2: Effect of a Diet Consisting in Astigmatid Mite Eggs on Fecundity of Arthropod Biological Control Agents

(12) Young A. swirskii females of the same cohort were individually deposited in experimental cells at 25° C., 75% HR and 16/8 (L/D), and a male was given to each female.

(13) The A. swirskii females were fed with one of the two following conditions: a mixture of all stages of A. ovatus, only A. ovatus sub-lethal eggs.

(14) The fecundity (mean number of eggs/female) of 30 to 60 A. swirskii was then noted daily between the first mating and their death.

(15) Results are represented FIG. 2.

(16) The longevity of those females was also noted for the two modalities given above, and is represented FIG. 3.

(17) It appears that when the food given to A. swirskii females only consist of sub-lethal eggs, longevity is much higher than when the food is composed of a mixture of all stages of A. ovatus. The inverse trend is observed about fecundity for the two modalities tested. No global performance is lost while giving only A. ovatus sub-lethal eggs to A. swirskii, but an advantage is obtained in term of longevity.

(18) Conclusion: The fecundity of Amblyseius swirskii females fed with Aleuroglyphus ovatus eggs is more important than the fecundity of the same females fed with all stages of Aleuroglyphus ovatus.

(19) The fecundity of arthropod biological control agents reared on astigmatid mite eggs are likely to be more important than the fecundity of arthropod biological control agents reared on all stages of astigmatid mite.

Example 3: Effect of a Diet Consisting in Astigmatid Mite Eggs on Survival of Arthropod Biological Control Agents

(20) Young A. swirskii females, were maintained at 25° C., 75% HR and 16/8 (L/D).

(21) The A. swirskii females were fed with one of the two following conditions for at least 3 days: a mixture of all stages of A. ovatus, only A. ovatus sub-lethal eggs.

(22) Amblyseius swirskii females were then transferred to individual cells. They were then starved.

(23) Escape was noted daily from the first day of starvation until the end of the experiment.

(24) Results are represented FIG. 4.

(25) The escape rate was higher when A. swirskii were given a mixture of all the stages of A. ovatus as food, compared to eggs.

(26) Conclusion: populations of Amblyseius swirskii fed with Aleuroglyphus ovatus eggs suffer less death and escapes from individuals than populations of Amblyseius swirskii fed with all stages of Aleuroglyphus ovatus, even after they have been deprived of food. Populations of arthropod biological control agents reared on astigmatid mite eggs are likely to be more healthy and numerous than populations of arthropod biological control agents reared on all stages of astigmatid mite.

Example 4 Sub-Lethal Astigmatid Mite Eggs do not Develop Fungus

(27) A population of A. ovatus fed with yeast and wheat bran was prepared. At the end of the preparation, the population of A. ovatus contained a mixture of all stages of A. ovatus.

(28) A sample of the prepared population was taken, from which eggs were isolated. The isolated eggs where put in a cold storage, in the appropriate conditions to induce a sub-lethal state.

(29) Another sample of the prepared population was taken, and put in a cold storage. This second sample thus contained a mixture of all stages of A. ovatus.

(30) After two months, the isolated eggs (A) and the mixture of all stages of A. ovatus (B) were taken out of the storage and put back to ambient temperature for a week.

(31) Fungus development was then observed on the sample containing all the stages of A. ovatus (B), while no microorganisms' development was observed on the sample containing only sub-lethal eggs (A).

(32) After a week, a picture was taken to illustrate the evolution of both samples.

(33) Results are given FIG. 5.

(34) Conclusion: These results show that sub-lethal astigmatid mite eggs do not develop fungus, and therefore do not deteriorate as fast as populations comprising all stages of astigmatid mites that had been stored in the same conditions.

Example 5: Specific Temperature Exposure and Duration of Exposure to Such Temperature Lead to Sub-Lethal Eggs

(35) Eggs of A. ovatus were isolated from a lab population and stored at different temperatures in an experimental cell (30 eggs/cell/treatment) for 4, 5 or 6 weeks −5° C. 0° C. 8° C.

(36) After storage, all eggs were put back to 25° C. and 75% HR conditions.

(37) Every day during a week, every hatched or collapsed egg was noted, resulting in egg hatching, collapsing and edible rates.

(38) Results are represented Table 1.

(39) TABLE-US-00001 TABLE 1 A. ovatus egg collapsing and hatching rates depending on the storage temperature and on storage time. Exposure Collapsing Hatching Edible time Treatment (A) (B) (1 − A − B) 4 weeks −5° C. 43.3% 0% 56.7% 0° C. 32.3% 3.2%.sup.  64.5% 8° C. .sup. 60% 23.3%   16.7% 5 weeks −5° C. 56.7% 0% 43.3% 0° C. 13.3% 0% 86.7% 8° C. 61.3% 29%   9.7% 6 weeks −5° C.  100% 0%   0% 0° C. .sup. 40% 0% .sup. 60% 8° C. 36.6% 56.7%    6.7% Storage at 0° C. provokes a massive egg’s collapse and no hatching. Storage at 8° C. still induces hatching and a high collapsing rate. Storage at 0° C. conserves the egg turgescence, and reduces hatchability to zero after 5 week of exposure.

(40) Conclusion: Astigmatid mites eggs exposed to a temperature of 0° C. for 4 to 6 weeks do not hatch, proving that the obtained eggs are sub-lethal eggs. Moreover, in those conditions, collapsing is minimized and it is possible to obtain more than 60% edible eggs.