WO1995026633A2

WO1995026633A2 - Insects' egg-laying substrate

Info

Publication number: WO1995026633A2
Application number: PCT/US1995/003803
Authority: WO
Inventors: Amir Ariv; Leonid Zlutchevsky
Original assignee: Dikla International; Gerstenzang, William, C.
Priority date: 1994-03-31
Filing date: 1995-03-27
Publication date: 1995-10-12
Also published as: WO1995026633A3; AU2129695A; IL109182A0

Abstract

The present invention concerns a substrate capable of inducing insects to lay eggs thereon at extremely high numbers. The substrate can be used in order to obtain large amounts of insect larvae which can be raised on manure or organic waste. The substrate also can be used as an attractant in the extermination of insects or isect eggs. The present invention further concerns insect larvae and manure processed by insect larvae. The invention also provides a method for creating insect larvae which do not develop to adult insects.

Description

INSECTS ' EGG-LAYING SUBSTRATE

FIELD OF THE INVENTION

The present invention concerns an egg laying substrate for insects and method for growing insect larvae as well as insect larvae and processed manure obtained by said method. The present invention also concerns a method for destroying insects in general and insects' larvae in particular. The present invention further provides a method for halting the metamor¬ phosis of insects from one stage to the next.

BACKGROUND OF THE INVENTION Accumulation of organic waste both in the form of manure of domestic animals and as a by-product of various industries is a major problem in many countries both developed and developing. The cost of organic waste disposal is composed of two main factors: * actual cost involved in physical disposal of the waste, and cost due to loss of valuable nutrients in the form of protein, fat and carbohydrates present in the disposed waste. It has been suggested to use organic waste as a food source for larvae of various insects and then use the larvae as a food supplement for domestic animals. Since insects are known by their high fertility rate and since insects' larvae are notorious for their mass gaining rate, it was believed that growing insects' larvae in organic waste is the best way to extract valuable nutrients present therein, and to convert them to a more accessible form of nutrients.

However, prior art attempts to grow larvae on organic waste were economically disappointing. It was found that in order to make the whole process feasible, a large number of insect eggs had to be collected and placed on the organic growth medium. The number and concentration of laid eggs in an insect growing cage became the limiting factor of the whole operation. Even under optimum conditions of nutrition, temperature, humidity, etc., insects kept in cages did not lay eggs in high enough concen- trations in terms of number of eggs per fly, per time unit per cage volume to make the whole procedure economically feasible.

Another problem encountered today is the extermination of insects such as flies, mosquitos, wasps, etc. It is today a well accepted notion that chemical insecticides have a tremendous damaging effect on the environment and are eventually rendered useless due to the insecticide-resistance the insect usually develops. Biological means for extermination of insects such as specific bacteria or insect-eating insects are less damaging to the environment but suffer from other drawbacks, such as: narrow conditions required for the insect-destroying organism to operate, specificity of the insect-destroying organism to one species of insects, etc. New and effective means for destroying insects are highly desirable. SUMMARY OF THE INVENTION

The present invention provides an egg-laying substrate for insects which is able to induce insects to lay eggs thereon at extremely high concentrations. By using this substrate it was possible for the first time to grow insect larvae in an economically feasible manner, since it was possible to obtain a high enough yield of eggs per insect per time unit, per volume of cage.

Thus the present invention provides an egg-laying substrate for insects of a kind which either grow or feed on manure or organic waste in at least one stage of their life cycle, the substrate comprising an inert material soaked with a substance which induces egg-laying, said substance being ammonium bicarbonate or an organic substance capable of releasing ammonium. The egg-laying substrate is suitable for any type of insect which lays eggs or which grows or feeds on manure or organic waste in at least one stage of its life cycles. For example the insect may lay eggs and grow larvae in manure or organic waste, the adult insect may feed on manure or organic waste and the like. Examples of the above insects are flies, mosquitoes, beetles and wasps.

The egg-laying substrate of the invention is especially useful for flies such as the common house fly (Musca domestica).

The substrate of the invention comprises an inert material such as cotton wool, cloth, porous sheet, sponge-like material which is soaked either with ammonium bicarbonate or with organic substances capable of releasing ammonium such as extracts from urine, mature and the like.

The ammonium bicarbonate should be in a concentration of 4% to 38%, preferably 18.5% to 21.5% and most preferably 20%. The egg-laying substrate may comprise in addition to the organic substance capable of releasing ammonium another organic nutrient. Examples of such organic nutrients are dry recovered milk, baking yeast, sugar, various types of flour, grains, etc. The present invention further provides a method for growing larvae of egg-laying insects, which have at least one life-cycle associated with manure or organic waste, comprising:

(a) breeding adult insects in a container having an egg-laying substrate, which comprises ammonium bicarbonate or an organic substance capable of releasing ammonia under conditions allowing egg-laying;

(b) collecting eggs laid on the substrate and transferring them to growth medium comprising manure or organic waste;

(c) providing conditions allowing egg hatching and growth of larvae; and

(d) separating larvae from the manure or organic waste.

The adult insects are kept in a container having an egg-laying substrate as described above. The insects are kept under conditions of temperature, humidity, lighting and nutrition, specific for each type of insect, which enable egg-laying.

The eggs, which are laid in extremely high numbers on the egg- laying substrate of the invention, are periodically collected. If desired, it is possible to keep eggs in cold storage until a sufficient number has accumu¬ lated and then transfer the eggs all at once to the growth medium. The growth medium can be any kind of manure or organic waste which is able to support the growth of larvae to be hatched from these eggs. Examples of manure are: pigs' manure, chickens' manure, cattle manure, human manure or a combination of several types of manures. Examples of organic waste is waste products of the meat, fish or poultry industry, left- overs of fruits or vegetable processing, organic household garbage, etc. It is also possible to use a combination of several types of manure or several types of organic waste or a combination of manure and organic waste together. The eggs are transferred to the growth medium and are kept under temperature, humidity and illumination conditions allowing hatching of larvae therefrom and of subsequent growth of said larvae. The larvae feed on said manure or organic waste and grow until they reach their maximum size, which is usually just prior to metamorphosis to the next stage - pupa or adult.

When the larvae reach their maximum size they are separated from the growth medium. Separation can be carried out by inducing the larvae to translocate to one side of the growth medium container, for example, to the surface or the bottom, by heating or cooling the bottom or surface of the container respectively or by illuminating the surface of the container. Larvae tend to escape as far as possible from the extreme temperature or illumination conditions and concentrate at the other side of the container from which they can be collected, for example, with the aid of a mesh. The present invention also concerns larvae obtained by the above method. The larvae can be in a fresh, i.e. live form and thus can be used for feeding fish or as baits for fishing. The larvae can also be frozen, or dried and grounded to give larvae flour and then be used as a food supple¬ ment for fish, cattle, pigs, chickens and for further generations of adult insects.

The present invention still further concerns processed manure, which served as a growth medium for larvae, after the larvae have been separated therefrom. The processing of the manure by the larvae stimulate development of nitrogen-fixing microorganisms and thus such manure is especially useful as a fertilizer since it enables efficient biological fixation of nitrogen in soil. In addition, the processed manure is especially rich in ammonia and phosphoric acid as compared to non-processed manure, a fact contributing to its efficiency as a fertilizer. Finally, during the process of hatching from eggs and growth both the larvae and the eggs secrete into the surrounding manure anti-parasitic substances. Thus, the manure which served as growth medium for larvae and is used as a fertilizer is useful in preventing developments of parasites such as bacteria, nematodes, wireworms and field slugs in the fertilized soil. The egg-laying substrate of the present invention may also be used as an aid in the extermination of insects. Ammonium bicarbonate or organic substances capable of releasing ammonium may be used as an attractant for insects which are later destroyed, for example on sticky-sheets to which the attracted insects are glued. The substrate of the invention can also be dispersed at specific locations in order to induce insects to lay eggs only in those locations. These locations are then visited periodically by an exterminator and the eggs destroyed, or alternatively the substrate of the invention may further comprise egg-destroying agents.

Thus the present invention further provides a method for destroying insect eggs comprising providing a substrate on which insects lay eggs and destroying the eggs laid thereon, the substrate comprising an inert material soaked with ammonium bicarbonate or an organic substance capable of releasting ammonium.

The substrate of the invention induces the insects to lay eggs thereon and no place else so that all newly laid eggs are concentrated at one place and thus can be destroyed, preferably periodically by any means known in the art.

During the course of development of the present invention it was surprisingly discovered that larvae fed by hard boiled eggs and then transferred to a cold temperature for at least 7 days metamorphose only to pupa but do not further metamorphose to adult insects. Such development- halted larvae are quite advantageous since when handling, shipping and storing them, for example as live fish food, one can be assured that adult insects will never develop. Thus the present invention also concerns a method for halting the development of larvae to adult insects, comprising:

(i) feeding larvae with a preparation of ground boiled eggs; and (ii) transferring the larvae to cold storage for at least 7 days.

DETAILED DESCRIPTION OF THE INVENTION Growing of adult flies

Musca domestica adult flies were kept in cages covered by a net having a hole size of 1-1.5 mm² at a volume of 5-6 cm³ per insect. The cages are kept at a temperature of 26-28°C, humidity 60-70%, illumination intensity 300-400 lax with 16 hours a day light and 8 hours a day darkness.

If desired, the cages can be cooled to 10°C for a period of 4 hours. It was surprisingly found that eggs laid by insects thus treated can be kept in cold storage for longer periods of time (for example 2-3 days) than eggs laid by non-treated insects. The adult flies were fed with a nutrient having the following composition (w/w): flour from dry larvae of flies 45-55%; baker's yeast 1-3%; powdered sugar the rest up to 100%. Drinking water was supplied by constantly running a water stream through a sloped open channel positioned in the cage.

Adult flies can be kept alive for longer periods, for example for shipping and storage purposes by freezing them up to 9 days at 0°C. During the freezing process temperature should decline at a rate of 1°C per minute.

Egg-laying substrate

For preparation of the egg-laying substrate the following composition was prepared: Dry recovered milk 7.6-7.8% (w/w); baker's yeast 2.4-2.5% (w/w); water up to 100%.

The composition was applied to cotton fabric which was folded to form 5-6 layers.

The amount of the above composition should be about 1.6 mg/per fly specimen. Onto the cotton fabric were applied a solution of 20% carbonic acid ammonia in water. The amount of the solution is about

5-7 drops/per 20,000 flies/per day. The cotton fabric was then placed at the bottom of the insect's cage.

Eggs laid on the cotton fabric were collected twice a day and transferred into cold storage at 4°C humidity 80-85% until a sufficient number has accumulated.

In order to keep eggs for longer periods of time, eggs collected from the cotton fabric are mixed with a small amount of cow's manure and a preparation of ground hard boiled eggs, and are kept at room^" temperature for 5 hours. Then the eggs are frozen, with a temperature decline at a rate of 1°C per minute until 0°C. Eggs thus frozen can be kept up to 4 days in refrigeration although this causes about 20% decline in hatching rate. Growth of larvae in manure

The eggs were transferred for growth to fresh pigs' manure at an amount of 300-600 gr eggs/1000 kg manure. Manure humidity was chosen to be no more than 80% and manure's temperature was no less than 20°C. The manure was kept in a temperature of 26-29°C and at an air humidity of 65-75%, which are conditions allowing egg hatching and subsequent larvae growth. The eggs were inserted about 7 cm into the manure layer. If desired, it is possible to maintain a very thick manure layer and insert the eggs in several depths, each egg-containing layer should be separate from the adjacent egg-containing layer by at least 7 cm of manure.

Larvae were allowed to grow for 5-6 24 hour cycles until they reached their maximum size and just before metamorphosis into pupa.

Separation of larvae from manure Before separation manure was leveled to give a layer 3-5 cm in width. The surface of the container holding the pig's manure was heated to a temperature of 40-60°C for 10-20 min. Larvae escaped from the heat towards a space present at the bottom of the container which space was separated from the manure containing part of the container by a net. The larvae were then collected from said space.

Alternatively, the surface of the container holding the pig's manure was illuminated with the aid of powerful fluorescent lamps. Larvae escaped from the intense illumination towards a space present at the bottom of the container which space was separated from the manure containing part of the container by a net. The larvae were then collected from said space.

Treatment of larvae to created development-halted larvae

Larvae were separated from manure as described above after 5 days from hatching. On day 6 they were kept separate in order to allow their body to purify from various substances present in the manure. On the same day 6, the larvae were fed ground hard boiled egg. On day 7 the larvae were transferred to a refrigerator with cooling taking place at a rate of l°C per minute up to 4°C. Larvae were kept at 4°C at least 7 days. This procedure ensured that the larvae, which turn into pupae on day 14, halt at the pupa stage of development and do not develop further to adult flies. Such development halted larvae having a great commercial advantage, for example as live fish food since the buyer or the shopkeeper are assured that no flies will develop from the larvae with all the consequent environmental problems flies cause.

Preparing larvae flour

The separated larvae were placed in a drying chamber and subjected to a stream of hot air at a temperature of 120-130°C for 15- 20 mins. The dried larvae were then grounded by a standard forge miller. Anti-oxidants were added to the flour to prevent oxidation of fat.

Chemical analysis of larvae (either in dry or fresh form):

Protein 53.94 ± 0.61% fat 20.15 ± 0.47% ash 9.44 ± 0.48%

The following Table 1 shows the amino acid content of fresh pig manure, of pig manure during and after processing with larvae and as a comparison, of other food supplement sources such as yeast and meat flour. The number are given as g/per kg of dry substance. Table 1

The following Table 2 shows the content of fatty acids in the fat of larvae.

Table 2

Acid ^{" "} . Code Concentration

-^".^" (mg/kg)

Laurie C₁₂ : 0 Traces

Tridecanoic C₁₃ : 0 Traces

Myristic U₃oC₁₄ : 0 0.3

Myristic C₁₄ : 0 3.4

Myristic + Cα₄ : l

+ Pentadecanoic

: 1 2.1

Pentadecanoic C₁₅ : 0 2.7

Palmitinic U₃oC₁₆ : 0 0.5

Palmitic + Oleic C₁₆ : l 20.9

Margaric C₁₇ : 0 2.1

Stearic "_{M S} : 0 0.9

Stearic C_l8 : 1 4.5

Linoleic C₁₈ : 2 7.3

Linoleic C_l8 : 3 1.3

The phosphorus content of the larvae is 6.12 gm/kg, the calcium content is 7.31 gm/kg and the fluorine content in the biomass was no more than 0.02-0.03%. Cobalt, copper and manganese contents of the larvae was about the same as standard mixed food for pigs. Larvae did not contain indole, skatols and other toxic substances and did not contain any cells of salmonellas or toxic anaerobic bacteria.

Fresh larvae have specific microorganism saturation count in the range of 1.3-2.7 cells/gr. Drying the fresh larvae in a steam of hot air at a temperature of 140°C for 4 mins. or in a temperature of 120°C^~ for 10 min. completely disinfects the larvae subsequently obtained. Larvae flour as a food supplement Fish

31% or 41% of regular fish food was replaced by dry larvae flour. Fish mass was increased by 11% and 22.1%, respectively, as compared to fish eating the regular diet.

Chickens

All the protein source of chickens' feed was supplied by dry larvae flour. After 41 days of feeding chicks showed an average weight increase of 11% as compared to chickens eating a regular diet. Biochemical analysis of blood obtained from experimental chickens did not feature any derivative from physiological norms.

Pigs 50 - 100% of protein source of pigs' feed was supplied by larvae flour. Pigs weighed about 45% more than pigs fed by normal diet. No visible changes were found by pathological and anatomical checking of a kidney, heart, spleen and liver of experimental animals as compared to control animals. Mucous membrane of digestion organs and lymph nodes of all pigs were within physiological norm.

Blind test trials did not distinguish any difference in the taste of boiled and roasted pigs and broth prepared from experimental pigs' meat as compared to pigs fed with normal diet.

Mink

10-50% of minks' normal feed were replaced by larvae flour. No weight change was detected in experimental animals as compared with control animals fed with a regular diet. Quality of experimental mink skins was determined, after slaughter, by a fur expert to be exceptionally good as compared to control animals.

Pigs' Manure Analysis One ton of manure having a humidity of 70% yields 150-200 kg of larvae biomass. The protein content of the manure drops from 17-20% to 15-17% due to consumption by the larvae.

The total bacterial specific saturation of unprocessed manure was 1.4xl0⁸-2.1xl0¹⁸ cells/kg. Manure analysis showed the presence of pathogenic types ol E.coli. After processing of the pigs' manure by larvae for 5 days the microbe specific saturation has fallen by a factor of 10³ to 10⁴. Salmonella and toxic anaerobic bacteria were not detected in processed manure. The manure can be further disinfected by self-heating. This reduction in bacterial counts enables reduction of use of various disinfectants in the fertilizer.

The process manure had anti-parasite effect on various pests such as wireworms (Athous niger), field slugs (Agriolimax agrestisi) and parasitic nematodes. The process manure also encouraged growth of nitrogen-fixing flora and converted various nutrients to a form more accessible to plants as compared to unprocessed manure.

Mushrooms fertilized with processed manure had a yield of 3-4 kg/m² higher than that of mushrooms fertilized with unprocessed horse manure, and a harvest time which was 6-9 weeks' shorter than that of mushrooms fertilized with unprocessed manure. Processed manure was also found to accelerate fruit making of cucumber plants and improved crops on an average of 2.1 kg/m² as compared to cucumbers fertilized with unprocessed manure. Destroying Insects

Standard fly-sheets were attached to a special apparatus which slowly dripped, at a rate of several drops per hour, the ammonia-containing substrate of the invention thereon. The sheets were placed at a vicinity to hen-roosts which were reported to be insect-ridden. The soaked sheets attracted tremendous amounts of flies and crawling insects such as flies, wasps, mosquitoes, ants, etc. Owners of the hen-roosts reported of a relative relief of the insects as compared to other methods tried by them.

Destroying Insect Eggs

Cotton fabric containing the ammonia-releasing substrate of the invention were placed at a vicinity to hen roosts. After several days the cotton fabric was covered with insect eggs of various types (fly eggs, wasp eggs, etc.). The eggs were periodically destroyed every two days by incineration and fresh cotton fabric containing the ammonia-releasing substrate was placed at the same location.

Claims

CLAIMS:

1. An egg-laying substrate for insects of a kind which either grow or feed on manure or organic waste in at least one stage of their life cycle, < the substrate comprising an inert material soaked with a substance which induces egg-laying, said substance being ammonium bicarbonate or an organic substance capable of releasing ammonium.

2. A substrate according to Claim 2, wherein the insect is of the species Musca domestica.

3. A substrate according to Claims 1 or 2 further comprising an organic nutrient other than said organic substance.

4. A substrate according to Claim 3, wherein the nutrient comprises one or more components selected from the group consisting of: bakers' yeast, dry milk, sugar, flour and grains.

5. A method for growing larvae of egg-laying insects which have at least one life-cycle associated with manure or organic waste comprising:

(a) breeding adult insects in a container having an egg-laying substrate, which comprises ammonium bicarbonate or an organic substance capable of releasing ammonia under conditions allowing egg-laying; (b) collecting eggs laid on the substrate and transferring them to growth medium comprising manure or organic waste;

(c) providing conditions allowing egg hatching and growth of larvae; and

(d) separating larvae from the manure or organic waste.

6. A method according to Claim 5, wherein the larvae are separated from the manure or organic waste by creating a temperature gradient within the growth medium by raising or lowering the temperature at one location of the growth medium container to a temperature that causes the larvae to move to anothbr location where the temperature is more physiologically compatible to the larvae and collecting the larvae from the other location.

7. A method according to Claim 5, wherein the larvae are separated from the manure or organic waste by illuminating the surface of the container of the growth medium, whereby the larvae move to the bottom of the container, and then collecting the larvae from said bottom.

8. A method according to Claims 5 to 7, wherein the insect is of the species Musca domestica.

9. A method according to Claim 5, wherein the egg-laying substrate comprises an organic nutrient other than said organic substance.

10. A method according to Claim 9, wherein the organic nutrient comprises one or more members selected from the group consisting of: bakers' yeast, dry milk, sugar, flour and grains.

11. Larvae obtained by the method of Claim 5.

12. Larvae according to Claim 11 in a fresh, frozen or dry-powdered form.

13. Larvae according to Claim 12 for use as baits.

14. Processed manure obtained in step (d) of Claim 5.

15. An insect attractant comprising ammonium bicarbonate or an organic substance capable of releasing ammonium for use in the extermination of insects.

16. A method for destroying insects comprising: attracting insects to a bait and destroying or trapping the insects attracted to the bait, wherein the bait is the insect attractant of Claim 15.

17. A method for destroying insect eggs comprising providing a substrate on which insects lay eggs and destroying the eggs laid thereon, the substrate being that of Claim 1.

18. A method for halting the development of larvae to adult insects, comprising:

19. A method according to Claim 18, wherein the cold storage is at a temperature of 4°C.