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Back to the List of the Granted Patents                                      Click here to download KE000105 PDF(11) Patent Number: KE 105
(45) Date of grant: 10/03/2005

(12) PATENT
 
(51) Int.Cl.5: A 01N 37/34
(21) Application Number: 1998/000237
(22) Filing Date: 19/06/1998
(73) Owner:INTERNATIONAL CENTRE FOR INSECT PHYSIOLOGY AND ECOLOGY-ICIPE of, P.O.Box 30772-Nairobi, Kenya
(72) Inventor:Magzoub omer Bashir, Peter G.N.Njagi, Baldwyn Torto Ahmed Hassanali, Daniel Obeng-Ofri
 
(54) Title: ORGANISATION -DISTRIBUTING FACTORS IN A NOVEL APPROACH OF CONTROLING LOCUST AND GRASSHOPERS.
(57) Abstract:
Phenylacetonitrile (benzyl nitrite), and related compounds are effective disruptants of gregarisation of locusts and make these insects more susceptable to insecticide, insect growth regulators, biopesticides and natural predation.
 
BACKGROUND OF THE INVENTION
1. Locusts belong to the family of grasshoppers that have the remarkable ability of transforming between two extreme phases, solitaria and gregaria. The transformation to gregaria is accompanied by a strong tendency for the individuals to aggregate in dense groups, march in bands as wingless hoppers or swarm over long distances as adults. Gregarious locusts also develop appetite for a wide variety of plants including agricultural crops. The desert locust, Schistocerca gregaria, is considered to be economically the most important locust species in Africa, the Middle East and Western Asia. In Africa, other species, such as the migratory locust (Locusta m. migratorioides), the brown locust (Locustana pardalina) and the red locust (Nomadacris septemfasciata) are also important. The conditions involved in giving rise to local outbreaks of locust swarms or sustained plagues differ in different locust species. In the case of the desert locust, outbreaks or plagues are normally associated with improvement of weather conditionslollowing long dry spells. Underthese conditions the soritarious individuals concentrate in areas with improved vegetation, breed and multiply. Gregarisation occurs in isolated patches of vegetation and may spread relatively rapidly across habitats. It is associated with the production of intra-specific signals (pheromones) which promote the grouping behavior of the individuals.
2. Various other grasshoppers, although not classified as locusts, show varying propensity to aggregate at certain stages of their development. These include the grasshopper Zonocerus variegates, Z. elegans, Anacridium melanorhodon, Hieroglyphus nigrorepktus etc.
3. The current control strategy is based on monitoring for signs of outbreaks of hopper bands or adult swarms followed by ground or aerial spraying with synthetic Insecticidesuntil recently, organochiorine based compounds have been the main toxicants used. Recently, these have been replaced by less persistent organophosphorous, carbamate and urea derivatives. However, concern for the effect of continued large-scale use of these on human personnel involved and on the environment, particularly the fragile ecosystems inhabited by locusts, have led to the search for alternative ways of controlling these periodic pests. In this regard, current research include the evaluation of effective biocontrol agents, hormone mimics and anti-hormones. In addition, research is concerned with finding behaviour-manipulating agents that would disrupt the grouping behaviour of locusts and reduce them to harmless or less harmful solitaries’ individuals.

DESCRIPTION OF THE INVENTION
The present invention is based on the discovery that certain compounds belonging to arylallcylnitrile inhibit gregarisation in nymphal desert locusts and enhance their susceptibility to predation, insecticides, biopesticides, insect growth regulators (IGRs) and natural products and are suitable as non-persistent, non-toxic and locust pacific, behaviour-modifying agents.
5. According to the invention, there is provided the use of compounds represented by the formula:
CX2CN

                                         A            R

                                          (I)                                                                   
Where "A" may be a benzene ring or a heterocyclic ring or either of this fused with another ring to give, for example, a naphthalene or a heteronaphthalene ring, X may be the same or different and stand for hydrogen, hydroxyl (one), alkoxy, carboxy, halogen, alkyl, fluoroalkyl or phenyl radical (substituted or unsubstituted); R a substituent or substituents on the aromatic ring such as alkyl, fluoroalkyl, halogen, alkoxy or phenyl (substituted or unsubstituted) radicals.
 
6. As examples of potentially useful compounds there may be mentioned ones where
in structure I, A is a benzene ring, X=H or F and R=hydrogen, alkyl or fluoroalkyl such as II, III, IV and V


CH2CN                  CHFCN            CF2CN             CH2CN

                                                  R                     R
                                                                                               CH3
(II)                            (III)                    (IV)                    (V)

Of these, the compound of choice as an anti-aggregation agent for the desert locust is represented by II with unsubstituted benzene ring (R=H).

7.As an important feature of the invention, there is provided the use of one or more of the compounds represented by formula I in disrupting the gregarious behaviour of nymphal stages of the desert locust and thereby dispersing the individuals (which exposes them to enhanced level of predation) either by direct application of the compounds on locust aggregates, whilst marching or roosting, or by barrier application on the ground where hopper bands are expected to cross.
8. As another feature of the invention, there is provided the use of one or more compounds represented by formula I with insecticides, insect growth regulators (IGRs) or biopesticides which may be delivered at normal or lower doses. As examples of insecticides or IGRs which may be used in such combinations there may be mentioned compounds of organophosphate group such as fenitrothion and malathion, pyrethroids such as deltamethrin and iambdacyhalothrin, carbonates such as propoxur and bendiocarb, benzoylurea group such as dimpling and triflumuron as well as natural anti-insect compounds such as those found in the neem tree. As examples of biopesticides which may be used concurrently with compound represented by formula I, there may be mentioned fungi such as A/mob/If/4m flavoviride and Baauveria bassiana and protozoa such as Nosema locustae and Malamoeha sp.
 
9. It is to be understood that the invention is meant to include the use of any of the compounds represented by formula I alone or in combination in disrupting locust and grasshopper aggregation. It is also to be understood that the invention includes the use of all compositions containing the said compounds prepared for the purpose stated above. These may include formulations or concentrates containing standard diluents, solvents, dispersing agents, surface-active agents, anti-oxidants, UV-screens etc. added for usage convenience, protection of the active agent(s) or for its (their) increased effectiveness. Likewise, it is to be understood that the invention includes all controlled-release formulations prepared for extending the duration of performance of the active agents defined above.
10. It is to be understood further that the invention is meant to include the use of compositions containing a compound(s) represented by formula I together with an insecticide(s), IGR(s) or biopesticide(s) in a single formulation or separate formulations. These formulations may include standard components listed in paragraph 9-added for protection of the active-agent, increased shetf:lives, or increased overall effectiveness on application.
11. In addition, it is to be understood that compounds represented by formula I with or without insecticides, IGRs or biopesticides may be similarly used to degregarise and control other locust or aggregating grasshopper species at sensitive stages of their life cycles. Examples of locusts (or grasshoppers) which may be controlled include the migratory locust, the red locust, the brown locust, the Moroccan locust, the tree locusts and the variegated grasshopper in essentially the way described above.
WHAT IS CLAIMED
A method of controlling the desert locust, Schistocerca gregaria, comprising the application on a locus of the said nymphal stage of the pest or on the ground where they are expected to arrive (barrier application) of an effective amount of a compound having the structural formula:

    CX2CN

                                              A           R

                                              (I)

wherein, A = benzene ring, heteroaromatic ring, a fused aromatic or a fused heteroaromatic ring;
X = H, halogen such as flourine, alkoxy, hydroxy, carboxyl etc. and may be the same or different;
R = one or more of alkyl, halogen, alkoxy, ester, aryl or 130    heteroatom containing-substituents.
2. The method of controlling desert locust as described in Claim I wherein the said compound is phenyl acetonitrile (benzyl cyanide), represented by structure II.
3. The method as described in Claim I wherein the pest may be any other acridid species such as Locusta m. migratorioides (migratory locust), Nomadacris septemfasciata (red locust), Locustana partcrlina (brown locust) etc. at any sensitive stage of their life cycles.
4. The method as described in Claims 1, 2 or 3 wherein the said compound(s) are applied as mixtures.

5. The method as described in Claims 1, 2, 3 or 4 wherein the said compound(s) is (are)
applied in a suitable inert carrier.
 EXAMPLES
The invention is illustrated but not limited by the following examples:
Example l
Anti-aggregation activity of compound VI was tested in a single chamber 2-choice olfactometer according to the procedure described by Obeng-Ofori et al. (J. Chem. Ecol., 1993, 19, p. 1665-1676). Tests were carried out on groups of 5 mixed-six fifth Molar nymphs (3-6 days after ecdysis). Each group of insects was given a choice of nymphal volatiles admixture with compound VI (phenylacetonitrile). Nymphal volatiles were delivered from light paraffin solution representing an equivalent of 100 locust hours (J. Chem. Ecol., 1993, 19, p 1665-1676) of the volatiles. Compound II was presented from   the solution at the concentration shown in Table 1).
Results are presented in Table 1 These results show clearly that inclusion of very low levels of phenytacetronitrile leads to a substantial drop in the aggregation propensity of the nymphal insect.
Table 1: Aggregation responses of 5th instar gregarious desert locust nymphs to nymphal volatiles with varying amounts of compound II present in aqueous polyethylene glycol (PEG).
% compound II                 % Nymphs
in aqueous PEG    aggregating
0                                      72 + 0.55O
0.1    4b
0.25    2b
0.5   0b
1.0    0b
2.5    0b
5.0                                   0h

 6. The method as described in Claims 1,2,3,4 or 5 wherein the said compound(s) is(are) applied as a blend with suitable additives such as surface-active compounds anti-oxidants, diluents and UV screens or as controlled-release formulations.
7. The method as described in Claims 1, 2,3,4,5 or 6 wherein the compound(s) is(are)
applied directly on hopper individuals in marching, roosting or basking state.
8. The method as described in Claims 1, 2,3,4,5 or 6 wherein the compound(s) is (are applied on the ground over which hopper bands are expected to cross or around a hopper band (barrier application).
9. The method as described in claims 1-8 wherein the said compound(s) is(are) applied on adult stages.
10. The method as described in claims 1-9 wherein the said compound(s) is(are) applied sequentially or concurrently with a conventional insecticide(s), IGR(s), natural anti-insect agent(s), a biopesticide(s) applied in a suitable carrier(s) with or without additives listed in Claim 6.
11. The method as described in Claims 10 wherein the components are formulated ant
applied as a single composition.
 
Example 2:
Compound II at 0.01% in aqueous acetone was applied to hopper bands at the rate of I l/hectare. For controls, bands were treated with the aqueous acetone without compound II and others were left untreated. The number of marching days, leading edges of the bands, roosting groups, and overall displacement were recorded. In addition, level of predation principally by birds, was estimated (Table 2). As the table suggests, bands treated with compound II showed abnormal behaviour including less marching, les displacement (frequent changes in direction or arrestment), more leading edges, more roosting blotches, etc. Treated bands fragmented into smaller and smaller groups, and eventually, into individuals. They suffered much greater predation by birds compared with bands not exposed to compound II.
Table 2: Behaviour of desert locust nymphal bands exposed to compound II compared to control bands.

Treatment:
Effects     Compound II    Aqueous acetone    Untreated
Marching days    4+0.63    14 + 1.41    15.5 + 0.71
Total displacement (m)    3173 + 103.5    1572 + 158    1958 + 84
Displacement/day (m)    80.6 + 26.9    112 + 40    126 ± 68
Leading edges    2.0 + 1.2    1.24 + 0.44    1.21 + 0.43
    (range    1-5)    (range    1-2)    (range : 1-2)
Roosting groups    8.9 + 8.6    4.46 + 1.79    4.19 + 1 76
    (range : 2-50)    (range    2-8)    (range    2-8)
Predation-relative'                0.64 + 0.21                   0.20  + 0.01                0.22  + 0.04
absolute                                0.13 + 0.04                   0.04  + 0.01                0.04  + 0.01

Number affected relative to the sizes of the relevant bands.
…………………………………….size of all observed bands.
 
Example 3: 4th instar desert locust nymphs were each briefly sprayed with 0.01 and 0.05% of compound II in aqueous acetone followed by a sublethal dose of Propoxur (at 15-fold normal dilution). Mortality data at day 6 and 13 after treatment are presented in Table 3.
The results show clearly that compound II enhances the susceptibility of the nymphs to the insecticide.
Table 3:
Mortality of 4th instar desert locust nymphs treated with 15-fold dilution of the normal dose of Propoxur normally used for control and compound II compared to that of untreated nymphs.
Treatment    Compound II    Compound II    Aqueous    Water
0.05%    0.01%   Acetone    + Propoxur
+ Propoxur    + Propoxur    + Propoxur

Day 6                   0.33 + 0.13a          0.40 + 0.14a               0.28 + 0.1a 0.23 + 0.55a
Day 13                 0.80 + 0.12a          0.75 ± 0.13a               0.43 + 0.05b         0.30 + 0.08b
Example 4:
4th instar desert locust nymphs were treated with compound II as in Example 3 followed by low doses ofMetarrhizium anisopliae (2.7x 103 in an oil formulation). The mortality data of the insects at day 6 and 15 are presentedin Table 4. The results show higher susceptibility of insects exposed to compound II to the fungus.
Table 4. Mortality rate of gregarious 4th instar nymphs of desert locusts treated with different levels of compound 11 with/without M. anisopliae.
Treatment    day 6   day 15
Fungus + oil    0.31 + 0.071b    0.60 + 0.05b
Fungus + II (0.05%)     0.60 + 0.05a   0.91 + 0.00a
Fungus + II (0.01)           0.31 +0.19b              0.64 + 0.05b
II (0.05)         0.01 + 0.01c               0.04 + 0.00c
II (0.01%)                        0.06 + 0.02c               0.11 + 0.04c
Aqueous acetone             0.01 +0.01c                0.03 + 0.03c
Oil                                   0.01 + 0.01c                0.12 + 0.01c

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