GB2446644A

GB2446644A - Antifeedant compositions for control of insect pests comprising volatile flavour chemicals

Info

Publication number: GB2446644A
Application number: GB0702926A
Authority: GB
Inventors: William Anthony Jonfia-Essien
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-02-15
Filing date: 2007-02-15
Publication date: 2008-08-20
Anticipated expiration: 2027-02-15
Also published as: WO2008099223A3; GB2446644B; GB0702926D0; WO2008099223A2

Abstract

Acetophenone, ethyl butyrate and 2-phenyl ethanol were used as additives to media on which young adult Tribolium castaneum (Herbst) and Lasioderma serricorne (Fabricius) were cultured for 65 days. Acetophenone and ethyl butyrate had a positive impact on the weight of the insects when used alone. A mixture of the three flavour volatiles deterred the insects from feeding well which subsequently affected the growth of the insects and just after 65 days, all the insects died. But when the concentration was increased, the insects became week and died within few minutes. Similar findings were observed with direct exposure to the mixture. Thus a mixture of the three flavour volatiles could be used in the formulation of effective control measures for the two insect pests both as an antifeedant and insecticide.

Description

AN ANTIFEEDANT AGENT WITH INSECTICIDAL EFFECT

Field of Invention

This invention relates to the application of a mixture of three flavour volatiles chemicals as antifeedant with insecticidal effect.

Description of the Invention

The traditional attack on insect pests has been chemical, physical, biological control, radiation techniques and the use of cultural methods. Currently, the use of physical control and radiation techniques are waning. Biological control has entered a new phase in which genetically and microbiological techniques are employed. The use of chemicals, which are the chief weapons against insect pests, as a control measure has encountered a major problem. Most of the chemicals have negative effect on the environment. For example, methyl bromide is well known to be an effective fumigant (see Patent number CA63071 8) against insect pests in storage but its hazardous effect on the environment has resulted in a strong move to phase it out completely.

According to the Montreal protocol (UNEP Handbook, 6th Ed. 399pp (2003) ISBN: 9280723162), stock pilling of the fumigant should stop and there is a phasing out of it and other ozone depleting substances in the quest for global environmental protection. Phosphine (Heseltine, H.K., Tropical Stored Products Information, 24: 25-36 (1973)) which is a more environmentally friendly fumigant recommended to replace methyl bromide (UNIDO Montreal Protocol -technology transfer to developing countries, 25pp (2003)) is confronted with application problems with the major one being the duration of fumigation. Much has gone into the replacement of methyl bromide (see Patent number W0992275 1 US). There is therefore the search for more environmentally friendly chemicals that would be accepted by all the stack holders.

Recently, the use of chemicals that reduces consumption by the insect pests (Koul, 0., CRC Press, lOOSpp (2004)) or deters feeding of the insect pests (Isman, M.B., Pesticide Research Journal 6: Il - 19 (1994)) has come under sharp focus as an area of research to institute a control measure that has global environmental protection. Such chemicals are known as an antifeedants (Koul, 0., CRC Press, lOO5pp (2004); Isman, M.B., Pesticide Research Journal 6: 11-19 (1994)). Researching into the environmentally friendly chemicals, the effect of acetophenone, ethyl butyrate and 2-phenyl ethanol flavour volatiles on the behaviour of two insect pests were studied. It was conclusive at the end of the study that, application of a mixture of the three chemicals acts as antifeedant with insecticidal effect. This is a novel finding since it is the first time such an observation has been made on the effect of a mixture of the three flavour volatiles on insect pests.

Pure standards of acetophenone, ethyl butyrate and 2-phenyl ethanol flavour volatiles were prepared by diluting the solutions with known volume of HPLC analytical methanol to 12.5, 25, 50 and 100 t1m11 (Figure 1 -6) and tested on young adult Tribolium castaneum (Herbst) and Lasioderma serricorne (Fabricius) singly and in various combinations. The solvent methanol was also tested against a blank (Figure 7 -8) to determine the effect on the insects. The insect was allowed about 5 mm (accommodation period) to acclimatize after which a video camera positioned directly above the bioassay area was used to record its behaviour or movements for 20 mm. The videocassettes were reviewed and the time spent in each flavour volatile by the insect was recorded.

Also Twenty adults of Tribolium caslaneum (Herbst) and Lasioderma serricorne (Fabricius) were introduced separately into culture bottles containing I 50g each of wholemeal wheat flour and brewer's Yeast (20:1 by weight) plus 0.5m1 of three flavour volatiles, singly and in various combinations at concentrations of 50tl/ml and 25tl/ml for Tribolium and Lasioderma respectively.

The treatments were eight in total including one control and they were all replicated three times. The control contained only the feed media 150g wholemeal wheat flour and brewer's yeast. The cultures were maintained at 30 1 C and relative humidity of 70 2 % in the dark for 65 days in I litre Kilner jars. The mean weight of single insects was determined on day 40 (Table 1) by weighing 3 replicates of 10 insects using a side loading analytical balance.

Examples

Figure 1 shows the responses of Tribolium caslaneum to different concentrations acetophenone T. castaneum responded positively to acetophenone at 50 j.iiml* The insects spent significant time (P < 0.001) at the volatile at 50 j.tlml but were not attracted to the volatiles at the other three concentrations of 12.5, 25 and 100 1.tlml".

Figure 2 Responses of Tribolium castaneum to different concentrations of ethyl butyrate T castaneum responded positively to ethyl butyrate at 50 i1m1'. The insects spent significant time (P < 0.001) at the volatile at 50 p.lmF' but were not attracted to the volatiles at the other three concentrations of 12.5, 25 and 100 j.tlmF'.

Figure 3 Responses of Tribolium castaneum to different concentrations of 2-phenyl ethanol T castaneum responded positively to 2-phenyl ethanol at 50.tlmr'. The insects spent significant time (P <0.001) at the volatile at 50 1tIml but were not attracted to the volatiles at the other three concentrations of 12.5, 25 and 100.t1ml'.

Figure 4 Responses of Lasioderma serricorne to different concentrations of acetophenone L. scrricorne responded positively to cetophenone at 25 t1mI'. The insects also spent significant time (P <0.001) at the volatile at 25 1tlml but were not attracted to the volatiles at the other three concentrations of 12.5, 50 and 100 j.tlml* Figure 5 Responses of Lasioderma serricorne to different concentrations of ethyl butyrate L. serricorne responded positively to ethyl butyrate at 25 tlmF'. The insects also spent significant time (P <0.001) at the volatile at 25 jlmF' but were not attracted to the volatiles at the other three concentrations of 12.5, 50 and 100 j.tlml.

Figure 6 Responses of Lasioderma serricorne to different concentrations of 2-phenyl ethanol L. serricorne responded positively to 2-phenyl ethanol at 25!.tlmi'. The insects also spent significant time (P <0.001) at the volatile at 25 tlml1 but were not attracted to the volatiles at the other three concentrations of 12.5, 50 and 100 j.tlmF' Although T. castaneum and L. serricorne were attracted to acetophenone, ethyl butyrate and phenyl alcohol, they showed greater preference for acetophenone (P <0.001). T caslaneum did not survive at 100 tlmr' beyond 10 mm and L. serricorne also did not survive at 50 tlml' beyond 10 mm.

Figure 7 Responses of Tribolium castaneum to the methanol (solvent) control T castaneum spent 88.35% of it time at the blank chambers but spent very little time at the solvent odour field. The significant discrimination of T castaneum against the methanol solvent (P <0.001) used in diluting the standard volatile compounds is an indication that the methanol solvent was not responsible for attraction of the insects to any of the prepared samples of volatile compounds.

Figure 8 Responses of Lasioderma serricorne to the methanol (solvent) control L. serricorne spent 90.65% of it time at the blank chambers but spent very little time at the solvent odour field. The significant discrimination of L. serricorne against the methanol solvent (P <0.001) used in diluting the standard volatile compounds is an indication that the methanol solvent was not responsible for attraction of the insects to any of the prepared samples of volatile compounds.

Table I shows the weight of adult insects after 40 days of feeding on feed media containing various combinations of flavour volatile.

Feeding of insects occurred in all of the cultures with and without the addition of the flavour volatile standards. Compared with their weight before the experiment, adults of Tribolium were twice as heavy at the end of the experiment. The Tribolium fed on media containing acetophenone or ethyl butyrate as an additive were heavier than the control. Those that fed on media containing all three flavour volatile standards, acetophenone, ethyl butyrate and 2-phenyl ethanol, weighed the least followed by the acetophenone and 2-phenyl ethanol combination. In contrast, there was only a slight increase in weight of the Lasioderma that fed on media containing acetophenone, ethyl butyrate or both.

The significant increase in the weight of Tribolium adults (P < 0.001) 40 days after introduction is an indication that feeding occurred in all the feed media. This also implies that the insects were well nourished, with a positive impact on their multiplication. However, it was very surprising to observe over 100% increases in weight of Tribolium adults. This is beyond expectation considering the hard cuticle of the insect that normally would prevent moulting to allow growth. It is not very certain whether the inclusion of the flavour volatile to the feed medium has any effect on shedding of the exoskeleton by insects. The weight of Lasioderma, in contrast, did not increase as much, which implies low feeding and poorly nourished with little effect on their multiplication. Thus, the feeding behaviour of Tribolium was completely different from that of Lasioderma. It is possible that the amount of the flavour volatile was high enough to deter the Lasioderma from feeding.

The highest weight of insects fed with media containing acetophenone indicated that the volatile alone could be used to boost the multiplication of the insect. However, when acetophenone was combined with the other two volatiles, ethyl butyrate and 2-phenyl ethanol, the insects showed lower weight increase than the control. None of the insects in feed media dosed with the mixture of the three flavour volatiles survived beyond 65 days. The mixture seems to show more negative effect and therefore, beneficial effect on insect control could be achieved by increasing its concentration.

This invention is a major advancement in insect pests control analysis of data especially in the search for environmentally friendly chemicals for insect control. The reduction to practice of this invention will grant easy accessibility to scientists investigating into the control measures that have global environmental protection.

Table I Weight of adult insects after 40 days of feeding on feed media containing various combinations of flavour volatile Weight of insect Feed media (mg) Tribolium Lasioderma AP 1.69 0.001 0.54 0.001 EB 1.60 0.001 0.5 1 0.001 PA 1.32 0.010 0.45 0.001 AP+EB 1.36 0.002 0.49 0.001 AP+PA 1.14 0.005 0.45 0.000 EB+PA 1.33 0.002 0.45 0.000 AP+EB+PA 1.10 0.007 0.44 0.000 Control 1.46 0.001 0.46 0.002 Insects before feeding 0.63 0.009 0.45 0.002 Key: Key: AP -acetophenone; EB - ethyl butyrate; PA -2-phenyl ethanol

Claims

1. An antifeedant for the control of insect pests, comprising one or more flavour volatile chemicals.

2. An antifeedant according to claim 1, comprising a mixture of flavour volatile chemicals.

3. An antifeedant according to claim I or claim 2, comprising the flavour volatile chemical acetophenone.

4. An antifeedant according to claim 1 or claim 2, comprising the flavour volatile chemical ethyl butyrate.

5. An antifeedant according to claim I or claim 2, comprising the flavour volatile chemical 2-phenyl ethanol.

6. An antifeedant according to claim 2, comprising a mixture of acetophenone and 2-phenyl ethanol.

7. A method according to claim 4 or claim 5, wherein the insect pests include Lasioderma serricorne. * ** * * * * .. * * ** ** *S * * *

S

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S * S. * S * S... * S* * .*

7. An antifeedant according to claim 2, comprising a mixture of acetophenone, ethyl butyrate and 2-phenyl ethanol.

8. An antifeedant according to any preceding claim, in which the flavour volatile chemicals are present at a concentration sufficient to act as an insecticide for the target pest species.

9. A method of deterring consumption of a foodstuff by insect pests, by administering to the foodstuff an antifeedant according to any preceding claim.

10. A method of killing insect pests, by administering to the foodstuff an antifeedant according to claim 8.

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AMENDMENT TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS

1. An antifeedant for the control of insect pests, comprising a mixture of the flavour volatile chemicals acetophenone and 2-phenyl ethanol.

2. An antifeedant according to claim 1, further comprising the flavour volatile chemical ethyl butyrate.

3. An antifeedant according to any preceding claim, in which the flavour volatile chemicals are present at a concentration sufficient to act as an insecticide for the target pest species.

4. A method of deterring consumption of a foodstuff by insect pests, by administering to the foodstuff an antifeedant according to any preceding claim.

5. A method of killing insect pests, by achninistering to the foodstuff an antifeedant according to claim 3.

6. A method according to claim 4 or claim 5, wherein the insect pests include Tribolium castaneum.