FIELD OF THE INVENTION

This invention relates to the control and in particular, the attraction of snout beetles (true weevils), particularly Eremnus setulosus and Phlyctinus colosus.

BACKGROUND TO THE INVENTION

Snout beetles damage crops such as fruits and the present invention seeks to prevent or at least inhibit such damage.

Snout beetles are small insects that over-winter in the soil as pupae, which hatch in early spring and then crawl up the stems of plants such as vines or fruit trees to feed in the canopies on leafs and young fruits.

Snout beetle populations can be controlled by mass application of pesticides, e.g. by cover sprays of the trees.

The present invention seeks to provide an effective attractant (odorant compound or combination) for snout beetles, which can be used in effective and environmentally sound pest control to minimise cover sprays with their concomitant residue problems.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided an odorant substance for use in as an attractant for snout beetles, said odorant substance including at least one, or each of the following compounds:

Cyclopropane carboxylic acid;

5-Methyl-2-hexanone;

2,5-Dimethyl-4-methoxy-3(2H)-furanone ("Mesifurane or berry furanone");

Anisole; and

3-Methoxy acetophenone. The substance may include each of the compounds: Cyclopropane carboxylic acid, 5-Methyl-2-hexanone, 2,5-Dimethyl-4-methoxy-3(2H)-furanone, and Anisole and the compounds may be included in the substance in generally equal parts, by volume. The substance is contained in a capsule with a polymeric wall through which the compounds can pass by diffusion.

The substance may include 20 % 3-Methoxy acetophenone, diluted in water, by volume.

According to another aspect of the present invention there is provided a method of controlling snout beetles, said method including the step of applying the odorant substance described herein above, to attract the snout beetles, e.g. by applying the odorant substance to mechanical traps, combining the odorant substances with insecticides, or the like.

The method may include placing a capsule containing at least one of Cyclopropane carboxylic acid, 5-Methyl-2-hexanone, 2,5-Dimethyl-4-methoxy-3(2H)-furanone, and Anisole in the mechanical trap, and the capsule may have a polymeric wall through which said compounds can pass by diffusion. The capsule may contain each of the Cyclopropane carboxylic acid, 5-Methyl-2-hexanone, 2,5-Dimethyl-4-methoxy-3(2H)- furanone, and Anisole in generally equal parts, by volume.

The method may include applying a 20% dilution of said 3-Methoxy acetophenone in water, by volume, to a surface of the mechanical trap.

The snout beetles may be Eremnus setulosus and/or Phlyctinus calosus.

EXPERIMENTS

For a better understanding of the present invention, and to show how the same may be carried into effect, the invention will now be described by way of non-limiting example, with reference to practical experiments, to assess the extent to which different test odorants attracted snout beetles. Experimental procedure for individual odorants

Yellow Delta traps fitted with bottom sticky pads upon which odorant dispensers of the various test odorants were applied, were placed on ground level against the trunks of bearing apple trees in the Koue Bokkeveld area in the Western Cape Province, South Africa. Test orchards infested with snout beetles were selected on the farms Dennekruin and Voorsorg in the Ceres- Koue-Bokkeveld area.

Unloaded or "blank" traps with no odorants, but identical to the other traps in all other respects, were used as a control. There are no attractants registered for use on snout beetles on deciduous fruit in South Africa with which to compare the experimental results.

After one week the traps were collected and the snout beetles caught were counted and noted. Six replications were used per odorant tested. In Table 1 below the summarised results of the experiments are presented.

Results

Table 1 . Numbers of snout beetles caught in yellow Delta traps.

Attractant/odorant Rep.1 Rep. 2 Rep.3 Rep. 4 Rep.5 Rep.6 Mean

Blank control 0 0 0 0 0 0 0

Cyclopropane 6 7 5 7 3 19 7.8 carboxylic acid

2,5-Dimethyl-4- 2 4 3 2 3 7 3.5 methoxy-3(2H)- furanone

Anisole 4 1 3 3 2 3 2.7

5-Methyl-2- 4 1 1 5 3 2 2.7 hexanone

3-Methoxy 3 1 6 2 1 2 2.5 acetophenone Comments

The strongest attraction of snout beetles was achieved from Cyclopropane carboxylic acid with a mean trap catch of 7.8 snout beetles from six replications. By comparison, the mean of trap catches traps with 2,5-Dimethyl-4-methoxy-3(2H)- furanone was 3.5 and the mean of trap catches with each of anisole and 5-Methyl-2- hexanone, was 2.7. 3-Methoxy-acetophenone caught 2.5 snout beetles.

By comparison, the unloaded "blank control" traps caught no snout beetles. Similar test were also conducted for other substances - 51 in total, but no snout beetles were caught in any of them, apart from those mentioned above. There are no attractants registered for use on snout beetles on deciduous fruit in South Africa with which to compare the above results.

Experimental procedure for combined odorants

Equal parts of the compounds Cyclopropane carboxylic acid, 5-Methyl-2-hexanone, 2,5-Dimethyl-4-methoxy-3(2H)-furanone, and Anisole, by volume, were combined and the combination used to fill capsules with polymeric walls that are sufficiently pervious to serve as a reticular diffusion membrane, through which the compounds can escape very slowly by diffusion, over extended periods.

3-Methoxy acetophenone is quite viscous and was diluted in a 20% solution in water.

The solution was applied to surfaces of mechanical traps and the filled capsules were placed in the traps and the traps were placed in the same orchards described above. The snout beetles caught in the traps were too numerous to record accurately, but it was quite clear that the odorant attractants were acting

synergistically and were extremely effective in attracting the snout beetles.