USE OF TERPENOID COMPOUNDS IN AGRICULTURE OR HORTICULTURE AND FOR PREPARING PREPARATIONS FOR CONTROLLING WHITEFLY SPECIES

Abstract: The invention relates to the use of terpenoid compounds such as alpha - and beta -humulene and (-)- beta -caryophyllene for controlling whitefly species, the active substances, for example in the gas or vapour form, being allowed to act on the habitat of the insects to be controlled. The invention also relates to the use of the said compounds for preparing preparations suitable for use in agriculture and horticulture.

Description: Use of terpenoid compounds in agriculture or horticulture and for preparing preparations for controlling whiteflv species. The invention relates to the use of terpenoid compounds in agriculture or horticulture and for preparing preparations for controlling hitefly species. It is known that certain terpenoid compounds, for example the sesquiterpene (E)-β-famesene, cause an alarm reaction in aphids. It is also now* that, when it is brought into contact in liquid form with aphids, (E)-β-farnesene exerts a lethal effect on these insects (compare EP-A-0 073 080). EP-A-0 266 822 discloses that famesene, in particular E-B- farnesene, influences hormonal processes in insects and Acarinε. These processes relate in particular to the development, reproduction and morphogenesis. In the case of this hormonal use, the famesene in gas or vapour form is allowed to act on the animals to be controlled in a concentration which is higher than the concentration in which fa esene acts as an alarm pheroπone for aphids. A preferred concentration of at least 10 nanograms per ml of air is mentioned. The following are mentioned as examples o insects and Acarina which, according to EP-A-0 266 822, can be controlled via the hormonal mechanism of action: whitefly (Trialeurodes vaporariorum) , green peach aphid (Myzus persicael and in general the Homoptera, red spider mite (Tetranychus urticae), thrips (Thysanoptera), house fly (Musca domestica), fruit flies (Licosinε sp.), lesser mealworm beetles (Alphitobius diaperinus), Diptera, Lepidoptera and Coleoptera, for example the cacao moth (Ephestiε elutella) , the cigarette beetle (Laεioderma serricorne), the confused flour beetle (Tribolium confusu ) and the khapra beetle (Trogodermε granarium). Cockroaches (Dictyoptera) , bugs (Heteroptera) and ants (Hymenoptera) , and grasshoppers (Orthoptera) and Colorado beetles , 1 (Coleoptera) are also mentioned. It has now been found that certain terpenoid compounds, the structure of which is related to (E)-β-farnesene, can be used more successfully for controlling whitefly species. The invention therefore relates to the use of terpenoid compounds in agriculture or horticulture and for preparing preparations for controlling whiteflv species, the terpenoid compounds having a structure of the formula (1) in which the broken lines indicate the positions of possible C-C bonds. Within the framework of the present application, the white- flies belong to the entomological superfeasily of the Aleurodinae; specifically, the genera Bemisia and Trialeurodes. in particular eziεia tabaci and Trialeurodes vaporariorutf!. are of interest. The whiteflies belong to the family of the Aleurodidae. The following may be mentioned as terpenoid compounds which are used according to the invention: α-humulene, (j-husuler (-}-£-caryophyllene. Amongst these substances, caryophyllene and α-humuler.e in particular are found to possess a rapid and effective action. It has been found that the essential ylang-ylang oil, which, inter alia, contains a number of terpenoid compounds, exerts a toxic action as well. Tnis oil contains approximately 10-. of caryophyllene. Reference is made to the following overview for a more complete composition: Main components of ylang-ylang oil 8 % p-methylanisole 2 % δ-cadinene 19 * linalool 3 % γ-cadinene * c-farnesene 10 % (-)-β-caryophyllene 8 % geranyl acetate k % methyl benzoate 2 % geraniol 3 % α-humulene 2 % (E.E)-farnesyl acetate 10 % germacrene-D 1 % (E.E)-farnesol 5 * benzyl acetate 85. benzyl benzoate 2 % benzyl salicylate However, it has been found that the action of ylang-ylang ci! is more powerful than can be explained on the basis of the presence cf caryophyllene only. This could indicate a synergistic effect of other components which are present in ylang-ylang oil and/or an effect of other toxic components. Ylang-ylang oil has a very low toxicity for mammals, including humans. The use thereof in the odour and flavouring industry is generally known, J. Agric. Food Che_c. 1986, __ . , Hδl -ll8~ . According to a preferred embodiment of the invention, the terpenoid compounds can be in the gas or vapour form. For example, the active substance is converted to the vapour or gas form in horticultural greenhouses with the aid of a so-called time-release system. Automatic dosing takes place at intervals of, for example, 10 minutes. This is continued for a few days, after which the greenhouse is aired. If necessary, parasites such as ichneumonid wasps can be employed after the treatment with the terpenoid compound. Usually, this type of rounding-off of the control of the whitefly is not necessary. However, it should be pointed out that the use of the terpenoid compounds can readily be combined with biological control techniques. The invention also relates to a method for controlling whitefly, in which method an active substance is allowed to act on the habitat of the insects to be controlled, the active substance used being at least one terpenoid compound having a structure of formula (1) in which the broken lines indicate the positions of possible C-C bonds.. The terpenoid compounds preferably mentioned for the method according to the invention are those which have been reported as " , " preferred compounds for this purpose, including the indicated ylang-ylang oil. In an embodiment of the method according to the invention, the sesquiterpenes being in the gas or vapour form, it is preferable that the concentration of the terpenoid compounds during the treatment is between 0.1 and 1000 nanograms per ml of air, that is to say that the concentration can even be up to the saturation concentration. The said amounts are measured under standard conditions, that is to say a pressure of 1 atmosphere and a temperature of 20°C. The said concentrations of active substance can easily be achieved with the aid of, for example, slow-release systems or the dosing system described above, using spray cans. The use in the gas or vapour form can take place analogously to th methods described in EP-A-0266822. The method according to the invention can be carried out both in horticulture (use inside and outsid greenhouses) and in agriculture (in the open field), although in the cas of use in the open field it will be more difficult to maintain effective vapour concentrations over a prolonged period of tine. It should be emphasized that killing of whitefly is also possible by direct spraying with the terpenoid compounds, for example oy using a mist of very fine droplets of the substances. Tests have showr. that all animals are killed in the case of direct spraying. Examples In all experiments greenhouse whiteflies (Trialeurodes vaporariorum) were cultured on large tobacco plants (Kicotiana xanthi,. Approximately one week old adult whiteflies were collected from this mother culture and transferred to small tobacco plants. The animals were then used in various experiments. All experiments were carried out at a temperature of lδ-2 c C and a light regime of IS hours light and 6 hours dark. Small tobacco plants were grown from seed in small flowerpots having a diameter of 10 cm, under the light of a high-pressure mercury vapour lamp. The light regime was identical to that just described. Unambiguous and reproducible results were obtained in experiments with greenhouse whiteflies o the small tobacco plants already mentioned. For this purpose, the plants were placed in perspex tubes cf approximately covered at the top with nylon gauze. About 100 adult whiteflies were placed on one plant. A wooden stick holding a filter paper with 1, 10, 5^ or 1CI mg of substance to be tested without solvent was pushed into the soil adjacent to the plant. In the control group a filter paper was positioned in a similar manner without applying a substance thereto. It can be seen from Table 1 that caryophyllene is toxic for whiteflies and paralysis occurs amongst the animals, from which they do not recover anymore. After 1 day 82% are already dead. (E)-β-farnesene, used for comparison, is also toxic (see Table 1). In this case we find 7^ mortality after 2 days. The substance α-humulene has a similar effect: three days after application of 100 mg a high mortality of 9^ '- was observed. Table 1 Terpenoid Mortality ( % ) after (100 mg) 1 day 2 days 3 days 4 days (E)-β-farnesene 7^ (-)-β-caryophyllene 82 100 α-humulene 3 94 no treatment 0 18 Results of experiments using a ten times lower dosage are given in Table 2. In this case, the animals were monitored for 11 days in order to be able to detect any possible long-term effects. Table 2 Terpenoid Mortality (_.) after day (10 mg) 1 2 3 5 6 11 (E)-β-farnesene 41 (-)-β-caryophyllene ylang-ylang oil * no treatment 100 mg of this oil were administered. At a dosage of 10 mg, the effects fall far short of being'-as powerful as those at 100 mg. Moreover, the mortality is also found to increase slowly in the untreated group. It is evident that (-)-β- caryophyllene, but especially ylang-ylang oil, has a more rapid action than the fa esene used for comparison. Ylang-ylang oil was administered here in 100 mg. This amount of ylang-ylang oil contains Ϊ0 mg of caryophyllene. Tne effects of ylang- ylang oil are, however, appreciably more powerful than those of the exclusive use of caryophyllene. 73 mortality is found after 1 day, while after 3 days all animals are dead. A separate experiment in small plastic cages of 0.5 1 was conducted to establish more precisely the effects of various dosages cf α-humulene on whitefly mortality. The results are shown in Table 3- A strong dose-effect relationship can be observed with strong and fast effects of even the smallest dose used here. Table 3 Adult whitefly mortality ( } after exposure to various dosages of α-humulene

Claims: CLAIMS 1. Use of terpenoid compounds in agriculture or horticulture and for preparing preparations for controlling whitefly species, the terpenoid compounds having a structure of the formula (1) in which the broken lines indicate the positions of possible C-C bonds. 2. Use according to Claim 1, the terpenoid compounds being chosen from α-humulene, β-humulene and (-)-β-caryophyllene. 3. Use according to Claim 1 or 2, the terpenoid compounds being in the form of ylang-ylang oil. 4. Use according to Claims 1-3, the terpenoid compounds being in the gas or vapour form. 5- Method for controlling whitefly species, in which method an active substance is allowed to act on the habitat of the insects to be controlled, the active compound used being at least one terpenoid compound having a structure of formula (1) in which the broken lines indicate the positi -onvs of possible C-C bonds. 6. Method according to Claim 5. characterised in that the terpenoid compounds are chosen from α-humulene, β-humulene and (-)-β- caryophyllene. - 7. Method according to Claim 5 or 6, the terpenoid compound being in the form of ylang-ylang oil. •> -' 8. Method according to Claims 5~7. the terpenoid compounds being in the gas or vapour form. 9- Method according to Claim 8, the concentration of the terpenoid compounds being between 0.1 and 1000 nanograms per ml. 10. Method according to Claims 5"8, the insects being sprayed directly with the terpenoid compound or a preparation which contains such a compound.

Inventors: GUT JIRI, VAN OOSTEN ADRIAAN MAARTEN, GUT, JIRI, VAN OOSTEN, ADRIAAN, MAARTEN
Applicants: TNO, NEDERLANDSE ORGANISATIE VOOR TOEGEPAST-NATUURWETEN
Application year: 1992
Main classification: A01N27
IPC codes: A01N27, A01N65