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Plant derived extracts and phytochemicals have long been a subject of research in an effort to develop alternatives to conventional insecticides but with reduced health and environmental impact. In the present study, the aphid settling deterrent activity of extracts obtained from garlic (Allium sativum L.), wormwood (Artemisia absinthium L.) and tansy (Tanaceum vulgare L.) against peach potato aphid (Myzus persicae [Sulz.]) was investigated. The settling of M. persicae on host plant leaves was strongly deterred by soap 1%, soap 4%, Bioczos Forte 2% + soap 1%, Bioczos 1% + tansy extract 1%. Their effect was observed after 1 hour aphid had got access to the plants and it lasted until the end of the experiment, i.e. 24 hours after application. After 24 hours, aphid settling was deterred by the following combinations of extracts: Bioczos 2%, Bioczos 2% + soap 1%, Bioczos 5%, Bioczos 5% + soap 1%, Bioczos 1% + wormwood extract 1%, Bioczos 1% + wormwood extract 1% + soap, tansy extract 1% + wormwood extract 1% and tansy extract 1% + wormwood extract 1% + soap 1%.
The aim of this work was to investigate the relative susceptibility of selected varieties of yellow lupine Lupinus luteus L. (Juno and Taper) and narrow-leaved lupine Lupinus angustifolius L. (Baron and Karo) to feeding of the pea aphid Acyrthosiphon pisum Harris. The studies were carried out using the EPG (Electrical Penetration Graph) technique. Susceptibility of selected varieties of both lupine species was determined upon the analysis of non-sequential parameters derived from 8-hour registration of aphid probing. The results of the study revealed that two species of lupine showed a low level of susceptibility to the pea aphid feeding. This was evidenced by a short time phloem phase (less than 3% of experimental time). The varieties Karo (narrow-leaf lupine) and Taper (yellow lupine) were the least susceptible. On variety Karo, aphids did not show phloem phase. On variety Taper, aphids showed phloem phase, but the the phloem sap ingestion phase (E2) did not occur.
Feeding site selection by the pea aphid Acyrthosiphon pisum Harris was studied using the technique of electronic registration of stylet penetration in plant tissues (EPG) on leaves and stems of white lupin (Lupinus albus L.), yellow lupin (L. luteus L.), and narrow-leaved lupin (L. angustifolius L.). The EPG revealed waveform C (probing in parenchyma) and waveforms E1 and E2 (salivation in phloem vessels and ingestion of sap, respectively). The differences in the duration, frequency, and proportion of various behavioural activities between aphids on stems and on leaves depended on the lupin variety. A. pisum was the most feeding site-sensitive on white lupin, var. Butan and the leaves were the preferred site. The preference was manifested mainly in the longer duration of probing and phloem sap ingestion, and shorter time to reach phloem vessels.
Nootkatone is a natural sesquiterpene ketone that shows insecticidal activity against insects and ticks. The deterrent activity of (+)- nootkatone (1) and six products of its biotransformation: (+)-9α-hydroxynootkatone (2), (+)-13-hydroxynootkatone (3), (+)-11,12- epoxy-9α-hydroxynootkatone (4), (+)-11,12-epoxynootkatone (5), (+) 11,12-dihydroxynootkatone (6), (+)-7,11,12-trihydroxynootkatone (7) to the peach-potato aphid (Myzus persicae Sulzer) was investigated in the current study. The deterrent activity of compounds studied (1−7) was evaluated using an infesting bioassay, in which the aphids were offered a choice between treated (with tested compound) and control leaves. If aphids settled mainly on the control leaves (p < 0.05; Student’s t-test), the tested compound in the respective choice test was stated as a deterrent. The most active compounds are (+)-nootkatone (1) and three products its biotransformation: 11,12-dihydroxynootkatone (6), (+)-7,11,12-trihydroxynootkatone (7), (+)-9α-hydroxynootkatone (2). The deterrent effect of these compounds was relatively strong and stable. It was observed for at least 24 hours after treatment, i.e., until the end of experiment.
The cyclitols: D-pinitol, D-chiro-inositol are naturally present in the tissues of Lupinus angustifolius. The effect of these cyclitols on the behaviour of the pea associated clone of Acyrthosiphon pisum during various stages of probing was studied. The main stage of probing studied was the stylet penetration in mesphyll and vascular bundle. D-pinitol, D-chiro-inositol and their mixture were exogenously applied to pea Pisum sativum explants and the aphid probing behaviour was evaluated using the Electrical Penetration Graph technique (EPG). Feeding of peas with cyclitols at a concentration of 10 mM, caused a selective accumulation of D-pinitol and D-chiro-inositol in stems, leaf petioles, and leaf blades. In aphid bodies, both cyclitols were traced, respectively, to the host plant treatment. The new cyclitols in pea tissues did not significantly affect the total duration and frequency of aphid activities during probing in peripheral as well as vascular tissues. However, the aphid behaviour on cyclitol-treated plants as compared to their behaviour on the control was slightly altered. Non-probing and probing in mesophyl prevailed among aphid activities during the initial period of stylet penetration. Aphids on D-pinitol+D-chiro-inositol-treated plants reached phloem vessels relatively later than aphids on the control and D-chiro-inositol plants. There were recurrent switches between E1 (salivation) and E2 (sap ingestion) patterns in some aphids during the phloem phase on D-pinitol and D-pinitol+D-chiro-inositol - treated plants. This may reflect difficulties in the uptake of the phloem sap, and point to lupin cyclitols as being responsible, at least in part, for the rejection of L. angustifolius as a host plant by the pea clone of A. pisum.
The behavioural effect of trans,trans-farnesol and its structural derivatives on M. persicae was evaluated. The incorporation of carboxy group into the molecule did not alter the strong deterrent activity of farnesol. The lactonization and the epoxidation of farnesol caused the delay in expression and the loss of deterrent activity, respectively. The ester, product of Claissen rearrangement of farnesol and iodolactone did not exhibit significant biological effect.
The feeding deterrent activity of alkyl-substituted y- and S-lactones, including a group of lactones obtained from linalool against peach potato aphid (Myzus persicae [Sulz.]) and Colorado potato beetle (CPB) (Leptinotarsa decemlineata Say), was investigated. The deterrent activity was species-specific and developmental-stage-specific (CPB). The strongest antifeedants for L. decemlineata larvae and adults were linalool-derived unsaturated lactones (Z) 5-(1.5-Dimethyl-hex-4-enyldiene)-dihydro-furan-2-one and (E) 5-(1.5-Dimethyl-hex-4-enyldiene)-dihydro-furan-2-one, and for CPB larvae - saturated lactone with three alkyl substituents, the 4-Isobutyl-5-isopropyl-5-methyl-dihydro-furan-2-one. The settling of M. persicae on plants was strongly deterred by iodolactones: 5-(1-Iodo-ethyl)-4.4-dimethyl-dihydro-furan-2-one, 5- Iodo-4A6-trimethyl-tetrahydro-pyran-2-one, 5-Iodomethyl-4-isobutyl-5-isopropyl-dihydro-furan-2-one, and the saturated lactones: 4.4.6-Trimethyl-tetrahydro-pyran-2-one and 4-Isobutyl-5-isopropyl-5-methyl- dihydro-furan-2-one. None of the tested lactones deterred aphid probing, but the probes were significantly shorter as compared to the control. The reduction in probing time may decrease the ability to transmit virus diseases by aphids.
The behaviour of the peach potato aphid Myzus persicae (Sulz.) was studied during settling on plants. The experiment involved observing peach potato aphid activity after the application of some natural and synthetic cyclohexanones and the, respective ε-lactones and epoxy-ε-lactones which were obtained from the cyclohexanones. Stereochemistry, and the number and position of methyl substituents were important for the biological activity of the starting compounds: only trimethyl-substituted cyclohexanones were active, i.e. 3.3.5-trimethylcyclohexanone (deterrent) and 2.2.6-trimethylcyclohexanone (attractant). The effect of oxygen incorporation into the cyclohexanone ring on deterrent activity varied depending on the starting compound. The ε-lactones that derived from saturated cyclohexanones were either weak attractants or were inactive, except the deterrent ε-lactone with three methyl groups at positions 3.7.7. None of the products of unsaturated ketone isophorone (weak deterrent) oxidation, i.e. epoxy isophorone, epoxy lactone, or unsaturated lactone, affected aphid settling. Of the two epoxy ketones obtained from (+)-dihydrocarvone that was inactive, only (2S, 5S)-2-methyl-5-((S)-1-methyloxiranyl)-cyclohexanone was a strong deterrent. Both epoxy-ε-lactones that derived from (+)-dihydrocarvone were strong deterrents.
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