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The aim of the study was to determine whether extracts of tobacco leaves may reduce feeding of the large pine weevils on twigs of pine – Pinus sylvestris. The research was conducted in laboratory conditions. The research proved statistically significant decrease in damage size on the pine twigs as a result of application of each tested extract.
The aim of the study was to verify whether methanolic extracts prepared from plants of 26 selected species contained substances reducing feeding of Hylobius abietis beetles on shoots of Pinus sylvestris. Experiments were conduced under laboratory conditions. A statistically significant reduction in the size of damage was recorded on pine twigs treated with methanol extracts of leaves of Trifolium repens, Lupinus polyphyllus, Robinia pseudoacacia, Tanacetum vulgare, Nicotiana tabacum, Sambucus nigra, Convallaria majalis and Lycopersicon esculentum. Probably the strongest antifeedants were methanolic extracts of leaves of Lupinus polyphyllus, Robinia pseudoacacia and Convallaria majalis.
The insecticidal and antifeedant activity of extracts derived from different plants of the Liguidamber orientalis Mill. (Hamamelidaceae), Tanacetum vulgare L. (Compositae), Achillea coarctata Willd. (Compositae), Buxus sempervirens L. (Buxaceae), Diospyros kaki L. (Ebenaceae), Arum italicum Mill. (Araceae), Achilea biebersteinii Willd. (Compositae), Origanum vulgare L. (Labiatae), Hypericum androsaemum L. (Hypericaceae) and Ocimum basilicum L. (Labiatae). are reported. The 70% alcohol extracts of plants were tested for toxicity against the 3–4th instar larvae of the Yponomeuta malinellus Zell. (Lepidoptera.: Yponomeutidae). Antifeedant activity of the extracts was assessed through tests conducted on the larvae of Y. malinellus by the feeding protection bioassay. In tests carried out on the larvae of Y. malinellus, L. orientalis, O. basilicum and A. coarctata extracts showed high toxicity within 48 hour LC50’s of 75, 75 and 65% respectively. The toxicity effects of the other extracts were determined as 60, 50, 50, 50, 45, 45 and 40% within the same period, respectively. No mortality was noticed in control groups. Alcohol extract from L. orientalis, T. vulgare and B. sempervirens showed high antifeedant activity (80.90, 46.12) on the larvae of Y. malinellus. In addition to both T. vulgare and L. orientalis extracts caused decrease consumption of food per 1 mg of larvae body weight decrease showed high –8.465, –0.845, mg respectively. The highest consumption (557.6 mg) was observed with alcohol extract from, D. kaki whereas the minimum one was using alcohol extract from L. orientali. The other tested extracts showed similar activity.
The effect of some terpenoid lactones (monocyclic δ-hydroxy-γ-lactone; bicyclic δ-hydroxy-γ-spirolactone and bicyclic δ-hydroxy-γ-lactone) and azadirachtin on feeding and growth of Leptinotarsa decemlineata Say larvae was studied. Among lactones bicyclic δ-hydroxy-γ-spirolactone showed a strong feeding deterrency. Larvae treated with this compound consumed 0.163 cm² (per larva) of potato leaves during 6 days, whereas control larvae ate 0.892 cm². When lactones were used, a slight increase in body weight was observed. Azadirachtin, in comparison with lactones, much stronger reduced food consumption and growth rate of insects.
Neuropeptides are regulators of critical life processes in insects, but are subject to rapid degradation by peptidases in the hemolymph (blood), tissues and gut. This limitation can be overcome via replacement of peptidase susceptible portions of the insect neuropeptides with non-natural residues or moieties to create analogs with enhanced biostability. Two neuropeptide families, the insect kinins and insectatachykinins, stimulate gut motility and Malpighian tubule fluid secretion in certain insects but unmodified members demonstrate little or no effect when fed to pea aphids (Acyrthosiphon pisum) in an artificial diet. Nonetheless, biostable analogs developed via the strategic introduction of either bulky Aib residues and/or β-amino acids demonstrate potent antifeedant and aphicidal effects when administered orally; whereas other biostable analogs are inactive. Although the precise mechanism of action has not been delineated, the activity may be associated with disruption of the physiological processes that these neuropeptides regulate in insects. The most active of the biostable insect kinin and insectatachykinin analogs show LC50 values of 0.063 nmole/μl (LT50 = 1.68 days) and 0.0085 nmole/μl (LT50 = 1.1 days), respectively; matching or exceeding the potency of some commercially available aphicides. The biostable analogs represent important leads in the development of alternative, environmentally sound aphid control agents.
Characterisation of two-spotted spider mite (Tetranychus urticae Koch, Acari: Tetranychidae) response to aqueous extracts from selected plant species. Aqueous extracts from four plant species of known insecticidal activity on arthropods were tested against two-spotted spider mite females to describe their mode of action on the spider mite. The extracts effects on: (a) the mite establishment on host plant; (b) initiation of feeding (probing behaviour); (c) initiation of permanent feeding and (d) the mite mortality (a toxic effect) was measured using various experimental techniques. The highest toxic action was shown by NeemAzal-T/S (an extract from Azadirachta indica; production of Trifolio-M GmbH company) and repellent by water extract from Allium sativum and Urtica dioica. NeemAzal T/S also shown a strong activity as a feeding suppresant for T. urticae.
The aim of the work was to study the feeding deterrent activity of precocenes, their synthetic analogues, and some related compunds to storage pests: Sitophilus granarius L., Tribolium confusum Duv., Trogoderma granarium Ev., and aphids: Myzus persicae (Sulz.). Among all tested compounds precocenes I and II exhibited the best feeding deterrent activity against all tested insects. 4-Chromanols (16, 17 and 18), alcohols 19, 20 and 3-chromanone ( 15) showed high deterrence towards the larvae of T. confusum. The best antifeedant activity towards the adults of both T. confusum and S. granarius was observed for substituted phenols with methoxy group at benzene ring. The biological tests carried out on aphids showed that the presence of methoxy group in the molecule was a crucial structural factor for the appearance of antifeedant activity against these insects.
Najczęstszym źródłem mechanicznych uszkodzeń roślin jest żerowanie owadów - agrofagów, których liczebność musi być kontrolowana. Przez ponad 50 lat dominującą strategią zwalczania szkodników było stosowanie pestycydów, które jednak w wyniku długotrwałego stosowania indukują odporność agrofagów na te chemikalia. Skuteczność zintegrowanych metod zwalczania szkodnika wymaga, aby insektycydy były używane z minimalnym wpływem na środowisko i naturalnych wrogów agrofagów (ich pasożytów lub drapieżców). Podejmowane są badania nad zastąpieniem pestycydów nietoksycznymi produktami pochodzenia biologicznego, wprowadza się także zmodyfikowane genetycznie rośliny (GMO), posiadające geny odporności na szkodniki i choroby. Rośliny dysponują szeregiem mechanizmów odporności, jak lignifikacja ściany komórkowej, synteza wosków pokrywających powierzchnię liści, wytwarzanie toksyn i metabolitów wtórnych oraz uruchamianie sygnałów chemicznych emitowanych w celu wabienia naturalnych wrogów agrofagów. Manipulowanie zależnościami w układzie roślina-agrofag-drapieżca/pasożyt agrofaga może usprawnić kontrolę szkodników i zredukować ilość zużywanych pestycydów. Praca zawiera przegląd różnych biologicznych metod zwalczania szkodników.
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