Comunicación corta. Actividad antialimentaria de fitoquímicos naturales en larvas de Spodoptera littoralis

Worms are becoming difficult pests to control since many insecticides are now forbidden and the present alternatives are insufficiently effective. Antifeedants of plant origin may have potential against such pests. In this work, several diterpenoids, flavones and coumarins extracted from plants were assayed as antifeedant agents against Spodoptera littoralis larvae. Among these compounds, four diterpenes (eriocephalin, salviacoccin, aethiopinone and oxocandesalvone) and four coumarins (oxypeucedanin, xanthotoxin, isoimperatorin and prangol) showed significant activity, whereas all the flavones tested were inactive. Some aspects of the structure-activity relationships of these compounds are briefly discussed.En la actualidad, debido a que se están prohibiendo muchos insecticidas y a que las alternativas disponibles no son completamente eficaces, las orugas están resurgiendo como plagas difíciles de controlar. Los compuestos antialimentarios de origen vegetal se consideran con posibilidades para desarrollar nuevos agroquímicos. En este trabajo, diversos diterpenoides, flavonas y cumarinas procedentes de plantas han sido ensayados como antialimentarios frente a larvas de Spodoptera littoralis. Cuatro diterpenos (eriocefalina, salviacoccina, aetiopinona y oxocandesalvona) y cuatro cumarinas (oxipeucedanina, xantotoxina, isoimperatorina y prangol) presentaron una actividad significativa, mientras que las flavonas fueron inactivas. Se discuten brevemente algunos aspectos de la relación estructura-actividad

Effects of material and extracts of Trigonella foenum-graecum L. against the stored product pests Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) and Acanthoscelides obtectus (say) (Coleoptera: Bruchidae)

cited By 20International audienceInsecticidal activity of plant material (seeds and leaves) and extracts of Trigonella foenum-graecum from two sources against the stored product pests Tribolium castaneum and Acanthoscelides obtectus was investigated. Topical applications of extracts produced a high degree of mortality in both insects (at 6 and 30 μg/insect). Powdered fenugreek seeds or extracts applied to Phaseolus vulgaris beans produced mortality and inhibited oviposition and larval penetration by A. obtectus. The presence of the plant material decreased A. obtectus fecundity and reduced its longevity. Fenugreek seed appeared moderately toxic to young larvae of T. castaneum (LD25 = 18% in diet), and surviving adults showed progressively decreased fecundity as the dose of seeds, especially ripe seed, was increased. Significant effects of dose, seed ripeness and their interaction were produced. The seed affected the fertility of both sexes. Some fertility was recovered on reversion to the standard diet. Possible active compounds and the implications of the results for pest control are discussed

(E)-Anethole microspheres as an alternative insecticide in funnel traps

Pyrethroids are the insecticides most commonly used inside traps, and the lack of alternatives poses the risk of pests developing resistance. In this paper we present two (E)-anethole formulations (spray drying (SD) and oil emulsion entrapment (OEE) processes) that provide a controlled release of their bioactive ingredient in the vapour phase with insecticidal potential in funnel traps. An experiment with the two pyralid moths Ephestia kuehniella Zeller and Plodia interpunctella Hübner was set up at two pilot stores in Spain for a four-month period. The microspheres (4 g of SD powder/trap or 6 g of OEE beads/trap) remained effective for 100 days, killing the moths by volatile activity. The efficacy values were within the interval of 70–100% for the first half of the experiment, with a decrease afterwards. The OEE beads performed better than did SD powder in the long run: over 80% efficacy for the whole experiment. The OEE process gives more loading capacity (19.7 g of (E)-anethole per 100 g of beads) and entrapment efficiency (28.6 g of (E)-anethole encapsulated per 100 g of (E)-anethole added) and is slower in releasing the product. In a laboratory study for E. kuehniella, the LC50 was 58.2 mg/L for SD after 24 h exposure to vapours and 111.6 mg/L for OEE after 48 h exposure to vapours. Therefore, the SD powder provides a quicker release of the bioactive ingredient. The results indicate that encapsulated (E)-anethole could be a promising insecticide for mass trapping, mating disruption and attract and kill strategies.info:eu-repo/semantics/acceptedVersio