Impact of some insecticide applications on wheat insect pests and their associated natural enemies in winter wheat

• Published in: Gesunde Pflanzen 2014-09, Vol.66 (3), p.121-128
• Main Authors: Gaafar, Nawal, El-Wakeil, Nabil, Abdel-Moniem, Abdellah SH, Volkmar, Christa
• Format: Article
• Language: ger
• Subjects: Araneae; Arthropoda; Hymenoptera; Rhopalosiphum padi; Triticum aestivum
• ISSN: 0367-4223; 1439-0345
• DOI: 10.1007/s10343-014-0325-x

Wheat insect pests and the beneficial arthropod populations were assessed using sweep net across a large scale winter wheat field in Bad Lausick (Free State of Saxony, Germany) before and after insecticide applications. The insecticides used were Karate (pyrethroid), Biscaya (neonicotinoid) and NeemAzal T/S (botanical insecticide). The tested compounds were sprayed twice during the early season growth stage (Elongation- GS 32) and at the heading stage (GS 55), and their effects were evaluated on wheat insect pests. The side effects of these insecticides on associated natural enemies were also studied. Monitoring was conducted for 4 weeks after each treatment. Cereal aphids, thrips, leafhoppers, cereal leaf beetles, cereal bugs and also many natural enemies such as predators (lady beetles, lacewings, syrphids, dance flies and spiders) and parasitoids (parasitic wasps) were surveyed. The dose of these insecticides resulted in reductions of wheat insect and natural enemy populations and this reduction was corrected based on Abbott equation. The results showed that Karate is correlated with the highest percentage reduction (79.5 %) to wheat insect pests. Karate use also resulted in a percentage reduction to natural enemies (30-60 %). Biscaya and NeemAzal T/S is correlated with an equivalent mortality percents (50-65 %) to wheat insect pests and resulted in a smaller percentage reduction of natural enemies (10-40 %) compared to Karate. Thrips and cereal bugs were more affected than leafhoppers. Lacewings and dance flies were more susceptible; while spider, syrphids and parasitoid wasps were more tolerant. Compatibility between natural insecticides and natural enemies is highly required to keep the environment clean.Original Abstract: Im Sommer 2012 wurde das Auftreten von Weizenschaedlingen und ihrer natuerlichen Gegenspielern mit der Methode des Kescherfangs auf einem Winterweizenfeld in der Feldflur Bad Lausick im Freistaat Sachen untersucht. Das Auftreten wurde durch den Einsatz der Insektizide Karate (Pyrethroid), Biscaya (Neonicotinoid) und NeemAzal T/S reguliert. Die Insektizide kamen zum Schossen (BBCH 32) und zum Aehrenschieben (BBCH 55) zum Einsatz. Die Wirkungsgrade der Praeparate (Abbott %) auf Schaedlinge und Nichtzielorganismen wurden ueber einen Zeitraum von vier und acht Wochen erfasst. Aussagen zu den direkten Wirkungen auf Blattlaeuse, Zikaden, Thripse und Getreidehaehnchen wurden getroffen. Fuer die Gruppe der Nichtzielorganismen konnen Aussag