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An improved technique was developed to assay the toxicity of insecticides against aphids using an artificial diet. The susceptibility of the pea aphid Acyrthosiphon pisum (Harris) (Hemiptera: Aphidoidea) was determined for a selection of novel biorational insecticides, each representing a novel mode of action. Flonicamid, a novel systemic insecticide with selective activity as feeding blocker against sucking insects, showed high toxicity against first-instar A. pisum nymphs with an LC(50) of 20.4 microg/ml after 24 h, and of 0.24 microg/ml after 72 h. The toxicity was compared with another feeding blocker, pymetrozine, and the neonicotinoid, imidacloprid. In addition, four insect growth regulators were tested. The chitin synthesis inhibitor flufenoxuron, the juvenile hormone analogue pyriproxyfen, and the azadirachtin compound Neem Azal-T/S showed strong effects and reduced the aphid population by 50% after 3 days of treatment at a concentration of 7-9 microg/ml. The ecdysone agonist tested, halofenozide, was less potent. In conclusion, the improved aphid feeding apparatus can be useful as a miniature screening device for insecticides against different aphid pests. The present study demonstrated rapid and strong toxicity of flonicamid, and other biorational insecticides towards A. pisum.

International audience; Seasonal population dynamics of Brevicoryne brassicae (L.) and Diaeretiella rapae (McIntosh) were studied in two canola (Brassica napus) fields with two different irrigation methods (flooding and sprinkler irrigations) from April to June 2010. Aphid and parasitoid (mummies) populations were sampled once a week. The highest aphid density was recorded on May 12th (792.5 +/- 55.5) and on May 18th (1701.1 +/- 195) in the sprinkler and flood irrigated fields, respectively. Parasitism rate recorded ranged from 0.4 to 19.5% and from 1.0 to 11.9% in sprinkler and flood irrigated fields, respectively. During the course of the study, there was no significant relationship between the weather values recorded and aphid populations observed in the field. However relationship with weather values was found in the case of D. rapae populations. Secondary parasitism was higher at the end of growing season and two hyperparasitoid species were dominant: Pachyneuron aphidis (Bouche) and Alloxysta fuscicomis (Ashmead). We discuss role of seasonal parasitism and irrigation systems for management of B. brassicae.