Semiochemicals for the control of cereal pests

Abstract

The potential of three semiochemical treatments, each having a different mode of action, in controlling pests of cereals was evaluated under laboratory, semi-field and small plot field conditions in the UK. The treatments were (a) Tasmannia stipitata plant extract containing the antifeedant polygodial, (b) cis-jasmone, a stress related volatile plant activator inducing defence mechanisms within the wheat plant, and (c) nepetalactone, an aphid sex pheromone component attractive to aphid parasitoids. Oat cv. Revisor and wheat cultivars Axona, GS 11-12 and Riband were used in the experiment. Settlement of the grain aphid, Sitobion avenae, was significantly reduced on wheat seedlings treated with either T. stipitata extract or cis-jasmone in laboratory and field simulation experiments. Aphid numbers in field plots were reduced by both cis-jasmone and T. stipitata treatments, although not significantly. T. stipitata was more effective against autumn than spring aphid populations. T stipitata also reduced the number of larvae of orange wheat blossom midge, Sitodiplosis mosellana, and gout fly, Chlorops pumilionis. Although in semi-field trials, parasitism of S. avenae by the parasitoid Aphidius ervi increased significantly on nepetalactone baited plants compared to untreated controls, field populations of parasitoids and predators were too low for statistical analyses. However, the numbers of aphids were lower in the nepetalactone plots compared to the controls..