Abstract :
[en] Abstract: The concept of pest control has been changed from traditional “kill” to scientific “regulation”. Ecological regulation has become one of the hotspots in the field of sustainable agriculture. Intercropping (i.e., the simultaneous growing of two or more species in the same field for a significant period but without necessarily being sown and harvested at the same time), is one way to increase the plant diversity. In addition to intercropping, semiochemicals (i.e., informative molecules used in insect-insect or plant-insect interactions) have been widely considered within various Integrated Pest Management (IPM) strategies. Laboratory and field studies have demonstrated that releasing semiochemicals has the potential to simultaneously repel pests and attract natural enemies. For instance, methyl salicylate (MeSA) is a herbivore-induced plant volatile that is repellent to Rhopalosiphum padi (L.) and other cereal aphids, while being attractive to aphid predators such as ladybeetles, lacewings and hoverflies, and increasing parasitism rate. Moreover, the aphid alarm pheromone, which major component is E-β-farnesene (EBF), acts as a repellent for plant herbivores, and attracts predatory beetles, hoverflies and increase parasitism rate. Combining both strategies could be an interesting way to maximize pest control.
In a 2 year set-up (March-August 2015, 2016), a wheat-pea strip intercropping combined with the release of EBF or MeSA was tested in Gembloux to improve push-pull strategy by repelling aphids and by attracting beneficials simultaneously. The results showed that the abundance of aphids, lacewings and mummified aphids on both pea plants and wheat tillers were all affected by the release of oil formulated EBF and MeSA. Parasitism rate was also affected by the treatments on both crops in both years. The occurrence of wheat aphids and pea aphids were reduced by 35% and 30%.
In the case of wheat and pea, pea aphids peak earlier than wheat ones (in the present study on plants, pea aphids: 17 June 2015 and 3 June 2016, while wheat aphids: 25 June 2015 and 10 June 2016), hence associating these two crops allows natural enemies to quickly move from pea to wheat and controlling pests in the course of their occurrence, in fine protecting both crops. Wheat–pea intercropping combined with EBF oil and MeSA release, enhanced the abundance of predators and parasitoids on the pea, our results strongly support the efficacy of combining intercropping and semiochemical release to attain improved pest control.
Key words: Ecological regulation; Methyl salicylate; Aphid alarm pheromone; Push-pull; Green control
