| Winter wheat Triticum aestivum Linn.(Poales: Poaceae) is one of the most important crops in the world. Wheat aphid is the important pests on wheat plants in China and many other countries, especially the Macrosiphum avenae(Fabricius). Aphids can not only induce direct damages by feeding on phloem but also transmit virus of plant diseases as efficient vectors. The traditional method of prevention is given priority to with chemical control, but it has more and more negative effects on environment, ecological balance and lives, so biological control became more and more popular, and the insect semiochemicals has been recognized as the safe, effective and sustainable new tools for the control of pests. Wheat plants defend the feeding behavior of pests like aphid who has the piercing-sucking mouthparts via salicylate pathway, and methyl salicylate(MeSA) is one of the most important volatile semiochemicals induced by wheat aphid that has great potentiality for control of wheat aphids. MeSA can be employed on plants to enhance the resistance of plants, it can also be used at repelling pests like aphids and thrips, besides, MeSA can induce the natural enemies like lady beetle and lacewing. To make the insect semiochemicals be used more adequately and effectively, we excogitated a slow-release formulation of MeSA by combined MeSA with sodium alginate, and detected the slow rates in laboratory as well as the effect on aphids and the natural enemies in the field.The research in the field was established by three treatment field plots: MeSA10, MeSA2.5 and Control(CK). We selected 1 m, 5 m and 10 m away from the releaser to investigate the related data of aphid and natural enemies. For the investigation of natural enemies and the alatae, we took a random sample survey around the yellow traps. The investigation conducted every week. The main results as following:1 Slow release rates of the MeSA sodium alginate beads in laboratoryThe slow release rate of the MeSA slow-release beads was significantly extended from 4 to more than 10 days demonstrated by our study in laboratory. The slow release rate decreased when the relative humidity increase from 60% to 75%. So the release rate of MeSA slowrelease beads effect by the environment, just like relative humidity and tempreture.2 Effect of MeSA sodium alginate beads on aphidsDuring this study, the treatment of different MeSA slow-release beads effect on alatae and apterae(Palatae < 0.01, Papterae < 0.01), and reduced the population of alatae and apterae significantly. The distance had no significant effect on alatae and apterae(P alatae = 0.628, Papterae = 0.137). The interaction of treatment and distance did not have significant effect on the population of aphids.3 Effect of MeSA sodium alginate beads on natural enemiesTreatment of different MeSA slow-release beads improved the population of mummified aphids(F = 5.442,P = 0.045)and ladybeetles(F = 31.857,P = 0.01)on the plants. The population of ladybeetles(F = 33.379,P = 0.00) and Syrphidae(F = 13.544,P = 0.00)in the yellow traps was significantly higher.The experiment of slow-release rates in laboratory showed that our formulation can be regard as slow-release formulation in biological control of pests because the exactly efficiency of slow release.The behavioral experiment of aphids and natural enemies in the field showed that the slowrelease formulation can do some effects on the behavior of aphids and natural enemies. The formulation can reduce the number of aphids and do some effects on aphid control and enhance the population of natural like lacewing, lady bird and aphidiidae, as well as the mummified aphid. |
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