Control of the grapevine moth lobesia botrana through genetic modification of kairomones biosynthesis in the host plant
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The European grapevine moth Lobesia botrana (Denis & Schiffermu¨ller) (Lepidoptera: Tortricidae) is one of the key pests of grape: current control systems are based either on the use of insecticides or on mating disruption, but while the first is not environmentally friendly, the second is not particularly suitable for small and isolated areas, or regions where pest population is high. Here we explore the possibility to develop a new control strategy of L. botrana by interfering with the female host-finding and egg-laying behaviors, which are mostly mediated by the volatile organic compounds (VOCs) emitted by the host plant (kairomones). Wind-tunnel studies have shown that a blend of 3 specific grapevine plant terpenoids, namely E-(ß)-caryophyllene, E-(ß)- farnesene and E-(4,8)-dimethyl-(1,3,7)-nonatriene (DMNT) elicited attraction comparable to that of the complete plant odor profile. After characterizing E-(ß)-caryophyllene synthase, the enzyme that produces the most abundant grapevine sesquiterpene, we chose a genetic engineering approach and produced grapevine and Arabidopsis plants with altered headspace profile. Arabidopsis was used to study the role of E-(ß)- caryophyllene and E-(ß)-farnesene in oviposition, and to try to create a model for the emission of DMNT. Grapevine was used to study how a change in kairomones ratio can impact on plant attractiveness from the distance, using the wind tunnel. Overall, the role of these kairomones in oviposition remains unclear, but we could prove that a modification of the E-(ß)-caryophyllene / E-(ß)-farnesene ratio leads to a decreased attraction, creating the rationale for a new pest control method.