A genetic engineering approach to study the adaptation of the grapevine moth Lobesia botrana from its wild hosts to Vitis

The grapevine moth Lobesia botrana is an extremely polyphagous insects, endemic of the Palearctic Region and known across all the Mediterranean area as an economically important pest in the vineyards. Since the chemical ecology of the moth has been a major topic of research for decades, much is known about its behavior. Larvae of the moth can feed up to 40 plant species belonging to 27 different families and the major targets of feeding, if available, are always the reproductive tissues (flowers, fruits). A crucial role in host finding and egg-laying behaviors is played by specific volatile compounds, released by the plant and perceived by the insect olfactory system. Since the adaptation to Vitis is recent (the first intense damages were recorded only from the early 20th century), experiments were carried out in the last years comparing the emission of volatiles between grapevine and Daphne gnidium, considered the first host of L. botrana in the wild: as expected, the volatiles profile partially overlapped. Recent wind-tunnel studies have also shown that a blend of the 3 specific terpenoids (E)-β-caryophyllene, (E)-β-farnesene and (E)-4,8-dimethyl-1,3,7-nonatriene (DMNT) elicits in laboratory assays the same L. botrana attraction than the complete grapevine headspace collection. Of these terpenoids, only one (β-caryophyllene) is common between the two plants, while the others are present only in Vitis and were thus the target of the recent adaptation. To better understand the evolution of the plant-insect interaction, we decided to take a non host plant - the model Arabidopsis thaliana - and by means of genetic engineering to insert the genes responsible for the production of the three terpenoids, in order to mimic the volatile profile of the known hosts. Recently we also undertook experiments aimed at the genetic engineering manipulation of the pathway of the three terpenoids in Vitis: the alteration of the volatile profile will be studied as a possible starting point for the creation of a new pest control strategy.