Climate change is reshaping agriculture and insect biodiversity worldwide. With rising temperatures, insect species with narrow thermal margins are expected to be pushed beyond their thermal limits, and losses related to herbivory and diseases transmitted by them will be experienced in new regions. Several previous studies have investigated this phenomenon in tropical and temperate regions, locally and globally; however, here, it is proposed that climate change impact on agriculture can be traced through the study of Nearctic migratory insects, specifically leafhoppers. To test this hypothesis, leafhoppers in strawberry fields located in the province of Québec, eastern Canada, were evaluated. The strawberry-leafhopper pathosystem offers a unique opportunity because leafhoppers can transmit, among other diseases, strawberry green petal disease (SbGP), which is associated with pathogenic phytoplasmas. Here, we found that in the last ten years, the number of leafhoppers has been increasing in correspondence with the number of SbGP cases detected in eastern Canada, reporting for the first time ten species new to eastern Canada and two to the country, although the leafhopper diversity has been seriously affected. Our model using more than 34 000 leafhoppers showed that their abundance is influenced by temperature, a factor that we found also influences the microbiome associated withMacrosteles quadrilineatus, which was one of the most abundant leafhoppers we observed. One of our most striking findings is that none of the insecticides used by strawberry growers can control leafhopper incidence, which could be linked to microbiome changes induced by changing temperatures. We suggest that Nearctic leafhoppers can be used as sentinels to trace the multilayered effects of climate change in agriculture.

Tomato (Solanum lycopersicum L.) is one of the most important vegetables in the world. Its extensive cultivation has made this plant the target of many viral, fungal, and bacterial diseases. Among them, the bacterial canker of tomato caused by Clavibacter michiganensis (Cm) has been named one of the most devastating diseases affecting the tomato industry worldwide. It can significantly reduce the yields and profitability of this crop. One of the big challenges we found when working with Cm and trying to characterize the virulence of different isolates was the lack of a consensus methodology to inoculate tomato plants, how to fertilize them and characterize Cm virulence. This research aimed to identify an artificial inoculation method to induce bacterial canker on tomato plants in greenhouse conditions to homogenize the results of different studies with Cm. We compared two inoculation methods, including the scalpel and syringe method with two levels of fertilization, low and high fertilization. After evaluating several variables like the percentage of necrotic leaves and the height of the plants, the results showed that the syringe inoculation with low fertilization was the most effective inoculation method allowing the development of a multilevel scale that can be used to study the interaction between tomato plants and Cm isolates.

Tomato (Solanum lycopersicum L.) is one of the most important vegetables in the world. Its extensive cultivation has made this plant the target of many viral, fungal, and bacterial diseases. Among them, the bacterial canker of tomato caused by Clavibacter michiganensis (Cm) has been named one of the most devastating diseases affecting the tomato industry worldwide. It can significantly reduce the yields and profitability of this crop. One of the big challenges we found when working with Cm and trying to characterize the virulence of different isolates was the lack of a consensus methodology to inoculate tomato plants, how to fertilize them and characterize Cm virulence. This research aimed to identify an artificial inoculation method to induce bacterial canker on tomato plants in greenhouse conditions to homogenize the results of different studies with Cm. We compared two inoculation methods, including the scalpel and syringe method with two levels of fertilization, low and high fertilization. After evaluating several variables like the percentage of necrotic leaves and the height of the plants, the results showed that the syringe inoculation with low fertilization was the most effective inoculation method allowing the development of a multilevel scale that can be used to study the interaction between tomato plants and Cm isolates.