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Promoting adaptability of Amblyseius swirskii predatory mites to tomato crop
ESR Update - Amblyseius swirskii is a predatory mite very effective for controlling whiteflies and thrips in protected crops. However, on tomato (Solanum lycopersicum) its survival and efficacy as biological control agent is hindered, most probably due to lack of adaptation to plant defenses, such as the tomato trichomes and their exudates. Tomato trichomes are physical and chemical barriers limiting the performance of A. swirskii on this crop. Our aim is to select a strain adapted to tomato.
Angeliki Paspati MSc.
Currently we are running selection experiments using the whole tomato plant or detached tomato leaves to rear A. swirskii. However, the adaptability of the commercially available strain of A. swirskii seems rather low, most likely due to the low genetic variation in this strain. For this reason we packed our bags and we are ready to go to find A. swirskii in Israel, where it was first identified. In collaboration with Israeli colleagues, we will be collecting native populations from various citrus orchards and horticultural crops along the coastal line of Israel. Our plan is to capture as much genetic variation as possible.
Next step: isofemale lines, established from wild samples, and properly identify as A. swirskii will be artificially selected. Different concentrations of tomato trichome extracts will be used as selection agent. Also, in order to understand the effect of the most abundant secondary metabolites of tomato trichomes on the performance of the predatory mite, we will test synthetic analogues from three main groups, terpenoids, acyl-sugars and methyl-ketones.
Another goal of my project is to characterize the molecular mechanisms of the negative effect of the trichomes and identify genetic markers that are in and/or linked to genes underpinning the adaptation of A. swirskii to tomato plants. In order to achieve this goal, mites were exposed to pepper, a common host plant of A. swirskii, and tomato plants, and then the whole RNA was extracted and sent for next generation sequencing. We will receive these sequencing data soon and after the sampling trip we plan to analyze the transcriptomic response of the mite on pepper and tomato and to identify key metabolic pathways involved in the differential response to the different host plants.