The biocontrol agent Amblyseius swirskii cannot disperse on tomato plants, because of the presence of dense, hair-like protuberances called trichomes. Trichomes are found on the surface of leaves, stems and petioles and confer resistance against arthropods, some types functioning as physical barriers and others producing defensive phytochemicals. To know which type(s) of trichomes affect mostly the survival of A. swirskii, I planted three tomato mutants with different compositions of trichomes that will be tested once they are grown enough. For the moment I give them all my care and love!
Also, I observed under the microscope that when the mite walked on the tomato, plant exudates were accumulated on its body. So, then the most abundant tomato exudate called acyl sugars was stained and the mites were released on the stained surfaces. These mites were used to observe under fluorescent microscopy and as you can see on the photo, the result was illuminating;) The acyl sugars were accumulated on the main body openings such as the mouth parts and the joints between leg segments, but also in lower concentration they were detected all over the mite cuticle. Hence, it is likely that two mechanisms contribute in the acaricidal activity of the acyl sugars: (1) they mechanically block the body openings and respiration pores leading to mite suffocation; and (2) they are either consumed by the mite, or absorbed by the cuticle and disrupt the cellular membranes causing desiccation. Finally, acyl sugars from the plants surface have been extracted and now I want to develop a protocol that can permit the fast estimation of their concentration, in order to test their effect at different doses on the predators.