Screening of some cucumber accessions to two-spotted spider mite (Tetranychus urticae)

Abstract:The two-spotted spider mite, Tetranychus urticae (Koch) is one of the most important pests of cucurbits, that can infests more than 200 species. In order to finding resistance sources in cucumber, ten accessions from Gene Bank were selected for further studying. Ten seeds of each accession were cultivated in seed trays (one seed per pot). At six leaf stage, one leaf (about 4 cm2) from each plant was detached and placed around a circle with a diameter of 100 cm. In order to determine the antixenosis, ten adult females were released at the center of circle for each leaf. Experimental plots were arranged as a randomized complete block design with three replications. The number of mites feeding on each leaf was recorded after 24 and 48 hours. Statistical analysis showed significant differences between accession and indicated antixenosis resistance (p < 0.05). Maximum number of mites were observed at C104 (12.79±0.53) and C118 (12.3±0.4) and the minimums were observed in C90 (5.58±0.65) and C39 (5.82±0.46). Therefore, the mentioned accessions are supposed to be typically susceptible and resistance to T.urticae respectively. The content of cucurbitcin B, D, E and I in extreme susceptible and resistant genotypes was also by HPLC to declare the relation between pest attraction or and secondary metabolites.