Investigation on resistance of different almond cultivars/genotypes to twospotted spider mite, Tetranychus urticae Koch in laboratory and greenhouse condition

Resistance of different almond cultivars/genotypes including: ‘Sefid‘, ’Mamaei’, ‘Rabie’,‘Shokofeh’, ‘Azar’, ‘Non pariel’, ‘Shahrood 6’, ‘Shahrood 7, ‘Shahrood 12‘, ’Shahrood 13’ and ‘Shahrood 21’ were studied to two-spotted spider mite (TSSM, (Tetranychus urticae Koch. All cultivars/genotypes were grafted on ‘Gf677’ rootstock in 4 replications. Study was done in the laboratory and greenhouse conditions. Leaf discs (2.5×1.2 cm) were prepared from leaves and placed on wet cotton in a plastic petri dish and infested with 5 adult female mites (3-5 days in age). Leaf discs were kept in an incubator at 25±1  C, RH= 55 ±5% and a photoperiod of 14:10 (L:D). After 72 h, mite oviposition and mortality were measured. Based on the results, the highest and lowest oviposition were observed on ‘Mamaei’ and‘ Shahrood 21’ cultivars. The highest mite mortality was observed on ‘Shahrood 13’. Biological characteristics study of TSSM on different cultivars in the laboratory showed that cultivars significantly affected survival, immature period, mature period and mite oviposition. The highest survival percentage was recorded on‘ Azar’ (88%) and the lowest on ‘Shokoofe’ (47%) and ‘Shahrood. (% ) ’ The longest (5.27 days) immature period was observed on‘ shahrood 21’. The shortest mature period was observed on‘ Shahrood 21’ (5.15 days) and ‘Shokoofe’ (5.2 days); whereas, the longest (10.45 days) was observed on ‘Mamaei’. The highest ovipositional rate (57.6 eggs/female) was observed on ‘Mamaei; ’whereas, the lowest was recorded on ‘Shokoofe’ (15.1eggs/female (and ‘Shahrood 21’ (31eggs/female). Greenhouse study showed that the highest density of mite population was supported on ‘Non pareil’ and ‘Shahrood 6’ cultivars while the lowest one was reared on ‘Shokofeh’ and ‘Shahrood 21’. Results indicated that ‘Shokofeh’, ‘Shahrood 21’ and ‘Shahrood 13’variety/genotypes were the most resistant, whereas‘, Mamaei ’and ‘Non pariel ’were the most susceptible varieties to two-spotted spider mite.