Two-spotted spider mite, TETRANYCHUS URTICAE Koch is a serious pest of different crops over the world. Different strategies are used to regulate the population of this mite. To this end, as a first step, a population growth model has been developed for describing the dynamics of T. URTICAE population growth. In this regard, the population abundance of T. URTICAE was estimated weekly from 29 June to 29 September 2016 at two bean fields, each field was planted with Goli and Akhtar cultivars, separately. During each sampling period in each field, 30 plants were randomly chosen and a leaf was selected as a sample unit from the middle of a plant, then a simple population growth model was constructed for T. URTICAE on two bean cultivars. The result showed that T. URTICAE had a distinct seasonal pattern of abundance but differed between two cultivars. A logistic growth model was developed based on relationship between the cumulative density of T. URTICAE and time (day) and demonstrated high prediction capability for T. URTICAE population on Goli (R2 =0.99) and Akhtar (R2=0.99) cultivars. According to the logistic equation, carrying capacity was recorded 463.9 ±9.73 (mite/leaf) and 59.67 ± 8.72 (mite/leaf) on Goli and Akhtar cultivars, respectively. Furthermore, it has been shown that the logistic growth model can be used to make population predictions. The model parameters estimated for two different cultivars, providing a new mathematical tool for ecologists to predict two-spotted spider mite outbreaks, and ultimately to develop effective two-spotted spider mite control strategies.

Population growth parameters of TETRANYCHUS URTICAE Koch on four bean varieties including Talash (Colorado bean), Sadaf (Navy bean), Goli (Kidney bean) and Parastoo (Black-eye bean) were investigated in laboratory conditions at 25±1oC, 60±5% RH and a photoperiod of 16: 8 (L: D) h. In this experiment, one-day old eggs of T. URTICAE were selected and reared in growth chamber until the death of the last female mite, and the survival rate and female progeny of the mite were measured. Net reproduction rate (R0) on four bean varieties, was 8.822, 3.622, 4.908 and 2.043, intrinsic rate of increase (rm) was 0.142, 0.079, 0.095 and 0.038, and finite rate of increase ( l) was 1.152, 1.082, 1.099 and 1.039, respectively. Mean generation time (T) was determined 15.381, 16.283, 16.715 and 18.308 and doubling time (DT) was 4.901, 8.787, 7.292 and 18.125 days, respectively. The results indicated that the rate of population growth of T. URTICAE on Talash variety was more than other varieties. The rates of population parameters on Parastoo variety were the least.

Two spotted spider mite (TSSM), TETRANYCHUS URTICAE Koch, is an important pests on bean in Markazi Province (center of Iran). To evaluate the bioacaricidal activity of extracts of three essential oils of thyme (Thymus vulgaris), lavender (Lavandula officinalis) and eucalyptus (Eucalyptus camaldulensis) against T. URTICAE on cherry bean (Vigna unguiculta subsp. sinensis), five different concentrations (0.5%, 1%, 2%, 3% and 4%) were used, during 2009-2011. The type of design was randomized complete block design with four replications. The results showed that lavender revealed the most acaricidal properties against T. URTICAE followed by thyme and eucalyptus. The LC50 values of lavender, thyme and eucalyptus for adult mites were 0.65, 1.84 and 2.18, respectively. Our findings revealed that essential oils of thyme, lavender and eucalyptus possess acaricidal activity against two spotted spider mite on cherry bean.

The two-spotted spider mite, TETRANYCHUS URTICAE Koch is one of the most important pests of strawberry plants worldwide. The present study compared the biology and life table parameters of T. URTICAE on four strawberry cultivars, including Wanter star, Markez, Fortona and 029 under laboratory conditions. Female developmental times showed a significant difference when recorded on tested cultivars, while such a difference was not observed for the male ones. The developmental time was significantly longer on Wanter star and Fortona in comparison with the others (P = 0. 00). Females of T. URTICAE exhibited the shortest oviposition period and adult longevity on Fortona and Wanter star, while having the longest periods on 029 in this report (P = 0. 00). The lowest fecundity and daily eggs laid by females were recorded on Wanter star. The highest rate of fertility was recorded on 029 as compared to other cultivars; therefore, Wanter star is introduced as a resistant cultivar against T. URTICAE infestation.