The current study demonstrates that T. urticae could successfully survive, feed and complete the development of different tomato cultivars; however, their development, fecundity and population growth parameters were greatly affected by these cultivars. Indeed, the data reveal that the tomato cultivars significantly influenced T. urticae development stages, the net reproductive rate (R0), intrinsic rate of natural growth (rm), female offspring, and adult survival. The immature development time of T. urticae females ranged from 11.96 days on BARI Tomato-2 to 13.45 days on BARI Tomato-11. In harmony with our findings, the total immature development duration of T. urticae was recorded at 12.09 days by Azadi-Qoort et al. (2019) and from 11.36 to 11.52 days by Atalay and Kumral (2013) on different tomato cultivars. At 25.0 ± 1oC, Osman et al. (2019) reported 10.41 days, as an immature developmental time of T. urticae on tomato. Also, Keskin and Kumral (2015) observed that the total immature development of T. urticae was influenced by tomato cultivars and ranged from 8.26 to 11.37 days. Conversely, Nawar (2019) and Nasr et al. (2019) opined that the total immature developmental time was 6.20 and 9.25 days at 25°C, which was lower than our present findings. The discrepancies in developmental times of published data could be attributed to various factors, including plant suitability, leaf surface characteristics, rearing methods and the presence of phytochemical compounds (Greco et al., 2006; Uddin et al., 2015). The resistance cultivars for instance, BARI Tomato-11 and F1 hybrid that extended the time needed to complete the immature developmental stage may promote the efficacy of their management strategy by employing predators and insecticides or acaricides. Thus the use of aforementioned cultivars can be included in the IPM approach for controlling T. urticae.
The sex ratio of T. urticae is an important trait that greatly influences the intrinsic rate of natural increase (rm) value and the selection of resistant and susceptible varieties or cultivars in a study. Consistent with earlier investigations on Tetranychoid mites (Jafarian and Jafari, 2016; Uddin et al., 2017; Sepahvandian et al., 2019), all the tomato cultivars showed a female-dominated sex ratio. Moreover, Osman et al. (2019) found a 78% sex ratio of females at 25.0 ± 1oC on tomato. In contras at 25 ± 2°C, Beyranvand et al. (2019) documented a lower female sex ratio of T. kanzawai (40–41%) in different soybean genotypes. This result demonstrated that, despite the sex ratio of TSSM being generally female-biased; this may be modified by extrinsic factors, for instance, temperature, host plant quality and suitability. In T. urticae, fertilized eggs generate females, whereas unfertilized eggs produce males. The amount of sperm transmitted to the female largely determines the sex ratio, as noted by Takafuji and Ishii (1989). So it can be suggested that increasing the population of males in future studies potentially enhances sperm transfer, which may lead to a more pronounced effect on the resulting sex ratios.
However, the fecundity of TSSM varied significantly among different tested tomato cultivars. Its value ranged from 60.0 eggs on BARI Tomato-9 to 74.56 eggs on BARI Tomato-5. The fecundity of TSSM on tomato at 25°C was 74.6 eggs (Nawar 2019), which is consistent with the present findings. Osman et al. (2019) and Nasr et al (2019) found 61.56 and 48.67 eggs in tomato varieties at 25°C, which is lower than our current study. Also, Keskin and Kumral (2015) observed lower fecundity of T. urticae in the same host plant. Conversely, Atalay and Kumral (2013) reported 85.31 to 276.00 eggs on tomato at 27 ± 1°C, which is higher than our present data. These variations could be attributed to the morphological structure of the leaf, the photochemical compound of the host plant, the farming method, geographical strain and experimental circumstances (Islam et al., 2017; Osman et al., 2019).
The demographic parameters such as the intrinsic rate of natural increase (rm) and the net reproductive rate (Ro) are important essential criteria for determining plant resistance to insects (Uddin et al., 2015; Chen et al., 2017). The intrinsic rate of natural increase (rm) is a typical indicator for determining the potential severity of a pest species (Gotoh et al., 2010; Safuraie-Parizi et al., 2014). Numerous factors including developmental rate, survival, fecundity and mostly generation time influence rm. In the present findings, the estimated rm values ranged from 0.2285 to 0.2461 ♀/ ♀/ day. Kasap (2004) reported a rm value of 0.243 ♀/ ♀/ day on apple cultivars at 25°C which is near to our present findings. The rm value for this mite on sweet pepper and bean at 25°C was reported as 0.130 (Karimi et al., 2006) and 0.038 to 0.142 ♀/ ♀/ day (Ahmadi et al., 2007), respectively which is lower than our current study. Conversely, Nasr et al (2019) reported 0.65 ♀/ ♀/ day as the rm value on tomato at the same temperature higher than the present study. There is a wide discrepancy in the rm values of T. urticae on different cultivars. The absence of primary essential nutrients, chemical composition, leaf surface morphology, chemical contents, food quality, secondary chemical compounds and experimental status could lead to this variation (Uddin et al., 2015; Beyranvand et al., 2019). The result indicates that the BARI Tomato-11 is the least unfavorable host compared to the other tomato cultivars for T. urticae. The net reproductive value (Ro = 45.51 to 57.51) in our study of this mite at 25°C was lower than those reported by Osman et al. (2019) (36.49) and Nasr et al (2019) (21.9), respectively on tomato. Keskin and Kumral (2015) also observed a lower net reproductive rate (5.818 to 26.105) of this mite in seven tomato varieties. On the other hand, Kasap (2004) reported a higher net reproductive rate (92.19) on apples which are higher than the values obtained in the present findings. The disparity of the Ro may be due to the plant age, cultivar differences, moisture and soil nutrient availability in excised leaves.
Finally, our research has shown that the BARI Tomato-11 cultivar is less suitable for the two-spotted spider mite compared to other tomato cultivars. This is due to its extended immature developmental time and slower population growth. This study provided valuable information regarding the preference of the T. urticae food source, which is important for developing integrated pest management for this mite in tomato fields. Resistant plants contain chemical defense mechanisms like antixenosis, antibiosis, and tolerance to protect themselves from arthropod herbivores. The utilization of resistant plants confers substantial benefits because it reduces the number of frequent applications of pesticides, therefore preserving natural enemies of pests.