---

The melon aphid, Aphis gossypii (Glover), is one of the major pests of cucurbits and an efficient vector of plant viruses such as Cucumber Mosaic Virus. Host-plant resistance is one of the management strategies that can be used to control this pest. In this study, choice test was conducted to identify antixenotic resistance against melon aphid in eight Cucumis genotypes, namely Hormozgan, Bushehr, Guilan, Girtap, Negeen, Sepehr, Pouya and Armenian cucumber. Choice tests were conducted at 25 ± 1 ºC, 60 ± 5% RH and a photoperiod of 16:8 (L: D) h. After introduction of apterous adult aphids to test arena, the number of aphids on each entry was counted at 2, 4, 6 and 24 hours of release. Total phenolic content, NPK essential elements, leaf thickness and leaf trichome density were also measured to discover any association between these factors and aphid host choice. The most antixenosis effect was observed on 'Bushehr'. Increase in antixenosis correlated with increase in leaf trichomes. Antixenosis can be important mode of resistance by reducing host selection and delaying aphid colonization. The identification of antixenotic resistance in several genotypes provides additional options for management of this pest. Moreover, the factors associated with this mode of resistance can be considered in plant breeding programs.

---

Root-knot nematode Meloidogyne javanica is an economically significant plant parasitic nematode in muskmelon farms in Ardestan, Isfahan province, Iran. A two-year experiment was conducted in two muskmelon farms in this region. We assessed the application of 3, 6, and 9 t/ha fresh (unrotten) chicken manure separately or in combination with summer plowing. To evaluate the efficacy of each treatment, the number of galls, egg masses, reproduction factor, plant growth factors, and yield were recorded at harvesting time. The results showed that combining double summer plowing with nine t/ha chicken manure was the most effective treatment for controlling M. javanica. Nematode population indices including: the egg mass number, gall number, total population in root and soil, and reproduction factor, were significantly lower than the control treatment. The application of double plowing with nine t/ha chicken manure treatment caused 83.5%, 79.1%, 80.2%, and 78.3% decreases in egg mass number, gall number, total population per root, and soil, and reproduction factor, respectively. Moreover, total fruit weight and root dry weight in each plot (24 m²) increased by 81.8% and 50.4% compared to the control.


 

---

The effect of eight Cucumis L. (Cucurbitaceae) genotypes, including native cucumber genotypes (Hormozgan, Bushehr and Gilan), greenhouse cucumber genotypes (Girtap, Negeen, Sepehr and Pouya) and Armenian cucumber (Cucumis melo var. flexuosus) was studied on the life table and population growth parameters of Aphis gossypii Glover to evaluate antibiosis resistance. The experiment was conducted at 25±1°C, 60±10% RH and a photoperiod of 16:8 hour (L:D). The data were analyzed by Two-Sex MSChart program. The most pre-adult mortality (22.6 %) and the shortest total life span (14.5 days) were recorded for ‘Bushehr’. The net Reproductive rate (R₀) ranged from 43.70 for ‘Bushehr’ to 92.39 nymphs per individual in the case of ‘Pouya’. The lowest value of the intrinsic rate of increase (r) and the finite rate of increase (λ) was observed in ‘Gilan’ (0.378 and 1.460 day⁻¹, respectively) and the highest in ‘Pouya’ (0.471 and 1.602 day⁻¹, respectively). The maximum and minimum mean generation Times (T) were 10.20 and 9.23 days in ‘Gilan’ and ‘Negeen’, respectively. On the basis of these parameters, ‘Gilan’ had the highest antibiosis resistance to A. gossypii. Information on life table of pests and subsequent host resistance evaluation improves IPM programs and leads us to genotype selection for crop breeding programs.