فصلنامه فن آوری های نوین کشاورزی
سال پنجم شماره 3 (1391)

The rice stem borer is one of the most damaging pests on rice in Iran. The proteaese inhibitors are used for producing resistant transgenic plants to pests. The first step for resistant plant is identification of dominant proteases in deigestive system of a pest. Therefore، the biochemical properties of proteases from digestive system of Chilo suppressalis were determined in this study. Fifth larval instars were collected from rice seedling stems، Oryza sativa L. ‘variety of Hashemi’ in the northern provinces of Iran and were randomly selected for measuring of enzyme activity. Larval gut was dissected، homogenized and the resulted supernatants were stored at -20 °C for further analyses. The effect of pH، temperature، ions and inhibitors on digestive protease activities were measured using 50 mM acetate sodium- glycine- phosphate buffer with azocasein as the substrate. Tryptic and chymotrptic activities were assayed using BApNA and BTEE as substrates، respectively. Results showed that the activity of total protease، trypsin and chymotrypsin in digestive system were 0. 47 IU/mg protein، 0. 387 and 22. 41 µmol-1min-1mg protein-1، respectively. Results showed that the optimal pH for protease activity in digestive system was 10-11. Also optimal temperature for protease activity in digestive system obtained as 55°C. Effect of ions on protease activity showed that Hg+، Co2+، Fe2+، Zn+2 and Mn2+ decreased protease activity in the digestive system of C. suppressalis، whereas Na+، K+، Mg2+، Ca2+ and Ba2+ increased its activity. Effect of inhibitors on protease activity showed that idoasetamid، idoasetat، EDTA، TLCK، TPCK and PMSF decreased 24%، 33%، 8. 21%، 25. 71%، 14. 9% and 26. 15% protease activity، respectively. Therefore، the serine was active in digestive system of C. suppressalis.

The dried fruit mite، Carpoglyphus lactis L. (Acari: Carpoglyphidae) is known as one of the most important pest species of dried fruit worldwide. Recently، damage of this pest on stored date fruits has been reported from Iran. In the past few decades، herbal essential oils have received much attention as potential control agents for stored-product pests، because of their lethal، repellent and antifeedant effects. In this experiment، fumigant toxicity of cumin (cuminum cyminum L.)، fennel (foeniculum vulgare Mill) and spearmint (Mentha spicata L.) essential oils were tested against female adults and eggs of C. lactis at 25± 1°C، 75±5% relative humidity and full darkness condition. The essential oils were extracted using Clevenger-type water distillation. After 24h of exposure، the LC50 value of cumin، fennel and spearmint against female adults were 3. 17، 3. 38 and 2. 48 μl/l air، respectively. In ovicidal bioassays، the LC50 values for the above mentioned essential oils were 16. 99، 21. 29 and 7. 64 μl/l air، respectively. The results show that spearmint oil had the highest adulticidal effect rather than the other essential oils، but there was no significant difference between the lethal effect of cumin and spearmint essential oils. Spearmint essential oils also had significantly the highest lethal effects against eggs of C. lactis in comparison with those of cumin and fennel.

Root-knot nematode، Meloidogyne javanica، was isolated from infested olive seedlings and after identification it was propagated on tomato seedlings. One-year-old seedlings of olive cultivars، Koroneiki، Manzanilla and Roghani، were transplanted to pots containing 2000g of sterilized sandy loam soil. Experiment was conducted in completely randomized design with four treatments and five replications. Pots were inoculated with secondary juvenile (J2) (2000، 3000 and 4000 no/pot) of nematode. Pots were arranged in glasshouse benches with the temperature of 25-27°C and natural light. Quantitative activity of catalase (CAT) in root was measured using phosphate sodium buffer and hydrogen proxidase according to change in absorbance of the reaction mixture at 240 nm per minute per milligram of total protein، on 1،5،10 and 15 days after inoculation. Results showed that CAT activity decreased in seedlings inoculated with nematode reaching its minimum level at the 10th and 15th day (p≤0. 05).

Host quality is an intrinsic feature that is determined by quantitative and qualitative differences in hosts. These differences can change nutritional resources available and consequently affect on life history traits of parasitoid. Competition plays an important role in the size، structure and stability of insect communities. The aim of this paper was the effect of host density and host quality on Habrobracon hebetor oviposition strategy. The experiments was performed on 5th instar larvae of Ephestia kuehniella in growth chamber at 25±1° C، 50-60% RH and a 16:8 (L: D) photoperiod. Results showed that access to more number of hosts (10 larvae) caused to increase the number of hosts parasitized and total number of eggs laid in the presented patch. Wasps that encountered with previously parasitized hosts by conspecific parasitized the less number of hosts and the total number of eggs laid was reduced than females that encountered only healthy larvae. In treatment that females were only introduced into paralyzed hosts the most number of eggs laid on parasitized host. Furthermore، patch quality did not effect on egg hatching rate and sex ratio. The results of this study could provide better conditions for mass rearing of H. hebetor. It is important to use the proper ratio of H. hebetor females and larvae host، because in trade off between the number of parasitized hosts and the average eggs laid، the maximum progeny with the best quality to be produced.

The polyphagous mould mite، Tyrophagus putrescentiae (S.) feeds on kinds of various stored product، fungus and plant seeds also is used as an alternative host for commercially mass rearing of predatory mites. In this study، life table parameters of mould mite were examined on baker´s yeast under laboratory conditions of 25 °C، 70±10% relative humidity and full darkness، based on age-stage، two-sex life table theory. The intrinsic rate of increase (rm)، finite rate of population increase (λ)، net reproductive rate (R0)، gross reproductive rate (GRR) and mean generation time (T) were 0. 344 day-1، 1. 411 day-1، 276. 7 offspring، 337. 02 offspring and 16. 3 day respectively calculated. The mean fecundity of mould mite females was estimated 528. 24±47. 06 eggs per female during their lifetime. This study suggests baker´s yeast as a suitable food in order to mass rearing of T. putrescentiae as an alternative prey for rearing of predatory mites.

The two-spotted spider mite، Tetranychus urticae Koch، is one of the most important polyphagous pests that cause considerable damage to agricultural crops. Frequent pesticide applications have caused development of pest resistance to pesticides، undesirable effects on non target organisms، secondary pest outbreak، pest resurgence and environmental pollution. In recent years، herbal essential oils have been received attention as natural plant protection compounds. In this study، contact toxicity of three formulated compositions based on herbal essential oils including)chinaberry oil 10%+peppermint oil 7%+pennyroyal oil 2%)، (chinaberry oil 5%+ peppermint 7%+ pennyroyal oil 2%) and (rosemary oil 10%+peppermint 2%) by leaf dipping method were tested against female adults of T. urticae. The essential oils were obtained by Clevenger-type water distillation. Experiments were carried out at 25±1°C، 50±10% relative humidity and under a photoperiod of 16L: 8D. The LC50 values for the formulated compositions were 21. 962، 30. 894 and 56. 783 ml/L، 24hrs after treatment، respectively. The results showed that formulated composition based on rosemary and peppermint oils showed the highest lethal effects against female adults of T. urticae rather than the other compositions and have significant potential for two-spotted spider mite management.

Life table construction is an important practice in population dynamics determination. Moreover، calculating life history and growth parameters is critical for effective decision making in pest management. Pea aphid Acyrthosiphon pisum Harris is a cosmopolitan and important pest of alfalfa fields. In this study، life history traits of pea aphid، under controlled conditions including 25 ± 1º C، 65 ± 10% R. H. and 16:8 (L: D) photoperiod were calculated. 55 first instar nymphs of A. pisum (less than 12 hrs. old) were selected as cohort and placed on detached faba bean leaf discs individually. Mortality and fecundity rates were recorded daily until the death of all aphids. The results showed that the preadult period and longevity of pea aphid were 7. 88 and 16. 53 days respectively. Maximum daily and total fecundity were 13 and 118 nymphs and intrinsic rate of increase (rm)، finite rate of increase (λ)، net reproductive rate (R0)، doubling time (DT) and mean generation time (T) were 0. 44 (/day)، 1. 56 (/day)، 132. 65offsprings، 1. 56 day and 12. 56 day respectively.

This study was conducted to investigate the allelopathic effects of different concentrations of wheat aqueous extract on rye seedling growth using image analysis. Shoot aqueous extract of the Shahriar cultivar at different concentrations (10، 25، 50، 75 and 100%) was made to determine its effect on rye root and shoot length over time، root and shoot dry weights، root area and spread of 10-day-old rye seedlings. The experiment was carried out in a completely randomized design with three replication. Data on Root and shoot length over time، root spread and area of rye collected using image analysis. Shoot aqueous extract significantly inhibited rye seedling growth when compared with the distilled water (control). The inhibition of seedling growth was concentration dependent and، the degree of inhibition increased with increasing concentration. Significant inhibition of root length at all concentrations showed that root length is a more sensitive indicator of phytotoxic activity. In this study، the area and spread of rye root system were reduced significantly with increasing extract concentrations. Therefore، it was suggested that the spread and area of root can be used as new credit traits to determine allelopathic activity.

The root-knot nematode Meloidogyne javanica often occurs on tamato roots wherever this crop is cultured. In this study the effects of antagonistic fungus Trichoderma viride were assessed on the reproduction of M. javanica. In this study M. javanica was recovered from infested tomato plants in Varamin farms, and after identification it was propagated on tomato cv. local seedlings. In this study six-leaf seedlings of tomato cultivars, Bony best, Falat, Mobile and Walter were transplanted to pots containing 2000g of sterilized sandy loam soil. Experiment was conducted in completely randomized design with four treatments and five replications. Treatments were as fallows: control, nematode, fungus, nematode+fungus and nematode+Rugbi. Pots were inoculated with 2000 J2 of the nematode, 1×106 propagule/ml of fungus, and 2g/pot of Rugbi (nematocide) according to the treatments. Pots were arranged in glasshouse benches with the temperature of 25-27°C and natural light. Experiment was terminated after two months and fallowing parameters were determined i.e., no. of gall and egg mass of nematode per root system. The result showed that application of antagonistic fungus resulted in a significant decrease in the activity of nematode on plants. The use of fungus and Rugbi resulted in a maximum reduction in galling and nematode multiplication (P≤0.05). Galling maximum and minimum on root system were on cv. Walter and Mobile, respectively (P≤0.05).