نشریه نامه انجمن حشره شناسی ایران
سال سی و ششم شماره 1 (پیاپی 64، بهار 1395)

Two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is one of the most important pests of tomato crops. Using resistant cultivars is a useful control method against the pest in integrated pest management programs. In this study, resistance of the tomato cultivars Super Chief, Super Strain B, Korral, Khorram, HAS 2274, Super H, Calji, Early Urbana Y and Mobil to two-spotted spider mite were evaluated under laboratory conditions at 25 ± 2 °C, 60 ± 10% R.H. and a photoperiod of 16: 8 (L: D).The shortest pre-adult stage was recorded on Super Strain B. Female life span ranged from 26.47 to 30.40 days, on Super Chief and Early Urbana Y, respectively. The intrinsic rate of increase (rm) was from 0.091 to 0.163 day-1 which the lowest rm was observed on Super Chief and the highest rm was on Super Strain B. The lowest net reproductive rate (R0) and finite rate of increase (λ) belonged to Super Chief cultivar. Super Chief cultivar showed the highest antibiosis resistance against the two-spotted spider mite.

Parasitism rate of Trichogramma brassicae Bezdenko at laboratory conditions with six constant temperatures of 15, 20, 25, 30, 32 and 35 ± 1 °C, relative humidity of 65 ± 5% and a light period of 16 h. was evaluated on the eggs of gelechiid moth Sitotroga cerealella (Olivier). Parasitism rate of T. brassicae was significantly affected by different temperatures. The highest (40.257 hosts) and the lowest (3.731 hosts) values of net parasitism rate (C0) was obtained at 32 and 15 °C, respectively. The transformation rate of host population to parasitoid offspring (Qp) was equal to 1 at all temperatures. The values of stable parasitism rate (ψ) increased from 0.074 to 0.451 (host/parasitoid) with increasing temperature from 15 to 30 °C, but the values for this parameter at 32 and 35 °C significantly decreased. The highest recorded value for finite parasitism rate (ω) was obtained at 30 °C (0.654 day-1). The temperature thresholds for finite parasitism rate of T. brassicae were estimated by nonlinear models of Briere-1 and Lactin-2. The Lactin-2 better fitted the related data (SSE = 0.004833, R2adj = 0.977, AIC = -38.7438). The obtained values for the lower temperature threshold (Tmin), optimum temperature (Topt) and upper temperature threshold (Tmax) of parasitism activity of this parasitoid were 13.20, 31.20 and 35.40 °C, respectively.

Population density and infestation rate of alfalfa weevil Hypera postica L. in mixed cropping of alfalfa (Medicago sativa L.) and red clover (Trifolium pretense L.)were evaluated. Different rates of alfalfa (Al) and red clover (RC) RC0AL100, RC20AL80, RC40AL60, RC50AL50, RC60AL40, RC80AL20 and RC0AL100 were studied as treatments.Using standard sweep nets, sampling was carried out weekly and data analyzed in Randomize Complete Block Design. Damage and infestation rates of alfalfa weevil were caculated by inspection of 20 stem tips of alfalfa in each plot. The results showed that forage yield was higher in mixed treatments comparing to pure alfalfa and red clover treatments (p = 0.01). Average number of alfalfa larvae, pest population and infestation percentage were significantly lower in mixed treatments in comparison with pure alfalfa (p = 0.01). Average dry weight was significant in pure alfalfa treatment (p = 0.01). Alfalfa weevil larvae and adults were not observed feeding at pure red clover treatments. Increase of red clover amount, led to higher average dry weight. In mixed treatments, the infestation and damage percentage decreased, but the yield increased. It is concluded that using 20-40% red clover (RC20AL80, RC40AL60) treatments efficiently increase the yield and reduce the damage of the pest.

Nowadays, a basic understanding of population biology is necessary to establish ecological strategies of pest management. In the present study, the population behavior of the diamondback moth after a perturbation was examined. For this purpose, a long-term experiment with three treatments (control, a perturbation using density reduction and a perturbation using density increase) was performed. The experiment was started with 10 pairs of adult moths in ventilated cages under the standard constant environment. The experiment was continued for 10 generations. After five generations, the perturbation was applied and each treatment was replicated 10 times. Adults and larvae were fed with honey solution (20%) and Chinese cabbage, respectively. The population trend and stability were monitored by weekly census counts of live adults, and the data used as a measure of abundance for the population dynamics. The results showed that the populations of the diamondback moth persisted at equilibrial levels when there was no perturbation. On the contrary, when the populations were perturbed using density reduction, the population equilibrium was shifted to a lower level; in this situation perturbations using sustainable strategies, such as the release of natural enemies or the application of microbial insecticides, may set the equilibrium beneath economic injury threshold. While, a perturbation using density increase can cause instability of population equilibrium toward a decreasing trend that may drive the population to extinction. The causes and effects of the findings in relation with the moth life history, resource competition and its ecological consequences on the population behavior were discussed.

Ozone is a powerful oxidant potent agent for killing insects and microorganisms. In this study, ozone gas was used to evaluate the effect of ozone on the mill moth Ephestia kuehniella Zeller (Lep.: Pyralidae) in raisins. The samples of infested raisin (50gr each) with fifth-instar larvae of E. kuehniella were exposed to ozone at three concentrations (2, 3 and 5 ppm) in five different periods (15, 30, 45, 60 and 90 min).The mortality of the larvae was proportional to the exposure time. 100% mortality was observed at 5 ppm of ozone concentration within 90 minutes. There was no adverse effects on raisins in terms of changes of quality, organoleptic properties or color factors, fragility and stiffness during the ozone treatments. But ozone had negative impact on the aroma of raisins.

Olfactory experiments were performed to study the predation behavior of Orius niger Wolff (Hemiptera: Anthocoridae) on the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) in presence or absence of Beauveria bassiana (Bals.). The experiments were carried out with six day old female bugs by recording the predator direction towards each of the Y-tube olfactometer arms and through three dependent replicates consisted of 15 replicates each. The predatory bug showed a significant preference towards the odors related to infested cucumber leaves by T. urticae in the absence of fungus and when the predator received odors related to T. urticae infested leaves v.s. B.bassiana fungus treated, spider mite infested leaves (72 hours). There was no significant difference in the predator olfactory experiment when the alternative arms consisted of treated v.s. untreated spider mite infested cucumber leaves (0, 24 and 48 hours after treatment). The results showed the capacity of the predatory bug to recognize the patches infected by B.bassiana fungus and successfully avoiding it.

The aphid species, Cinara pinihabitans (Mordvilko 1894), is newly recorded from Iran. It was collected from mountain pine, Pinus mugo,during a survey on the insect fauna of urban green landscapes of the city of Mashhad, Iran from June 2014 to July 2015.

A survey was conducted to study the parasitoid wasps associated with the pistachio gall aphids, Forda hirsuta and Slavum mordvilcovi on Pistacia atlantica,in the southern Iranian Fars province during 2013. The overwintering galls were randomly collected and reared inside plastic jars at room temperature until the emergence of adults wasps . We identified the species Macrocentrus oriens (van Achterberg & Belokobylskij 1987) (Hym.: Braconidae, Macrocentrinae) and report it here from Iran for the first time.

The Family Apionidae economically important beetles, which feed on the seed of various rangland plants. This report is part of survey conducted during 2009-2012 to identify the seed - eating pests of Astragalus sp. Rangland plants in the Fars province of Iran. The Apionid species prapion hydrolapathi Marsham, 1802 was collected on plant, Astragalus camptoceras (Bunge.), and is first recorded from Iran.