فصلنامه تحقیقات حشره شناسی
پیاپی 3 (پاییز 1388)

Asian citrus psylla, Diaphorina citri Kuwayama (Hem., Psyllidae) is one of the most important pest of citrus in south Asia. In Iran, the pest has spread in Hormozgan, Sistan- Baluchestan and Kerman Provinces. The pest sucks plant sap and able to transferring the Liberobacter asiaticum Grining bacteria which is a dangerous disease of citrus throughout the word. In this survey, natural enemies of D. citri in Hormozgan province were studied during 2007–2008. As a result of this study, two parasitoid species belonging to Encyrtidae and Eulophidae, one common lace wing species (Chrysopidae), five lady bird species (Coccinellidae), and two spider species from the families of Salticidae and Linyphidae were collected and identified. Among the natural enemies of Asian citrus psylla, Tamarixia radiata (Waterston) (Hym., Eulophidae) is new record from Iran and its morphological features are presented.

Population density of Tydeus longisetosus El-Bagoury & Momen, Tetranychus turkestani (Ugarov & Nikolskii) and their predator Zetzellia mali (Ewing) on two varieties of apple (Golden delicious and Golab) was studied in Maragheh (Northwestern of Iran) during summer of 2006. The result showed that the mean density of T. longisetosus and T. turkestani on Golden delicious and Golab varieties were 3.35±0.67, 4.02±0.91 and 1.022±0.12, 1.26±0.45 per leaf, respectively. The mean density of Z. mali were 0.829±0.23 and 1.057±0.25 per leaf on Golden delicious and Golab varieties, respectively. Comparison of mean densities on two varieties was done by t-test and showed no significant differences between mean densities on two varieties. Spatial distribution of two species was determined by Taylor's power law, Morisita's coefficient and index of dispersion. Taylor's power law showed that spatial distribution of T. longisetosus on Golden delicious and Golab varieties wasaggregated and random, respectively. T. turkestani was distributed in aggregated pattern on Golab variety and there was no significant relationship between its parameters on Golden delicious, in this way Z. mali was distributed randomly on two varieties too. Aggregated spatial distribution of all species was determined by Morisita's coefficient and index of dispersion on two varieties in most cases. Linear regression between mean density of phytophagous and predaceous mites showed that the predator acts as density independent. Apple varieties have no effect on population density of studied mites but make an effect on spatial distribution of them to some extents.

Essential oils are suitable components as alternate for chemical pesticides. Indian meal moth Plodia interpunctella Hubner is one of the most important stored product pests. In this research, effects of essential oils of 18 medicinal plants were studied on nutritional indices of 15 days-old larvae of this pest. Nutritional indices determined in this study were Relative Growth Rate (RGR), Relative Consumption Rate (RCR), Efficacy of Conversion of Ingested Food (ECI) and Feeding Deterrence Index (FDI). In this study, 20 µl from 3, 12 and 24 ppm of the oil solution was mixed with one gram of the food. The experiment was conducted using a completely randomized design in a factorial experiment with three replications. The results showed that essential oils had not any significant effect compare with control on RGR and ECI. The index of RCR was significantly decreased except in Ziziphora clinopodioides Lam. Decreasing RCR in treatments might be due to feeding deterrency of the essential oils. FDI was positive in all treatment except in Z. clinopodioides with the least FDI. Nutritional indices were significantly not affectd by increasing concentration. The highest deterrency was observed by Mentha piperata L., Cinnamomum zelanicum Bl., Salvia multicaulis Vahl., Melissa officinalis L., Achillea millefolium L. As these essential oils at low concentration of 0.06, 0.24 and 0.5 µg/kg caused the high deterrency, therefore these essential oils could be applicable on the management of Indian meal moth in storage.

In order to find recyclable, environment friendly and easy accessible insecticides, the essential oils of three plant species including Mentha aquatica L., M. piperita L. and Anethum graveolens L. were used against the eggs of Callosobruchus maculatus. The experiment was conducted in 6 replications using a completely randomized design of factorial experiment. The essential oils were prepared by water distillation method. Experiment was carried out at 30±2 ˚C and 60±5% R. H. under dark condition. Results show that all three plant essential oils reduced percentage of egg hatching significantly. At the concentration of 37.03 µl/lessential oils of M. aquatica, M. piperita and A. graveolens caused 100, 100 and 92.73% mortalities of eggs, respectively.Values of 50% lethal concentrationon eggs were 2.628, 3.806 and 4.468 µl/l for M. aquatica, M. piperita and A. graveolens, respectively.

The flight is one of the most important character of insects which help them in their dispersion for finding the mate, food and etc. In Trichogramma, flight activity is important in both distribution and quality control assessment. The effects of three generations (18, 24 and 31) and three temperatures (20, 25 and 30±1◦C) on flight activity of T. brassicae were studied in 12 replications under conditions 70±5 RH% and 16:8 L:D. The testing units consisted of a glass cylinder with 20cm height and 9cm diameter covered by black paper. The numbers of flying (on the top), walking (on the ring) and motionless individuals (on the floor) were counted. Data were analyzed as a factorial compltely randomized design. Results showed that flying wasps decreased significantly as generation increased and increased significantly as temperature increased. The highest percentage of walking wasps were observed at 20◦C for all generations and the lowest were calculated in generation of 31 for all temperatures. The highest percentage of no action wasps (on the floor) were recorded in generation of 31. The results showed that the flight activity of T. brassicae can be affected by generation and temperature and these factors must be considered for quality control assessment and augmentation of Trichogramma wasps.

Arboridia Kermanshah Delabola (Hem., Cicadellidae) is a dominant species of leafhoppers in vineyards of Isfahan, central region of Iran. The most abundant parasitoid of the leafhopper is Anagrus atomus in the region. This research was conducted to study the effects of the spatial distribution and density of the parasitoid and host on searching efficiency of parasitoid and parasitoid-host stability. Results showed a significant difference between host and parasitoid distribution on arms of vine trees. The highest density of parasitized and non-parasitized eggs of the leafhopper eggs were observed on leaves 7-12 in the middle of each vine arm. There was a significant density dependent relationship between host and parasitoid. Studying on the host and parasitoid density relationship showed that a high searching efficiency was observed in the first generation of host when the parasitoid density is low. The parasitoid searching efficiency was decreased by increasing the parasitoid density. When the parasitoid was leaving vineyard for wintering, the searching efficiency increased with decreasing in number of parasitoid. Interference coefficient (m) was higher when the parasitoid-host ratio was high and the searching efficiency decreased in this condition. The value of m was close to Q (searching constant) when the parasitoid-host ratio was high and host- parasitoid relationship was more unstable.

Lasioderma serricorne (Fabricius) is one of the damaging agents in all producing stages of tobacco, from processing to cigarette, in almost all over the world. To control this pest in Iran every year costly fumigation programs are carried out which sometimes cause hygienic problems for fumigation workers too. In this study four tobacco storages in Sari, Bandar-e-Torkman (2 stores), and Gorgan (totally 15575 m3) were fumigated with current recommended phosphine fumigation doses. That is, one 3-gram Phostoxin® tablet (Degesch; Germany) was used to fumigate every m3 of bales and tobacco boxes. For this purpose tablets were put in metal trays over the boxes covered by gas-proof plastic sheet for 96 hours. To investigate the efficiency of fumigation, pheromone traps were employed. Traps were examined from late June through early November every week and the numbers of collected insects were recorded. The results of the study revealed insect control failure in all the storages and insects had been trapped from the second week after phosphine treatment. The reason might be deficiency of current recommendations for fumigations or occurrence of resistance to phosphine due to these regions.

Vine cicada, Psalmocharias alhageos (Hem., Cicadidae), is one of the period important pests of vine trees in Iran. Main damage of P. alhageos is caused by long feeding period of nymphs on the vine roots and laying eggs of females under the bark of the shoots. The adults appear from mid May in Qom region. Three insecticides: Diazinon (10% granule), Carbaryl (Sevin® 85%) and Imidacloprid (Confidor® SC350) by soil application and gardening activities (pruning of top branches and shoveling of soil under vines) were compared. In this study The treatments were compared with the number of nymphal exuviae under vines and grape vine yield. The results showed that the maximum number of nymphal exuviae was recorded on the control treatment (14.2) and the minimum was on trees using the treatment of Imidacloprid (4.9). The highest and lowest of grape yield were recorded in Imidacloprid (54.1 kg) and control (15.7 kg) treatments, respectively. Based on treatments ranking, application of Imidacloprid (20 ml at each vine tree) at nymphs emergence time from soil was effective in decreasing of vine cicada damage and increasing of the grape vine yield.