PLANT PEST RESEARCH
Year:2018 | Volume:8 | Issue:3 |Papers Count:7

Aphids in urban ecosystems, damage host plants directly by feeding on leaves, sucking up nutrients, and weakenig the host, resulting in yield reduction. The results of a study conducted in 2016 and 2017 on the interactions between population of the rose aphid, Macrosiphum rosae and the parasitoid wasps, Aphidius rosae and Lysiphlebus fabarum indicated that in all cases, there was a positive and significant correlation between the numbers of both species of parasitoid wasps and the population of the rose aphid. As the population of aphid raised, the density of parasitoid wasps increased as well, and these parasitoids exhibited an aggregative behavior to different densities of the aphid host. The relationship between the number of rose aphid and the percentage of parasitism by A.rosaeand L. fabarum wasps showed that there was a positive correlation between percentage of parasitism by these two parasitoids and aphid density. In 2016, during the spring, the highest percentage of parasitism of aphid nymphs by A. rosae wasp was 42.17 and the highest percentage of parasitism byL. fabarum wasp was 21.15. In 2017, during the spring, the highest percentage of parasitism of aphid nymphs by A. rosae wasps was 41.89 and the highest percentage of parasitism by L. fabarumwasps was 21.02. Therefore, considering the positive correlation between the population of rose aphid and the population of parasitoid wasps and the effective performance of these parasitoids in parke-shahr in Tehran, these useful agents can be efficiently employed in biological control of rose aphids.

In this study, fauna of laelapidae mites (Laelapidae) of Guilan province have been reviewed. The examined specimens of Guilan province belonged toa period of twenty years from 1998 to 2018 that are present in mite collection of Department of Plant Protection, Faculty of Agricultural Sciences at University of Guilan, Rasht Iran. The number of examined specimens was about 2000 mites, which are preserved as slide-mounted specimens. A total of 46 species from 16 genera And rolaelaps, Cosmolaelaps, Euandrolaelaps, Eulaelaps, Gaeolaelaps, Gymnolaelaps, Haemogamasus, Hypoaspis, Laelaspis, Laelaspisella, Ololaelaps, Pnemolaelaps, Pseudoparasitus, Reticulolaelaps Stratiolaelaps and Stratiolaelaps of laelapid mites were introduced from Guilan province, an identification key to genus and species were also provided. Gaeolaelaps iranicus Kavianpour & Nemati and Hypoaspis (Hypoaspisella) linteyini (Samsinak) which collected in recent surveys are introduced as new record for Guilan province mites fauna. The male specimen of G. iranicus, which has not been reported so far, is also collected and described from Guilan province.

Citrus red mite, Panonychus citri (McGregor) (Acari: Tetranychidae) is one of the most important pest of citrus in the citrus regions of the world and Northern provinces of Iran. Application of various chemical pesticides against citrus pests has destroyed natural enemies, the occurrence of resistance and the resurgence of the pests. In this research, resistance mechanisms of citrus red mite to abamectin were investigated in four populations. To determine the LC50, the spray potter tower method was used. In this method, the resistance level in Gorgan, Ramsar, and Sari populations was 6.48, 6.19 and 5.11 times higher than the susceptible population. The measurement of esterase activity in Gorgan's resistant population usingα-naphthyl acetate and b-naphthyl acetate substrate was 7.960 and 3.575 times more than that of the susceptible population. Estimation of kinetic parameters and glutathione-s-transferase activity level using 1-chloro-2, 4-dinitrobenzene (CDNB) as substrate also showed a significant difference between the four populations, so that the activity of this enzyme in resistance population was 2.79 fold higher than that of resistant population. Also, Km and Vmax in resistant population were 16.12 and 5.33 fold than susceptible population, respectively. Due to the increasing trend of resistance, the results of this study indicated the role of esterase and glutathione-s-transferase enzymes in resistance mechanism to abamectin.

The Sunn pest, Eurygaster integriceps Put. is one of the main pests of wheat and one of the most important plant protection problems in Iran. Multiple linear regression models have been used to predict the fluctuation of various pest populations by using environmental variables. Using intelligent systems to better estimate insect population fluctuations can lead to better results.Therefore, the current study was conducted to predict population fluctuation of the Sunn pest by using a neuro adaptive fuzzy inference system, a response surface method and multiple linear regression. This study was done during in 2015 and 2016 on two wheat farms each one with an area of one hectare in the Chadegan county. In these models, average temperature, average relative humidity, rainfall, wind speed and direction, sampling date, degree- day and altitude from sea level were used as response variables. The collected data randomly divided in two categories of training (70%) and testing (30%) and they used for train and test of ANFIS and response surface methodology. The accuracy of the prediction was evaluated by R2 and RMSE. The higher performance of the ANFIS model (R2=0.93, RMSE=0.0614) and RSM (R2=0.88, RMSE= 0.0836) resulted comparing to the multiple linear regression (R2=0.23, RMSE=0.34). Also the results of sensitivity analysis indicated that the average of temperature, relative humidity, wind speed and date of sampling were the most important parameters for predicting density of adult Sunn pest.

The Mediterranean flour moth (MFM), Ephestia kuehniella (Zeller), is one of the major pests of stored products.Eggs and larvae of this moth are widely used for rearing parasitoids and predators. In this study, the effect of the standard diet including a mixture of wheat flour (68%), wheat bran (29, %) plus 3% yeast and also the standard diet+sesame meal (30%), soybean (30%) and rapeseed (30%) on biological characteristics and life table parameters of E. kuehniella were studied by using the Twosex, Age-stage life table theory. The condition of experiments were; 25±1ºC, 65±5% RH and complete darkness. The results showed that the flour moth fecundity significantly increased by adding sesame meal (477.69 eggs) compared to soybean meal (451.77 eggs), rapeseed meal (411.21eggs) and standard diet (393.20 eggs). Also, significant differences were found between the larval stage durations being 34.31, 31.40, 33.26 and 30.37 days for sesame meal, soybean meal, rapeseed meal and standard diet, respectively. The intrinsic rate of increase (r) for sesame meal, rapeseed meal containing and standard diet was 0.102, 0.108, 0.103 and 0.109 day-1, respectively. Therefore, the results showed that diets containing sesame meal, soybean meal and rapeseed meal did not have much more efficiency on population parameters of this insect than standard diet at least in this study conditions.

Habrobracon hebetor Say (Hym.: Braconidae) is one of the most important larval parasitoids that has been exposed to many pesticides. In this research, the biological effects of pesticides and herbal extracts on this wasp were investigated by contact and poisonous host methods. Bioassay tests of Biscaya Ò, Neem azal Ò and Tondexir Ò on this parasitoid wasp was determined in laboratory conditions (8: 16 h L: D, 65% humidity and 25 ± 2°C) in 5 replicates and each replicate with 30 wasps at contact method. The LC50 of these treatments in contact method were 0.185, 1.16 and 122.070 mg/l, respectively, and in the poisonous host method on the laboratory larval host, Ephestia kuhniella Zeller (Lep.: Pyralidae), were 5.388, 68.97 and 1.997 mg/l, respectively. The highest growth period after control (25.95 ± 0.79 days) was related to Tondexir Ò in contact method with lethal dose (22.52 ± 0.99 days). The highest longevity of female wasps was related to Tondexir Ò in the sub lethal dose by contact method (30.39 ± 0.27 days) and the highest longevity of male wasps were related to sub lethal dose of Neem azal Ò in contact method (20.85 ±0.31 days). The highest numbers of eggs belonged to lethal dose of Tondexir Ò in contact method (245.14 ± 4.18). The results of this study showed that the use of Tondexir ® had the least effect on growth factors of this wasp.

In order to control Ennomus quercinaria, toxicity of different concentrations of Bacillus thuringiensis on was studied against the larvae of this pest to estimate LC50 levels of this biopesticide in this study.Laboratory evaluations by dipping method indicated more sensitivity of second instar larvae than the first ones, so that LC50 values of 2.14 and 0.6 ppm were calculated for the first and second instar larvae, respectively. Then, three calculated concentrations (1, 2, 3 ppm) of B. thuringiensis were sprayed on 2-year-oldParrotia seedlings using a back mounted sprayer, followed by releasing 30 second instar larvae on the seedlings. Results of LSD test showed significant differences in the mortality of second instar larvae between the control (water) and each of the three B. thuringiensis concentrations (p<0.01). The highest mortality rate (62%) caused by a concentration of 2 ppm. In the field conditions, B. thuringiensis caused 35% mortality versus a mortality rate of 2.8% in the control. The results of this study can be an important step in introducing a low-risk and healthy compound for pest control in the forest ecosystem and its beneficial insects.