PLANT PEST RESEARCH
Year:2015 | Volume:5 | Issue:2|Papers Count:7

The elm aphid, Tinocallis nevskyi (Hemiptera: Aphididae) is an important pest of elm trees in Shahrekord. In addition to direct damage through feeding and reducing plant vigor, the aphid excretes considerable amounts of honeydew, creating a nuisance, especially in recreational areas. Considering growing concerns about using chemical pesticides in urban areas, it is necessary to apply other pest control tactics such as biological control. In order to collect natural enemies of the aphid and determine their seasonal fluctuations, weekly samplings were performed during 2002-2003. Seasonal population fluctuations of the aphid and its natural enemies were also compared. Identified natural enemies were as follow: Trioxys pallidus as a hymenopteran parasitoid, Erythraeus (Erythraeus) hypertrichotus as a parasititic mite, 12 ladybird species from nine genus (Clitostethus, Stethorus, Hippodamia, Oenopia, Chilocorus, Exochomus, Adalia, Coccinella, Scymnus), five dipteran species from Chamaemyiidae and Syrphidae and five hemipteran species from Miridae, Antocoridae and Lygaeidae as predators. The total predator population peak nearly coincided with that of the aphid, but there was no synchrony between seasonal fluctuations of the aphid and its parasitoid.

In this investigation, three concentrations of methyl Jasmonate, MeJa (0.01, 0.1 and 1 mM) and the control (distilled water, ethanol 96% and Tween-20 in foliar spray method, distilled water and ethanol 96% in seed priming method) with two different methods of foliar application and seed priming was used and their effects on wheat (cv. Sardari) resistance to the Russian wheat aphid, Diuraphis noxia (Hemiptera: Aphididae), was investigated. Analysis of variance indicated that the total nymphal development time was increased significantly in the 0.01 and 1 mM MeJa treated plants in foliar spray method. In seed priming method, the 1 mM MeJa significantly increased the total nymphal development time. Additionally, the pre-reproductive period was lengthened in plants treated with 0.1 mM MeJa in comparison with the control plants in foliar spray method. Moreover, in both methods, the reproductive period was significantly short on all the treated plants compared to the control plants. There was no significant difference in post- reproductive period between the treatments and the control in the both methods. Further, the mean number of offspring produced per female was significantly less on all treated plants than that on control plants in both methods. Furthermore, all the concentrations of MeJa reduced the total longevity in foliar spray method. In seed priming method, the total longevity was significantly short on 0.1 and 1 mM MeJa treated plants compared to the control plants.

Rice striped stem borer (RSSB) is the most important insect damaging rice crops. The quantification of damages and yield loss caused by this pest is crucial in IPM. In order to determine rice striped stem borer damages on native varieties of Hashemi, experiments were conducted at the Rice Research Institute in 2011. The pest damages could be found in the form of dead hearts and white heads. The relationship between nutrition, damages and rice yield losses were also assessed. This study was carried out in a randomized complete block design with 7 treatments and 3 replications of artificially contaminated rice with eggs masses in cages with dimensions of 2×1×2 m (height × width× length). Treatments were performed at vegetative stage of rice by installing one, three and five egg masses (45-50 numbers) on the leaf blade and in the reproductive stage on leaf sheath with similar density. A control was considered alongside treatments. The results of this study showed that in the vegetative stage of rice plants, five eggs masses treatments caused infection with 9.44 percent of dead hearts with 3828 kg per hectare and 6.17 percent yield loss it compared to the control. Also in the reproductive stage, this treatment showed the lowest yield level with 3492.48 kg per hectare. In the above mentioned treatments, the greatest amount of white heads with 16.88 percent, and grain yield crop loss by 14.4 percent was observed as compared to the control. The yield of the control was 4080 kg per hectare. The results showed that for one percentage of dead hearts contamination up to 30 kg and for one percentage of white heads up to 50 kg of yield loss was observed by stem borer infestation.

Poplar leaf aphid, Chaitophorus populi Koch (Hemiptera: Aphididae) is one of the important sucking pests that cause direct and indirect damage on poplar trees (Populus spp.) in Iran and East Azarbaijan province. In this study antibiosis resistance of 13 poplar clones belonging to the three species against poplar leaf aphid under laboratory conditions (25±2oC, 55 ± 5% relative humidity and 16L: 8D h photoperiod) was investigated in 2008. Ten rooted cuttings of each clone (with 20 cm long and 1.5 cm in diameter) were used for testing. By releasing one-day-old nymphs on cuttings, the process of their life until natural death of adult aphid such as establishment, feeding, developmental time, survival rate, pre-reproductive time and the number of progeny was determined. After collecting the necessary data, intrinsic rate of natural increase (rm) was calculated. The ANOVA of results indicated that there is significant difference among the effects of poplar clones on rm. Based on compared rm means, all five clone of white poplar, P. alba due to having higher rm-values (0.271 to 0.302) were susceptible clones to the aphid and among them, P. a 82.5 with the highest rm was the most susceptible clone of P. alba species. Among the P. nigra clones, p. n 82.4, p. n 82.8 and p. n 56.12 were more susceptible to the pest, respectively. While p. n 82.7 and p. n 62.154 clones were relatively resistant to pest. Finally, two others (p. n62.191 and p. n82.6 clones) with the only one clone of P. euramericana, given the minimal impact on rm-value (0.0591 to 0.0717) were determined as the most resistsnt among tested clones.

Today different geostatistical techniques being widely used to predict the spatial variations of the pests. The pod borer, Heliothis viriplaca Huf. is the most important pest of chickpea, Cicer arietinum L. in the west areas of Iran. In this study in order to achieve the goal of Site Specific Integrated Pest Management (SSIPM) to reduce the application of chemical insecticides, geostatistical characteristics of the infestation pods by pest were studied in Delfan (Golestane & Dehsefied villages). For this, two chickpea fields (variety Bunij of Kermanshah) each about 2 hectares, were chosen. In each field, 88 points or stations with the certain coordination were marked, and in each station, 3 plants were chosen as sample unit, then the number of infested pods was determined. After data normalization, they were analyzed using Gs+ version 5.1. Semivariograms were calculated to model the change in spatial correlation with increasing distance between samples. Results showed that the spatial distribution of the pods infestation by H. viriplaca was described by an exponential model for five out of eight data sets, a spherical model for two out of eight data sets. One data set was fitted to any model due to pure nugget effect. The range of spatial dependence varied from 311 to 933 m, and the degree of spatial dependence (DD= C/(C0+C)) varied from 0.501 to 0.547.

In this research, fumigant toxicity and repellency of essential oil of sweet lemon, Citrus limetta fruit peels were investigated against sawtoothed grain beetle Oryzaephilus surinamensis, rice weevil Sitophilus oryzae, lesser grain borer, Rhizopertha dominica and confused flour beetle, Tribolium confusum. In fumigant toxicity assays, in addition to common bioassays and probit analysis of the data, two indices of effective concentration and mortality were used for evaluating the essential oil efficacy. In the first method, the minimum concentrations that caused effective mortality (over 90%) were determined against the four pests. In the second one, two constant concentrations; low (0-50% mortality) and high (50-100% mortality) were tested to evaluate different susceptibility of these four insects. Repellency of the essential oil was estimated by applying four concentrations; 0.1, 0.2, 0.41 and 0.83 μl/cm2. LC50 values were 208.9, 248.99, 328.66 and 257.212 μl/L air for the pests, respectively, demonstrating the more sensitivity of sawtoothed grain beetle. In the assays of the concentration as an index, estimated concentrations for the species were 600 (100% mortality), 625 (95% mortality), 700 (100% mortality) and 375 µl/L air (92.5% mortality), respectively. In the assays of the mortality as an index, the low concentration (175 μl/L air) caused 42.5±13.1, 20±0, 15±6.4 and 12.5±9.4% mortality and the high concentration (350 μl/L air) caused 72.5±4.7, 65±6.5, 52.5±8.5 and 72.5±8.5% mortality, respectively. The mean repellencies of four concentrations at three hours after treatment were 61.6±15.9, 49.9±9.6, 48.3±16 and 83.3±4.1%, respectively. The results of this research revealed the average efficacy of citrus lemon peels essential oil for controlling these coleopteran stored products pests.

Fauna and biodiversity of laelapid mites (Acari: Mesostigmata: Laelapidae) were studied in south of Guilan Province, during 2012–2013. In this research, 18 species belong to eight genera were collected and identified, among them two species were new records for science, one species was new record for Iran and six species were new records for Guilan Province mite fauna. Biodiversity indexes on the basis of species richness were calculated using standard formulas and ecological methodology software. Data processing was performed using SAS software. The estimated Shannon-Wiener’s diversity index and Margalef index showed the significant difference among studied habitats and seasons. The highest and lowest values of Shannon-Wiener’s diversity index and Margalef index were calculated for forest (0.9) and (2.7) and field areas (0.8) and (1.7), respectively. Moreover, among different seasons, spring with 0.94 and 3.2 and winter with 0.8 and 1.4, respectively had greatest and lowest values. According to finding of this study, in fields habitats Gaeolaelaps aculeifer (23%), G. praesternalis (15%), Cosmolaelaps vacua (13%) and C. lutegiensis (11%), were the most abundant species. The evenness index was higher in forest areas (1.5) than field’s habitats (1.3). Collected species from forest areas had almost equal relative abundance.