نشریه نامه انجمن حشره شناسی ایران
سال سی و چهارم شماره 4 (پیاپی 62، زمستان 1393)

The sugar beet weevil, Lixus incanescens Boheman, is an important insect pest of sugar beet, Beta vulgaris L., in many parts of Iran. Strip cropping of sugar beet and alfalfa, Medicago sativa L., is a suitable strategy for improving the effectiveness of biocontrol agents of the sugar beet weevil. In this research, the population density of the sugar beet weevil and diversity of its natural enemies were studied in the strip cropping of sugar beet-alfalfa in comparison with the monoculture of sugar beet, in Juvein countryside, Khorasan Razavi province, from 2012 to 2013. In each sampling, the abundance of the sugar beet weevil and its natural enemies per plant were recorded. The densities of the sugar beet weevils in the strip cropping were significantly lower comparing to the monoculture. The larva of the hymenopteran parasitoid species Bracon intercessor Nees in both culture systems as well as seven egg predator species in strip cropping system and three egg predator species in the monoculture system were found. The percentage of larval parasitism and the densities of each predator in the strip cropping were significantly higher than the monoculture. The Shannon diversity index for the complexity of natural enemies in the strip cropping was higher comparing to the monoculture. The value of Morisita-Horn index for the complexity of the natural enemies between the experimental sugar beet cropping systems was calculated as 0.923. Based on these results, we have concluded that the strip cropping of sugar beet-alfalfa leads to higher diversity of natural enemies of the sugar beet weevil and lower population density of L. incanescens. In addition, the quantification of the predators’ species richness and abundance in the sugar beet fields remains as an effective method to improve the management of the sugar beet weevil.

Between 2010 and 2011, spatial distribution and fixed precision sequential sampling plans were determined for two aphids, Rhopalosiphum maidis F. and Schizaphis graminum R., in wheat fields in Badjgah countryside of Iranian Fars province. For this purpose, two fields of two hectares each were selected and sampled on weekly basis. Each sample consisted of 200 randomly selected wheat plants along with the total number of counted aphids. Based on RV, the best sample unit was four stems. This data was used to describe spatial distribution pattern of R. maidis and S. graminum by Taylor’s power law (TPL) and Iwao’s patchiness regression methods. The results indicated aggregated spatial distribution of aphid's populations in wheat fields, based on the mentioned methods. The TPL provided a better description of the aphid's spatial distribution. Since regression line slopes were not significantly different for S. graminum and R. maidis, the same Green model was proposed for both species. In this model, minimum numbers of samples were 20, 12 and 9 for precision levels of 0.15, 0.25 and 0.3, respectively. Comparing Green and conventional methods in 0.15, 0.25 and 0.3 precision levels showed that the number of required samples were reduced 77.8 ± 1.05, 78.3 ± 0.91 and 81.4 ± 0.81 percent, respectively. Based on Wilson and Room's model, when the mean populations of aphids were 1.6, 3.86 and 5.62, the proportion of infestation in the field were 0.5, 0.75 and 0.85, respectively. Therefore, by increasing the infestation percentage of the samples, the number of required samples will be reduced.

The economical loss from stored product pests and their resistance to phosphine and methyl bromide, necessitate replacing these chemicals with other compounds. The toxicity of ozone was evaluated on two important stored product insects, Sitophilus oryzae L. and Oryzaephilus surinamensis (L.). The insects were exposed to ozone in separate date, wheat and rice storehouses at the depths of 30, 40, 45 and 100 cm. The mortality was determined after 24 h of exposure. The results demonstrated a lower mortality caused by ozone in date compared to wheat and rice on S. oryzae and O. surinamensis. Treatments with ozone under different depths led to different levels of mortalities, but at 100 cm, mortality for both species were significant. Calculated omega square (w2) values showed that this criterion (w2) for the depth of the foodstuff (0.05) is more than the corresponding value (0.004). Therefore, depth of the foodstuff was more effective than the type of foodstuff on the pests’ mortalities. The relative median potency tests revealed higher LC50 values of ozone for S. oryzae and O. surinamensis in date comparing to the LC50values for wheat and rice at a depth of 100 cm.

Efficacy of the essential oil of the plant species Lavandula angustifolia on the mortality, physiology and biochemistry of diamondback moth, Plutella xylustella L., was studied under laboratory conditions (24 ± 2ºC, 75 ± 5% R.H. and 16 L: 8 D hours). The LC10, LC30 and LC50 values of the essential oil were estimated as 0.0857%, 0.270% and 0.599% (V/V), respectively. The repellency effect for the LC10 and LC30 concentrations on third instar larvae were 19.2 ± 3.61 and 34.29 ± 4.87, respectively. The approximate digestibility (AD), efficiency of conversion of ingested food (ECI), efficiency of conversion of digested food (ECD), relative growth rate (RGR) and relative consumption rate (RCR) for the treated larvae in three days showed significant differences compared with the controls. The effectiveness of plant essential oils on digestive enzymes, total protein, triglycerides, alkaline phosphatase, protease, lipase, alfa amylase, glutathione S-transferase and esterase were also significantly different. Our finding suggests that the essential oil of L. angustifolia can be efficiently used as a botanical insecticide.

Greenhouse whitefly, Trialeurodes vaporariorum (Westwood), is an important pest of greenhouse throughout the world that causes serious damage on agricultural products. In this research, some biological parameters of the pest were studied in four cucumber cultivars (Royal Sluis, Soltan, Negin and Vida) at two heights (60 and 90 cm) in a greenhouse at 19-26 °C and 80% ± 5 RH. The developmental time of all immature stages were 27.49 ± 0.34, 28.23 ± 0.3, 26.63 ± 0.24 and 27.44 ± 0.3 days, in all cultivars, respectively, but it was slightly longer at the height of 90 cm compared to 60 cm (28.65 ± 0.24 vs. 26.43 ± 0.14 days, respectively). The preimaginal mortality percent ranged from 4 to 7% in different treatments, although this difference was not significant. Female longevities were 27.9 ± 0.67, 21.35 ± 0.34, 26.71 ± 0.6 and 22 ± 0.46 days in the cultivars, respectively (P < 0.01). It was also averaged as 23.29 ± 0.4 and 26.4 ± 0.66 days at both heights. The number of eggs / female were 203.82 ± 4.89, 132.26 ± 3.57, 210.68 ± 5.31 and 162.79 ± 5.15 in different cultivars with an average of 167.66 ± 5.68 and 187.98 ± 4.75 in 90 and 60 cm (P < 0.01). The sex ratio showed no significance among the cultivars at all heights.

Olive fruit fly, Bactrocera oleae (Rossi), is one of the most injurious pests of the olive in Iran. Since its introduction to Iran, in 2004, it has caused considerable economic loss to the domestic olive industry, especially in the years when the climate is favorable to its activity. In this research, we evaluated the infestation rates of olive fruit fly in 22 imported and native olive cultivars at Tarom Olive Research Station, Zanjan, Iran, from 2005 through 2009. The first sampling was started at hard pitting time and continued until harvesting time in which 20-50 fruits were collected from each tree (replicate). Totally 60-150 fruits, from 3 replications, were carefully examined under stereomicroscope in the laboratory. Using the formula of Sqrt (x + 0.5), the data were transformed and subjected to analysis based on Randomized Complete Block Designs usingsoftware SAS, 9.0. The results revealed that among the four recommended cultivars for the region, the cultivar "Arbequina" showed the lowest rate of infestation, while "Konservolia"," Zard", and "Koroneiki" were the most susceptible cultivars due to their higher rates of infestation in 2005 (11.62%, 13.74% and 7.56%), 2007 (3.23%, 1.01% and 1.49%) and 2009 (10.03%, 34.75% and 15.10%), respectively. The cultivars "Lechin de sevilla" and "Manzanilla cacereña" were found to be unfavorable to olive fruit fly.

Greenhouses and urban landscapes provide favorable conditions for the development of scale insects. Scale insects are destructive pests on many species of ornamental plants. This study presents a list of 64 species of Coccomorpha belonging to six families reported on 72 ornamental plant species within 42 families. The scale insect families are as follows: Diaspididae (45 species), Pseudococcidae (11 species), Coccidae (5 species), Eriococcidae (1 species), Monophlebidae (1 species) and Rhizoecidae (1 species). The polyphagous species of Aspidiotus nerii Bouché, Chrysomphalus dictyospermi (Morgan), Coccus hesperidium (L.), Lepidosaphes ulmi (L.), Lopholeucaspis japonica (Cockerell), Parlatoria crypta McKenzie, Pa. oleae (Colvée), Phenacoccus solenopsis Tinsley, Planococcus citri (Risso), Pseudococcus viburni (Signoret), as well as the monophagous species Eriococcus spurius (Modeer), Leucaspis pusilla Löw, and Planococcus vovae (Nasonov) are among the most harmful scale insects in both greenhouses and urban landscapes of Iran.

During a survey on seed-feeding insects of legume plants (Fabaceae) of rangelands in the East-Azarbaijan province of Iran, some infested seeds of Vicia cappadocica (Fabaceae) were collected in Horand region (1500 meters above sea level). The specimens were reared in the entomological laboratory at 25 °C and 65% humidity. The emerged adult beetles were later identified as Perapion violaceum (Kirby, 1808) by Dr. Karel Schön (Czech Republic). This species is new record for the Iranian fauna.

During a survey on edaphic mite fauna of the superfamily Dermanyssoidea in the Lorestan’s provincial capital of Khorramabad, 16 species belonging to 12 genera and two families, Laelapidae and Hirstionyssidae, were collected and identified from 2012 through 2013. Here we record eight species new to the province of Lorestan, including the heteromprphic male of Cosmolaelaps vacua (Michael, 1891), which is a new record for Iran.

In the course of a faunistic survey on oribatid mites (Acari, Oribatida) of Caspian coast city of Rasht, Guilan province, the species Eremobelba geographica Berlese, 1908 of the family Eremobelbidae was collected and identified. This species is newly recorded from Iran and Asia.