فصلنامه تحقیقات حشره شناسی
سال چهاردهم شماره 2 (پیاپی 54، تابستان 1401)

The common pistachio psyllid, Agonoscena pistaciae is a key pest of pistachio trees in Iran. Both adults and nymphs cause great economic damages by sucking sap and produce large amounts of honeydew. The continued use of pesticides to control A. pistaciae leads to resistant of its populations to several pesticides and inefficiencies in biological control, resulting in pest outbreaks.  In the present study, Field experiments were conducted during 2019–2020 on pistachio trees, the Ahmad Aghaei cultivar, in Kerman, Yazd, Qom, Khorasan Razavi, Khorasan Shomali, Khorasan Jonoubi, Semnan, Fars, Markazi, and Esfahan provinces to evaluate the effect of DG oil on A. pistaciae in comparison with the two pesticides Spirotetramat and Dinotefuran. The sampling was carried out a day before spraying and 1, 3, 7, 14, 21 and 28 days post-treatment. The experiments were conducted based on complete randomized blocks with four treatments (included the recommended dosage of DG oil (0.5 liter1000 liter water/ha), Spirotetramat (1 liter/1000 liter water/ha), Dinotefuran (0.75 kg/ 1000 liter water/ha and control (Spraying with water) and four replications. Results showed a high performance of DG oil starting from the first day after spraying and Continued for four weeks. Compared to Spirotetramat and Dinotofuran, DG oil had a suitable and satisfied performance. DG oil is recommended as the most environment-friendly and IPM compatible compound to control A. pistaciae.

Stressors in bees affect them individually as well as at the colony level. Changes in beekeeping practice, such as inspection on a warm day or heating hives on cool days can be stressful to bee colonies. Hive transport and inspection also may cause stress. In addition, warm humid air conditions or sudden change of temperature by pulling air through the base of the hive, as well as the presence of natural or newly introduced enemies (e.g. Vespa velutina, or hive beetles), or sudden alterations of signals around the hives such as constructions or posters may be stressful to bees. Stress signals are received in the brain and free radical formation in cells affects cell metabolism and may cause a reaction to the stressors. The cell endoplasmic reticulum (ER) in response to stress can cause cell apoptosis. Gene expression may respond through transcription factors in cells and may repair DNA by antioxidant pathways. Epigenetic responses by DNA methylation may affect cells and the germ line in reaction to stress and their effects in queen reproduction can produce adaptation in their next generation. Following is a description of general effects of stress on Apis mellifera, Apis florea, Bombus terrestris, Blastophaga psenes and parasitic insects.

The saw-toothed grain beetles, Oryzaephilus surinamensis L. (col., Silvanidae) is one of the most important pests that damage to stored products in Iran. The efficacies of three IGR insecticides, Tebufenozide, Chromafenozide and Lufox® have been evaluated on eggs and larval stages of O. surinamensis during this study. The Efficiencies of these  insecticides have been  considered by different concentrations on one day old eggs, 5 day old (young) and 19 day-old  larvae. The results of bioassay tests showed that Lufox® has the most and Tebufenozide has the least efficacy on eggs and larval stages. Also, the mortality effects directly increased by raising the IGRs concentrations. In the other aspect, the eggs of O. surinamensis were the most susceptible stage in response to IGR insecticides. The LT50 value of Lufox® was shorter than that of Tebufenozide and Chromafenozide. Finally the high toxicity and strongest efficiency can be resulted by using of Lufox® in comparison with Tebufenozide and Chromafenozide.

The wasp Habrobracon hebetor (Say) (Hym.: Braconidae) is an external and social larve stage parasitoid of a large number of pests, including the raisin moth Ephestia figulilella (Gregson) (Lep.: Pyralidae). Wasps of the Braconidae family are one of the most important pest parasitoids. The performance of parasitoids can be affected by use of insecticides. In order to simultaneously use of biological control agents and pesticides in pest management, it is necessary to know the effect of pesticides on biological control agents. In this study, the side effects of Lufenuron and Hexaflumuron on the biological parameters of the parasitoid wasp H. hebetor in laboratory conditions and the host flour moth Ephestia kuehniella (Zeller) (Lep.,: Pyralidae) in the form of a two-factor randomized complete design, the first factor is the type of insecticide (Lufenuron and Hexaflumuron each with a consumption concentration of 500ppm) and the second factor is the wasp life stage including three stages (larve, pupa and adult insect) were performed with three repetitions (5pairs of wasps per repetition). Hexaflumuron and Lufenuron insecticides are chitin synthesis inhibitors and belong to the group of insect growth regulators. Consumption of these two compounds disrupts the normal activity of the internal secretory systems and disrupts the growth and development of insects. The results of the present study showed that the insecticides Lufenuron and Hexaflumuron have an effect on the life span parameters, the average total egg, the number of daily eggs, the hatching rate and the sexual population ratio of the wasp H. hebetor. Both insecticides caused a decrease in the mentioned parameters, and this decrease was more observed in Hexaflumuron insecticide than in Lufenuron insecticide. Also, the life stages of the insect affected the above parameters and minimal effects and changes were obtained in the pupal stage.

The stimulating effect of low concentrations of chemicals on organisms is called hormesis. Hormesis is recognized as an adaptive mechanism by which mild stressors can enhance the protective capacity of the host, while the same factors are harmful or lethal at excessive levels. Insects in agricultural ecosystems are exposed to many stressors (chemicals, heat, and lack of nutrients) that are often at low levels. The stimulatory (hormetic) effects of insect exposure to mild stress are now well known, with implications for insect management, structure and ecological function in agricultural ecosystems. Many biotic and abiotic processes also spatially and temporally change the pesticide dose to which an insect is exposed in the field. Therefore, hormesis is an important phenomenon in pest management. However, this phenomenon has received relatively little attention from insect toxicologists in Iran. Considering the importance of the hormesis, this article has investigated the hormetic effects of various factors in insects according to previous researches.

Xanthogaleruca luteola (Coleoptera: Chrysomelidae) is considered as one of the most important pests of Ulmus trees at the adult insect stage, especially at the larval stages. The effect of toxicity and nutritional indicators of essential oils of Cinnamomum zeylanicum L., Rosmarinus officinalis L. and Lavandula angustifolia L. on different biological stages of X. luteola investigated under standard environmental conditions. Four replications were considered and after 24 hours, losses were counted. LC50 values for toxicity of C. zeylanicum L., R. officinalis L. and L. angustifolia L. essential oils on adult X. luteola were estimated to be 11.57, 28.83 and 737.87 ppm, respectively, indicating that Cinnamomum essential oil is more toxic than other essential oils. With increasing concentrations of essential oils, eating indicators of second-instar larvae reduced. The relative consumption rate (RCR) of second-instar larvae in Cinnamomum essential oil at concentrations of LC25, LC35 and LC50 showed a significant difference with the control treatment at the level of 5%. The results of essential oil analysis showed that cinnamaldehyde (91.8%), 1, 8-cinnamol (37.8%) and borneol (8.4%) are the predominant compounds in C. zeylanicum L., R. officinalis L. and L. angustifolia L. essential oils, respectively. Increased nutritional inhibition in Cinnamomum essential oil compared to R. officinalis L. and L. angustifolia L. essential oils can be attributed to the strong toxicity of cinnamaldehyde available in this essential oil. The study results show that Cinnamomum essential oil is a more suitable option for controlling this pest than R. officinalis L. and L. angustifolia L. essential oils.