Journal of Entomological Society of Iran
Year:2018 | Volume:38 | Issue:2 (74)|Papers Count:11

The inclination of rice growers towards double cropping system has raised new concerns about changes in pest biological parameters and the excessive release of pesticides in the environment. In this study, some biological traits of the overwintering larvae of Chilo suppressalis (Walker) was compared between single and double cropping rice fields in the northern Iran during 2016 and 2017. Under the same geographical locality, a significantly higher density of the overwintering larvae was observed in double cropping fields during November-March of both years, while larval mortality was lower in double cropping fields. The larvae collected from double cropping fields had significantly wider head capsules and tended to be heavier than those from single cropping ones. Additionally, both male and female pupae collected from double cropping fields had significantly higher body mass than those from single cropping fields. A significant increase in the number of days required for pupation of the overwintering larvae was observed under double cropping system. However, the adult moths emerged from these pupae were significantly higher fecund than those reared from single cropping fields. Results of this study highlight significant changes in some biological traits of C. suppressalis under double cropping system. At least, some of these changes are expected to affect the level of crop damage in the next growing season and thereby, demand higher rates of pesticides for satisfactory management of the pest. Therefore, further studies are needed to explore the pest status and management of C. suppressalis under double cropping system.

Aphis gossypii Glover is considered as the most important polyphagous pest of a wide range of economically important plants in fields and greenhouses. In this study, the demography of cotton aphid, reared on six different host plants, including cucumber (Cucumis sativus L. var. Beith Alpha), tomato (Solanum lycopersicum var. Falat111), eggplant (Solanum melongena var. Yummy), okra (Abelmoschus esculentus var. Clemson Spineless), squash (Cucurbita pepo var. Hybrid Rajai), and pepper (Capsicum annuumvar. Bertene) was investigated using the age-stage, two-sex life table under microcosm conditions (23± 2° C and 70± 5% RH and a photoperiod of 16L: 8D h). The results revealed the differential effect of host plants on developmental duration, fecundity, and life table parameters of A. gossypii. The shortest nymphal duration (4. 57± 0. 177 days), the longest adult longevity (21. 87± 0. 184 days), the highest fecundity (73. 6± 0. 85 offspring/female), the highest intrinsic rate of increase (r) (0. 369± 0. 006 day-1) and the lowest mean generation time (T) (11. 646± 0. 202 days) of the aphid were obtained on squash. Furthermore, the results of the population projection revealed that the population growth of cotton aphid was higher on squash, compared to other host plants. These findings suggested that squash as the most suitable host plant for A. gossypii among the tested hosts.

We established and characterized a hymenopteran cell line from Arge ochropus for the first time. The established cell line was named AOU-G, standing for Arge ochropus University of Guilan. This cell line was derived from larval hemocytes of the rose sawfly whose characteristics and susceptibility to 20-hydroxyecdysone have been verified. We also noticed four types of hemocytes such as prohemocytes, plasmatocytes, granulocytes and oenocytes. The population doubling time of 20th passage of this new cell line in EX-cell or Grace medium at 28˚ C was 3 and 5 days, respectively. Biochemical studies in rose sawfly hemocytes showed considerable changes in some component: protein, glucose, cholesterol and urea. Except urea, all components were significantly reduced. We suggest that the AOU-G cell line as a productive new cell line that could be very useful in studies concerning bio-insecticides, immunology, endocrinology and toxicology.

Growing concerns of chemical pesticides lead the researchers around the world to find new avenues of insect pest control. Plant essential oils could be considered as one of the ecofriendly alternative for synthetic pesticides. In the present research, lethal and sublethal toxicity of Ziziphora clinopodioides Lam. and Ferula gummosa L. oils were studied against Plodia interpunctella (Hü bner). Results of bioassays showed that the estimated LC50 values of Z. clinopodioides and F. gummosa oils were 96. 98 and 49. 82 µ l/l air against one-day-old eggs and 40. 68 and 38. 91 µ l/l air for four-day-old eggs, respectively. LC50 values of Z. clinopodioides and F. gummosa oils were 10. 12 and 7. 49 µ l/l air on 1st instar larvae and 34. 11 and 12. 66 µ l/l air on 5th instar larvae, respectively. Moreover, Z. clinopodioides oil (LC50 = 25. 77 µ l/l air) was significantly more toxic than F. gummosa oil (LC50 = 28. 72 µ l/l air) to the adult moths. Based on the estimated LT50 values, it was determined that persistency of Z. clinopodioides and F. gummosa oils were 6. 31 and 7. 56 days, respectively. Increasing the oils concentration resulted in a significant increase in oviposition deterrenc. Also, hematology assays indicated that total hemocyte population of one-day-old 5th instar larvae was decreased as the oils concentration and exposure time increased. Collectively, results of the present study demonstrated the potent fumigant toxicity of Z. clinopodioides and F. gummosa oils against P. interpunctella. Also, tests on different growth and developmental stages of the studied moth showed clearly differential susceptibility levels of this pest against the oils.

A faunistic survey was carried out to study on parasitoid wasps of the genus Encarsia Fö rster in the southern part of the Caspian Sea during 2013-2016. In this study, 12 species of Encarsia were identified, of which Encarsia gennaroi Pedata & Giorgini, 2017 is newly recorded from Iran and six, three and two species are considered to be new records for the Mazandaran, Golestan and Guilan provinces, respectively. Several new host records for Encarsia species are also reported. Moreover, an identification key for the studied female specimens of Encarsia is provided. The identified Encarsia species are as follows: E. aleurochitonis (Mercet, 1931), E. aurantii (Howard), E. azimi Hayat, E. berlesei (Howard), E. brimblecombei (Girault), E. citrina (Craw), E. fasciata (Malenotti), E. formosa Gahan, E. gennaroi Pedata & Giorgini, E. inaron (Walker), E. inquirenda (Silvestri), E. lutea (Masi).

Sugarcane whitefly, Neomaskellia andropogonis Corbett is one of the relatively new pests of sugarcane fields in Iran. Control of this pest is an arduous work if its populations reach outbreak level. It seems using chemical insecticides along with resistant varieties can reduce pest population to an acceptable level after reaching economic injury level. In this study, the efficacy of three insecticides with different mode of actions including; deltamethrin, dinotefuran, and spiromesifen was examined on survival percentage of different life stages of sugarcane whitefly on IRC99-02 and CP69-1062 varieties of sugarcane. Among evaluated insecticides, deltamethrin had the most toxic effect against the adults of N. andropogonis with LC50 values of 39 and 62 ppm on IRC99-02 and CP69-1062 varieties, respectively. The higher concentrations of all insecticides significantly decreased egg hatching rate, survival percentage of nymphs, pupae and adults on both sugarcane varieties. The results revealed that evaluated insecticides, considering their different mode of actions, can be used alternatively in integrated management of the sugarcane whitefly along with the mentioned sugarcane varieties. However, in order to confirm these findings, complementary experiments regarding ecological risk assessment and determination of insecticides MRLs in yield are necessary.

The Braconinae fauna of Kerman province (South-Eastern Iran) was studied from 2013 to 2017. A total of 23 species belonging to five genera were identified, of which three species, Bracon (Bracon) speerschneideri Schmiedeknecht, 1897, B. (Ophthalmobracon) lissothorax Tobias, 1967 and B. (O. ) nocturnus (Tobias, 1962) are recorded for the first time for the fauna of Iran.

Plant bugs of Miridae (Hemiptera: Heteroptera) are one of the most species rich families of insects, with nearly 11020 described species (Cassis & Schuh, 2012). This family includes eight subfamilies. The subfamily Mirinae comprises many species and genera. The genus Camponotidea belongs to the subfamily Mirinae, with the following taxonomic characteristics; body shape elongated, like a large ant, similar to the Messor Forel or Camponotus Mayr (Hymenoptera: Formicidae) (Wagner, 1974), abdomen oval, rostrum short, reaches to the front or middle coxa, body color black or brownish. Only two species, including C. fieberi and C. saundersi has been recognized so far in this genus around the world, occurring in the Mediterranean region (Puton, 1874, Reuter, 1879, Tamanini, 1981, Wagner, 1974). Linnavuori in 2009 reported C. fieberi from the Azerbaijan-e Gharbi, Iran (Linnavuori, 2009). This is the first report of C. saundersi from Iran.

Eulophidae is a large family of hymenoptera with over 4470 described species in 297 genera (Noyes, 2008). This family were introduced for the first time by Westwood (1840). Studies on Eulophid species of Iran include a list of 106 species belonging to 37 genera reported by Talebi et al. (2011). This family is divided into four sub-families including Eulophinae, Euderinae, Entedoninae and Tetrastichinae (Gibson et al., 1999). Eulophids have scattered in all tropical and temperate regions worldwide. Many species of Eulophidae have been identified as biological agents (Gauthier et al., 2000). The majority of species in this family are parasitoids but there are a few phytophagous or predatory species. Parasitoids species can attack eggs, larvae, pupae or adult stages (Gauthier et al., 2000). In this paper, we report a new specious of this family from Iran.

In an online updated site (ThripsWiki, 2018) only 10 genera of the order Thysanoptera have more than 100 species of which the genus Thrips L. with 294 extant species is the largest one. Minaei et al., (2007) provided an information on four genera of Thrips genus-group in Iran. An illustrated key to 33 species of the genus has recently been prepared by Mirab-balou (2016a). A total of 34 species of the genus Thrips have hitherto been recorded from Iran (Mirab-balou, 2016b) and another species of the genus is here newly recorded and illustrated. Thrips specimens discussed in this paper were macerated in 5% NaOH solution for 4-5 hours. The specimens were then mounted onto slides in Hoyer’ s medium using the protocol described by Mound and Kibby (1998). The observations on structure were made using an Olympus BX51 phase-contrast microscope. Photomicrographs and measurements were made using this microscope with DP27 digital camera and cellSens software. Terminology follows that of Mound and Masumoto (2005). The slides are deposited in the Department of Plant Protection, College of Agriculture, Shiraz University, Shiraz, Iran.