فصلنامه تحقیقات آفات گیاهی
سال دوم شماره 2 (تابستان 1391)

Effects of fungus Lecanicillium longisporum was studied on reproductive capacity of Encarsia formosa at laboratory conditions. Fungal infection on whiteflies was carried out using 9.5×105 conidia/ml of fungus on the third instar of whitefly exposing to parasitoid at four different time intervals; 0, 24, 48 and 72 hours post-inoculation. Longevity, pre-oviposition period, oviposition period and other parameters were evaluated and compared. Results showed that the intrinsic rate of increase (rm) for control was 0.203. There was a significant decreasing trend on the intrinsic rate of population decrease at different time intervals. Other life table parameters consist of net reproductive ratio (R0), gross reproductive rate (GRR), cohort generation time (T), and finite rate of increase (λ) for control were 41.75, 43.42, 18.32 and 1.22, respectively. The results indicated that infected hosts caused decreased reproductive potential of parasitoids.

It is necessary to have enough knowledge on the preferred prey of the insect predators before to mass rearing and using them in pest control programs. Prey preference of four days old Aphidoletes aphidomyza Rondani larvae to three prey species as Aphis craccivora Koch, Aphis gosssypii Goeze and Brevicoryne brassicae L. was evaluated under laboratory conditions (22±1°C and 70±5% RH, with a 16:8 L: D hours photoperiod). The results showed that the larvae of A. aphidimyza preferred B. brassicae (more than 40%) to A. gosssypii and A. craccivora (P <0.0001). The manly´s α index of B. brassicae, A. gossypii and A. craccivora were also 0.498, 0.33 and 0.168, respectively indicating the same trend of prey preference. The results showed that the larvae of this predator play an important role in controlling of B. brassicae rather than A. gossypii and A. craccivora.

Laelapid mites are one of the most important predators of small arthropods and nematodes in soil habitats. During 2010-2011, a faunistic survey was conducted for collection and identification of edaphic laelapid mites (Laelapidae Berlese, 1892) in Jiroft Township. A total of 12 species belonging to six genera were collected and identified. An identification key is provided for Jiroft Laelapid mite species. List of identified species is as follows: A) Genus Haemolaelaps Berlese [1. Haemolaelaps casalis (Berlese)] B) Genus Gaeolaelaps Evans & Till [2. Gaeolaelaps nolli (Karg), 3. G. queenslandica (Womersley), 4. G. angustiscutata Willmann, 5. - G. aculeifer (Canestrini), 6. G. kargi Costa, 7. G. minor Costa] C) Genus Cosmolaelaps Berlese [8. Cosmolaelaps vacua (Michael), 9. C. lutegiensis (Shcherbek)]. D) Genus Laelaspis Berlese [10. Laelaspis astronomica (Koch)]. E) Genus Pneumolaelaps Berlese [11. Pneumolaelaps sclerotarsa Costa]. F) Genus Euandrolaelaps Bregetova [12. Euandrolaelaps karawaiewi (Berlese)]

A number of soil samples were collected from different districts of Kohgiluyeh and Boyer Ahmad province to study the entomopathogenic nematodes in 2010. Steinernema carpocapsae (Weiser) was isolated from the collected soil. Due to limitations of chemical pesticides uses against storage pests, a study performed to determine the effectiveness of the isolated entomopathogenic nematode on Indian moth, Plodia interpunctella (Huebner), a major pest of stored products. In this experiment, larval and pupal stages of Indian moth were exposed to concentrations of 0, 250, 500, 1000 and 2000 infective juvenile/ml of distilled water at 27˚C. Insects were placed on filter paper impregnated with 1 ml of nematode suspension in Petri dishes (9 cm in diameter) for 2 days. Number of dead insects was counted every 24 hrs. The highest mortality was recorded after 48 hrs which was 99% pupal stage at the concentration 1000 IJs, whereas it was 2000 IJs for the larval stage which caused a total mortality of the tested insect. In this study, pupal stage was more sensitive than larval stage to lower concentration of entomopathogenic nematodes.

Olive psylla, Euphyllura straminea Loginova (Hemi: Aphalaridae) and the alternate bearing are two important factors that lead to decrease of yield in Tarom olive orchards in north of Zanjan province. In order to achieve to appropriate method of pest control and investigation on effect of pruning and this pest on alternate bearing of olive trees, two above factors were examined in the base of factorial trials in a randomized complete block design with three replications during 1999-2001. Results showed that, spring pruning decreased the pest density and increased the rate of drying mesocarp oil with significant effect (α=0.05) comparing to autumn pruning and control. Also, olive psylla decreased the rate of drying mesocarp oil (about three percent, equal to 30 lit/ha) with significant difference (α=0.05) in comparison to control. On the base of these results, the spring pruning is recommended in the olive orchards. Results of this study indicated that, in spite of pruning and psylla decreased the alternate bearing of olive trees during the three years, but this decrease had no significant difference.

The Pistachio twig borer moth, Kermania pistaciella (Lepidoptera: Tineidae) is one of the most important pests of Pistachio in Iran. In this study the effects of type, side of trap placement on the tree canopy and location of pheromone traps in capturing the adults were evaluated. The experiment was designed in factorial trails in a completely randomized design including two shapes of traps (Delta and Funnel) and two cardinal directions (north and south) in Pistachio orchards of Shahinshahr Meimeh district (Isfahan, Iran) in three locations. The distance between traps was 50 meters with two replications and they were checked from late March until May 2012 once a week and captured adult moths were counted. According to the results obtained, start, peak and end of male moth capture in pheromone traps were 8 and 28 of April and 19 May, respectively. Funnel trap captured significantly more adults than Delta trap and no significant difference were found between cardinal directions and orchard locations in capturing the adults.

Various cell types, total and differential counts of hemocytes in different life stages of larva, pupa and adult of elm leaf beetle Xanthogaleruca luteola were investigated. Five types of hemocytes based on the morphology were identified; Prohemocyte, Plasmatocyte, Granulocyte, Oenocytoid and Spherolucyte. Differential count showed the plasmatocyte as the most abundant cell type in Ist, IInd, III larval instar and adult insect as 39, 39.5, 46.5 and 44.5 percent, while the granulocyte was the most abundant cell type (59.5 percent) in pupa. Total hemocyte count was calculated and it was found to be 620±40.4, 940±50.3, 1253.3±29, 1956.6±34.8 and 1326.6±43.3 in Ist, IInd, III larval instar, pupa and adult insect. The identification of cell types and their characteristics could be used as a basse for further investigation on the immunological system of this important pest.

The Streblote siva Lefebrve. (Lep: Lasiocampidae) is reported as a leaf-eating pest invaded Conocarpus trees in Khuzestan, Bushehr and Hormozgan provinces of Iran. The plant has been imported from neighboring Arabic countries to Iran and has been widely planted at urban landscapes in the mentioned provinces. The moth has 5 larval instars and severly feed on the host plant leaves, especially Conocarpus, causing failure in plant development. S. siva has complete 1-2 generations per year.Vast cultivation of Conocarpustrees in south and south western provinces of Iran may cause this moth to be a key pest not only for Conocarpus plants, but also for Christian thorn trees. This report is a precaution against the pest outbreak for researchers and authorities.