Journal of Entomological Society of Iran
Year:2011 | Volume:30 | Issue:2 (47)|Papers Count:19

Effect of five soybean varieties (Sahar, JK, BP, Williams and L17) on life cycle and fecundity of the beet armyworm, Spodoptera exigua Hübner was evaluated at temperature of 25±1°C, 60±5% r.h. and a photoperiod of 16:8 (L:D) h. The preimaginal development period of males and females was longest on L17 (30.17±0.28 and 29.63±0.23 days) and shortest on BP and Sahar. The adult longevity of males and females was longest on Williams (13.86±1.14 and 20.20±1.12 days) and shortest on Sahar (9.36±0.59 and 12.75±0.69 days), respectively. The life span was longest on L17 (44.86±0.85 days) and shortest on Sahar (39.00±0.50 days). The highest percentage of egg and larval mortality was observed on L17 (73.48 and 39.35%, respectively), but the highest percentage of pupal mortality was on Sahar (12.50%). The lowest percentage mortality of egg (57.96%) and larval (10.81%) stages was obtained on Williams. The pupal weight of females was heaviest on Sahar (88.10±3.01 mg) and lightest on BP (73.00±4.18 mg) compared to the other varieties. The highest number of eggs laid per female per day was 58.19±4.53 on L17 and the lowest number of eggs was 37.91±3.01 on BP. The results showed that total number of eggs laid per female was highest on Williams (569.50 ±29.8 eggs) and lowest on Sahar (448.90±19.5 eggs). Knowledge of the biology of S. exigua on soybean varieties can aid us to detect and monitor the pest infestation, variety selection and crop breeding.

In this study, two fungus isolates Beauveria bassiana EUT105 and B. bassiana EUT116 were evaluated for production of aerial conidia on simple and complemented wheat, wheat flour, wheat bran, rice flour, rice bran, rice paddy, millet and corn flour using two phasic liquid-solid system. Data analysis showed that there are significant differences among treatments (simple media) in both isolates. In B. bassiana EUT105, the maximum and minimum productions were achieved on wheat bran, 2.3×1010 conidia/g and on rice paddy, 1.5×109 conidia/g of medium, respectively. In B. bassiana EUT116, wheat bran with 6.1×109 conidia/g and millet with 8×108 conidia/g had the maximum and minimum productions, respectively. Effect of adding nutritional complementary compounds to the growth media was significant in increasing of conidial yield. Related results showed that adding permeate increased the production but molasses did not it in comparison with control in both isolates. Wheat bran plus permeate had the maximum production, 5×1010 and 4.6×1010 conidia/g in B. bassiana EUT105 and EUT116, respectively and minimum production was obtained with rice flour plus molasses, 1.5×108 and 6×108conidia/g in B. bassiana EUT105 and EUT116, respectively.

Food choice in omnivorous animals is influenced by the balance of nutritional needs, food availability, and quality of a particular food items. Here, we study whether omnivorous onion thrips Thrips tabaci Lindeman (Thysanoptera: Thripidae) feed on the eggs of its competitor Tetranychus urticae Koch (Acari: Tetranychidae) when an alternative supplemental source is, or is not, available. Thrips were either fed a cucumber leaf alone, or this diet was supplemented with pollen, mite eggs, or both. We demonstrated that the supplemental food sources improved several fitness-determining traits of thrips with pollen being nutritionally superior to mite eggs. Pollen reduced the development time and increased the population growth of thrips compared to mite eggs. When both pollen and mite eggs were available, thrips fed on both; pollen to improve nutritional status and eggs to eliminate the opponent, despite the latter’s consisting lower of nutritional benefit. In all, this study showed that omnivorous thrips benefit from a cucumber leaf diet that is supplemented with other food sources and that pollen and mite eggs increase several fitness traits and positively affect the dynamics of future thrips generations.

In an attempt to find a natural and safe method for the control of stored - product pests, insecticidal activity and repellency effect of essential oil from Salvia mirzayanii Rech. F. & Esfand were investigated against one day old adults of Callosobruchus maculatus F. (Col.: Bruchidae) and Tribolium confusum J du Val. (Col.: Tenebrionidae). The essential oil was obtained by hydrodistillation method, using a modified Clevenger - type apparatus. Experiments were carried out at 27±1°C and 65±5% R.H. in dark condition. Results of fumigant toxicity tests showed that the mortality of C. maculatus was increased significantly with increases in concentration and exposure time. LC50 value was 2.58 µL/L air for C. maculatus. Results indicated that C. maculatus was so susceptible to S. mirzayanii oil. LT50 values for C. maculatus were 9.73, 8.52, 7.17 and 7.08 h at 37.03, 111.11, 148.14 and 185.18 µL/L air, respectively. No mortality was observed on T. confusum at highest concentration (3703.7 µL/L air). Repellency was increased significantly with increases in concentration in both of species of the insects. The essential oil was significantly more repellent to T. confusum than C. maculatus. It is concluded that S. mirzayanii essential oil can be used as a safe pesticide to control of stored insect pests, especial for C. maculatus.

We investigated the effects of interaction between Cotesia plutellae (Kurdjumov) and Bacillus thuringiensis Berliner on parasitism and an immune effector (phenoloxidase activity) of a Bt-susceptible and a Bt-resistant population of Plutella xylostella (Linnaeus) in laboratory. Parasitism success of C. plutellae varied depending on the use of B. thuringiensis or its toxin, and the timing of application. Percentage parasitism was significantly greater on Cry1Ac-treated hosts than B. thuringiensis var. kurstaki-treated hosts (the susceptible population), and greater when hosts were treated with B. thuringiensis var. kurstaki before parasitism compared to that after parasitism (the resistant population). Specific phenoloxidase activity was significantly reduced in Cry1Ac-treated or parasitized hosts, but combined effect of the toxin and the parasitoid caused a greater reduction in phenoloxidase activity. The lower phenoloxidase activity in unparasitized resistant population of P. xylostella compared with the susceptible one is likely to be due to fitness costs, manifesting a possible trade-off between pathogen resistance and parasitoid resistance. However, C. plutellae overwhelmingly suppressed phenoloxidase activity of both the susceptible and resistant populations of P. xylostella. We found that the interaction between B. thuringiensis and C. plutellae was synergistic, which is promising for integration of the pathogen and the parasitoid in management of P. xylostella populations.

Varroa destructor Anderson & Trueman is one of the most important pests of Apis mellifera L. all over the world. It causes great economic loss to the beekeeping industry by feeding on various developmental stages of bees and by transmission of pathogenic viral agents. During the last years, application of chemical pesticides has led to the occurrence of mite resistance and contamination of hive products. Therefore, the objective of the current study is to evaluate fumigant toxicity of essential oil from Mentha longifolia L. against Varroa mite and honey bee. Adult female of Varroa mites were treated with different concentrations of essential oil (from 0.5 to 3.75 µl/l air) at 25°C and 40% RH in darkness for 10 h. Also, worker honey bees were exposed to concentrations of essential oil (from 0.62 to 6.25 µl/l air) in incubator set at 32°C and 45-50% RH in dark for 10 h. All experiments were conducted with four replications. The number of dead and live treated animals was counted each hour from commencement of exposure. Results showed that the mortality was increased as concentration and exposure time of the oil increased. Estimated LC50 value of M. longifolia treated on V. destructor 9 and 10 h after exposure was 2.05 and 1.65 µl/l air, respectively. However, LC50 values of the oil on A. mellifera at the same exposure times were 5.08 and 4.76 µl/l air, respectively. These findings indicated that Varroa mite is more susceptible than A. mellifera. Therefore, more comprehensive experiments are necessary to find appropriate concentration and exposure time of M. longifolia essential oil in Varroa mite control programs in apiaries.

During conduction a survey of entomopathogenic nematodes throughout Arasbaran forests and rangelands, north-west of Iran in 2007-2008, an entomopathogenic nematode was isolated by Galleria baiting method from soil samples collected from rangelands, near Chichakloo, Varzeghan. It was identified as Steinernema kraussei (Steiner, 1923) Travassos, 1927 based on morphology and morphometric characters, cross breeding test, as well as molecular data. This species can be separated from other members of the genus by medium body length of infective juvenile (818 µm), lateral field with eight ridges in which the central pair are less distinct than others, head smooth, long cephalic papillae, secretory-excretory pore located at the level of middle of esophagus and anterior to the nerve ring; broad, slightly yellowish and short spicules, low D% value and tail with fine mucron in males. The analysis of ITS-rDNA sequence placed Iranian population of S. kraussei in the ‘feltiae-kraussei-oregonense’ group in the clade that containing different isolates of the species. It has some morphological and morphometric differences such as long cephalic papillae of IJ, more curvature of spicules and absence of mucron in some males as compared with type species. The mentioned differences are considered as intraspecific variations, and the described population from Iran is another isolate of S. kraussei. This is the first record of S. kraussei from Iran.

Hemocytes of two lepidoptrans Hyphantria cunea (Lep.: Arctiidae) and Glyphodes pyloalis (Lep.: Pyralidae) were studied by light microscopy. From each species, six types of hemocytes based on available literature were recognized: prohaemocyte, plasmatocyte, granulocyte, oenocyte, spherolocyte and adipohemocyte. In general, hemocytes in Glyphodes pyloalis were smaller than those of Hyphantria cunea and this difference were quiet obvious in prohemocytes and spherolocytes. Differential hemocyte counts showed the granulocytes and plasmatocytes to be the most abundant hemocytes and were recorded 27 and 23 percent for Glyphodes pyloalis and 28 and 36 percent for Hyphantria cunea respectively. Total hemocyte count were also worked out and it was 1800±0.081 cells/mm3 for G. pyloalis and 3013.3±413 cells/mm3 for H. cunea. The JHI in 0.004 µL/Larva on topical application while bringing about major structural changes to important cell types i.e. plasmatocytes and granulocytes induced significant changes in total and differential counts compared to controls.

A list of 20 species of the subfamily Tephritinae (Diptera: Tephritidae) from the Urmia region (Azarbaijan-e Gharbi Province, Iran) is presented. The specimens were collected during 2005-2008 from six different localities. Adults were obtained from overwintering and mature seed heads of 17 plant species of Asteraceae. The species, Urophora xanthippe (Munro, 1934) is newly recorded for the fauna of Iran. Thirteen new host plants are also reported for the first time. The host plants, collection date, locality as well as general distribution and associated plants of each species are given.

Trissolcus grandis Thomson (Hymenoptera: Scelionidae) is a solitary egg parasitoid of Sunn Pest, Eurygaster integriceps Puton (Hymenoptera: Scutelleridae). Although widely distributed, it has often been overlooked in field surveys. Our objectives were to develop an efficient rearing technique for T. grandis, and to determine the basic bionomics and demographic parameters, necessary for future augmentative biological control programs. Exposure of 0-4h-old Sunn Pest egg masses to parasitoids at 1-1, 2-1 and 3-1 host-parasitoid ratios resulted in a parasitism rate of >80%. The results demonstrated that the age of the host and the exposure time affected parasitism rate. However, parasitism rate did not differ significantly among 24, 48 and 72h-old Sunn pest eggs. The percent of emerged parasitoids during the 24-h host exposure period was relatively high when host eggs were 24-h old. Moreover, the mean sex ratio showed a definite trend, suggesting that host age had an effect on the sex ratio of the T. grandis offspring. The mean developmental time obtained as 11.091 ±0.1 and 9.68±0.15 d. for female and male progenies, respectively. The longevity of females was~30% lower compared to that of males. The average net fecundity reached 181.83 eggs per female. On the other hand, a female laid averagely~7 eggs per day. Similarly, the daily population increase and mean generation time were 34.2%, and 14.61 d, respectively. The developing population consisted of 99% immature (egg, larvae, pupa), and only 1% adults. The importance of these findings to the population biology of this parasitoid is discussed.

Two-spotted spider mite (Tetranychus urticae) is one of the important pests of common bean which causes serious damage to agricultural crops. In this study, nineteen common bean genotypes were evaluated for resistance to the two-spotted spider mite. The trial was carried out at field conditions of Karaj, Brojerd and Khomein. One week after mite infestation, the total number of female and eggs were counted for two times. Also, mite damage feeding was evaluated whit a 1-6 scale. Khomein had the fewest infested mean and relative resistance of many genotypes was failed in comparison to susceptible standard genotype (Akhtar) at Khomein. So they should be eliminated in alternative breeding programs. But only Ks41128 that had good relative resistance at other regions had the most relative resistance at Khomein. Then we propose Ks41128 as the most resistance and also the most stable genotypes.

In a faunistic survey of aphids and their aphidophagous predators in cereal fields of Mashhad and vicinity, During 2006-2008, several coccinellid species were collected and determined. Among the collected species, Coccinella magnopunctata Rybakow is reported for the first time from Iran.

Based on study on the parasitengona mite fauna of East Azarbijan province (iran) accomplished in 2007 and 2008, several specimens were collected. Among them, Erythraeus (Erythraeus) adanaensis saboori & cobanoglu, 2010 is getting reported for the first time from iran.

During the spring 2007, a survey was carried out at Chavarzagh area, in Zanjan province (Iran) in order to collect and identify aphidiine parasitoids attacking to the black bean aphid, Aphis fabae Scopoli. Samples of Vicia fabae plants bearing the colonies of healthy and mummified aphids were taken from fields into the laboratory. Parts of plants with aphid colonies were cut and put in plastic containers covered with nylon mesh. The containers were kept at a constant temperature of 20ºC, 65% relative humidity and under a 16: 8 (L: D) photoperiod until the emergence of parasitoids. Some of the emerged parasitoids were identified as Lysiphlebus fabarum (Marshall).

The cosmopolitan mite family of Cheyletidae includes more than 360 predacious and parasitic species in 73 genera (Bochkov & Fain, 2001). Predacious species occur on plants, soil and stored products, as well as in vertebrate nests where they feed on mites or small insects (Volgin, 1987; Gerson et al., 1999; Gerson et al., 2003). Bochkov et al. (2005) reviewed the Iranian Cheyletidae and included a key to 18 genera and 28 species. Herein we report six species of cheyletid mites associated with stored rice in Guilan province, Iran, including the first report of Chelacheles strabismus Baker from Iran. A key for their identification is provided.

During the faunistic studies on Auchenorrhyncha (Hemiptera) of sugarbeet fields in Isfahan province (Iran) between 1995 and 1997, specimens of genus Empoasca Walsh (Cicadellidae: Typhlocybinae: Empoascini) belonging to the group species Empoasca decipiens were collected. Based on reliable literature (Ribaut, 1936; Emeljanov, 1967; LeQuesne & Payne, 1981), the collected specimens were then determined as Empoasca decipiens (Paoli) (Karimzadeh, 1997; Karimzadeh et al., 1998). However, this determination was somewhat controversial because of the earlier report of Empoasca meridiana Zachvatkin from the same region (Kheyri & Alimoradi, 1968). Due to lack of data on discrimination of the two mentioned species and inaccessibility of the original description of latter species the problem remained unsolved.

The family Issidae is one of the largest families of the Fulgoroidea which has worldwide distribution, with many species in arid regions of Western Palaearctic. The members of this family are usually subbrachypterous, with rounded or ovoid body shape.Around 43 issid species have been recorded from Iran (Dlabola, 1971, 1974, 1980, 1981, 1982; Behdad, 1988; Mirzayans, 1995; Abaii, 2000). Dlabola actually discovered Iranian issid fauna, he described 37 species which is 86 % of the fauna. At least 3 of them have been recorded as pests on almond and oaks. (Abaii, 2000). About 11 species had been identified by Dr. J. Dlabola in 1970s and deposited in the Hayk Mirzayans Insect Museum (Mirzayans, 1995).