نشریه نامه انجمن حشره شناسی ایران
سال سی و یکم شماره 2 (پیاپی 49، زمستان 1390)

The postharvest pests، including the dried fruit moth Cadra cautella Walker، are important limiting factors in the exportation of dates. The biology of C. cautella، its survivorship، developmental time، fecundity، oviposition، post oviposition period، as well as longevity of the adults were studied on four date palm varieties of Zahedi، Piarom، Rabbi، and Deyri under laboratory conditions in Iran. The experiments were carried out at constant temperature room (29 ± 1 °C، 60 ± 5% RH and photoperiod 16L: 8D hrs.). The highest survivorship of egg and larval stages was recorded 92. 66%، 85. 89% on Zahedi and 100% for pupal stage on Rabbi. The shortest larval period was 32. 93 ± 1. 41 days and 33. 37 ± 1. 87 days on Deyri and Zahedi respectively. The shortest total development time for males from egg to adult was 40. 91 ± 1. 15 days and 40. 97 ± 1. 59 days on Zahedi and Deyri respectively and for females was 43. 76 ± 2. 47 days on Deyri. The longest total development time for males was 47. 61 ± 1. 50 days on Piarom and for female was 55. 88 ± 2. 31 and 55. 37 ± 3. 87 days on Piarom and Rabbi respectively. The highest (247. 00 ± 8. 53 eggs per female) and lowest (147. 40 ± 12. 06 eggs per female) fecundity occurred on Zahedi and Piarom، respectively. The date palm varieties Zahedi، Deyri، Rabbi and Piarom are found to be on preferrence order for C. cautella. The results of this study would be useful for planning pest management strategies in date palm fruit storages.

The elm leaf beetle، Xanthogaleruca luteola (Muller)، is one of the most destructive pests of elm trees that overwinters as diapausing adult. The main cryoprotectants and their seasonal fluctuations in the elm leaf beetles were analyzed based on the monthly level of polyhydric alcohol from October 2008 through June 2009، using high performance liquid chromatography (HPLC). The compounds myo-inositol، trehalose، glucose and glycerol were found to be the most important polyols in the overwintering adults، of which myo-inositol content exhibited an inversely significant correlation with temperature fluctuations (r = -0. 814، P = 0. 014). The highest level of myo-inositol was observed in December (32. 6 ± 2. 7 µmol g-1 fresh body weight)، while its lowest level was recorded in April (3. 0 ± 0. 4 µmol g-1 fresh body weight). The total concentration of all cryoprotectants was 100. 7 ± 7. 6 µmol g-1 fresh body weights in January. The results underline the influential role of myo-inositol، trehalose and glucose compounds in enhancing the cold tolerance of elm leaf beetles and their chance of survival during freezing winter days.

The beet armyworm، Spodoptera exigua (Hübner)، is a polyphagous pest that causes serious damages to a wide range of agricultural crops including beet، potato and cotton. In order to deepen our understanding of the biology of the pest during the winter، overwintering larvae of beet armyworm were collected from the fields from November 2008 through March 2009. Using HPLC technique، the level of cryoprotectants (antifreeze compounds) inside the body of larvae was measured and the following five compounds were detected: trehalose، glucose، myo-inositol، glycerol and sorbitol. It is found that the amount of polyols and trehalose is always higher than the other compounds and during the coldest days of the winter their level sharply increases from 0. 99 mg/g fresh weight in November to 3. 9 mg/g fresh weight in January. The results suggest that trehalose is the key cryoprotectant that helps overwintering larvae of beet armyworms survives during the harsh winter days.

The cornicle secretion is a defensive mechanism in many aphid species to warn the related individuals of predation by natural enemies. Many researches have been conducted on the benefits of cornicle droplet and alarm pheromone but the cost of this phenomenon is poorly investigated. This study is intended to evaluate the direct fitness cost of cornicle secretion of immature as well as mature cotton aphids، Aphis gossypii Glover. Aphids were artificially forced to produce cornicle droplets at different stages of their development (second، third and fourth instars as well as adults). They were lightly stroked on the anterior portion of the thorax with a fine brush، resulting in the secretion of visible cornicle droplets. After this manipulation، life-history parameters of aphids were recorded until the death of the last adult individual. Experiments were conducted in a growth chamber at 25 ± 1°C، 50 ± 5% RH and a photoperiod of 16 L: 8 D hours. The results showed that the secretion of cornicle droplets by second and third instar nymphs of cotton aphid did not affect their survivorship and the number of offspring produced by their adult stage. In contrast، fourth instar nymphs as well as adults that emitted cornicle droplets had significantly lower survivorship and offspring production than non-secretors. The cornicle secretion has also fitness costs on the late instar and adult cotton aphids.

The induced galls by oak gall wasps were collected from various oak forests of Iranian province of West Azerbaijan in the regions of Ghabre-Hossein، Mir-Abad، Vavan، Shalmash، Rabat and Dar-Ghabr during from April to November 2009. The optimum number of samples was found to be 40 oak trees. In each tree، as a sampling unit، all of the existing galls were counted. The species richness of oak gall wasps in the West Azerbaijan province was measured and the parameters such as Simpson’s، Shannon’s H''، and Sorensen similarity indexes were calculated. In this study، 35 species of oak gall wasps on the oak tree species of Quercus infectoria، Q. brantii and Q. libani were identified. Most galls were observed on Q. infectoria. All of the collected oak gall wasp species belonged to the genera Andricus Hartig، Cynips L.، Neuroterus Hartig، Biorhiza Westwood، Pseudoneuroterus Kinsey، Chilaspis Mayr and Aphelonyx Mayre. The genus Andricus included 23 species of oak gall wasps. The highest Simpson and Shannon indexes were recorded for the spring galls of Mir-Abad and for the fall galls of Ghabre-Hossein and Dar-Ghabr regions. The Sorensen similarity index reached its peak for the spring galls (sexual generation of oak gall wasps) of Ghabre-Hossein and Mir-Abad and for the fall galls (asexual generation of oak gall wasps) of Ghabre-Hossein and Dar-Ghabr. The distribution of oak species and subspecies، and geographical and climatic aspects are believed to be among the key factors for the species diversity of oak gall wasps.

The cabbage aphid، Brevicoryne brassicae (L.)، is one of the major pests of the plant family Brassicaceae that causes serious damages to cabbage and oilseed rape. The cabbage aphid is also able to build up populations on ornamental cabbage during the winter months. To determine the level of cold tolerance in its overwintering populations، adult aphids were collected on cabbages planted in the field of Faculty of Agriculture، Tarbiat Modares University in autumn 2008 and winter 2009. The supercooling points and survivorship of the adults were studied at sub-zero temperatures for 24 h. The mean supercoolig point varied from -23. 9 ± 0. 46ºC in November to -19. 8 ± 0. 34ºC in May. About 70-95% of the cabbage aphid adults could tolerate -5°C/24 h in all months. The survival rate for the treated adults at -10ºC/24 was about 55% from October through November and 87% in December. The LT80 (the temperature at which 80% of population die after 24 h exposure to cold temperatures) was at its highest (-11. 32°C) in May، showing the lowest level of cold tolerance in the population. The LT80 ranged from -13. 81 to -14. 79 °C from December to February، showing the highest level of cold tolerance. Findings indicated that cabbage aphid populations hold a high capacity to tolerate cold temperatures in the course of winter while being active and sexually reproductive at the same time that leads to their quick grow and emergence as an economic severe pest early in the next season.

During the study of natural enemies of insect pests of forest trees and shrubs in Arasbaran forest of Iranian province of East Azarbaijan، a number of larvae of Yponomeuta evonymella L. were collected on wild cherry trees. The specimens were reared in the laboratory، where parasitoid wasps of the family Ichneumonidae emerged and later identified as Agrypon canaliculatum (Ratzeburg، 1844). The identification was confirmed by the second author. This species is newly recorded from Iran.

The cecidomyiid species Rabdophaga heterobia (Loew) induces gall on willow''s male catkins، and causes small rosettes at the extremities of shoots and swollen lateral buds or lateral rosettes on some species of willow. During the years 2006-2007، a study on willow pests in the West Azarbaijan province (Saatloo Poplar Research Station) was conducted. The following nine willow species were used in this study: Salix elborsiensis، S. triandra، S. excelsa، S. elaegnosa، S. babylonica، S. alba، S. aegyptiaca، S. pycnostachya، and S. matsudana. The willow species S. triandra was found to be the only host for the gall-inducing cecidomyiid. This is the first record of R. heterobia from Iran.

A faunistic study of the order Thysanoptera was conducted in cereal crop fields of the southwestern Iranian province of Khuzestan during 2007-2009. The species Florithrips traegardhi (Trybom) was collected from various grasses including corn، rice and wheat and later found its genus and species are new records for Iran.

The side-effects of amitraz, buprofezin and propargite were studied on Encarsia formosa (Gahan) in the laboratory, using a life table response experiment and the IOBC system for their toxicity. Bioassays were conducted by dipping bean leaves containing third instar nymphs of the whitefly Trialeurodes vaporariorum (Westwood), parasitized by E. formosa, in insecticide solutions or caging adult parasitoids in treated petri dishes. The insecticide buprofezin caused 19.87% and 11.87% mortality in adults and pupae respectively. Amitraz showed the highest level of toxicity for the adults (100% mortality) and the pupae of parasitoids (83.3% mortality). Both buprofezin and propargite caused no adverse effect on the fecundity and longevity of parasitoids, but amitraz significantly reduced the fecundity and longevity of adults. Life table assay indicated that buprofezin and propargite have no major impact on the intrinsic rate of natural increase (rm), while amitraz lowered the rm value by 7.03%. According to the IOBC classification of toxicity, buprofezin was found to be harmless for the pupae and adults and amitraz proved to be harmful for adults. Based on both the life table and IOBC methodology, buprofezin and propargite are found to be relatively safe for E. formosa and can be used in integrated pest management programs where this parasitoid is involved.

Two-spotted spider mite (TSSM) is becoming resistant to many of the pesticides used in the tomato fields. A potential alternative method of control is host plant resistance، which may be mediated by glandular trichomes. In this experiment، level of entrapment and mortality of the pest by type IV glandular trichomes were studied on accessions of Lycopersicon hirsutum Humb & Bonpl، L. pennellii (Cor.) D’Arcy and L. esculentum Mill on leaflets with trichomes intact or with exudates removed. Three accessions of L. hirsutum (LA1740، LA1777 and LA2860)، two accessions of L. pennellii (LA2963 and LA2580) and one susceptible variety (Sankranthi) of L. esculentum were used. Leaflets from the terminal pair of the third-last fully expanded leaves were excised and leaf disks prepared. Ten female mites of Tetranychus orticae Koch were placed on the adaxial leaflet surface of each disk and after 2 h، the number of mites trapped، untrapped and moved into water were recorded. Again after 24 and 48 h، mites were recorded either dead، morbid or moved into water. Results indicated that the highest number of entrapment was on L. hirsutum LA1777، followed by L. pennellii accessions. None of the mites was entrapped on L. esculentum. Moreover، L. hirsutum (LA1777 and LA1740) and L. pennellii accessions had greater number of dead mites than L. esculentum after 48 h. Lycopersicon esculentum did not possess type IV glandular trichomes. The highest density of type IV glandular trichomes was recorded on abaxial and adaxial leaf surfaces of L. hirsutum LA1777 (86. 72 and 34. 44 trichomes/mm²، respectively). Removal of trichome exudates has significantly increased the mite survival in resistant accessions. Correlation between the density of type IV glandular trichomes and entrapment rate of TSSM was significantly positive.

The compatibility of Beauveria bassiana isolate DEBI 002 (Atashgah) with fipronil، pyriproxyfen and hexaflumuron insecticides was assayed. To determine the impact of the insecticides on the germination of the fungal spore، different concentrations of the compounds were added to the culture medium (malt agar). In order to calculate the mycelial growth in different treatments، each colony diameter was measured and the spores were counted in the surface area to assess its sporulation. The results showed that pyriproxyfen at 1500 ppm and hexaflumuron at 80 ppm completely inhibited mycelial growth، while the inhibitory effect of fipronil at 1600 ppm remained at 76. 6%. The inhibitory effect of lower concentrations of all three insecticides was between 10 and 20%. All tested insecticides inhibited the spore production between 80 to 100% at the highest concentrations without any significant differences. Pyriproxyfen at 400 ppm and hexaflumuron at all concentrations completely inhibited spore germination، with significant difference، comparing with the rest of treatments. The results indicate that hexaflumuron has the highest inhibitory effect on the spore germination and is not recommended to be used simultaneously with B. bassiana against the insect pests.

The foraging behavior of a natural enemy is greatly affected by temperature. The influence of different constant temperatures on the functional response and prey consumption of the mated female of Neoseiulus barkeri Hughes on nymphal stages of Tetranychus urticae Koch was evaluated. Four ambient temperatures (20، 25، 30 and 35 ± 1°C) and six prey densities (2، 4، 8، 16، 32 and 64 individuals) were used during a 24-h period in functional response experiments. The effect of seven constant temperatures (15، 20، 25، 27، 30، 35 and 37 ± 1°C) on prey consumption of N. barkeri on nymphal stages of T. urticae was also determined. Using the logistic regression، the type II functional response was determined for adult female of N. barkeri at all temperatures. The type II Rogers'' model was used to estimate the values of the searching efficiency (a) and handling time (Th). The value of the searching efficiency increased with increasing temperature from 20 to 30°C (0. 0364 to 0. 0731 h-1 respectively)، then decreased at 35°C (0. 0646 h-1). The handling time of this predator decreased when the temperature increased from 20 to 35°C، and the minimum value was observed at 35°C (0. 5548 h). Similarly، temperature had a significant effect on the prey consumption of adult females of N. barkeri over the range of 15-37ºC. The minimum and maximum daily prey consumption of whole immature stages of N. barkeri was observed at 15°C and 35°C respectively. The highest and the lowest number of total preys consumed by all immature stages of N. barkeri were 14. 61 and 8. 79 preys that occurred at 20°C and 15°C respectively. During the oviposition period، the total prey consumption increased with increasing temperature from 15 (160. 43 preys) to 30°C (286. 71 preys) and then declined and reached to 191. 57 preys at 37°C. The results of this study underscore the effect of temperature on searching efficiency and prey consumption of N. barkeri.

All wasp species in the genus Lysiphlebus Förster are solitary endoparasitoids of aphids and considered a taxonomically difficult group. In this study a part of COI and ITS2 was used to distinguish two closely related species L. fabarum (Marshall) and L. confusus Tremblay & Eady in Iran. The sequencing with a similarity about 99. 5% showed COI''s inability to separate the species L. fabarum and L. confusus. The ITS2 region of the rDNA partly separated the species with the similarity of 96. 5-98. 5%. The result is indicative of DNA barcoding deficiency in the identification of the species، as the two gene regions fail to efficiently separate the species.

In the course of this study، the number of recorded chalcidids (Hym.: Chalcididae) from Iran increased to 42 species (including one unidentified species of the genus Lasiochalcidia Masi)، of which fifteen species and four genera are new to Iranian chalcidid fauna. The family Chalcididae is repredented by three subfamilies in Iran as follows: Chalcidinae (16 species)، Dirhininae (two species)، and Haltichellinae (24 species). The genus Varzobia Nikol''skaya is here synonymized with Tanycoryphus Cameron and the type species transferred to that genus as Tanycoryphus tibialis (Nikol''skaya، 1960) comb. n. The species Lasiochalcidia indescripta Bouèek، 1952 stat. rev. is removed from synonymy with L. guineensis (Steffan، 1951). The validity of the species Peltochalcidia ferrierei Steffan is restored، being removed from junior synonymy with P. benoisti Steffan، and transferred to the genus Psilochalcis Kieffer. The species Peltochalcidia oranensis Bouèek، 1952 is here synonymized with P. benoisti. Complementary information on the biology، morphology and distribution of the species as well as a preliminary list of the Iranian chalcidid species are presented.